ISSN 0038-3872 eee CALIFORNIA ACADEMY OF SCIENCES BULLETIN Volume 99 Number 1 BCAS-A99(1) 1—58 (2000) APRIL 2000 Southern California Academy of Sciences _ Founded 6 November 1891, incorporated 17 May 1907 © Southern California Academy of Sciences, 2000 i997—2000 Robert S. Grove David Huckaby Robert Lavenberg Kenneth E. Phillips Susan E. Yoder OFFICERS David Huckaby, President Robert S. Grove, Vice-President Susan E. Yoder, Secretary Daniel A. Guthrie, Treasurer Daniel A. Guthrie, Editor Hans Bozler, Past President David Soltz, Past President BOARD OF DIRECTORS 1998-2001 Kathryn A. Dickson Donn Gorsline Robert F. Phalen Daniel Pondella 1999-2002 Ralph G. Appy Jonathan N. Baskin John W. Roberts Tetsuo Otsuki Gloria J. Takahashi Cheryl C. Swift Membership is open to scholars in the fields of natural and social sciences, and to any person interested in the advancement of science. 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All other communications should be addressed to the Southern California Academy of Sciences in care of the Natural History Museum of Los Angeles County, Exposition Park, Los” Angeles, California 90007-4000. : Date of this issue 3 April 2000 & This paper meets the requirements of ANSI/NISO 239.48-1992 (Permanence of Paper). SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 2000 ANNUAL MEETING May 19-20, 2000 UNIVERSITY OF SOUTHERN CALIFORNIA CALIFORNIA ACADEMY OF SCIENCES MAY 15 2000 LIBRARY SYMPOSIA Understanding the Urban Influence on Santa Monica Bay organized by Steve Bay (SCCWRP), (714) 894-2222 Coastal Habitat Restoration organized by Ralph Appy (Port of Los Angeles) (310) 732-4643 The Ecology of Kelp Beds in Southern California organized by Bob Grove (SoCal Edison) (626) 302-9735 Research at Public Aquaria organized by Judy Lemus (USC Sea Grant) (213) 740-1965 New and Rare Fish and Invertebrate Species in California during the 1997-98 El Nino organized by Jim Allen (SCCWRP) (714) 894-2222 Conservation of California Lichens organized by D. L. Magney (Consultant, California Lichen Society) (805) 646-6045 Los Angeles River Symposium organized by Tina Hartney (Occidental College) thartney @oxy.edu There will be additional sessions of Invited Papers and Posters and of papers by Junior Academy members. For further information on registration see the Southern California Academy of Science web page at: www.lam.mus.ca.us/~scas/ or contact gorsline @earth.usc.edu PLENARY ADDRESSES: Plenary Sessions will occur each day at 11 a.m. Speakers will be; Friday: Wheeler North, “Kelp Beds of San Diego, Orange and Los Angeles Counties: Past, Present and Future Considerations.” Saturday: Joan Greenwood, ‘‘Friends of the Los Angeles River, River Watch; Addressing Wa- tershed Issues in the New Millenium.” YMAGADIA AMAOUIAD vamerrsoe SonPRePePe Sitter nia ‘heads , onr TIAN LALOR. (i eno HOOS OS-LT isl 40 Presa MVSOILIAD VEAITTUOF AMAOALIAL a (Br: wr? 2 AC)» MIAO ; 4 pons & f YAM atsey ae) Pal , F i ’ i 2 ‘ \A [ ris n ’ $14 Midve if. alnec harbéne Uy ne owroufhal ooedi yp aah | : I : : mie «ef 7 é Ja iJ i ‘ iolnvohre A iathdall (? 1] Oa? Ves inlss va ve)’ ; Wy ibe restive, mh ales i Gina ale a ay ant he a : ’ _t Leo 4S \ } 7 beads Mittin @) 4 & - if 15 is bai — bne salt 95 Se Phy ") : ; mil rt ah Tt aw 4 ‘ “cote ) i Bee Cod GSsiie : : ] ris i >is ‘ \ Bull. Southern California Acad. Sci. 99(1), 2000, pp. 1-24 © Southern California Academy of Sciences, 2000 The Range, Habitat Requirements, and Abundance of the Orange-throated Whiptail, Cnemidophorus hyperythrus beldingi Bayard H. Brattstrom Department of Biology, California State University, Fullerton, CA 92834-6850 Abstract.—A survey was done over a 2% year period on the Orange-throated Whiptail, Cnemidophorus hyperythrus beldingi, throughout its range in Southern California. The species has been presumed to be threatened by loss of habitat due to human activity. The study included determining the lizard’s past and present distribution from museum and California Department of Fish and Game records, the literature, questionnaires, correspondence, and field surveys. Field surveys also were used to evaluate lizard habitat requirements and abundance. Detailed studies at the population level and laboratory and field studies on habitat require- ments and behavior rounded out the study. The range of the species can be defined as below 853m (2800 ft) elevation, with one record to 1058m (3,475 ft), from coastal and foothill Orange County, and from the Corona-Riverside-Colton areas of Riverside County southward through the Elsinore and Perris Basins, through all of the coastal and low ele- vation, San Diego County. Within its range, the Orange-throated Whiptail occurs primarily in open (50% cover) Coastal Sage Scrub vegetation, associated with Buckwheat (Eriogonium fasciculatum), low, open Chamise Adenostoma fascicu- latum), White Sage and Black Sage (Salvia apiana and S. mellifera). The lizard also occurs in open chaparral, along the edge of open, dry, riparian areas, along trails, along dirt roads, and in areas of light off-road vehicle use. This study has tripled the number of locations at which the lizard is known to occur, and has shown, by field work or correspondence, that the lizard still exists at 96% of all known localities. The whiptail occurs in large numbers locally (10— 40 whiptails/hectare). A minimum estimate of 1 million Orange-throated Whip- tails occur in the area of its range occupied by Coastal Sage Scrub and 10.1 million individuals within the area of the total range for this species in California. Even if these are over-estimates, they are over by a great many times the number needed in order to consider the species endangered. Estimates of habitat remaining for the species, range from 80—90% of values in 1900. The lizard does not meet any of the current criteria for listing as Rare, Threatened, Endangered, or Vul- nerable. It is therefore not recommended for listing. Instead, Coastal Sage Scrub habitat should be protected wherever possible in open space and reserves. The Orange-throated Whiptail Lizard, Cnemidophorus hyperythrus beldingi, a small striped teiid lizard, is listed in California as a “‘Species of Special Concern’”’ (Natural Diversity Data Base 1994) and is a Federal Species of Concern (Federal Register 1996). The Orange-throated Whiptail, hereafter referred to as whiptail or lizard, is the northern named subspecies of a series of subspecies that range from Orange and Riverside Counties, southward through San Diego County to the tip of Baja Cal- l Z SOUTHERN CALIFORNIA ACADEMY OF SCIENCES ifornia and on some adjacent islands (Burt 1931; Murray 1955; Walker and Taylor 1968). According to Bostic (1965, 1966 a,c) and McGurty (1980), the lizard occurs primarily in open coastal sage scrub vegetation. Termites constitute 57-95% of the whiptail’s diet (Bostic 1966a). Additional foods consist of other soft-bodied arthropods such as spiders and insect larvae. The whiptail feeds by actively for- aging in the leaf litter at the base of shrubs. The whiptail has been found active every month of the year when soil tem- perature and air temperature are high (Bostic 1966b,c; Rowland 1992; Rowland and Brattstrom in prep.). It is a lizard with high thermal preference (36.8—41.6°C *¥: 39.0°C; Brattstrom 1965), and hence is active on very warm, but not excessively hot days. The adults are especially active in the spring, with activity decreasing by mid-July. Young are hatched in August through October and are active through November, or if weather permits until December (Rowland and Brattstrom, un- published data; Bostic 1966b). Adults are less active in the fall. The lizard occurs in habitats that have been modified for agriculture and graz- ing, and in natural habitats that have been declining rapidly because of increasing human population impacts such as housing, highways and industrial development. With the presumed destruction of its natural habitat, the current distribution and population numbers of the whiptail were not known, hence the need for this study. Materials and Methods The Orange-throated Whiptail Lizard, Cnemidophorus hyperythrus beldingi, was studied in Orange, Riverside, San Diego, and San Bernardino Counties, Cal- ifornia. Additional specific studies were done on three military bases: Miramar Naval Air Station, Fallbrook Naval Weapons Station, and Camp Pendleton (all in San Diego County); as well as a detailed mark and recapture study (Rowland 1997). All laboratory, field activities, and research were done with a Memorandum of Understanding (MOU) from the California Department of Fish and Game (CDFG), the Guidelines for Use of Live Amphibians and Reptiles in Field Re- search of the ASIH, HL, and SSAR (as published in the Journal of Herpetology, supplement, 1987), the Public Health Service Policy on Humane Care and Use of Lab Animals (Rev. Ed., Sept. 1986), and the California State University, Ful- lerton, Animal Care, Committee Policies of the Office of Faculty Research. To determine the past distribution of the whiptail, the distributional localities were obtained from museum records, the literature, and the California Natural Diversity Database (NDDB). Data were compiled and placed in R:Base 5000. A list of localities is available from the author. Locality data have been recorded on DeLorme maps, which consist of four 7.5 minute USGS Topo Maps. Locality data for the military bases have been placed into the U.S. Navy GIS Data Base only. All localities were also incorporated into OSUMAP software Geographic Information System (GIS). Records collected by Brian Mcgurty (to 1980) and Mark Jennings (to 1982) have been verified, sometimes corrected, and incorpo- rated herein. Major United States and several local museum and university records were examined (see Brattstrom 1993, for list). To determine the present distribution and abundance of this lizard, the historical distributional data and GIS maps of vegetation, soils, past fire history and current BIOLOGY OF THE ORANGE-THROATED WHIPTAIL 3 land use were prepared. Examination of these maps suggested that a few localities appeared to be in error, and that areas of apparent good habitat had no lizard locality records. In order to determine if the lizard actually occurred there and was missed by previous collectors or if this was poor habitat for the species, specific general areas (i.e., Moreno Valley, Perris Basin, Otay Mesa, Jamul) were selected for the 1989 summer and fall field surveys. Each area was explored by the lizard survey team (Dennis Strong and Brian Leatherman) for a week or two depending on the size of the area. The lizard survey team stopped randomly to survey for lizards wherever there was public access. If no lizards were found after a reasonable search (15—60 minutes), the team would move to another site. Some- times this move involved a few hundred meters, sometimes kilometers. In 1990, the survey team, in addition to working on the military bases, went to very specific locations and completed a transect, whether lizards were found there or not. Transects were also done in 1989 at localities where lizards were present. These specific locations were chosen in order to check habitat islands where records were missing, in an attempt to determine why whiptails were not present at some localities, to confirm whiptail presence at known historical or museum record localities, and to confirm or test the habitat quality index that was developed after the 1989 field season. During these surveys, two new techniques for collecting lizards were invented and developed (Strong et al 1993). The present distribution and current status of the lizards was also determined by a survey questionnaire. The survey was sent to local professional and amateur herpetologists and herpetological clubs. In addition, the San Diego Herpetological Society and the Southwestern Herpetological Society reprinted this questionnaire in their respective newsletters. A total of 115 questionnaires were sent out and 50 questionnaires (or 43%) were returned. Of those returned, 33 surveys (or 29%) had information on whiptail distribution and abundance. With the use of ques- tionnaires, correspondence, and actual field work, verification of whiptail pres- ence, within the previous five years, was made at 103 (and possibly 113) of 116 of the previously known (museum and literature records) localities (Table 2). Field transects were done in areas with and without lizards and in areas of different vegetation types and soil types. All transects were completed during thermally optimal times for the lizards (air temperature 15—42°C, soil temperature 25-55°C; Rowland 1992). All transects consisted of straight line transects that were 10m wide X 100m long. The length of the transect was oriented so as to be entirely within a single microhabitat. If a transect was one done only when a whiptail was seen, the survey was started, in so far as possible, at the location of the lizard sighting. If no lizards were sighted and a transect was to be done, it was usually located, in the center of a microhabitat and oriented so that the length of the transect was all in the same microhabitat. The exact locations and direction of surveys were recorded on large scale maps provided separately to CDFG (Thomas Guides) and the military (detailed maps they provided). With these maps, an interested investigator should be able to locate the survey line within 5m. In this sense, all transects are permanently recorded. At the start of a transect, the workers would complete a form with regard to location, elevation, weather, veg- etation, topography and soil. The survey team would then walk the transect in one direction, counting lizards, and, on the return trip, count other on-site features such as ant mounds, rodent burrows, and logs. At the end of the transect, addi- 4 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES tional information on the presence of predators and past fire history was noted. In 1990, transects completed at military bases were done on very specific sites drawn a priori on vegetation maps provided by the bases. Transects were located in all vegetation types on the base and each vegetation type had several transects. Transects were further located so as to sample the same vegetation type in dif- ferent parts of the base. While a large part of each base consisted of open space and even reserves, some parts of each base could not be surveyed due to military activity or installations. Lizard surveys were done on the bases whether lizards were present or not. Lizard transects on the bases were repeated about a month or two following the original survey. Detailed data for the bases are presented in separate reports to the military and CDFG. Transects were intended to assess habitat requirements quantitatively and not necessarily to characterize a specific location. Transect data and habitat charac- teristics were quantified in a series of graphs and tables. These data were then used to construct a Habitat Quality Index (HQI) for the Orange-throated Whiptail. A scale of poor to good habitat was developed for each of the variables tallied. For example, whichever habitat characteristic had the most lizards on it (i.e. the tallest bar on the graph; Figs. 3,4) was ranked high. A habitat with no or few lizards ranked low. Those with intermediate numbers of lizards ranked medium. The characteristic and its conditions are presented as the HQI. Using 12 charac- ters, and the ranking of each character (high, medium, low), each character can be scored by any surveyor so that a number can be given to each habitat. Scores of O—12 result in a low designation, 13—24 are medium, and 25-36 rank as high. A potential habitat can thus be graded as poor to good for an Orange-throated Whiptail without having to see a lizard present. The HQI is simple enough so that it can be completed by most field-trained biologists. It allows the habitat to be quantified in times and seasons when lizards are not active. It must be used, like all other evaluation forms, with caution. Field soil size was determined based on the standard U.S. Forest Service and U.S. Soil Conservation Corps methods; coarse soil (large grain size, does not roll between fingers), sand (intermediate size, rolls between fingers), or fine soil (small grain size, does not roll between fingers). Laboratory experiments were conducted at California State University, Fullerton, between June 28 and August 24, 1989. Three aquarium tanks measuring 60cm X 53cm were each divided into quadrants by cardboard. Four different substrates were put into each one of the quadrants. The gravels and soils were sifted through various sized screens to achieve a basically uniform size in each quadrant. The grains were counted and sized individually under a dissecting scope. The photoperiod for these experiments was provided by white IR and vitalite lamps on between 0700 and 2000. The ambient temperature was kept between 15°C and 21°C. GIS Analysis To further analyze the habitat and distributional information, Orange-throated Whiptail locality data were entered into a Geographic Information System (GIS) using OSUMAP software. Other data put into the program included: elevation, vegetation, rainfall, basic geology, fire history, known open spaces (including parks, reserves, and forests), and urban areas. Locality data for lizards on the military bases was put directly into their GIS system by Tierra Data, Inc. where BIOLOGY OF THE ORANGE-THROATED WHIPTAIL 5 other ecological data was already stored. The combined information was examined for the base reports. Abundance In addition to range and habitat requirements, it is also important to know how many lizards occur in a given area, habitat, or its entire range. Lizard survey transects were 10 X 100 meters. Lizard abundance per transect, per hectare, or the number of lizards seen per person-hour was calculated. To test whether tran- sects were counting lizards effectively, the survey team completed a typical lizard transect on the permanent study plot of Scott Rowland (1992) located on the Motte-Rimrock Reserve on September 25, 1990. Study plot personnel did not know when survey teams would check the site and the survey team did not know how many lizards had been marked on the site, thus this was a double blind test for the field transects. Two passes (each 10 X 100m) were made on the 100m X 100m study plot. The average number of lizards seen on the two surveys was multiplied by 10 to give the number of lizards per hectare. That number should be close to the known number of marked lizards (from mark-recapture studies) on the site. While habitat destruction decreases the amount of habitat available to these lizards daily, some measure of habitat availability is needed to estimate population numbers, therefore the total area of Coastal Sage Scrub in Southern California was determined from the literature (Atwood 1992; Minnich 1983) and then the amount of that vegetation within the actual range of the whiptail was calculated from GIS data. This area was multiplied by the lowest (conservative) value of the field-determined lizard densities per hectare. This provides an estimate of the minimum number of these lizards in Southern California. This is a minimal num- ber since, while the lizard occurs primarily in Coastal Sage Scrub, it also occurs in a variety of other habitats, including some disturbed habitats. It assumes that all such habitat is equally suitable for the lizard. Field data clearly indicate that this is not true. Some Coastal age Scrub and some transects had no lizards, but other transects had many lizards and extensive areas of other habitats that had whiptails are not included in calculations. Hence, transects and areas with no lizards, hopefully, will average out in these estimates. The function of this analysis was to determine at least some order of magnitude of the number of whiptails in California. For the same reasons, estimates were also made of the minimal num- bers of lizards throughout its range, even though the whiptail is not equally dis- tributed. It was not the function of this analysis to determine an absolute number of animals, but only a minimal estimate. This method of determining population estimates is similar to that used with birds and mammals, including rhinos, ele- phants, and tigers (Atwood 1992) but has seldom been used with lizards. In order to study the characteristics of whiptail population structure, a 1 hectare study site was selected at the Motte-Rimrock Reserve of the University of Cali- fornia, in Perris, Riverside County, California; and activity, population structure, home range and reproductive activity were studied by Scott Rowland (1992). These studies and additional information from the main study are being published elsewhere (Rowland and Brattstrom in prep.) 6 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Results Distribution Figures | and 5 show the range and distribution of the Orange-throated Whip- tail, Cnemidophorus hyperythrus beldingi, in Southern California. The range of the species continues southward to the tip of Baja California, Mexico and some adjacent islands. Lists of all known locality records for the species in Southern California and detailed dot-locality maps are presented in Brattstrom (1993) and are available from the author. The localities have been entered also into Bureau of Land Management (BLM) Data Bases for Southern California, and into several other County, Environmental Companies’, and U.S. Navy and Marine Data Bases. The localities have not yet been entered into the CDF&G National Diversity Data Base (NDDB). Figure 2 presents the elevation records for the locality records. As can be seen, 99% of all locality records are below 3000ft (913m). In fact all records, except one, are below 2800 feet (853m). The lone exception is a record at 3475 ft (1058m) about 11km NE of Aguanga, Riverside County. This is a very open, dry area of Riversidian Coastal Sage Scrub. Many low elevation species, including Stephen’s Kangaroo Rat, Dipodomys stephensi, occur at higher elevations in this area. A CDF&G NDDB record (#105) of 3400 ft (1036m) at “‘Cahuila Road, North of Aguanga”’ is in error, the elevation is 2400 ft (731m) according to the collector). There are 116 historical records for this species based on museum records (Table 1, 2). Whiptails were first collected in San Diego County in 1891, in Riverside County in 1893, and not until 1946 in Orange County. Field work, questionnaires, and correspondence tripled the number of known localities for the species to 343 (Table 2). Since the majority (66%) of these localities come from this study (including 26% from the 1989-91 field surveys), it indicates that the whiptail has been seen at these additional 227 sites sometime since 1985. Field work in this study, data from questionnaires, and correspondence (including ask- ing colleagues to please go out to a given locality and check for the lizard’s presence) have confirmed (=verified) the whiptail’s presence in 1985—1993 at 103 of the 116 literature, historical, and museum localities. Thus the Whiptail is pres- ent at 96% of all known localities. The word locality or record refers to a known location where specimens of the species have been collected or seen. In some detailed environmental studies, liz- ards are reported at localities only .1 or .5 miles apart. In other cases, it is im- possible to know, without detailed notes, where, for example, in the locality ““San Diego’’, these lizards may have been actually collected. Localities given as city suburbs or parks within a city, for example San Diego, are placed at those loca- tions on the map and are considered as different localities. Collections made in different years by different collectors from a location as vague and as large an area as the city of San Diego are treated as separate localities for purposes of calculation, but are plotted as a single dot. The words exist or extant are used if a population of whiptails still occurs at a location and extinct if a former or known population no longer occurs at a specific location. Many conservation biologists like to use the word extirpated rather than extinction for local populations. By definition, extirpation requires that the absence is due to human causes. The cause BIOLOGY OF THE ORANGE-THROATED WHIPTAIL i Fig. 1. Three maps of Southern California showing the range and distribution of the Orange- throated Whiptail, Cnemidophorus hyperythrus beldingi. Upper: verified extant (dots) and extinct (stars). Middle: GIS plot of all locality records. Lower: GIS produced map of range. Due to space and scale not all localities could be plotted. 8 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES ELEVATIONAL DISTRIBUTION N=249 49 PERCENT { 0-999 1-1999 2-2999 3000+ feet 0-304 304.6-608 609-913 913+ meters ELEVATION 0 Fig. 2. Graph showing the distribution of elevation records of the Orange-throated Whiptail, Cnem- idophorus hyperythrus beldingi, in Southern California. Numbers at top of bars are percent of total localities. All but one record (at 3475 feet; 1058m) are below 2800 feet (853m), and 90% of all records are below 2000 feet (608m). for the animal’s absence is clearly due to human events (as in the paving over of the San Diego State University Campus locality) but in other cases the cause is not known; therefore I use the word extinct. On the other hand, just because an area is now urbanized, the assumption can not be made that the lizards must have occurred there before. The historical data argue otherwise. There are, for example, no historical (literature or museum) records for this whiptail in west, central, or north Orange County, All Orange County records are from Corona del Mar and the Laguna (=San Joaquin) Hills southward, and from Santa Ana Canyon and south. Whether their absence from the north, central, and western flat area of Orange County is due to disturbance by grazing and agriculture for the 400 years (Cleland 1941, 1952) prior to the first museum records (1946) or whether this area was not covered by suitable habitat is unknown. Extinction and rapid rein- vasion of areas and new invasions of new areas appears to be one of the results of the r-selected reproductive mode and dispersal of this whiptail (Bostic 1966c: Rowland 1992). This dispersal results in whiptails being present in some locations Table 1. Cnemidophorus hyperythrus locality records listed by county. Riverside San Diego Orange San Bernardino Total Literature and Museum (1891-1985) 60 44 10 2 116 Correspondence & Questionnaires (1985-1991) 69 83 LS 0 167 Surveys (This study) 1989 16 10 0 0 26 1990 1] 9 3 0 23 Bases na 1] na na 11 Total 156 157 28 f) 343 BIOLOGY OF THE ORANGE-THROATED WHIPTAIL 9 Table 2. Comparison of historical and recent (post 1985) locality records for Cnemidophorus hy- perythrus. Number Literature and Museum Records 116 Species extinct at: 3% Species probably extinct at: O* Species probably still existing at: 10 Species still existing at (verified): 103 Additional Recent Locations based on Correspondence & Questionnaires 167 Additional Recent Locations based on field surveys: 1989: 26 1990: pe) Bases: 11 Total: 60 Total known localities: 343 Total known localities with verified, existing populations 330 * Extinct and probably extinct at 11% of the originally known historical museum locations. Extinct locations: San Diego State University Campus in San Diego County; 1 mile southeast of Corona del Mar and Corona del Mar Bluff in Orange County. These Orange County locations may not really be extinct at the population level, as there are recent verified records (June 1991) for Crystal Cove and Pelican Hill, which are within three miles of Corona del Mar. ** With the addition of the populations added from this study, the species is extinct at only 1% of a total possible 343 locations, and extinct or probably extinct at 3.8% of all possible localities. where they were not present a year or two before. In contrast, an area with lizards in one month or year may be devoid of them in a later month or year, only to be repopulated again shortly. Often the lizards may be absent from a specific area of land where they occurred last year or five years ago, only to be 200 meters away. These local changes may be due to local population dynamics and/or subtle habitat changes that take place over the years of data records. In any event, even historical localities have been checked and given the arbitrarily selected error of 5 miles (equivalent to the space covered by one dot in Figure 1) the whiptails still exist (i.e. verified presence since 1985) at 103 of the 116 or 89% of all known historical localities and 96% of all known localities (Table 1, 2). The species is extinct at three localities. This is less than 1% of all known localities. The extinct localities are: San Diego State University Campus in San Diego Coun- ty; 1 mile southeast of Corona del Mar, and Corona del Mar Bluff in Orange County. These Orange County populations may not be really extinct (and thus don’t meet the definition of extinction) as there are recent, verified records (June, 1991) for Crystal Cove and Pelican Hill, which are within three miles of Corona del Mar. The species may be extinct (lizard presence possible, but not verified) at 10 additional locations, thus the total extinct or probable extinct number of localities is 13 or 3.8% of all known locations (i.e. the species is known to exist, 1985-91, at 96% of all known 343 localities). The total range occupied by whip- tails is shown in Figures 1 and 5. While urban and suburban development occupy much of this area (Fig. 5), and since the lizard still exists at 96% of all known localities, the lizard appears to be co-existing with some, but not all, human habitat disturbance. Analysis of the GIS data suggest that 40% of the lizard’s original habitat is occupied by human activities or is otherwise disturbed. Yet, 10 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES based on field work, an examination of GIS and range data, and due to the diverse topography of Southern California, the lizard still exists in most of its original range. For example, lizards are still present (verified by field observations) on U.S. Navy property at the tip of Point Loma, San Diego County where they were collected in 1893! The species still occurs in coastal sage scrub canyons within Balboa Park, a park completely surrounded by the city of San Diego. The lizard was also found, to be present in high numbers along such human disturbances as railroad tracks, freeways, xerophytically planted yards, and in open riparian areas. In summary, in California, the Orange-throated Whiptail occurs from sea level to 853m, (except north of Aguanga where it occurs at higher elevations), in Orange, Riverside, and San Diego Counties essentially south of California State Highway 91 and Interstate Highway 10. The species occurs north of Hwy 91 only in east Norco and within the city of Riverside. The species occurs north of State Highway 60, only in the Riverside City, Box Canyon, Pigeon Pass Valley, Reche Canyon area. Two localities (““Reche Canyon near Colton” and *‘2 miles up Reche Canyon’’) are old records and are so vague that it is not clear whether the localities should be located in Riverside or San Bernardino County. They are listed for San Bernardino County in Table 1. The species exists today in Reche Canyon, but in Riverside County. Perhaps these historical records are for Riverside County as well. Several erroneous locality records for the whiptail were discovered in the lit- erature, museum records, and the CDFG NDDB. Most of these records are based on errors of identification of specimens, clerical errors by collectors, errors by museum catalog personnel, or simple typographic errors. Museum curators have been advised of these errors. The following locations are NOT VALID LOCALITY RECORDS: San Diego County: 3 mi. S Buckman’s (clerical error); 18 miles E of Julian (clerical error for W of Julian, but that location has the wrong habitat and elevation); San Bernardino County: Cajon Wash, 2.5 air miles SE of Devore (error of identification; LaPre, personal communication; the specimen was a Cnemidophorus tigris); Riverside County: End of Whitewater Canyon by trout farm, and Jenson Canyon, San Gorgonio Pass (clerical error by collector; both localities have creosote bush habitat and both sites were examined several times during this study and only C. figris was present). Habitat Requirements Field surveys were designed to obtain habitat as well as distributional data Raw data for all lizard surveys are presented in Brattstrom (1993) and are available from CDFG or the author. A total of 362 survey-transects were completed: 274 were on military bases, 88 of these were not. Of the 362 surveys, 65 of them had lizards on the transect, 49 (13.5%) had whiptails. On all surveys, dominant plants were listed in order of apparent numerical dominance by visual estimate. Notes were also taken on whether grasses, mustard, and wild oats (see Table 3 for scientific names) were present. The latter two suggest past human disturbance. Table 3 shows that Orange-throated Whiptails are found predominantly in areas with Buckwheat (70% of surveys), Chamise (65%) and White Sage (35%). Black Sage (26%), and California Sagebrush (13%), Mule Fat (9%) and Laurel Sumac (13%) were present on some surveys. Buckwheat, White Sage, Black Sage, and California Sagebrush are the charac- BIOLOGY OF THE ORANGE-THROATED WHIPTAIL 11 Table 3. Rank order of species of perennial and annual plants on 32 surveys with Cnemidophorus hyperythrus based on occurrence and dominance. The rank order describes habitat for Orange-throated Whiptails and is a useful predictor of its occurrence. PERENNIALS % of Surveys 1. California Buckwheat, Eriogonum fasciculatum 70 2. Chamise, Adenostoma fasciculatum 65 3. White Sage, Salvia apiana 35 4. Black Sage, Salvia mellifera 26 5. California Sagebrush, Artemisia californica 13 6. Laurel Sumac, Malosma laurina 13 7. Mule Fat, Baccharis salicifolia 9 8. Prickly-pear Cactus, Opuntia sp. Ne) 6 . Deer Weed, Lotus scoparius 3 . Scrub Oak, Quercus dumosa 3 3 3 — at) . Mexican Elderberry, Sambucus mexicana 12. Lemonade Berry, Rhus integrifolia ANNUALS 1. Grasses 59 2. Mustard, Brassica sp. 59 3. Wild Oats, Avena fatua 28 teristic species of Coastal Sage Scrub vegetation in the range of the whiptail. Other members of the Coastal Sage Scrub and Chaparral plant communities were present on less than 6% of the plots. Chamise, Adenostoma fasciculatum, is nor- mally considered to be a member of the chaparral plant community, but in inland Riverside and San Diego Counties and coastal Orange County and San Diego Counties, Chamise also occurs within the typical Coastal Sage Scrub Vegetation Type (Buckwheat, Black and White Sage, California Sagebrush). In these areas Chamise is usually low (less than Im high) and wide spread, in contrast to its tall (to 4m), dense (ie 100% cover) occurrence in chaparral. The presence of Chamise in Coastal Sage Scrub vegetation is not inconsistent with the low, open nature of that vegetation type. Orange-throated Whiptails thus prefer Coastal Sage Scrub vegetation with Buckwheat, Chamise, White and Black Sage. Mustard and grasses were present in 59% of Orange-throated Whiptail surveys. The weedy Wild Oats, Avena fatua, was present in only 28% of surveys. Vegetation alone is not always a good predictor of whiptail presence as 25% of transects in Coastal Sage Scrub did not have whiptails (Fig. 4) and whiptails did occur in other hab- itats. Other habitat characteristics such as cover, soil, and slope, also important for whiptails may not have been suitable at those sites. Figure 3 presents the data for habitat variables on transects where whiptails were present. The same data expressed as “‘percent of lizards’? and “‘percent of transects with lizards” are presented in Brattstrom (1993). They do not differ in any significant way from Figure 3. Figure 4 presents data for transects where no whiptails were found. Some of these graphs are the opposite of graphs for the same variable where whiptails are found indicating that certain characters are especially important. Yet other graphs (Fig. 4) show that similar habitats may not have whiptails. This is probably due to the fact that not all variables are in sync or that populations of whiptails were low at that site. For example, whiptails are 12 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES TRANSECTS WHERE WHIPTAILS WERE FOUND 1-Riparian 25 1-Fine = 2-Grass ip 2-Sandy = 25 3-Coastal Sage 3-Coarse 4-Chaparral 5-Bare 6-Pinyon-Juniper 7-Oak Woodland 4-Very Coarse 5-Clay Number of Lizards (N Number of Lizards (N =48) 3 3 4 Vegetation Ss 6 Type 7 Soil Texture ¥ 1-None © o 2-Plowed Hy 20 1-Flat © ae ir aie | z T griculture Ss 2-Gentle Slope z 35 4-Roads uv ~~ P45 3-Strong Slope m 90 5-Grazing 8 4-Cliffs E254 6-ORVs sar at 5 10 5-Big Rocks 204 7-Buildings . ‘So #65 © 5 oO z = 0 z 1 2 3 4 5 Topography $ 2 z Human Impact 1-No Bare Soil _ 30 2-50% Bare Soil S 40 NO 3-100% Bare Soil 0 1-None i w oi 2-Organic Humus 3-Leaves/Sticks 4-Logs/Branches Number of Lizards (N Number Of Lizards (N on 2 3 Soil Exposure Surface Litter Fig. 3. Habitat characteristics of Orange-throated Whiptails based on transects where whiptails were found. Topography: Flat: 0-15; Gentle: 15—45; Strong: greater than 45 slope. Because topography on a Single transect may vary, some transects had two or more categories. Soil categories are USDA Soil Conservation Service categories and are defined in the text. Roads: any type from paved to dirt. ORY: any indication of ORV activity. BIOLOGY OF THE ORANGE-THROATED WHIPTAIL 13 TRANSECTS WHERE NO WHIPTAILS WERE FOUND 1-Riparian 2-Grass geek 1-Fine 3-Coastal Sage a 34 2-Sandy 4-Chaparral iT 3-Coarse 40 5-Bare 40 4-Very Coarse 6-Pinyon-Juniper 7-Oak Woodland 5-Clay % Transects (N=138) ine) (o) Transects (N Ditty ei A Su oO. bel 8 Vegetation Type 2 3 4 5 Soil Texture 1-Flat 2-Gentle Slope 3-Strong Slope 4-Cliffs 5-Big Rocks 18) 130) o (eo) 5-Grazing 6-ORVs 7-Buildings 8-Garbage %Transects (N ine) oO %Transects (N nh =) PBS aU Bs Gi eee Human Impact Topography 1-No Bare Soil 2-50% Bare Soil 3-100% Bare Soil 16) =88) oO ro) 1-None 2-Organic Humus = 3-Leaves/Sticks = wm 30 4-Logs/Branches a 40 Oo 2) ® g 30 c & 2 ehh be F 10 2 S Surface Litter 1 2 3 Soil Exposure Fig. 4. Habitat characteristics of transects made where no Orange-throated Whiptails were found. Categories are the same as in Figure 3. most often found in Coastal Sage Scrub vegetation, but not all Coastal Sage Scrub habitat had whiptails (Fig. 4). Note further that whiptails are found where there is leaf litter (Fig. 3), but some sites with leaf litter (Fig. 4) did not have whiptails. Perhaps, in spite of the presence of leaf litter some other characteristic was not right for the whiptail. To summarize the habitat data, Figure 3 indicates that Orange-throated Whip- tails are found primarily in Coastal Sage Scrub vegetation. They are also found 14 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 4. Soil size choice of Cnemidophorus hyperythrus in laboratory experiments where four choices of soil size were available. (N = 3 and tally times = 5, so total choices = 15.) One lizard had not made a choice during one tally, so the numbers are given as a percent of 14 choices. Soil size names Size of soil* Percent of lizards choosing Fine 0.1-0.5 (0.39) 0 Medium 0.5-2.6 (1.8) 100 Coarse 3.0-6.4 (4.6) 0 Very Coarse 9.0-—15.2 (11.6) 0 * Soil sizes are given as a range and a mean size in mm. based on microscopic examination. in grassy areas and in broad open disturbed riparian areas. Whiptails also occur in chaparral, but the chaparral must be open. Whiptails occur in flat, gentle (15°), and even strong slope (45°) areas, but not on cliffs (Table 5). Whiptails were most often found in areas with 50% cover and 50% bare soil. The absence of vegetation (100% bare soil) implies the absence of food, and the few lizards present on such surveys may have been just passing through these areas. Whiptails are found primarily on coarse soil (see definition above), and almost never on fine soil, or sand. However, in laboratory experiments (Table 4), these lizards selected medium soil 100% of the time in a four soil-size choice experi- ment. Whiptails dig their own burrows and seldom utilize rodent burrows except for extreme emergencies (Rowland 1992; Bostic 1965, 1966 b,c). A coarse soil must be important in holding the lizard-sized burrows open and medium sized soil may be easier for this small lizard to escape in. While most transects did not have roads or paths on them, Figure 3 shows that when present, whiptails are found most often on transects which have a dirt road or a few off-road vehicle paths. This is probably due to the fact that both off-road vehicle activity and dirt road construction break up hard surface soil, make a slope of loose coarse soil, or make a side berm of coarse materials. These coarse soil slopes and berms are where whiptails dig their burrows and lay their eggs (Bostic 1966c), Presumably, for this same reason, whiptails are also commonly found along the edge of hiking and equestrian trails and along fences. In fact, even though transects were done through dense chaparral, the only incursion of whiptails into chaparral vegetation is along roads, trails, and fences. Historically this disturbance and trail making presumably was done by erosion and large, now extinct, mammals. Note that whiptails are seldom found in plowed fields or fields with agricultural crops (Fig. 3). They are seldom found about buildings, though two correspondents who lived in open Coastal Sage Scrub vegetation reported whiptails in yards, even coming into xerophytically planted patios to feed. Figure 3 clearly indicates that whiptails do better with some light human disturbance such as roads and trails (see also Walker and Cordes 1990). Interestingly, whiptails are often found (personal ob- servation) where people have dumped garden and other debris. Whiptails eat primarily termites (Bostic 1966a). It is therefore not surprising to find that more whiptails occur in habitats with more leaves and small sticks (Fig. 3). They are not found in areas with large logs or even lots of logs. This is consistent with the rapid leaf litter foraging method of whiptails. Termites within large logs would be unavailable to the lizards and an abundance of logs may BIOLOGY OF THE ORANGE-THROATED WHIPTAIL 15 interfere with their need for open running room. Their presence about human debris may be due to the nature of that debris in attracting termites. Whiptails do not occur in areas where the number of harvester ant mounds is high which suggests that in open areas whiptails are not common in exactly the same micro- habitat as Coast Horned Lizards, Phrynosoma coronatum (which feed on the ants) (Brattstrom 1997; Hager and Brattstrom 1997). It may also be that whiptails are affected by the bites of the ants and choose to avoid them. Whiptails were not found in areas with lots of ground squirrel, gopher, and other rodent burrows. This may be due to the fact that these lizards make their own burrows, seldom use rodent burrows for escape, or that the rodents disturb the area or leaf litter too much. In addition, predators that dig rodents out of burrows such as skunks and fox, would also find and eat whiptails if they were in rodent burrows. One of the original working hypotheses was that large numbers of whiptails would occur in areas following fires. The idea was that after a fire there would be a lot of dead wood which would attract termites, the main food of whiptails. Orange-throated Whiptails in fact were usually found in areas (17/22 transects or 77%) that have not been burned recently (within the last 5 years). This supports observations that these lizards feed on termites in leaf litter under bushes. Fires would destroy that leaf litter and termites within logs would not be available to this small lizard. The Orange-throated Whiptail is a high thermophilic basking lizard and like teiids in general has a higher body temperature (36.8—41.6°C, *:39.0°C) than sym- patric phrynosomatid lizards (Brattstrom 1965). Transect data and Rowland (1992) showed that whiptails are not found out of retreats until the soil temper- ature is greater than 21°C for juveniles and 24°C for adults and air temperature is greater than 12°C for juveniles and 21°C for adults. They are out on very hot days (30—50°C), but are not found out when soil or air temperature exceeds 55°C (Rowland 1992; Rowland and Brattstrom in prep.). In addition, high environ- mental temperatures associated with the low humidities in their habitat cause rapid water loss due to evaporative cooling from mouth and lungs during respiration (which is very high at these temperatures and for this small lizard). As a result, like many such thermophilic lizards, the whiptail is inactive on some otherwise ideal days or some parts of the day, presumably, in order to conserve water. Figure 4 shows some of the characteristics of transects where no Orange-throat- ed Whiptails were found. Most of these graphs are the reciprocal or reverse of Figure 3 as this or some associated characteristic was not suitable for whiptails. In some cases no lizards were found on transects with some of the same char- acteristics as areas with lizards. Whiptails may have been on the transect but not seen. It is more likely, that while the area met one of these variables (ex. road) it did not meet another (50% cover). In other cases, sites looked just like similar sites with lizards. The lizard could have become extinct on that site, might never occurred on that site, or were not there because of other reasons (lack of termites) or because of some variable that we did not measure. In summary, Orange-throated Whiptails are found primarily on Coastal Sage Scrub vegetation with Buckwheat, Chamise, White Sage and occasionally Black Sage, with 50% of the land bare (=50% cover), in flat to sloping topography, in areas with leaves and small sticks under bushes, no evidence of fire, few or no ant mounds or rodent burrows, in coarse soil, with some loose dirt, as along dirt 16 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES roads and trails, and below 853m (max. 1058m) elevation in Coastal Orange, Riverside, San Diego Counties of California and southward to the tip of Baja California. GIS Analysis To further analyze the habitat and distributional information, the distribution of whiptails (locations from dots on maps Figure 1, and Brattstrom 1993) of the whiptail was entered into a OSUMAP-GIS program. Other data put into the pro- gram included: elevation, vegetation, rainfall, basic geology, fires, known open spaces (including parks, reserves, forests), and urban areas. Some of the resultant maps are presented in Figure 5. For calculation of areas of land use, the maps have been overlaid on a light table, and the area estimated visually using a graph paper overlay. There is thus an error in these area estimates which is a function of the size and scale of the map and the use of any GIS program at the scale of all of Southern California. The GIS maps support the basic observations made from field surveys: 1) Whiptails are found in the coastal and inland physiographic zone; 2) they are found primarily in Coastal Sage Scrub vegetation; 3) they are not found in areas of fire; 4) their range includes urban and suburban land; 5) about 40% of the known localities occur in public lands, parks and reserves. There are many advantages to GIS analysis, but many of these advantages disappeared when covering a large area, and where habitat variables have small and patchy distributions (such as vegetation or soil type on different slopes of a small hill). Habitat Quality Index A Habitat Quality Index (HQI) was made (Table 5) for the Orange-throated Whiptail by utilizing characters and their conditions presented in the graphs and tables just discussed. A scale of poor to good habitat was developed based on the quality of that habitat for each of the variables tallied. For example, for a variable such as vegetation or soil, that habitat characteristic which had the most lizards on it (i.e. the tallest bar on the graph or highest number on a table) was ranked high. A habitat with no or few lizards ranked low. Those with intermediate con- ditions were ranked medium. Using these 12 characters (numbers 2 and 3, Cover and Percent Bare Soil, are reciprocals of each other), any given habitat can be quantitatively placed into a low, medium, or high (C, B, or A grade) category. A habitat thus can be quantified as being poor to good for a whiptail without even having to see a lizard present. The HQI is simple enough to be completed by most field trained biologists. It allows the habitat to be quantified at times and seasons when lizards are not active. It must be used, like all such evaluation forms, with caution. It is a method for determining and quantifying potential habitat, not lizard presence. Quantitative data (Fig. 3) allow the prediction that those habitats with high rating probably do have whiptails present. The transect, characters tallied, and HQI has been adapted, slightly modified, for habitat char- acterization under California’s Coastal Sage Scrub Natural Community Conser- vation Planning process (CSS/NCCP) guidelines. Whiptails occasionally occur in peculiar habitats, such as in the exotic Ice Plant, Carpobrotus edulis, at the upper edges of beaches. Whiptails occasionally forage in Open riparian areas, such as those with Sycamore and thick brush. BIOLOGY OF THE ORANGE-THROATED WHIPTAIL Ry. URBAN AND SUBURBAN LANDUSE HO gli i tert, “ a lint wl" at ‘all we “a: “ “ig " ‘a il i i, il I" ry ES 3. i ie al, wh z 4 Gclagisseag hint wee Fig. 5. GIS analysis of some habitat information on Orange-throated Whiptails. Maps are of South- ern California and cover about the same area as Figure 1. The bottom of each map is the U.S.-Mexico border and the peninsula in the upper left part of the maps in Palos Verdes of southwestern Los Angeles County. Note that the fire history map is at a different scale due to data source. Maps of Parks, reserves, National Forests (Upper), and urban and Suburban land use(middle) are original data. Names and acres of parks are from Brattstrom (1993). The fire map comes mostly from Minnich (1983), with more recent fires added. There is apparent overlap between the range maps (Fig. 1) and the urban and suburban land use map as whiptails occur in some of these areas and because the GIS process at this scale cannot discriminate between, for example, a housing development on a hill from the Coastal Sage Scrub covered slopes which mat be occupied by whiptails. Abundance Lizard survey/transects were 10 X 100 meters. On transects with lizards, from 1 to 4 lizards occurred per transect (18 transects had one lizard, 8 had two, 4 had three, and 5 had four lizards) with a mean (64 lizards on 35 transects) or 1.8 lizards in a 10 X 100m area multiplied by 10 gives 10—40 lizards/hectare. The number of lizards seen ranged from 3 to 48 lizards per man hour. To test whether the lizard surveys were effectively counting (i.e. seeing) lizards on transects, the lizard survey team did a typical lizard transect on Scott Row- 18 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 5. Habitat Quality Index for Cnemidophorus hyperythrus. Character 1. Vegetation 2. Cover 3. Percent Bare Soil 4. Soil Texture 5. Surface litter 6. Slope 7. Annual Plants 8. Perennial Plants! 9. Fire History . Number of go pher and grd. squirrel burrows 11. Human Impact 12: i. Other Lizards Predators Present Temperature Con- straints**** Air Temp. Soil Temp. * rocks O.K. Low = C= 1 Bare O% 100% Fine/sandy Bare or logs & branches Cliffs Erodium only, agriculture Bare or thick chaparral Recent fire High 75/100m Plowing, grading, agri- culture, buildings C. tigris None 17-—29° C 25-34° C ** listed in order of importance *** Masticophus and Coluber **** These are the bad, good, and better times to assess the habitats if actually looking for or counting lizards. Medium = B = 2 Grass, chaparral, riparian edge 100% 0% Clay Organic humus Flat* 0-15° Wild Oats only Mule-fat, Laurel Sumac. Calif. Sagebrush Fire within last 5 years Medium 25-—75/100m ORV activity Sceloporus Scrub Jay, Northern Mockingbird, Shrike 30-35° C 35—45° C High = A = 3 Coastal Sage scrub 50% 50% Coarse—medium Leaves and sticks under bushes Gentle to strong* 15—45° Grasses, including wild oats: mustard Buckwheat**, Chamise, White Sage, Black Sage No evidence of fire Low O0-—25/100m Dirt roads especially with berm or raised shoul- der Uta Whipsnake/Racers*** Road runner Kestrel 36—42° C 45-55° C 'In beach habitats, ice plant and other strand vegetation may be good indicators. land’s permanent 100 X 100m study plot on the Motte-Rimrock Reserve on Sep- tember 25, 1990. In each of two passes (each 10 X 100m) on the study plot, 3 OTWs were observed (for a total of 6 lizards). Based on 3 lizards per 10 X 100m transect, multiplied by 10 to equal the size of the 100 'Center for Environmental Research and Conservation, 1200 Amsterdam Ave., Columbia University, New York, New York 10027 2Department of Entomology, University of California, Davis, California 95616 3The Evergreen State College, Olympia, Washington 98505 4Shaw Arboretum, P.O. Box 38, Gray Summit, Missouri 63039 >International Centre of Insect Physiology and Ecology, Box 30772, Nairobi, Kenya and National Museum of Natural History, Smithsonian Institution, Washington, DC 20560 Abstract.—We conducted ant surveys on Santa Cruz Island, the largest of the California Channel Islands, in 1975/6, 1984, 1993, and 1998. Our surveys yielded a combined total of 34 different ant species: Brachymyrmex cf. depilis, Campon- otus anthrax, C. clarithorax, C. hyatti, C. semitestaceus, C. vicinus, C. sp. near vicinus, C. yogi, Cardiocondyla ectopia, Crematogaster californica, C. hespera, C. marioni, C. mormonum, Dorymyrmex bicolor, D. insanus (s.1.), Formica la- sioides, F. moki, Hypoponera opacior, Leptothorax andrei, L. nevadensis, Line- pithema humile, Messor chamberlini, Monomorium ergatogyna, Pheidole califor- nica, P. hyatti, Pogonomyrmex subdentatus, Polyergus sp., Prenolepis imparis, Pseudomyrmex apache, Solenopsis molesta (s.1.), Stenamma diecki, S. snellingi, S. cf. diecki, and Tapinoma sessile. The ant species form a substantial subset of the mainland California ant fauna. We found only two ant species that are not native to North America, C. ectopia and L. humile. Linepithema humile, the Ar- gentine ant, is a destructive tramp ant that poses a serious threat to native ants. The California Channel Islands lie in the Pacific Ocean, 20 to 100 km off the coast of southern California. As a result of isolation from the mainland, many endemic plant and animal species have evolved on these islands (Wenner and Johnson 1980; Diamond and Jones 1980; Nagano et al. 1983; Junak et al. 1995), including more than 100 species of endemic insects (Miller 1985). Two ant spe- cies, Aphaenogaster patruelis Forel and Camponotus bakeri Wheeler, are recog- nized as endemic to the Channel Islands (Miller 1985). Santa Cruz Island (SCI) is the largest (245 km?) of the Channel Islands. In the past, SCI was used for ranching of cattle, sheep, and horses, as well as some agriculture and tourism (Junak et al. 1995). There were also several military installations. SCI is now entirely a nature reserve, with a resident human popu- lation of fewer than twenty people. One small, largely unmanned U.S. Navy installation remains. The western 90% of the island is owned by The Nature Conservancy, a private conservation organization, and the eastern 10% is part of * Correspondence to James K. Wetterer. Current address: Honors College, Florida Atlantic Univer- sity, 5353 Parkside Drive, Jupiter, FL 33458. 25 26 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Ant species recorded on Santa Cruz Island. Pub = previous records (see Introduction). * = unpublished record (see Results). T75/6 = Trager and Trager surveys in 1975/6. L84 = Longino survey in 1984. PW93 = Ward et al. survey in 1993. JW98 = Wetterer et al. survey in 1998. X = found in survey. Survey Species Pub T75/6 L84 PW93 JW98 Brachymyrmex cf. depilis xX Camponotus anthrax Wheeler x Camponotus clarithorax Emery Camponotus hyatti Emery Camponotus semitestaceus Snelling Camponotus vicinus Mayr Camponotus sp. near vicinus x Camponotus yogi Wheeler Cardiocondyla ectopia Snelling xX Crematogaster californica Wheeler Crematogaster hespera Buren Crematogaster marioni Buren Crematogaster mormonum Wheeler xX Dorymyrmex bicolor Wheeler Dorymyrmex insanus (Buckley) (s.1.) Formica lasioides Emery Formica moki Wheeler xX Hypoponera opacior (Forel) Leptothorax andrei Emery Leptothorax nevadensis Wheeler Linepithema humile (Mayr) Messor chamberlini Wheeler Monomorium ergatogyna Wheeler Pheidole californica Mayr Pheidole hyatti Emery Pogonomyrmex subdentatus Mayr Polyergus sp. Prenolepis imparis (Say) Pseudomyrmex apache Creighton Solenopsis molesta Say (s.1.) Stenamma diecki Emery xX Stenamma snellingi Bolton Stenamma cf. diecki Tapinoma sessile (Say) X X # of species 10 21 20 # not recorded in earlier surveys 13 4 x KK XM xx x xx Kam K KM MK ~ xxx KK KM xx KM KM KKM KK ROKK KM xx K KM * xxx XM x x xx x x KKK MK x x KKK KKK MK MM xx KK 23 w RK MM KM Channel Islands National Park. The island is far from pristine, with large popu- lations of exotic plants (e.g., fennel, Foeniculum vulgare Miller) and animals (e.g., feral pigs, Sus scrofa L.) (Junak et al. 1995). The California Channel Islands remain poorly studied by biologists. There have been no published comprehensive ant surveys of any of the California Channel Islands, and we found few published records of ants from SCI. Earlier published records noted only 10 different ant species on SCI (Table 1). Wheeler (1915) described Messor chamberlini Wheeler from SCI and also recorded Pheidole cal- ifornica Mayr. Fall and Davis (1934) collected Pheidole hyatti Emery on SCI, ANTS OF SANTA CRUZ ISLAND, CALIFORNIA Za incidental to their study of the island’s beetles. Mallis (1941) added Prenolepis imparis (Say), Camponotus sp. near vicinus (as Camponotus sansabeanus vicinus var. maritimus), and Formica moki Wheeler (as Formica rufibarbis var. occidua) to the list. More recent ant records from SCI include additional Formica moki (Francoeur 1973; Francoeur and Snelling 1979), as well as Crematogaster mor- monum Wheeler (Rentz and Weissman 1981), Pseudomyrmex apache Creighton (Ward 1985), Monomorium ergatogyna Wheeler (Dubois 1986), and Camponotus anthrax Wheeler (Snelling 1988). From the published records of only 10 ant species known from SCI, one might conclude that the diversity of ant fauna of this island is quite impoverished com- pared to the ant fauna of mainland California sites, where ant surveys typically collect more than 20 ant species (see Discussion). However, we present the results of four ant surveys conducted on SCI in 1975/6, 1984, 1993, and 1998, which greatly expand the known species list for SCI. This present synthesis was prompt- ed by the discovery on SCI of the Argentine ant, Linepithema humile, a highly destructive tramp ant that poses a serious threat to native ants. Adrian Wenner first found L. humile on SCI in January 1996. A follow-up study by Andrew Calderwood and Emily Hebard in July 1997 found that L. humile occupied two noncontiguous areas, surrounding two dismantled Navy support facilities, that totaled less than 1% of the island (Calderwood et al. 1999). Methods In the fall of 1975, G. Trager surveyed ants on Santa Cruz Island using hand- collecting. In the summer of 1976, G. Trager and J. Trager further surveyed SCI ants using hand-collecting and tuna bait transects. J. Trager identified the ants from 1975/6. Vouchers are in the personal collection of G. Trager and unavailable for this study. From 24—27 August 1984 and 26—29 October 1984, J. Longino surveyed SCI ants using hand-collecting. Longino identified these ants and placed vouchers in the Natural History Museum of Los Angeles County (LACM) and the University of California (UC) Field Station on Santa Cruz Island. On 25—28 June 1993, P Ward, B. Fisher, and M. Bennett surveyed SCI ants using hand- collecting and Winkler litter sifting. Ward identified the ants and placed vouchers in the Bohart Museum of Entomology, University of California, Davis, and du- plicates at the LACM and the Museum of Comparative Zoology at Harvard Uni- versity (MCZ). Finally, in March—May 1998, J. Wetterer, A. Wetterer, A. Wenner, A. Calderwood, and E. Hebard surveyed ants (with the assistance of numerous volunteers, primarily undergraduate students studying at Biosphere 2 Center), us- ing hand-collecting, bait transects (with tuna and Pecan Sandies cookies as bait), and litter samples in Berlese funnels. S. Cover at the MCZ and P. S. Ward iden- tified these ants. We have placed voucher specimens in the MCZ. Results Each of the four surveys of Santa Cruz Island yielded 20 to 24 ant species (Table 1). Altogether, a total of 34 different ant species were recorded by our surveys, including all 10 previously recorded species (Table 1). All 34 species are known from mainland California. Only 13 ant species were found in all four surveys, and only four of these had been previously recorded from SCI. Each of the surveys yielded at least three ant species not recorded in any earlier survey 28 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES (Table 1). None of the surveys collected either of the two endemic Channel Island ant species. There are a number of taxonomic problems concerning the ants of SCI. Two ants, Dorymyrmex insanus (Buckley) (s.1.) and Solenopsis molesta Say (s.1.), be- long to species-groups whose species boundaries have not been adequately defined (S. Cover, personal communication). Several researchers first identified the Po- lyergus specimens from SCI as Polyergus breviceps Emery. However, Trager (personal observation) determined the specimens to be an undescribed species with physical proportions quite distinct from P. breviceps. This undescribed spe- cies is unique to southern California and parasitizes only F. moki. We were unable to identify with certainty two ant species, listed as Brachymyrmex cf. depilis and Stenamma cf. diecki. Cover and Longino identified Camponotus sp. near vicinus as the ant Wheeler (1910) described as Camponotus maculatus vicinus var. maritimus Wheeler, but this ant was referred to Camponotus vicinus Mayr by Creighton (1950). Both Camponotus vicinus and Camponotus sp. near vicinus occurred on SCI where they are distinct and appear to represent separate species. Camponotus sp. near vicinus Was very common on SCI, whereas true C. vicinus was rare. In 1984, Longino found only one nest of true C. vicinus, under dead wood in the pine stand on the east end of SCI. In contrast, Longino (personal observation) found that Camponotus sp. near vicinus was rare in the chaparral around Santa Barbara on the adjacent mainland California, where true vicinus was common. Longino examined all C. vicinus and C. sp. near vicinus specimens at the Los Angeles County Museum, and concluded that some specimens from farther south in Cal- ifornia were apparently intermediate between the two forms. In northern Califor- nia, the two species are consistently distinct and recognizable (Ward, personal observation). Camponotus hyatti Emery is quite variable on SCI, in some cases approaching the morphology of the closely related species Camponotus bakeri Wheeler. Cam- ponotus bakeri is currently recognized as endemic to the southern Channel Islands of Santa Catalina, San Clemente, and Santa Barbara (Snelling 1988), but the relationship and distribution of C. hyatti and C. bakeri need critical review. Longino (personal observation) identified a single damaged and undated spec- imen in the collection of the UC Field Station on SCI as belonging to the Lep- tothorax nevadensis Wheeler group, corroborating the 1975/76 record of L. nev- adensis. Two species recorded in the 1975/76 survey (Camponotus dumetorum Wheeler and Camponotus sayi Emery) are excluded because identifications of the specimens are uncertain and no vouchers are available. Crematogaster mormon- um, also recorded in an earlier study (Rentz and Weissman 1981), warrants con- firmation, as it is easy to misidentify this species. Cardiocondyla ectopia Snelling and Linepithema humile (Mayr) are the only ant species we found on SCI known to be not native to North America. We collected Cardiocondyla ectopia, an Old World species (Snelling 1974), only around buildings of the Stanton Ranch, currently used as the island headquarters of The Nature Conservancy. Our 1998 survey confirmed the distribution of L. humile documented (see map in Calderwood et al. 1999) and failed to locate any additional L. humile populations on the island. ANTS OF SANTA CRUZ ISLAND, CALIFORNIA 29 Discussion The number of ant species found in our surveys of Santa Cruz Island was similar to ant surveys on mainland California. For example, Fisher (1997) sur- veyed eight sites in northern California and found a total of 27 different ant species. Holway (1998) surveyed a similar northern California area and found 26 ant species. Suarez et al. (1998) surveyed 47 sites in southern California and found a total of 50 different ant species. The ant species of SCI form a substantial subset of the mainland California ant fauna (Ward 1987, Fisher 1997; Holway 1998; Suarez et al. 1998; Ward, unpub- lished). Many common mainland ant species, however, were not found on SCI, including Camponotus essigi Smith, Liometopum occidentale Emery, Neivamyr- mex californicus (Mayr), N. nigrescens (Cresson), Formica francoeuri Bolton, Leptothorax nitens Emery, Messor andrei (Mayr), Pogonomyrmex californicus (Buckley), and Solenopsis xyloni McCook (Ward 1987; Fisher 1997; Human and Gordon 1997; Holway 1998; Suarez et al. 1998). The ocean appears to have been an effective barrier to colonization of SCI by many ants common on mainland California. It is unclear how many of the ant species now on SCI predate human habitation on the island. The two exotic ant species, Cardiocondyla ectopia and Linepithema humile, almost certainly arrived on SCI through human activity. We found both species only surrounding building sites. The arrival of Linepithema humile on SCI is particularly distressing. Originally from South America and commonly called the Argentine ant, this ant is now a pest in subtropical and temperate regions around the world, including Australia (Majer 1994), South Africa (Hattingh 1945), the Middle East (Tigar et al. 1997), southern Europe (Way et al. 1997), Bermuda (Hilburn et al. 1990), the southern mainland United States (Barber 1916), and Hawaii (Reimer et al. 1990; Wetterer 1998; Wetterer et al. 1998). Linepithema humile first arrived in California earlier this century and has steadily spread across the state (Ward 1987; Holway 1995; Human and Gordon 1997). Linepithema humile has become the most common pest ant in urban areas of California (Knight and Rust 1990). In areas where L. humile invades, native invertebrate species are heavily im- pacted (Erickson 1971; Cole et al. 1992; Ward 1987; Human and Gordon 1997; Way et al. 1997; Holway 1998; Suarez et al. 1998). This is true on SCI as well. Within the two areas that L. humile has invaded, only two other ant species have persisted, Monomorium ergatogyna and Solenopsis molesta (Wetterer et al., un- published data). Elsewhere on SCI, the native ant fauna appears to be fairly intact. The previous absence of destructive exotic ants on SCI has likely permitted many species of native invertebrates to persist. However, if L. humile spreads, these native species may be seriously threatened. Linepithema humile is also known from two other California Channel Islands. This ant is established on Santa Catalina Island (Cockerell 1940; Rentz and Weiss- man 1981), the only Channel Island with a sizable human population. There is also one record of L. humile from San Clemente Island (Straughan 1982). Com- prehensive ant surveys are needed on these and the other California Channel Islands to evaluate the distribution and impact of L. humile and to determine what, if anything, should be done to curtail its spread. 30 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Acknowledgments We thank A. Wenner, A. Calderwood, E. Hebard, J. Howarth, B. Fisher, M. Bennett, G. Trager, C. Mealey, A. Southern, M. Hill, C. Dunning, J. Burger, M. Patton, K. Bartniczak, A. Mingo, L. Geschwind, J. Rowe, J. Gallagher, D. Han, L. Patterson, M. Beman, A. Ghaneker, A. Aronowitz, and A. Anderson for field assistance; R. Klinger of The Nature Conservancy, T. Coonan of the National Park Service, and L. Laughrin of the University of California Field Station for technical assistance; S. Cover of the Museum of Comparative Zoology, Harvard University and R. Snelling of the Natural History Museum of Los Angeles County for ant identification; C. O’Connell for assistance in assembling ant databases; M. Wetterer and A. Wenner for comments on this manuscript; the National Park Service for transportation to and from Santa Cruz Island; the Santa Barbara Mu- seum of Natural History, the Los Angeles County Museum, the Bishop Museum, The Nature Conservancy, the Center for Environmental Research and Conser- vation, Columbia University, Biosphere 2 Center, and Florida Atlantic University for financial support. Literature Cited Barber, E.R. 1916. The Argentine ant: distribution and control in the United States. U. S. Dept. Agric. Bull., 377:1—23. Calderwood, A., A. Wenner, and J.K. Wetterer. Argentine ant invasion of Santa Cruz Island, California. in press in Proceedings of the 1999 California Islands Symposium. Cockerell, T.D.A. 1940. The insects of the Californian Islands. Proc. Sixth Pacific Sci. Congr., 4:283- yap Cole, ER., A.C. Medeiros, L.L. Loope, and W.W. Zuehlke. 1992. Effects of the Argentine ant on arthropod fauna of Hawaiian high-elevation shrubland. Ecology, 73:1313-—1322. Collingwood, C. A., B. J. Tigar, and D. Agosti. 1997. Introduced ants in the United Arab Emirates. J. Arid Environ., 37:505-—512. Creighton, W.S. 1950. The ants of North America. Bull. Mus. Comp. Zool. Harvard Univ., 104:1— 585. Diamond, J.M. and H.L. Jones. 1980. Breeding land birds of the Channel Islands. Pp. 597—612 in The California islands: Proceedings of a multidisciplinary symposium. (D. Power, ed.), Santa Barbara Museum of Natural History. Dubois, M.B. 1986. A revision of the native New World species of the ant genus Monomorium (minimum group) (Hymenoptera: Formicidae). Univ. Kansas Sci. Bull., 53:65—119. Erickson, J.M. 1971. The displacement of native ant species by the introduced Argentine ant /rido- myrmex humilis Mayr. Psyche, 78:257—266. Fall, H.C. and A.C. Davis. 1934. The Coleoptera of Santa Cruz Island, California. Can. Entomol., 66: 143-144. Fisher, B.L. 1997. A comparison of ant assemblages (Hymenoptera, Formicidae) on serpentine and non-serpentine soils in northern California. Insectes Soc., 44:23-—33. Francoeur, A. 1973. Révision taxonomique des espéces Nearctiques du groupe fusca, genre Formica (Formicidae, Hymenoptera). Mém. Soc. Entomol. Quebec, 3:1—316. , and R.R. Snelling. 1979. Notes for a revision of the ant genus Formica. 2. Reidentifications for some species from the T.W. Cook Collection and new distribution data (Hymenoptera: Formicidae). Nat. Hist. Mus. Los Angeles Co. Contrib. Sci., 309:1—7. Hattingh, C.C. 1945. Argentine ant versus indigenous ants. J. Entomol. Soc. South Africa, 8:25—34. Hilburn, D.J., PM. Marsh, and M.E. Schauff. 1990. Hymenoptera of Bermuda. Florida Entomol., 73: 161-176. Holway, D.A. 1995. Distribution of the Argentine ant (Linepithema humile) in Northern California. Conserv. Biol., 9:1634—1637. . 1998. Effect of Argentine ant invasions on ground-dwelling arthropods in northern California riparian woodlands. Oecologia, 116:252—258. ANTS OF SANTA CRUZ ISLAND, CALIFORNIA 31 Human, K.G. and D.M. Gordon. 1997. Effects of Argentine ants on invertebrate biodiversity in North- ern California. Conserv. Biol., 11:1242—1248. Junak, S., T. Ayers, R. Scott, D. Wilken, and D. Young. 1995. A Flora of Santa Cruz Island. Santa Barbara Botanic Garden, Santa Barbara, CA. Knight, R.L. and M.K. Rust. 1990. The urban ants of California with distribution notes of imported species. Southwest. Entomol., 15:167—178. Majer, J.D. 1994. Spread of Argentine ants (Linepithema humile), with special reference to Western Australia. Pp. 163—173 in Exotic ants. biology, impact, and control of introduced species. (D.E Williams, ed.), Westview Press, xiv + 332 pp. Mallis, A. 1941. A list of the ants of California with notes on their habits and distribution. Bull. So. Calif. Acad. Sci., 40:61—100. Miller, S.E. 1985. The California Channel Islands—past, present, and future: an entomological per- spective. Pp. 3—27 in Entomology of the California Channel Islands. (A.S. Menke and D.R. Miller, eds.), Santa Barbara Museum of Natural History, 178 pp. Nagano, C.D., S.E. Miller, and C.L. Hogue. 1983. Castaways of California. The origin of animal life on the Channel Islands. Terra, 29(4):23—26. Reimer, N.J., J.W. Beardsley, and G. Jahn. 1990. Pest ants in the Hawaiian Islands. Pp. 40—50 in Applied myrmecology, a world perspective. (R.K Vander Meer, K. Jaffe, and A. Cedeno, eds.), Westview Press, xiv + 741 pp. Rentz, D.C. and D.B. Weissman. 1981. Faunal affinities, systematics, and bionomics of the Orthoptera of the California Channel islands. Univ. Calif. Pub. Entomol., 94:1—240. Snelling, R.R. 1974. Studies on California ants. 8. A new species of Cardiocondyla (Hymenoptera: Formicidae). J. New York Entomol. Soc., 82:76—-81. . 1988. Taxonomic notes on Nearctic species of Camponotus, subgenus Myrmentoma (Hyme- noptera: Formicidae). Pp. 55-78 in Advances in Myrmecology. (J.C. Trager, ed.), E.J. Brill, Xxvli + 551 pp. Straughan, D. 1982. Inventory of the natural resources of sandy beaches in Southern California. Tech. Rep. Allan Hancock Found., Univ. So. Calif., 6:1—447. Suarez, A.V., D.T. Bolger, and T.J. Case. 1998. Effects of fragmentation and invasion on native ant communities in coastal southern California. Ecology, 79:2041—2056. Ward, PS. 1985. The Nearctic species of the genus Pseudomyrmex (Hymenoptera: Formicidae). Quaest. Entomol., 21:209—246. . 1987. The distribution of the introduced Argentine ant (/ridomyrmex humilis) in natural habitats of the Lower Sacramento Valley and its effects on the indigenous ant fauna. Hilgardia, 55(2):1-16. Way, M.J., M.E. Cammell, M.R. Paiva, and C.A. Collingwood. 1997. Distribution and dynamics of the Argentine ant, Linepithema (Iridomyrmex) humile (Mayr) in relation to vegetation, soil conditions, topography and native competitor ants in Portugal. Insectes Soc., 44:415—433. Wenner, A.M. and D.L. Johnson. 1980. Land vertebrates on the California Channel Islands: sweep- stakes or bridges? Pp. 497-530 in The California islands: Proceedings of a multidisciplinary symposium. (D. Power, ed.), Santa Barbara Museum of Natural History. Wetterer, J.K. 1998. Non-indigenous ants associated with geothermal and human disturbance in Ha- wai’i Volcanoes National Park. Pac. Sci., 52:40—50. , PC. Banko, L.P. Laniawe, J.W. Slotterback, and G.J. Brenner. 1998. Non-indigenous ants at high elevations on Mauna Kea, Hawaii. Pac. Sci., 52:228—236. Wheeler, W.M. 1910. The North American ants of the genus Camponotus Mayr. Ann. New York Acad. Sci., 20:295-354. . 1915. Some additions to the North American ant-fauna. Bull. Am. Mus. Nat. Hist., 34:389-— 421. Accepted for publication 13 March 1999. Bull. Southern California Acad. Sci. 99(1), 2000, pp. 32—44 © Southern California Academy of Sciences, 2000 Has Point Conception been a Marine Zoogeographic Boundary throughout the Holocene? Evidence from the Archaeological Record Kenneth W. Gobalet Department of Biology, California State University, Bakersfield, California 93311, kgobalet@cusbak.edu Abstract.—Fish remains recovered from archaeological sites along the California coast to the immediate north and south of Pt. Conception in San Luis Obispo and Santa Barbara counties are used to test the hypothesis that the ranges of marine fishes have remained constant during the Holocene. The archaeological record shows that as many as 16 species are only found in locations south of Pt. Con- ception and as many as eight are found only to the north. These prehistoric ranges are consistent with their present ranges. Currently, Pt. Conception is the northern extent of the range of many southern California marine fish species, and the approximate southern extent of central and northern California marine fishes (Eschmeyer et al. 1983). This investigation tests whether or not the archaeological record of fish remains reflects this zoogeograph- ical boundary role. In this survey, the results of the evaluations of fish materials from numerous archaeological sites in San Luis Obispo County, north of Pt. Con- ception, (many of which have been reported by Gobalet and Jones 1995), are compared with numerous sites in Santa Barbara County south of Pt. Conception (Figure 1). These archaeological sites are particularly suitable for this study be- cause they were all occupied by a single ethnic group of Native Americans, the Chumash (Holmes and Johnson 1998). The presence of this common culture should minimize any bias for fish capture or consumption, although as one goes back in time this assumption becomes problematic. The 12 archaeological sites reported by Gobalet and Jones (1995) were occu- pied at various times from 6200 BC to AD 1830. Archaeological site SLO-1796 is even older, at approximately 8300 to 7500 BC (T. Jones, personal communi- cation). Three Santa Barbara archaeological sites (SBA-1807, -2057, -2061) re- ported by Erlandson (1994) and SBA-1 were occupied within the range of 9000— 5000 BC with SBA-1 additionally yielding a date of approximately 800 BC (Er- landson 1991). The five sites (SBA-71, -72, -73, -1674, and -1731) on which Johnson worked (Table 2) were variously occupied from the first century AD to AD 1300 (J. Johnson personal communication) and SBA -3404 at a later time from AD1100—1804 (W. Hildebrandt, personal communication). In a study of over 77,000 remains from 51 archaeological sites from the central California coast, Gobalet and Jones (1995) concluded that the fishery resources were locally derived. As a consequence, the archaeological record for coastal sites should reflect the resources immediately available. The same can not be said of inland localities where numerous marine species were transported considerable 32 HOLOCENE RANGE STABILITY OF FISHES AROUND POINT CONCEPTION oa) SLO-267 © SLO-1797 ®SLO-1764 PACIFIC OCEAN SANTA YNEZ IVER SBA-71 SBA-72 SBA- SBA-73 1 731 = SBA-1674 © eSBA-54 N eSBA-27 SBA-1 BARBARA KILOMETERS Fig. 1. Location of archaeological sites considered in this paper in San Luis Obispo and Santa Barbara Counties. distances (Gobalet 1992) or in some freshwater localities, where the archaeolog- ical record has been used to expand known historic ranges (Gobalet 1990; 1993). Though most of the fish species found at sites in San Luis Obispo and Santa Barbara Counties range to the north or south of Pt. Conception, many can be used to test the hypothesis that the archaeological record reflects that Pt. Concep- tion had the same boundary role for these species prior to European contact as found in subsequent historic surveys of aquatic biota. Fishes found at the archae- ological sites under consideration (Table 1) that are generally restricted to waters south (east) of Pt. Conception include: horn shark, shortfin mako shark, swell shark, gray smoothhound, California scorpionfish, kelp bass, Pacific barracuda, California sheephead, sargo, salema, opaleye, blacksmith, giant seabass, white seabass, California corbina, yellowfin croaker, black croaker, queenfish, and rock wrasse (Miller and Lea 1972, Eschmeyer et al. 1983). Species generally restricted to marine waters north of Pt. Conception that have been recovered from archae- ological sites in San Luis Obispo and Santa Barbara Counties include: night smelt, northern clingfish, kelp greenling, monkeyface prickleback, rock prickleback, crevice kelpfish, and Pacific tomcod (Miller and Lea 1972, Eschmeyer et al. 1983). For the prediction to be supported, the species indicated north of Pt. Con- ception should primarily be found in the San Luis Obispo County archaeological sites and not in the Santa Barbara County sites, and the reverse should be true for the species found south of Pt. Conception. 34 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. List of scientific and common names of fishes used in this paper. Terminology and order of presentation follow Robins et al. (1991). Scientific name Common name Elasmobranchiomorphii Hexanchidae cow sharks Notorynchus cepedianus sevengill shark Cetorhinidae basking sharks Cetorhinus maximus basking shark Heterodontidae bullhead sharks Heterodontus francisci Lamnidae Carcharodon carcharias Tsurus oxyrinchus Lamna ditropis Alopiidae Alopias vulpinus Scyliorhinidae Cephaloscyllium ventriosum Carcharhinidae Carcharhinus brachyurus C. leucas C. longimanus C. obscurus Galeocerdo cuvier Galeorhinus zyopterus Mustelus californicus M. henleyi M. lunulatus Prionace glauca Rhizoprionodon longurio Triakis semifasciata Squalidae Squalus acanthias Squatinidae Squatina californica Rhinobatidae Platyrhinoidis triseriata Rhinobatos productus Rajidae Raja binoculata R. inornata Dasyatidae Dasyatis dipterura Urolophidae Myliobatidae Myliobatis californica Clupeidae Clupea pallasi Sardinops sagax Engraulidae Engraulis mordax Osmeridae Spirinchus starksi Actinopterygii horn shark mackerel sharks white shark shortfin mako salmon shark thresher sharks thresher shark cat sharks swell shark requiem sharks narrowtooth shark bull shark oceanic whitetip shark dusky shark tiger shark soupfin shark gray smoothound brown smoothound sicklefin smoothound blue shark Pacific sharpnose shark leopard shark dog fish sharks spiny dogfish angel sharks angel shark guitarfishes thornback shovelnose guitarfish skates big skate California skate stingrays diamond stringray round stingrays eagle rays bat ray herrings Pacific herring Pacific sardine anchovies northern anchovy smelts night smelt Table 1. Scientific name Salmonidae Oncorhynchus mykiss Ophiidae Chilara taylori Gadidae Merluccius productus Microgadus proximus Batrachoididae Porichthys spp. Gobiesocidae Gobiesox meandricus Atherinidae Atherinops affinis Atherinopsis californiensis Leuresthes tenuis Gasterosteidae Gasterosteus aculeatus Scorpaenidae Scorpaena guttata Sebastes spp. . auriculatus . carnatus . diploproa goodei . miniatus . paucispinis . rastrelliger . Serriceps Hexigrammidae Hexagrammos decagrammus H. lagocephalus Ophiodon elongatus Cottidae Clinocottus analis Hemilepidotus spinosus Leptocottus armatus Scorpaenichthys marmoratus Percichthyidae Steriolepis gigas Serranidae Paralabrax clathratus P. maculatofasciatus P. nebulifer Carangidae Seriola lalandi Trachurus symmetricus Anisotremus davidsoni Xenistius californiensis Sciaenidae Atractoscion nobilis Cheilotrema saturum Genyonemus lineatus Menticirrhus undulatus ANNHHANHAANRAN HOLOCENE RANGE STABILITY OF FISHES AROUND POINT CONCEPTION 35 Common name trouts steelhead (anadromous rainbow trout) cusk eels spotted cusk eel cods Pacific hake Pacific tomcod toadfishes specklefin and plainfin midshipman clingfishes northern clingfish silversides topsmelt jacksmelt California grunion sticklebacks threespine stickleback scorpionfishes California scorpionfish rockfishes brown rockfish gopher rockfish splitnose rockfish chilipepper vermillion rockfish bocaccio grass rockfish treefish greenlings kelp greenling rock greenling lingcod sculpins woolly sculpin brown Irish lord Pacific staghorn sculpin cabezon temperate basses giant seabass sea basses kelp bass spotted sandbass barred sandbass jacks yellowtail jack mackerel sargo salema drums white seabass black croaker white croaker california corbina Table 1. Scientific name Seriphus politus Umbrina roncador Kyphosidae Girella nigricans Embiotocidae Amphistichus sp. Brachyistius frenatus Cymatogaster aggregata Embiotoca jacksoni E. lateralis Hyperprosopon argenteum H. anale Hypsurus caryi Micrometrus sp. Phanerodon furcatus Rhacochilus toxotes R. vacca Pomacentridae Chromis punctipinnis Sphyraenidae Sphyraena argentea Labridae Halichoeres semicinctus Semicossyphus pulcher Stichaeidae Cebidichthys violaceus Plagiogrammus hopkinsi Xiphister mucosus Pholidae Apodichthys flavidus Anarhichadidae Anarrhichthys ocellatus Clinidae Gibbonsia montereyensis Heterostichus rostratus Gobiidae Eucyclogobius newberryi Gillichthys mirabilis Scombridae Sarda chiliensis Scomber japonicus Thunnus alalunga Xiphiidae Xiphias gladius Bothidae Citharichthys sp. Paralichthys californicus Pleuronectidae Atherestes stomias Hypsopsetta guttulata Platichthys stellatus Pleuronichthys coenosus P. ritteri SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Common name queenfish yellowfin croaker sea chubs opaleye surfperches barred, calico, or redtail surfperch kelp perch shiner perch black perch striped surfperch walleye surfperch spotfin surfperch rainbow seaperch reef or dwarf surfperch white seaperch rubberlip seaperch pile perch damselfishes blacksmith barracudas Pacific barracuda wrasses rock wrasse California sheephead pricklebacks monkeyface prickleback crisscross rickleback rock prickleback gunnels penpoint gunnel wolffishes wolf-eel clinids crevice kelpfish giant kelpfish gobies tidewater goby longjaw mudsucker mackerels Pacific bonito chub mackerel albacore swordfishes swordfish lefteye flounders sanddabs California halibut righteye flounders arrowtooth flounder diamond turbot starry flounder C-O sole spotted turbot HOLOCENE RANGE STABILITY OF FISHES AROUND POINT CONCEPTION | Methods Common and scientific names follow Robins et al. (1991) (Table 1). Original identifications in this study were made by comparison with skeletal materials at the Department of Biology, California State University, Bakersfield, and the Mu- seum of Natural History of Los Angeles County. The lowest possible taxon was determined except where discrimination was not useful or exceedingly time con- suming. For example, distinguishing between the 59 ecologically and morpholog- ically similar species of rockfishes (Lea 1992) is judged unlikely, especially when identification is based on vertebrae and fragmentary skeletal materials (Gobalet and Jones 1995). Therefore, identifications within the genus Sebastes are reported as rockfishes. The reports of findings of rockfish species of other authors, however, are included for completeness, but are viewed with suspicion. The kelp greenling was chosen over the rock greenling on the basis of their ranges (Eschmeyer et al. 1983). Within the genera Raja (skates), Porichthys (plainfin and specklefin mid- shipman) and Paralabrax (kelp, spotted, and barred sandbasses), the inability to discriminate between species prohibited further identification. With the exception of the chub mackerel and Pacific bonito, discrimination between mackerels (fam- ily Scombridae) was limited because of the shortage of comparative materials. Certain elements are diagnostic for requiem sharks (family Carcharhinidae); rays (order Rajiformes); Pacific sardine and Pacific herring (family Clupeidae); tops- melt, jacksmelt, and California grunion (family Atherinidae); surfperches (family Embiotocidae); clinids (family Clinidae); gobies (family Gobiidae); and numerous righteye and lefteye flounders (families Bothidae and Pleuronectidae). However, the broader groups were used because attempting to achieve species identifications using the most commonly recovered elements, vertebrae, for ray-fined fishes and centra for elasmobranchs, can be extremely time-consuming or impossible. Some appropriate comparative materials were not available. It is important that identi- fications be corroborated by more than one investigator because of dramatic dis- crepancies in interpretation by specialists (Gobalet unpublished data). Results and Discussion Published data from 12 sites in San Luis Obispo County, and unpublished data from three of these sites (SLO-165, -267, -179), as well as four additional sites (SLO-168, -1764, 1796, 1797) are included in Table 2. Table 2 also contains published data from four sites in Santa Barbara County (SBA-1, SBA-1807, -2057, and -2061,) along with unpublished data from 11 different sites and ad- ditional data for SBA-1 (Peterson 1984). In general, these data reflect that Pt. Conception has been a consistent zoogeographic barrier for the duration of human exploitation of the marine resources. Horn shark remains have been found by separate investigators at sites in Santa Barbara County south of Pt. Conception. Because the four unstipulated elements attributed to horn shark by Salls et al. (1989, in Gobalet and Jones 1995) have not been reinforced by findings in two subsequent studies of SLO-165, the data are considered unconfirmed. Both shortfin mako (5 elements) and swell shark (3 elements) have been found by independent investigators only in southern Cali- fornia locations and not to the north. 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I g pil Ol 9 v Jeroyoeu Yoel v I I (6 I I [TeymoToR 6t v ce I cé I I ‘ds xp1qv]DAvVd I I sseqeas UID 6 I I L v06 OVS SL 9 ELT uozeqe,) S S CLT Gill €9¢ urdjnos usoyseis sy1oed I I 67 ¢ € Ic surdynog 6C C LC rol (Ao € 6 6S poosury L I € € LvT 96 IL I 6L sulusais djay 8Le E 8S Iv 6l SC 6SI EL CSCYV 8 I¢0c O9P SI 9cLI Soysyyooy fs L ysyuordioss erusojsipeg [BI0IQNS (SOUS €) (SOUS ¢) (SOUS €) I - Svc- vOre- pS- [eIoIqns 96LT- 6LI- LOC S9I- (sens sarsedg Vas puos uosuyof ysiI®?S sVaS ;:VdS Vas -VdS OFS, .V9LI- 2907S», OTS O78 cl) Baral pOTS vOTS MIS [eorso;ooeyoiy ‘ponunuoy “7 219], SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 40 ‘(y661) UOspuRIq *[190T- “LSOT- “LO8I-WdS « ‘(eyep poyst{qndun uosuyos ‘f) TELI- ‘PLOI- “EL- ‘TL- ‘IL-WAS: ‘yoqin) poyods /Z ‘JoGin} puowrIp | ‘yreYsS [[ISUdAVS ZZ ‘a1OORqIe QI ‘UeWdIYyspru uyapyoods 7 ‘o1ls0"00qg 6 ‘YSYYOOI ssvis ¢ ‘YSYYoI uMOIQ Z ‘Ysysen | ‘Ysyyoo1 1oydos p spnypour saysyyoos (eyep poystqndun seg “yY) OO6I- “8b- “LT-WAS » ‘AeISUNS PUOUWIP p SYIeYS JaYSoIY} UOWIUIOD | ‘yIeYS ][][IsuaAes | ‘YSYPpIOMS L ‘ysyyoo1 uous Z ‘taddadiyrys [ ‘ysyyso1 asouqrds | ‘ysyyoo1 djoy | opnjour soysyyso1 (vep poystjqndun) uosuyos pue (8/6]) JoyIeg pue UO}sa;PpNH = “yaeys UOUW]TeS | Sepnyjout , ‘SOSSBIM € PUB ‘SOIgOS 6] ‘YOJodjins MoquIvi | sapnyout , “LOLI-O'TS Wor YsYASoI | SepnN[sut p “yreys uowyes | ‘Jauuns yurloduad | sapnyour , ‘uldjnos A[JOOM | SAPNIUT , ‘JoqIn} puowleIp / ‘joqin} poyods | “ds uoposauvygd TZ] ‘yosiodeas Moqutel 06 ‘seIqos 6z ‘Yyossd day Z ‘Jaa ysno poayods | ‘ajos O-| | ‘a[Os JaA0q | “epunoy yooymoure |[ “ds sdysyouvysID TZ “s[92 JOM OT] ‘yoeqopyoud sso1dssuo ¢ ‘yosodyins uyjods | ‘aXayedo Z ‘pio] Ysuy uMOIG | “eUloTes | SepnpoUl (C6G] SouOL puL Jo[VGOD) OI- “8- “L- ‘- “L6b- “66L- “S9I- “SOET- “6LI- “SLI- “L9T- “99T-OTS & TSETI =O 698 96ST O68It O09 TStT «= SEIT Ss SBGLI- LST eC OLEL. BVSL —6LS 888 [BIOL if I 9 Japunoy ARs OV VV I I e t nqiey eIUIOFITe) OI I 6 8 I ré G slapunoy oAaysu pue sAajaq Ser VC OF ie C 8el VIC E 14 £ Jeroyoru qny) aa C pEYE: ve I ouog 9yloed gs el (G4 S[eoyoeW I I al ec v € € ysydyjay yurip Oc Ol L el DISUOGGIHH (4 G 15) SI I I sprul[) (AWG I tv 10l L9 yorgapyoud yoy CCS S8I Sv € 687 yorgapyoud soejAoyuoypy EOE O9¢ L syoReqepPyoud Sc SC L £ YUWsyoe] | I I aSsSBIM YOOY 6v I. vl C I lt I peaydaays erusoytyeD C6 be Is Ol 6L Sl C 19 BILIOUIS [BIOIQNY (SoS ¢€) (SoS ¢)(Sous €) — [- Cyc- vOve- vS- RIoiqns 96LI- 89T 6LI- LIT COI- = (sauts sa1oadg Vds fuos = ,uosuyof ySII®@S sVES sVdS VdS -VdES Ojs i- O18 s01S O'S . OTS TI) -pueyiq pO'1S eO'lS DIS [ROIsO;OoRYyOIYV ‘ponunuoy “7 IqRL HOLOCENE RANGE STABILITY OF FISHES AROUND POINT CONCEPTION 41 Obispo County sites, is a strong reflection of their current zoogeographic range. This finding, however, must be qualified because the vertebrae of true smelts are so tiny that 1/16’ mesh screens must be used in their recovery, and many col- lections lack or have limited materials of true smelts among their comparative materials (e.g. Zooarchaeology Laboratory, UCLA; faunal collection of the De- partment of Anthropology, UCSB; and Santa Barbara Museum of Natural His- tory). Because of their tiny size, these fishes are likely to be missed during screen- ing or during the subsequent faunal identification. Northern clingfish are an ex- clusively northern California species and are found only in northern sites. The identification of a single vertebra of Paralabrax at SLO-165 by Salls et al. (1989, in Gobalet and Jones 1995), and confirmed by this author by examination of the same sample, is the only element of the generally southern California genus found at San Luis Obispo County sites. This contrasts with 39 elements within the genus found to the south. Since only two Pacific barracuda have been found at San Luis Obispo County sites in contrast with 91 at the Santa Barbara County localities, the findings are consistent with expectations. In addition, Pacific barracuda ele- ments are present in small numbers among midden materials on the Monterey, San Mateo, and Sonoma County coasts (Gobalet and Jones 1995, Gobalet 1997). California sheephead remains are consistently found in southern California. None have been identified at the San Luis Obispo County sites, while at least four different investigators have found their remains in the southern area where they are currently more abundant. The few California sheephead remains found in Monterey County reported in Gobalet and Jones (1995) have not been verified by a second specialist. The numerous monkeyface and rock prickleback elements found (including those identified only to family) exclusively at San Luis Obispo County (and even more abundant in middens in coastal Humboldt County sites in far northern Cal- ifornia [Gobalet 1997]) strongly reinforce the hypothesis of zoogeographic range stability. Though found only among midden materials in the northern sites, crevice kelpfish are a more tentative indicator because three members of the genus Gibb- sonia range far south of Pt. Conception. Only skeletal materials of G. monter- eyensis (crevice kelpfish) were available for comparative study. The few starry flounder found at San Luis Obispo County localities contrast with their extraor- dinary abundance at MNT-234 on Monterey Bay (Gobalet and Jones 1995) well to the north. Though they range to Santa Barbara (Eschmeyer et al. 1983), starry flounder would be rare at the extremes of their range and their scarcity or absence from the Santa Barbara County sites is expected. Findings by Salls et al. (1989, in Gobalet and Jones 1995) of single elements of sargo, salema, two elements of opaleye, and seven elements of blacksmith at SLO-165 would, at first appearance, be findings inconsistent with their predicted occurrence. These identifications have not been confirmed through the examina- tion of considerable additional material recovered during subsequent excavations of SLO-165. Four independent fish faunal specialists have been unable to confirm the presence of scales of northern anchovy, Pacific sardine, or bones of three genera of silversides, four genera of surfperches, California halibut, or opaleye in a sample of the materials evaluated by Salls et al. (1989, in Gobalet and Jones 1995) (Gobalet unpublished data). Consequently there is considerable suspicion that sargo, salema, blacksmith, and other elements have been misidentified as well. 42 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 3. Species found generally only at archaeological sites in Santa Barbara County or San Luis Obispo County. Santa Barbara County Sites San Luis Obispo County Sites horn shark night smelt shortfin mako northern clingfish swell shark monkeyface prickleback Paralabrax sp. rock prickleback California scorpionfish crevice kelpfish California sheephead starry flounder Pacific barracuda Pacific tomcod giant seabass kelp greenling rock wrasse queenfish white seabass sargo blacksmith California corbina yellowfin croaker black croaker The four sargo and 25 blacksmith remains Salls reported at sites in Santa Barbara County (Table 2) are within their expected range and would provide evidence to support the hypothesis, but they too require secondary verification. Additionally, secondary confirmation is required for two Pacific tomcod elements found only at SLO-165 and the finding of California scorpionfish, giant seabass, and rock wrasse remains only at Santa Barbara County sites. Salls reported a stunning array of members of the drum family at three Santa Barbara County localities (Table 2): 10 California corbina, 10 yellowfin croaker, 265 white croaker, 13 queenfish, 3 black croaker, and 12 white seabass. Of these only white seabass have been reported in an independent study at SBA-1 by Huddleston and Barker (1978). Queenfish and white croaker, have been confirmed by other investigators from Santa Barbara County sites (Huddleston and Barker 1978, Erlandson 1994, Johnson unpublished data, Table 2). The large number of queenfish at Santa Barbara sites with 292 elements contrasting with only eight at the San Luis Obispo sites is consistent with their abundance within their present range. The drums reported by Salls would be expected at the southern sites, providing additional evidence for past and present zoogeographic consistency. The presence of 16 confirmed or tentatively confirmed species mostly within their southern ranges and eight species with generally northern ranges collectively provide evidence that the prehistoric distribution of marine fishes to the immediate north or south of Pt. Conception has not changed from the time of Native Amer- ican habitation to the present (Table 3). Contradictory data are few. Gray smooth- hound, though rare north of Pt. Conception (Eschmeyer et al. 1983), were reported by Fitch (1972) at SLO-2 and confirmed at SLO-165 (Table 2). Their rarity, however, is consistent with their scarcity north of Pt. Conception (four elements at San Luis Obispo County sites versus 23 at Santa Barbara County sites). No soupfin shark have been found at the San Luis Obispo County sites, while being rather common at the Santa Barbara County localities. Soupfin shark range from British Columbia to Baja California (Eschmeyer et al. 1983). Pacific hake are HOLOCENE RANGE STABILITY OF FISHES AROUND POINT CONCEPTION 43 typical finds in archaeological sites in central California (Gobalet and Jones 1995), but would be expected at the Santa Barbara County sites as well: they are absent. Though occasionally common off central California (Love 1996), Pacific bonito are lacking in the San Luis Obispo sites. The real surprise is that, given the vagaries of the archaeological record, there are not more species with unpredict- able occurrence. The findings reported here are remarkably consistent with ex- pectations. Acknowledgments John R. Johnson and Roy Salls (deceased) shared their data on Santa Barbara County archaeological sites and permitted their use in this study. Geoff Hoetker did the bulk of the identifications at SBA-54, Antonio Sanchez at SBA-3404, and Todd Martin at SLO-165 (all work corroborated by the author). Ella Pedroza typed the manuscript. Other useful materials or advice were provided by David Ger- mano, Michael Glassow, William Hildebrandt, Debbie Jones, Terry Jones, and Valerie Levulett. Clay Singer provided materials from the excavation of SLO-165 in the 1980’s as well as the catalog. My thanks to Caltrans and Farwestern An- thropological Research Group, Inc. of Davis, California for financing much of the original work reported here. Literature Cited Erlandson, J.M. 1991. A radiocarbon series for CA-SBA-1 (Rincon Point), Santa Barbara County, California, J. Calif. and Great Basin Anthro. 13(1):110—117. Erlandson, J.M. 1994, Early hunter-gatherers of the California coast. Plenum Press, New York. 336 Pp. Eschmeyer, W.N., E.S. Herald, and H. Hamman. 1983. A field guide to Pacific Coast fishes of North America from the Gulf of Alaska to Baja, California. Houghton Mifflin, Boston. xii + 336 pp. Fitch, J.E. 1972. Fish remains, primarily otoliths, from a coastal Indian midden (SLO-2) at Diablo Cove, San Luis Obispo, County, California. San Luis Obispo County Archaeological Society Occasional Paper 7. Gobalet, K. W. 1990. Prehistoric status of freshwater fishes of the Pajaro-Salinas River system of California. Copeia 1990(3):680—685. Gobalet, K. W. 1992. Inland utilization of marine fishes by Native Americans along the central Cal- ifornia coast. J. Calif. and Great Basin Anthro. 14(1):72—84. Gobalet, K. W. 1993. Additional archaeological evidence for endemic fishes of California’s Central Valley in the coastal Pajaro-Salinas Basin. Southwestern Naturalist 38:218—223. Gobalet, K. W. 1997. Fish remains from the early 19th century Native Alaskan habitation at Fort Ross. pp. 319-327 in K.G. Lightfoot, A.M. Schiff, and T.A. Wake (eds). The Archaeology and Ethnohistory of Fort Ross. Volume 2. The Native Alaskan neighborhood, A multi-ethnic com- munity at Colony Ross. Cont. Univ. Calif. Archaeol, Res, Fac. Berkeley, #55. Gobalet, K. W. and T. L. Jones, 1995. Prehistoric Native American fisheries of the central California coast. Trans. Amer, Fish, Soc. 124:813-823, Holmes, M. S., and J. R. Johnson. 1998, The Chumash and their predecessors, an annotated bibliog- raphy. Santa Barbara Museum of Natural History Contributions in Anthropology number 1, XiV+228 pp. Huddleston, R. W. and L. W. Barker. 1978. Otoliths and other fish remains from the Chumash midden at Rincon Point (SBA-1) Santa Barbara-Ventura Counties, California. Natural History Museum of Los Angeles County contributions in Science 289. 36 pp. Lea, R. N. 1992. Rockfishes: overview, pp. 114-117 in California’s living resources and their utili- zation. W. S. Leet, C. M, Dewees, and C. W. Haugen (eds.). University of California, Davis, Sea Grant Extension Publication UCSGEP-92-12. 157 pp. Love, M. 1996. Probably more than you want to know about the fishes of the Pacific Coast. Really Big Press, Santa Barbara, California. 381 pp. 44 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Miller, D. J. and R. N. Lea. 1972. Guide to the coastal marine fishes of California. Calif. Dept. of Fish and Game, Fish Bulletin 157. 249 pp. Peterson, R. R. 1984. Early/Middle period subsistence changes at SBA-1, Rincon Point, coastal Cal- ifornia. J. Calif. and Great Basin Anthro. 6(2):207—216. Robins, C. R., R. M. Bailey, C. E. Bond, J. R. Brooker, E. A. Lachner, R. N. Lea, and W. B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. 5th edition. Amer. Fish. Soc. Spec. Publ. 20. 183 pp. Salls, R. A., R. W. Huddleston, and D. Bleitz-Sanburg. 1989. The prehistoric fishery at Morro Creek, CA-SLO-165, San Luis Obispo County, California. Unpublished report for Clay Singer and Associates, Cambria, California. Data reported by Gobalet and Jones (1995). Accepted for publication 9 December 1998. Bull. Southern California Acad. Sci. 99(1), 2000, pp. 45-54 © Southern California Academy of Sciences, 2000 Age and Size of Acacia and Cercidium Influencing the Infection Success of Parasitic and Autoparasitic Phoradendron Simon A. Lei Department of Biology, Community College of Southern Nevada 6375 West Charleston Boulevard, Las Vegas, Nevada 89146 E-mail: salei@juno.com Abstract.—The degree of parasitic and autoparasitic Phoradendron californicum (desert mistletoe) infections on various ages and sizes of Acacia gregii (catclaw) and Cercidium floridum (blue palo verde) host trees was quantitatively investi- gated in southern Nevada and southeastern California. Phoradendron californicum commonly parasitized A. greggii, but occasionally parasitized C. floridum trees. Autoparasitic P. californicum infested another parasitic P. californicum, which, in turn, infested these two host species. Parasitism and autoparasitism of P. cal- ifornicum were significantly positively correlated with age, and were consistently more correlated with size (height and canopy area) of A. greggii and C. floridum. Between the two host species, parasitism and autoparasitism were more positively correlated with age and size of A. greggii. Host age was significantly positively correlated with host size in both species. Area of parasite canopies was signifi- cantly greater than area of autoparasite canopies. A combination of age and size of A. greggii and C. floridum hosts partially limited the infection success of parasitic and autoparasitic P. californicum in southern Nevada and southeastern California. Phoradendron species (mistletoes) are autotrophic obligate parasites inhabiting branches of higher vascular plants (Kuijt 1969; Calder and Bernardt 1983). Branches of their host plants often swell from overinfestation by Phoradendron species (Holland et al. 1977). Phoradendron species are green and leafy. They mainly derive water and various mineral nutrients from their host plants by direct xylem connections (Leonard and Hull 1965; Raven 1983; Kaufman 1989). Yet, the genus Phoradendron produces some of its food photosynthetically, and derives little or no carbohydrate from its hosts (Barbour et al. 1987). Phoradendron cal- ifornicum (desert mistletoe) is a native parasitic plant that is sparsely distributed in southern Nevada and southeastern California. Phoradendron californicum fre- quently parasitizes several species of riparian and leguminous plant hosts, includ- ing Prosopis glandulosa (honey mesquite) and Acacia greggii (catclaw), but only occasionally parasitizes Cercidium floridum (blue palo verde), Larrea tridentata (creosote bush), and Tamarix ramosissima (saltcedar) trees (Holland et al. 1977). The biology of P. californicum is well documented, indicating that this parasite physically taps host xylems to acquire water and various mineral nutrients from xylem fluids (Kuijt 1969; Walters 1976; Calder and Bernardt 1983; Ehleringer and Schulze 1985; Ehleringer et al. 1985 and 1986; Overton 1992; Jordan et al. 1997). Phoradendron californicum can also be epiparasitized by other P. califor- 45 46 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES T 11500 W NEVADA CALIFORNIA Colorado River 36 00 N ARIZONA ik Kilometers Fig. 1. Sketch map showing location of four P. californicum infection study sites in southern Nevada and southeastern California. nicum individuals, which are in turn parasitic on A. greggii (Schulze and Ehler- inger 1984) and C. floridum (blue palo verde) hosts (Ehleringer and Schulze 1985). This epiparasitic phenomenon, known as autoparasitism, occurs infrequent- ly (Ehleringer and Schulze 1985). However, atypical host-parasite-autoparasite interactions involving the same three species remain poorly understood. This ar- ticle examines to what degree age and size of A. greggii and C. floridum hosts affect the infection success of parasitic and autoparasitic P. californicum in south- ern Nevada and southeastern California. Materials and Methods Study Area and Field Measurements Field studies were conducted in the Mojave and Colorado Deserts of southern Nevada and southeastern California, respectively, during the Fall of 1998 (Fig. 1). The Colorado Desert, ranging geographically from southeastern California to southwestern Arizona, is a major subdivision of the Sonoran Desert. Phoraden- INFECTION SUCCESS OF PARASITIC AND AUTOPARASITIC P. CALIFORNICUM 47 Table 1. Geographic characteristics of four P. californicum infection study sites in southern Nevada and southeastern California. Location, type of desert, as well as approximate elevation (m), latitude (N), and longitude (W) of these sites are shown. Study sites are arranged alphabetically within the Mojave Desert and Colorado Desert, a subdivision of the Sonoran Desert. Study site County, State Latitude Longitude Elevation Desert Las Vegas Valley Clark, NV 36°10’ PES OS’ 780 Mojave Rock Springs San Bernadino, CA 35°05’ 115°00' 620 Colorado Algodones Dunes Imperial, CA 33°00’ Mis tO! 90 Colorado Rice Valley Riverside, CA 34°00' 114°50’ 210 Colorado dron californicum and its A. greggii hosts occur along dry wash habitats in south- ern Nevada and southeastern California, whereas P. californicum and its C. flor- idum hosts occur in low-elevation sandy habitats of southeastern California (Fig. 1 and Table 1). Various stages of P. californicum infections (light, moderate, and heavy) on A. greggii and C. floridum hosts were evident. From a distance, large clumps of P. californicum individuals, with or without autoparasites, are easily visible among the bare and nearly bare branches of their hosts, appearing as slightly lighter green or brownish-green patches on host plants. Host species included individuals with parasitic and autoparasitic P. californi- cum (infested hosts) and included adjacent individuals without any visible P. californicum (control) on the canopies and branches. In Rock Springs and Las Vegas Valley, a total of 21 individuals of P. californicum were recorded as au- toparasitic on other P. californicum, which were parasitic on nine A. greggii host trees. In Rice Valley and Algodones Dunes, a total of ten individuals of autopar- asitic P. californicum were found growing indirectly on six C. floridum host trees. For this reason, 27 A. greggii and 18 C. floridum trees were evenly distributed among the three categories: hosts containing both parasites and autoparasites, hosts containing parasites only, and hosts without parasites at all. Uninfested hosts and hosts containing parasites only were randomly selected to provide unbiased sampling. An incremental borer was used to extract a core of main stems through pith to estimate age of A. greggii and C. floridum hosts. No attempt was made to account for missing or false rings. Since missing rings are common in desert woody plants, absolute ages are likely to be underestimates (Tonnesen and Ebersole 1997). With- in each infested host, all individuals of P. californicum (parasitic and autoparasit- ic) were counted. Host branch diameter and above-ground host branch height at the central point of P. phoradendron attachment were measured. Height and stem growth rate (diameter per ring) for main stems of infested and uninfested host plants were measured. Area of host, as well as area of parasitic and autoparasitic plant canopies were computed using the formula for the area of an ellipse. Statistical Analyses One-way analysis of variance (ANOVA) was performed to detect differences in age and size (height and canopy area) of infected and uninfected hosts. Tukey’s Multiple Comparison Test (Analytical Software 1994) was used to compare means of host age, size, and stem growth rate when a significant infection effect was detected. Student’s ¢ test (Analytical Software 1994) was conducted to compare 48 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 80 = WM Without parasites With parasites only HH] With parasites and autoparasites | 60 F - 40 - MEAN AGE OF HOSTS (yr) 20 ACACIA CERCIDIUM HOST SPECIES Fig. 2. Mean (+ SE) age of A. greggii and C. floridum hosts with both parasites and autoparasites, with parasites only, and without any visible parasites (control) (n = 27 in A. greggii and n = 18 in C. floridum trees). Within the same host species, different letters at the top of columns indicate statistical significant at P = 0.05. means of host branch diameter and above-ground host branch height, as well as to compare means of parasitic and autoparasitic canopy area in two host species. Pearsons correlation analysis (Analytical Software 1994) was performed to cor- relate abundance of P. californicum infection (total number of individuals on host canopy) with age and size of the two host species, and to autocorrelate the age and size of each host species. Mean values are presented with standard errors, and statistical significance is determined at P < 0.05. Results A number of A. greggii host trees were either uninfested or heavily infested by P. californicum plants (> 30 individuals per tree) in southern Nevada and southeastern California. Substantially more A. greggii trees were infested by P. californicum than C. floridum trees. Three hundred seventy-one (371) and 69 individuals of P. californicum were found parasitizing A. greggii and C. floridum trees, respectively. Age of the Acacia greggii stand was considerably older than age of the C. floridum stand (Fig. 2). Acacia greggii and C. floridum trees with P. californicum infestation were significantly (P <= 0.001) older (Fig. 2), taller (Fig. 3), and larger (Fig. 4) compared to adjacent uninfected hosts of the same species. Acacia greggii and C. floridum hosts showing autoparasitism were sig- nificantly (P = 0.001) older, taller, and larger than hosts showing moderate par- asitism (Figs. 2—4). Older, taller plants had a significantly greater stem diameter than younger, shorter plants (data not shown). However, stem growth rates (mean width of annual growth rings) for main stems of parasitized and unparasitized trees in both species were not significantly different (P > 0.05; Table 2). Indi- viduals of P. californicum primarily inhabited hosts’ secondary branches, although some individuals were found at the junction of main trunks and secondary branches. High levels of P. californicum infestation were significantly positively corre- lated (P = 0.001; Table 3) with age and size of A. greggii and C. floridum hosts. INFECTION SUCCESS OF PARASITIC AND AUTOPARASITIC P. CALIFORNICUM 49 7 WM Without parasites With parasites only 8 i FAA «With parasites and autoparasites a b Cc MEAN HEIGHT OF HOSTS (m) ACACIA CERCIDIUM H@ST) SPECIES Fig. 3. Mean (+ SE) height of A. greggii and C. floridum hosts with both parasites and autopar- asites, with parasites only, and without any visible parasites (control) (n = 27 in A. greggii and n = 18 in C. floridum trees). Within the same host species, different letters at the top of columns indicate statistical significant at P = 0.05. In both cases, parasitism and autoparasitism were most positively correlated with host canopy area, while least positively correlated with host age. Between the two host species, the abundance of P. californicum was more positively correlated (Table 3) with age, height, and canopy area of A. greggii. All possible two-way interactions between the age and size (height and canopy area) of A. greggii, as well as between the age and size of C. floridum hosts revealed significant positive correlations (P = 0.001; Table 4). The greatest pos- itive correlation was consistently found between height and canopy area in both host species (P = 0.001; Table 4). 20 T om WM Without parasites With parasites only FAH With parasites and autoparasites MEAN AREA OF HOST CANOPIES (m2) Ss is A ACACIA CERCIDIUM HOST SPECIES Fig. 4. Mean (+ SE) area of A. greggii and C. floridum host canopies with both parasites and autoparasites, with parasites only, and without any visible parasites (control) (n = 27 in A. greggii and n = 18 in C. floridum trees). Within the same host species, different letters at the top of columns indicate statistical significant at P = 0.05. 50 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 2. Mean (+ SE) stem growth rates (diameter per ring) of A. greggii and C. floridum hosts with both parasites and autoparasites, with parasites only, and without any visible parasites (control) (n = 9 inA. greggii and n = 6 in C. floridum trees). Mean values in rows followed by the same letter are not significantly different (P > 0.05). Mean Width of Annual Rings (cm/ring count) Host species Control Parasites only Autoparasites A. greggii 0.51 + 0.04 a 0.54 + 0.04 a 0.56 + 0.03 a C. floridum O57 = O3ra 0.60 + 0.04 a 0.62 + 0.04 a Mean heights and stem diameters of P. californicum-infested host branches, with or without autoparasites, did not differ significantly (P > 0.05; Table 5) in both A. greggii and C. floridum trees. Since C. floridum were considerably taller than A. greggii trees, P. californicum often established at C. floridum branches with a greater vertical distance from the ground surface. Areas of parasitic P. californicum canopies were significantly (P = 0.05; Table 5) greater than areas of autoparasitic canopies. Areas of parasite and autoparasite canopies were sub- stantially greater in A. greggii than in C. floridum trees (Fig. 5), even though C. floridum hosts were taller and had a considerably greater canopy area (Figs. 3—4). Discussion The degree of parasitic and autoparasitic P. californicum infestation on various ages and sizes of A. greggii and C. floridum hosts was examined in southern Nevada and southeastern California. Within each host species, data from two study sites were pooled to detect the significance of host age and size factors that appear to play a vital role in limiting P. californicum infection success. Ehleringer and Schulze (1985) saw occasional individuals of P. californicum parasitized oth- ers of the same species, which, in turn, grew on their A. greggii and C. floridum hosts near Oatman, Arizona. Nevertheless, no data from previous investigations are available to compare correlations between the abundance of parasitic and autoparasitic P. californicum and the age and size of their host plants species. There are several potential explanations for the higher levels of P. californicum infestation exhibiting a clumped distribution in older, taller, and larger A. greggii and C. floridum hosts. First, many taller, larger trees were significantly older with Table 3. Correlations (r-value) between the abundance of P. californicum and the age and size (height and canopy area) of A. greggii and C. floridum hosts (371 individuals of P. californicum growing on 27 A. greggii and 69 individuals growing on 18 C. floridum trees). Significance levels: *: Ps 0,05; .**:.P = 0.01; ***, P = :0.001; .NS:. Non-sienificant, Host species Interaction r-value A. greggil Host age * P. californicum abundance 0.807** Host height * P. californicum abundance 0.84*** Host canopy area X P. californicum abundance 0.86""" C. floridum Host age * P. californicum abundance 0.68** Host height * P. californicum abundance 0,737? Host canopy area X P. californicum abundance 0.31 *** INFECTION SUCCESS OF PARASITIC AND AUTOPARASITIC P. CALIFORNICUM 51 Table 4. Correlations (r-value) between the age and size (height and canopy area) of A. greggii and C. floridum hosts. Significance, levels: *; P = 0:05; **"°P = 0.01;-***: P = 0.001; NS: Non- significant. Host species n Interaction r-value A. greggii a Age X height 0325" Age X canopy area 0.84*** Height X canopy area O.33*** C. floridum 18 Age X height O72? Age X canopy area O88 247* Height X canopy area O:867** a significantly greater stem diameter than shorter, smaller trees. This phenomenon may indicate a time dependent P. californicum colonization rate (Lei 1999). In this study, autoparasitic P. californicum-infested hosts were significantly older than parasitic P. californicum-infested hosts, which were significantly older than uninfested hosts. Through time, P. californicum infestation intensifies consider- ably; the longer a host tree lives, the more opportunities for successful autopar- asites infestation. In this study, the abundance of parasites and autoparasites in- creased significantly with increasing host age irrespective to host stem growth rate. Second, large host tree size would provide a greater surface area, indicating more widespread secondary branches available for successful P. californicum col- onization and establishment (Lei 1999). In this study, most A. greggii trees ex- hibited multiple trunks, whereas C. floridum trees exhibited either single or mul- tiple trunks in relatively even frequencies. Mature or long-lived host trees were significantly taller and had a significantly greater canopy size compared to juvenile or short-lived trees of the same species in this study. Increasing in tree size, along with a greater surface area, may increase the host susceptibility of extensive P. californicum colonization and infestation, as evidenced by autoparasites inhabiting some of the tallest and largest hosts. Third, seeds of P. californicum are often dispersed by birds as they feed. Birds, such as Phainopepla nitens (phainopepla) and Minus polyglottos (northern mockingbird), ingest the seeds and may remain long enough on the infested hosts to deposit or defecate them onto branches of the same host plant (Haigh 1996). Fourth, dispersal of Phoradendron seeds can also be influenced by arboreal mammals and by gravity, but these are likely to be rare and minor mechanisms (Calder and Bernhardt 1983). Fifth, seeds of Phor- adendron species can be ejected from the fruits without avian or animal assistance (Kuijt 1969). These seeds may land on the same host plant through maternal Table 5. Mean (+ SE) host branch diameters and branch heights at the central points of parasitic and autoparasitic P. californicum attachments on A. greggii (n = 9) and C. floridum (n = 6) hosts. Mean values in rows followed by the same letter are not significantly different (P > 0.05). Host Host branch diameter (cm) Host branch height (m) species Parasite Autoparasite Parasite Autoparasite A. greggii Dodie = 2 a 3.0. .0;3.a LO Oa a 0.9.) 014a C. floridum 2:9 "O24 Say 3 O28 2 OS 212 O2a 52 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES WM Parasites V7] Autoparasites MEAN AREA OF PHORADENDRON CANOPIES (m2) ACACIA CERCIDIUM HOST SPECIES Fig. 5. Mean (+ SE) area of parasitic and autoparasitic P. californicum canopies (371 individuals of P. californicum growing on 27 A. greggii and 69 individuals growing on 18 C. floridum host trees). Within the same host species, different letters at the top of columns indicate statistical significant at i i kt oS influence or may land on another host, stick to its branches and germinate there (Belzer 1984). Although not examined in this study, significantly older, taller, and larger hosts may contain higher moisture content and nutritional value relative to younger, shorter, and smaller trees. In general, a number of essential nutrients, including N, PB, K, Ca, Mg, and Fe, are found highest in the autoparasitic P. californicum and lowest in the A. greggii hosts in northwestern Arizona (Ehleringer and Schulze 1985). In an parasite-autoparasite system involving P. californicum with A. greg- gii as the host, water use efficiency is highest in the host and lowest in the autoparasite, while transpiration rate appears to be greatest in the autoparasite and lowest in the host in northwestern Arizona (Schulze and Ehleringer 1984; Ehler- inger and Schulze 1985). The concepts of water use efficiency, as well as water and mineral nutrient acquisition from their hosts may partially explain a smaller canopy size observed in autoparasites than in parasites because a large canopy is energetically expensive to maintain over a long period of time. From casual ob- servations, autoparsites had little or no direct contact with host branches and xylems. Parasites obtain limited water and nutrients from their hosts; autopara- sites, in turn, obtain even more limited resources from their parasitic hosts. Low host-plant water potentials and water content may limit long-term P. californicum infection success in southern California (Jordan et al. 1997). Small, young trees may not have the physiological capabilities (insufficient water supply and essential nutrients) to support long-term parasitic and autoparasitic P. californicum infec- tion and reproductive success. Since both parasitic and autoparasitic P. califor- nicum tap to the same A. greggii host xylems (Ehleringer and Schulze 1985), they must constantly acquire limited resources from, and at the expense of, their A. greggii and C. floridum hosts. The distribution of Phoradendron californicum is scanty, and P. californicum is not an extremely important component of the Mojave and Colorado desert INFECTION SUCCESS OF PARASITIC AND AUTOPARASITIC P. CALIFORNICUM 53 vegetation in southern Nevada and southeastern California, respectively. Yet, lo- calized influences of P. californicum on A. greggii and C. flroidum hosts are conspicuous. Host age and size were two of the main factors that limited the long- term infection success of P. californicum. Larger, taller A. greggii and C. floridum plants were significantly older, and were significantly more likely to be infested with the parasites than younger, small plants. Within the same host species, trees exhibiting autoparasitism were significantly older, taller, and larger than trees ex- hibiting moderate or no parasitism. However, relationships between the infection success of P. californicum and the age and size of A. greggii and C. floridum hosts were purely correlative. Correlation between two variables does not nec- essarily mean that a cause-effect relationship actually exists between them. Host age and size appear to be strongly related to the availability of water and mineral nutrients. Future research at various geographical locations are required to deter- mine cause-effect relationships between the long-term infection or reproductive success of parasitic and autoparasitic P. californicum and the age, size, water and nutrient status of their host species. Acknowledgments I gratefully acknowledge Steven Lei, David Valenzuela, and Shevaun Valen- zuela for providing valuable field assistance. I also sincerely appreciate the De- partment of Biology of the Community College of Southern Nevada (CCSN) for providing logistical support. Literature Cited Analytical Software. 1994. Statistix 4.1, an interactive statistical program for microcomputers. Ana- lytical Software, St. Paul, Minnesota, 429 pp. Barbour, M.G., J.H. Burk, and W.D. Pitts. 1987. Terrestrial plant ecology. The Benjamin/Cummings Publishing Company, Inc., Menlo Park, California, 634 pp. Belzer, TJ. Roadside plants of southern California. Mountain Press Publishing Company, Missoula, Montana, 157 pp. Calder, M., and P. Bernhardt (eds.) (1983). The biology of mistletoes. Academic Press, New York. Ehleringer, J.R., and E.D. Schulze. 1985. Mineral concentrations in an autoparasitic Phoradendron californicum growing on a parasitic P. californicum and its host, Cercidium floridum. Am. J. Bot. 72:568—571. Ehleringer, J.R., E.D. Schulze, H. Ziegler, O.L. Lange, G.D. Farquhar, and I.R. Cowan. 1985. Xylem mistletoes: water or nutrient parasites? Science 227:1479-1481. Ehleringer, J.R., C.S. Cook, and L.L. Tieszen. 1986. Comparative water use and nitrogen relationships in a mistletoe and its host. Oecologia 68:279—284. Haigh, S.L. 1996. Saltcedar (Tamarix ramosissima) an uncommon host for desert mistletoe (Phora- dendron californicum). Great Basin Nat. 56:186—187. Holland, J.S., R.K. Grater, and D.H. Huntzinger. 1977. Flowering plants of the Lake Mead region. Southwest Parks and Monuments Association. Popular Series No. 23, 49 pp. Jordan, L.A., D.N. Jordan, EL. Landau, and S.D. Smith. 1997. Parasitism of two codominant desert plant hosts: low host-plant water potentials may limit long-term infection success. Abstract of the 1997 Ecological Society of America Annual Meeting. Albuquerque, New Mexico. 336 pp. Kaufman, P.B. 1989. Plants: their biology and importance. Harper and Row Publishers, New York, 757 pp. Kuit, J. 1969. The biology of parasitic flowering plants. University of California Press, Berkeley, California, 246 pp. Lei, S.A. 1999. Age, size and water status of Acacia greggii influencing the infection and reproductive success of Phoradendron californicum. Am. Midl. Nat. 141:358—365. 54 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Leonard, O.A., and R.J. Hull. 1965. Translocation relationships in and between mistletoes and their hosts. Hilgardia 37:115-—153. Overton, J.M. 1992. Host specialization in desert mistletoe Phoradendron californicum. Bull. Ecol. Soc. Am. 73:293. Raven, J.A. 1983. Phytophages of xylem and phloem: a comparison of animal and plant sap-feeders. Adv. Ecol. Res. 13:136—234. Schulze, E.D., and J.R. Ehleringer. 1984. The effect of nitrogen supply on growth and water-use efficiency of xylem-tapping mistletoes. Planta 162:268—275. Tonnesen, A.S., and J.J. Ebersole. 1997. Human trampling effects on regeneration and age structures of Pinus edulis and Juniperus monosperma. Great Basin Nat. 57:50—56. Walters, J.W. 1976. A guide to mistletoes of Arizona and New Mexico. USDA For. Serv., Southwestern Region, Forest Insect and Disease Manag., 7 pp. Accepted for publication 17 May 1999. Bull. Southern California Acad. Sci. 99(1), 2000, pp. 55-57 © Southern California Academy of Sciences, 2000 Research Note Helminths of the Channel Islands Slender Salamander, Batrachoseps pacificus pacificus (Caudata: Plethodontidae) from California Stephen R. Goldberg', Charles R. Bursey* and Hay Cheam! ‘Department of Biology, Whittier College, Whittier, California 90608, U.S.A. 2Department of Biology, Pennsylvania State University, Shenango Campus, Sharon, Pennsylvania 16146, U.S.A. The Channel Islands slender salamander, Batrachoseps p. pacificus (Cope 1865) is restricted to San Miguel, Santa Rosa, Santa Cruz and Anacapa Islands off the coast of Santa Barbara, California (Petranka 1998). The blackbelly slender sala- mander, B. nigriventris Cope 1869 occurs in sympatry with B. p. pacificus on Santa Cruz Island (Petranka 1998). The Pacific treefrog, Hyla regilla Baird and Girard 1852, western fence lizard, Sceloporus occidentalis Baird and Girard 1852, side-blotched lizard, Uta stansburiana Baird and Girard 1852, southern alligator lizard, Elgaria multicarinata (Blainville 1835), eastern racer, Coluber constrictor Linnaeus 1758, gopher snake, Pituophis catenifer (Blainville 1835) and spotted night snake, Hypsiglena torquata ochrorhyncha Cope 1860 also occur on Santa Cruz Island (Savage 1967). Populations of these species on Santa Cruz Island have not been examined for helminths; however, adjacent mainland populations (Los Angeles County, CA), of B. nigriventris, H. regilla, S. occidentalis, and U. stansburiana have been studied (Koller and Gaudin 1977; Goldberg et al. 1998a, 1998b, 1999). The purpose of this study was to determine the helminth fauna of a population of the channel islands slender salamander, B. p. pacificus. One hundred seventy four B. p. pacificus were examined: 96 females, mean snout-vent length (SVL) = 40.5 mm + 7.1 SD, range 27-56 mm; 78 males, SVL = 40.2 mm + 6.6 SD, range 28-54 mm were examined. There was no significant difference in SVL between male and female subsamples (ANOVA, F = 0.86, P > 0.05). These salamanders were collected in the western portion of the central valley of Santa Cruz Island, Santa Barbara County, California (33°65'N, 119°42'’W to 34°O1’N, 119°52’W), elevation about 76 m, March 1971 and have been deposited in the herpetology collection of the Natural History Museum of Los Angeles County (LACM 144880-—145053). The body cavity was opened, the gastrointestinal tract removed and the esoph- agus, stomach, small intestine, large intestine, bladder and body cavity of each specimen was examined separately under a dissecting microscope. Each nematode was removed and placed in a drop of glycerol on a glass slide. Some cestode larvae were stained regressively with hematoxylin, others were embedded in par- affin, cut into 5 wm sections, mounted on glass slides and stained with hematox- ylin followed by eosin counterstain. All specimens were examined with a com- pound microscope. Terminology is in accordance with Bush et al. (1997). Ninety nine salamanders (57%) harbored helminths (Table 1): 50 females a5 56 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Prevalence, mean intensity and abundance of helminths from Batrachoseps p. pacificus from Santa Cruz Island, CA. Mean Mean Number Site of Preva- intensity abundance? Helminth helminths infection lence! % +SD Range *+SD Cestoda Mesocestoides sp. 48 coelom 1 48 — 0.3 £36 (tetrathyridia) Nematoda Batracholandros 183 large 54 LO 2.6 1-25 [ene salamandrae intestine Oswaldocruzia aT small, large 9 |e ei sae Ie | 1-7 0.2 = 07 pipiens intestine ' Number of hosts infected with one or more individuals of a parasite species divided by the number of hosts examined. ? Total number of individuals of a parasite species divided by the total number of hosts examined. (52%), 49 males (63%). There was no significant difference in prevalence between male and female salamanders, Chi square = 1.26, P > 0.05. One male salamander (54 mm) had 48 tetrathyridia of the cestode Mesocestoides sp. encysted on its liver. Ninety four salamanders (54%) 48 females, 46 males, harbored 183 indi- viduals of the nematode Batracholandros salamandrae (Schad 1960), and 15 salamanders (9%), 6 females, 9 males harbored 27 individuals of the nematode Oswaldocruzia pipiens Walton 1929. There was no significant difference for prev- alence between male and female salamanders, Chi square = 1.39, 1.52, respec- tively, P > 0.05. Likewise, there was no relationship between SVL and helminth intensity, r? = 0.19. Ten salamanders had dual infections of B. salamandrae and O. pipiens; 1 salamander had a dual infection of Mesocestoides sp. and B. sala- mandrae. Each helminth infection represents a new host and locality record. Rep- resentative helminths were placed in vials of alcohol and deposited in the U.S. National Parasite Collection (USNPC), Beltsville, Maryland: USNPC # 88523 Mesocestoides sp.; USNPC # 88524 Batracholandros salamandrae; USNPC # 88525 Oswaldocruzia pipiens. Tetrathyridia of Mesocestoides sp. are commonly found in amphibians and rep- tiles (McAllister 1988; McAllister and Conn 1990); however, this is apparently the first report of Mesocestoides sp. from a salamander. Batracholandros sala- mandrae has previously been reported from salamanders of southern California as well as North America in general and is apparently restricted to the order Caudata (Goldberg et al. 1998a). Oswaldocruzia pipiens is a host generalist, oc- curring in amphibians and reptiles throughout North America (Baker 1987). Helminth communities of salamanders are difficult to analyze due to low spe- cies richness and dominance of the community by host generalists. Aho (1990) found salamanders in general to have per host individual a mean species richness of 0.70 + 0.04 SE and mean abundances of 5.2 + 1.38 SE. Mean species richness of helminths per host for this population of Batrachoseps p. pacificus was 0.63 + 0.05 SE and mean abundance of helminths was 1.40 + 0.33 SE. Apparently, the only other study of insular salamanders is that of Moravec (1984) in which the roughskin newt, Taricha granulosa (Skilton 1849) (N = 10) RESEARCH NOTE 57 was found to harbor two species of Trematoda Megalodiscus microphagus Ingles 1936, Brachycoelium salamandrae (Froelich 1789), and three species of Nema- toda, Cosmocercoides variabilis (Harwood 1930), Hedruris siredonis Baird 1858, Megalobatrachonema gigantica (Olsen 1938). Species richness and mean abun- dance cannot be calculated for the sample of 7. granulosa. But, as was true of the helminths harbored by B. p. pacificus, the helminths harbored by T. granulosa are found in adjacent mainland amphibian hosts (Baker 1987). Insular populations appear to follow the prediction of Goldberg et al. (1998a) that salamander species have helminth communities characterized by low species richness and dominated by host generalists. We thank Arden H. Brame, II, Jr. for the sample of B. p. pacificus. Literature Cited Aho, J. M. 1990. Helminth communities of amphibians and reptiles: comparative approaches to under- standing patterns and processes. Pp. 157-195 in Parasite Communities: Patterns and Processes. (G. W. Esch, A. O. Bush, and J. M. Aho, eds.). Chapman and Hall, London, xi + 335 pp. Baker, M. R. 1987. Synopsis of the Nematoda parasitic in amphibians and reptiles. Mem. Univ. Newfoundland, Occas. Pap. Biol., 11:1—325. Bush, A. O., K. D. Lafferty, J. M. Lotz and A. W. Shostak. 1997. Parasitology meets ecology on its own terms: Margolis et al. revisited. J. Parasitol., 83:575—-583. Goldberg, S. R., C. R. Bursey and H. Cheam. 1998a. Composition and structure of helminth communities of the salamanders, Aneides lugubris, Batrachoseps nigriventris, Ensatina eschscholtzii (Pletho- dontidae), and Taricha torosa (Salamandridae) from California. J. Parasitol., 84:248—251. ; , and . 1998b. Composition of helminth communities in montane and lowland populations of the western fence lizard, Sceloporus occidentalis from Los Angeles County, California. Amer. Midl. Nat., 140:186—191. : , and . 1999. Composition of the helminth community of a montane population of the side-blotched lizard, Uta stansburiana (Phrynosomatidae) from Los Angeles County, California. Amer. Midl. Nat., 141:204—208. Koller, R. L., and A. J. Gaudin. 1977. An analysis of helminth infections in Bufo boreas (Amphibia: Bufonidae) and Hyla regilla (Amphibia: Hylidae) in Southern California. Southwest. Nat., 21: 503-509. McAllister, C. T. 1988. Mesocestoides sp. tetrathyridia (Cestoidea: Cyclophyllidea) in the iguanid lizards, Cophosaurus texanus texanus and Sceloporus olivaceous, from Texas. J. Wild. Diseases, 24:160-163. , and D. B. Conn. 1990. Occurrence of tetrathyridia of Mesocestoides sp. (Cestoidea: Cyclo- phyllidea) in North American Anurans (Amphibia). J. Wild. Diseases, 26:540—543. Moravec, F 1984. Some helminth parasites from amphibians of Vancouver Island, B.C., western Canada. Vest. Cs. Spolec. Zool. 48:107—114. Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, D.C., xvi + 587 pp. Savage, J. M. 1967. Evolution of the insular herpetofaunas. Pp. 219-227 in Proceedings of the sym- posium on the biology of the California Islands. (R.N. Philbrick, ed.), Santa Barbara Botanic Garden, Santa Barbara, California, 363 pp. Accepted for publication 15 March 1999. tye ott pe Cy < we ba satuecit URGE teens erandigyerte brwininid roseathanil idkvalae tafe COBGET) cts 19 ‘avodhlud Io holtoibsAny st wolldl ‘oa : mjneol baa sesatioit eaigage wo, vd ppakeaioa test pending pene: ae = rea Pathe ly a Z Lo 2h step torsy ote’ 7 IF * Nam _ Ay eee of! ac). at Tl sme nabs, Hamels: i” 4 6.4 ae a ay 7 4 2 : k 4 ae ; peri | wririer Sh j f : “9 — = - & * An > 7" ~ 6 @ a? we ¢ dec cnanane epepeae Gea too Vadis o Z P ¥) : whi 4 ria lened d i =, a”. 10004, “Ser “Sikt Mitel ci ° a ¢* 7 “ THM Ae) HP ; | % ; j S ‘Co VIG ) ee na? ‘vate ; A 4 4 Fi . AA rs . wal “yu / imi vir n&. ,a\oasp ie é ® yen? pers ‘ ius a ‘ A - rf ; 4 7 1 ; J ih =| he ood An hen, = > oh a ’ 5= y » { t Md ave Pv 7 / . . i y INSTRUCTIONS FOR AUTHORS The BULLETIN is published three times each year (April, August, and December) and includes articies in English in any field of science with an emphasis on the southern California area. Manuscripts submitted for publication should contain results of original research, embrace sound principles of scientific investigation, and present data in a clear and concise manner. The current AIBS Style Manual for Biological Journals is recommended as a guide for contributors. Consult also recent issues of the BULLETIN. MANUSCRIPT PREPARATION The author should submit at least two additional copies with the original, on 8¥2 * 11 opaque, nonerasable paper, double spacing the entire manuscript. Do not break words at right-hand margin anywhere in the manuscript. Footnotes should be avoided. 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Evaluation of a paper submitted to the BULLETIN begins with a critical reading by the Editor; several referees also check the paper for scientific content, originality, and clarity of presentation. Judgments as to the acceptability of the paper and suggestions for enhancing it are sent to the author at which time he or she may be requested to rework portions of the paper considering these recom- mendations. The paper then is resubmitted and may be re-evaluated before final acceptance. Proof: The galley proof and manuscript, as well as reprint order blanks, will be sent to the author. He or she should promptly and carefully read the proof sheets for errors and omissions in text, tables, illustrations, legends, and bibliographical references. He or she marks corrections on the galley (copy editing and proof procedures in Style Manual) and promptly returns both galley and manuscript to the Editor. Manuscripts and original illustra- tions will not be returned unless requested at this time. All changes in galley proof attributable to the author (misspellings, inconsistent abbreviations, deviations from style, etc.) will be charged to the author. Reprint orders are placed with the printer, not the Editor. CONTENTS The Range, Habitat Requirements, and Abundance of the Orange-throated Whiptail, Cnemidophorus hyperythrus beldingi. Bayard Brattstrom _... Ants (Hymenoptera: Formicicae) of Santa Cruz Island, California. James K. Wetterer, Philip S. Ward, Andrea L. Wetterer, John T. Longino, James C. Trager and Scott E. Miller Oe a eee a Has Point Conception been a Marine Zoogeographic Boundary throughout the Holocene? Evidence from the Archaeological Record. Kenneth W. cients no oe Ie ee Age and Size of Acacia and Cercidium Influencing the Infection Success of Parasitic and Autoparasitic Phoradendron. Simon A. Let -... Helminths of the Channel Islands Slender Salamander, Batrachoseps pacificus pacificus (Caudata: Plethodontidae) from California. Stephen R.. Goldberg, Charles R. Bursey and Hay Cheam -------------- COVER: Photograph by John N. Tashjian of orange-throated whiptail, Cnemidophorus hyperythrus heldingi. ISSN 0038-3872 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES BOLLETIN Volume 99 Number 2 BCAS-A99(2) 59-113 (2000) AUGUST 2000 Southern California Academy of Sciences Founded 6 November 1891, incorporated 17 May 1907 © Southern California Academy of Sciences, 2000 OFFICERS David Huckaby, President Robert S. Grove, Vice-President Susan E. Yoder, Secretary Daniel A. Guthrie, Treasurer Daniel A. Guthrie, Editor Hans Bozler, Past President David Soltz, Past President BOARD OF DIRECTORS 1997-2000 1998-2001 1999-2002 Robert S. Grove Kathryn A. Dickson Ralph G. Appy David Huckaby Donn Gorsline Jonathan N. Baskin Robert Lavenberg Robert F. Phalen John W. Roberts Kenneth E. Phillips Daniel Pondella Tetsuo Otsuki Susan E. Yoder Cheryl C. Swift Gloria J. Takahashi Membership is open to scholars in the fields of natural and social sciences, and to any person interested in the advancement of science. Dues for membership, changes of address, and requests for missing numbers lost in shipment should be addressed to: Southern California Academy of Sciences, the Natural History Museum of Los Angeles County, Exposition Park, Los Angeles, California 90007-4000. Peofessignal Members: sok NS a ae ee MUOUREDEENE TV VCAUIIO RE oir. a OR AON nek et es ee gaetdy a ge Wrasse! oR) \ Se Secieten Che ele aaa a Memberships in other categories are available on request. Fellows: Elected by the Board of Directors for meritorious services. The Bulletin is published three times each year by the Academy. Manuscripts for publication should be sent to the appropriate editor as explained in “Instructions for Authors” on the inside back cover of each number. All other communications should be addressed to the Southern California Academy of Sciences in care of the Natural History Museum of Los Angeles County, Exposition Park, Los Angeles, California 90007-4000. Date of this issue 8 August 2000 © This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper). CALIFUANIA ' ACADEMY OF SCIENCES j Phe ' Bull. Southern California Acad. Sci. ’ ; : AU G d 9 7000 i 99(2), 2000, pp. 59-90 j © Southern California Academy of Sciences, 2000 LIBRARY i Ecological and Distributional Status of the Continental Fishes of Northwestern Baja California, Mexico ee Gorgonio Ruiz-Campos,' Salvador Contreras-Balderas,” Maria de Lourdes Lozano-Vilano,? Salvador Gonzalez-Guzman,! and Jorge Alaniz-Garcia! 'Laboratorio de Vertebrados, Facultad de Ciencias, Universidad Aut6noma de Baja California. Apdo. Postal 1653, Ensenada, Baja California, 22800, México. U.S. Mailing Address: PMB 64 P.O. Box 189003, Coronado, CA. 92178 *Bioconservacion, A.C. Apdo. Postal 504, San Nicolas de los Garza, Nuevo Leon, 66450, México 3Laboratorio de Ictiologica, Facultad de Ciencias Biolégicas, Universidad Auténoma de Nuevo Leon. Apdo. Postal 425, San Nicolds de los Garza, Nuevo Leon, 66450, México Abstract.—The ecological and distributional status of the continental fishes of northwestern Baja California, Mexico, was seasonally monitored between Feb- ruary 1996 and March 1997. A review of records in literature and of specimens collected between 1983 and 1995 in the study area, provide the data upon which this report is based. A total of 23 species (19 native and 4 exotic) belonging to 22 genera and 15 families was registered. This fish fauna is ecologically composed of species of marine derivation (78.9% sporadic and 21.1% diadromous) and by 8 permanent species (34.8%), 9 tidal visitors (39.1%) and 6 occasional visitors (26.1%). From the ichthyogeographical point of view, most of the species are of Californian affinity (68.4%) and the remaining related to northeastern Pacific (15.7%), Holarctic (5.3%) and circumtropical (5.3%) regions. Only one taxon (Oncorhynchus mykiss nelsoni) is endemic (5.3%) to the study region. Ten species are new continental records for Baja California [Norte], and seven taxa reach their southernmost continental ranges in northwestern Baja California. The conserva- tion status of Gasterosteus aculeatus microcephalus is considered as threatened. The main problem that affects the ecosystemic integrity of the streams of this region is the progressive alteration of the aquatic and riparian habitats caused by anthropogenic impact. Resumen.—E]| estatus ecoldgico y distributivo de los peces continentales del no- roeste de Baja California, México, fue evaluado estacionalmente entre Febrero 1996 y Marzo 1997. Una revision de registros de literatura y de ejemplares re- colectados entre 1983 y 1995 en el area de estudio, complementan los datos que soportan el presente estudio. Un total de 23 especies (19 nativas y 4 ex6ticas) pertenecientes a 22 géneros y 15 familias fue registrado. La ictiofauna continental se compone ecolé6gicamente por especies de estirpe marina (78.9% esporadicas y 21.1% diadromas) y en funcidn de tiempo por 8 especies permanentes (34.8%), 9 visitantes de marea (39.1%) y 6 visitantes ocasionales (26.1%). Desde un punto de vista ictiogeografico, la mayoria de las especies son de afinidad California (68.4%) y el resto a las regiones del océano Pacifico Nororiental (15.7%), Ho- lartica (5.3%) y Circumtropical (5.3%). Solamente un tax6n (Oncorhynchus my- kiss nelsoni) es endémico (5.3%) al area de estudio. Diez especies representan 59 60 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES nuevos registros en las aguas continentales de Baja California, y siete especies alcanzan sus distribuciones continentales mas surenas en el noroeste de Baja Cal- ifornia. El] estatus de conservaci6n de Gasterosteus aculeatus microcephalus es considerado como amenazado. El principal factor que atenta la integridad ecos- istémica de los arroyos de esta regiOn es la alteraci6n progresiva de los habitats acuaticos y riberefios causada por impacto antropogénico. The northwestern region of Baja California, Mexico, which includes the San Diego and San Pedro Martir faunistic districts, is of special interest due to its ecological and biogeographical peculiarities (Nelson 1921; Bancroft 1926). Its native continental fish fauna is entirely dominated by species of marine derivation or peripheral (Follett 1960; Ruiz-Campos and Contreras-Balderas 1987). The scarce representation of perennial streams in the Baja California peninsula (Blasquez 1959; Tamayo and West 1964; Murvosh 1994; INEGI 1995), combined with the paleohydrological discontinuity of its northwest region with that of south- ern California, as well as the great steepness of its eastern coast (Follett 1960) have been considered as the causative factors of the null dispersion of secondary and primary freshwater fishes (Myers 1951; Miller 1966) and the consequent invasion and establishment by fishes of marine derivation (e.g., vicarious, diad- romous, sporadic and complementary; Follett 1960; Ruiz-Campos and Contreras- Balderas 1987). Follett (1960) and Ruiz-Campos and Contreras-Balderas (1987) in their anno- tated check-lists of the continental fishes of the Baja California peninsula, cited only 13 species (6 native and 7 exotic) for the northwest region, the majority of which were from collections limited in time and space that were carried out about four decades ago. From the ichthyogeographical point of view, several taxa exist that reach their southernmost continental distribution ranges in northwestern Baja California; Lampetra tridentata Gairdner (Ruiz-Campos and Gonzalez-Guzman 1996), Fun- dulus parvipinnis parvipinnis Girard (Miller 1943), Gasterosteus aculeatus mi- crocephalus Girard (Miller and Hubbs 1969), and Leptocottus armatus australis Hubbs (Follett 1960). Additionally, one endemic taxon exists, the Nelson’s trout, Oncorhynchus mykiss nelsoni (Evermann), which is confined to the streams of the western slope of the Sierra San Pedro Martir (Ruiz-Campos 1993; Ruiz-Cam- pos and Pister 1995). In general terms, the continental ichthyofauna of the northwestern Baja Cali- fornia has been scarcely studied at ecological and taxonomical levels as compared with that of southern California (Swift et al. 1993). During the last two decades this region, particularly its coastal stripe, has been the focus of a growing an- thropogenic activity (e.g., urban, tourist, industrial and agricultural development) that puts at risk the stability of its aquatic and riparian ecosystems. The conservation of the aquatic ecosystems, especially those near the coast, is vital because they operate as reproduction and nursery habitats for a diversity of peripheral fishes, whose adult stages make up important links in the food chains of coastal environments or are of importance to fisheries (Horn and Allen, 1985; Horn, 1988; Zedler et al. 1992). Also, these biotopes are used by winter migrant CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA 61 birds that travel along the Pacific flyway (Ruiz-Campos and Rodriguez-Meraz 1993). For that reason, the present study evaluates the ecological and distributional status of the fish fauna inhabiting the coastal streams of northwestern Baja Cal- ifornia, Mexico. This study is mainly based on seasonal fish samplings carried out in twelve coastal streams during the period of 1996—1997. In addition, a review of literature records as well as specimens collected between 1983 and 1995, complete the data upon which this study is based. Finally, the information generated here can be used to support future conservation programs to protect regional biodiversity. Study Area The northwestern region of Baja California is characterized by possessing a mediterranean-type climate and exhibiting a distinctive pattern of rainy winters followed by dry summers (Archibold 1995). Its surface hydrology is represented by a series of small streams originating on the western slopes of the Sierras Juarez and San Pedro Martir, which flow toward the Pacific Ocean (Fig. 1). Most of these streams (Figs. 2 and 3) become intermittent in their middle and lower cours- es during extremely dry conditions (Tamayo and West 1964). The mouths of most streams are blocked from the ocean by sandbars, except during extreme flooding events or high tides that produce riverine-estuarine conditions. However, some streams (e.g., Santo Tomas, El Salado, San Simon and El Rosario) are perma- nently open to the sea due to tidal inflows. The average values of the physical-chemical variables registered seasonally in the studied streams are presented in Table 1. The salinity of the water was highly variable for most sampled streams and it was dependent of the opening or closing of the mouth during the big freshwater flows or the inflows of sea water at high tide. Localities at the mouths of the arroyos Cantamar, El] Descanso, San Miguel (El Carmen) exhibited little variation in salinity during the year because their mouths were frequently closed by sandy bars that prevented the entry of the high tide flows (Table 1). Most of the streams studied registered average pH values of slightly alkaline (7 to 9) and few were moderately alkaline (9 to 10). These pH variations were dependent on the alternation of freshwater and high tide flows. Other variables such as conductivity and total dissolved solids (TDS), exhibited seasonal variations in their average values at each locality studied. The riparian vegetation associated to the upper and middle courses of the streams is represented by Arroyo Willow (Salix lasiolepis), Red Willow (S. lae- vigata), Fremont Cottonwood (Populus fremontii), Western Sycamore (Platanus racemosa) and Coast Live Oak (Quercus agrifolia) (Wiggins 1980). The lower parts of the streams possess brackish marsh vegetation including Cattail (Typha domingensis), Ditch Grass (Ruppia maritima), Spiny Rush (Juncus acutus), An- nual Pickleweed (Salicornia bigelovii), Saltgrass (Distichlis spicata) and Bulrush- es (Scirpus californicus) (Delgadillo-Rodriguez et al. 1992). Aquatic macrophytes found along the streams, include Berula erecta, Ceratophyllum demersum, Chara sp., Potamogeton natans, and Ranunculus aquatilis (Ruiz-Campos 1993; Ruiz- Campos and Pister 1995). 62 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES STUDY AREA INT COLONET PROJECT CONACYT 4311005—1993PN STREAMS OF THE NORTHWEST OF BAJA CALIFORNIA, MEXICO LEGEND . COLLECTING LOCALITY A sSTATION OF SEASONAL SAMPLING SCALE Fig. 1. Geographical situation of the study area and of the fish collecting localities in northwestern Baja California, México. Black triangles indicate localities monitored during an annual cycle (February 1996-March 1997). See appendix | for description of localities. Methods Fish samplings were carried out in different streams of the northwestern Baja California, México, between 1983 and 1997 (Fig. 1, Appendix 1). Twelve streams CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA Fig. 2. (A) Slough adjacent to mouth of Arroyo El Descanso. (B) lower part of Arroyo La Mision. 64 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Fig. 3. (A) lower part of Arroyo Santo Domingo. (B) lower part of Arroyo El Rosario. CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA 65 Table 1. Average values of physical-chemical parameters registered in the lower parts of the streams of the northwest of Baja California, México. Measurements made with Hydrolab scout 2. TDS Cond. Temp. Salini. Locality (stream) ppt Oxyg. mg/l pH g/l mS/cm Time Date d/m/y Cantamar (El Médano) Cantamar (E] Médano) Cantamar (El Médano) Cantamar (El Médano) El] Descanso (mouth) El] Descanso (mouth) El Descanso (slough) El Descanso (slough) El Descanso (slough) El Descanso (slough) La Mision (Guadalupe) La Mision (Guadalupe) La Mision (Guadalupe) La Mision (Guadalupe) San Miguel (El Carmen) San Miguel (El Carmen) San Miguel (El Carmen) San Miguel (El Carmen) Santo Tomas Santo Tomas Santo Tomas San Vicente (Eréndira) San Vicente (Eréndira) El Salado (Loma Linda) El] Salado (Loma Linda) San Rafael San Rafael San Rafael Seco (tribut. San Rafael) San Telmo San Telmo San Telmo San Telmo Santo Domingo Santo Domingo Santo Domingo Santo Domingo San Sim6n (Papalote) San Sim6n (Papalote) San Simon (La Pinta) San Simon (La Pinta) San Simon (La Pinta) El Rosario El Rosario El Rosario El Rosario De a2 2 5.8 13.4 11.4 6.8 | 95 10 6.2 OE 8.4 3.8 PA 6.8 ISA 8.4 0.8 1.4 2.4 3:3 DS 48.2 Pi Dae s19 63.9 33.8 1s3 26 a 1.74 1.42 2.6 DS DS DS 88 32.4 NM 4.9 8.96 14.4 4.88 VTS 19.88 13.02 SS 3.45 SS 4.2 10.38 4.78 SS 3.04 10.57 8.63 6.46 5.38 9.37 13.67 7.94 = | 14.8 NM 10.31 NM oe DS a7 8.04 Wey di: 6.74 NM 7.42 a7 7.64 9.23 NM 8.96 DS DS DS De 4.8 6.06 7.54 257 4.62 cl e's 2.05 7.63 DS = dry streambed. NM = not measured. 7.94 8.35 8.95 8.31 8.69 8.26 8.4 93 O15 8.85 8.31 8.2 be vas 8.7 8.8 8.26 9.78 LOM 7.96 8.34 8.11 8.04 DS 8.37 8.32 7.86 $239 8.35 9.76 9.13 8.74 8.76 8.47 9.21 DS DS DS 8.26 S257 O98 7.84 8.22 8.84 8.57 8.15 TOF 7.94 3.62 2333 6.1 14.25 eee 7.05 | agp 10.41 10.96 6.98 10.4 233 4.36 1.36 7.6 14.05 SAD 0.94 1.56 NM 3.81 DS 45.1 NM 48.6 58.35 NM 15.6 2.54 6 2.05 NM 3.03 DS DS DS 80.6 Sit aD 5.58 9.86 14.97 5:55 8.58 20.39 4.03 05 A 3.64 10.04 22d | Pas 12.04 19x 16.31 17.09 10.88 16.2 14.5 6.72 DAZ 12.09 21.98 14.42 1.46 yd 4.4 x5 DS 70.4 Bo bite be eae 91.05 o9P:33 24.3 3,9 9.36 St 2.78 4.72 DS DS DS 130 49.52 35.1 8.74 15.53 2402 8.54 F553 S91 $£3:95 15:00 14:20 10:40 14:15 13:25 12:10 13035 12:14 13:00 16:30 12:00 1224 9:21 17:40 10:00 11:00 11:40 15:30 Let 8:50 11:00 DS 14:30 11:00 11:00 11:10 43:35 15:40 11333 43-82 14:45 16:50 11:56 DS DS DS 10:30 10:00 16:25 13:38 12:25 24 Hs 24 Hs 24 Hs 24 Hs 27-IV-1996 21-VIII-1996 23-XI-1996 20-III- 1997 22-XI-1996 20-III-1997 27-IV-1996 21-VIII-1996 22-XI-1996 4-ITV-1997 28-IV-1996 21-VIII-1996 23-XI-1996 19-III-1997 2-III-1994 29-IV-1996 29-XI-1996 21-III-1997 24-III-1996 26-IX-1996 18-I-1997 24-III-1996 28-IX-1996 28-IX-1996 19-I-1997 23-III-1996 28-IX-1996 20-I-1997 28-VI-1996 26-II-1996 28-VI-1996 13-X-1996 19-I-1997 25-II-1996 27-VI-1996 12-X-1996 20-I-1997 27-VI-1996 7-III-1997 27-VI-1996 12-X-1996 8-III-1997 24-II-1996 25-VI-1996 10-X-1996 8-III-1997 66 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES were seasonally monitored during an annual cycle (February 1996 to March 1997) in order to determine the spatial and temporal distribution of the fish fauna. In each locality a combination of passive (experimental gill nets, minnow traps) and active (minnow purse-seine and electrofishing) capture methods were used for the sampling of fishes at the different types of habitats. The same sampling effort was applied at each study locality. Electrofishing was used only in those streams with low salinities (< 1 ppt), such as the headwaters of streams. Simultaneous to the fish sampling the physical-chemical variables of the water were measured in situ by using an Hydrolab Scout 2 (Hydrolab Co., Austin, Texas) multiparameter equipment (precision + 0.01), which registered simulta- neously temperature (°C), conductivity (mS/cm), dissolved oxygen (mg/l), poten- tial of hydrogen ions (pH), salinity (ppt) and total dissolved solids (g/l). The fish material was quantified and representative subsamples of the species were fixed in 10% formalin for subsequent preservation at 50% isopropanol in the laboratory. The rest of the specimens were measured (total length [TL] in mm) and returned to the original collecting site. Voucher specimens were depos- ited in the Fish Collections of the Facultad de Ciencias, Universidad Aut6noma de Baja California (UABC) and the Facultad de Ciencias Biol6gicas, Universidad Autonoma de Nuevo Leén (UANL). The temporal occurrence of the species in the study area was classified as follows: permanent residents, those species collected throughout the year; tidal visitors, those peripheral species that penetrate stream mouths during high tides; and occasional visitors, species that appear incidentally in the mouths of streams and were represented by few collected specimens. We provide each taxon with a synopsis that includes: known geographical range, previous and recent collecting records within the study area, bioecological data, ecological derivation, current status, and comments. Previous records refers to collecting records for the study area published before 1983. Recent records, include the records resulting of the present study (period of 1983 to 1997), which are supported with voucher specimens catalogued and de- posited in the fish collections (UABC and UANL). The catalogue number(s) for each species is (are) given in parentheses, followed by the number of specimens in square brackets. Bioecological data, includes relevant information about the taxon, such as pref- erential habitat, reproductive evidence in the continental waters, size classes, range of salinity and other data. Ecological derivation, refers to the ecological category of the species according to its tolerance to salinity (cf. Myers 1938, 1951; Follett 1960): diadromous, species regularly migrant between fresh and salt water during a defined period of their life cycles; and sporadic, fishes that live and breed either in salt or fresh water or which enter fresh water only sporadically and not as a part of a true migration. Conservation status, is based on periodic evaluations of the species distribution and abundance within the study region, as well as the condition of its habitats and the causative factors of its current population condition. The conservation categories used here are based on Williams et al. (1989) and SEDESOL (1994). Comments, include diverse information about the distribution and abundance CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA 67 of the taxon in the study area or adjacent sites, or indicate the case of a new record for the continental waters of the State of Baja California and/or Peninsula of Baja California. Results and Discussion Species Accounts A total of 23 fish species (19 native and 4 exotic) belonging to 22 genera, 15 families and 8 orders was registered for the study area during the period of 1983-— 1997. The taxonomical arrangement of the species follows Eschmeyer’s (1998) classification. The common names of the species were based on Robins et al. (199T): Native Taxa Order Petromyzontiformes Family Petromyzontidae Lampetra tridentata (Gairdner, 1836). Pacific lamprey Distribution.—Hokkaido, Japan through the Bering Sea and Aleutian Islands (Hart 1973) to Punta Canoas, Baja California, México (Hubbs 1967; Miller and Lea 1972). The previous southernmost known freshwater record is the lower Rio Santo Domingo [= San Ramén], Baja California (Ruiz-Campos and Gonzalez- Guzman 1996). Previous records.—None. Recent records.—Arroyo Santo Domingo ca. 600 m above its confluence to the Pacific Ocean (UABC-111 [1]) (Ruiz-Campos and Gonzdélez-Guzman 1996), and Arroyo San Antonio (a third-order tributary of the Arroyo Santo Domingo) ca. 30 m before its confluence with Arroyo La Zanja, Sierra San Pedro Martir (UABC-597 [1]). Bioecological data.—The ammocoete of 126.5 mm TL from the lower Arroyo Santo Domingo (19-II-1995), was collected in a branch of the stream 5 m wide, 0.4 m deep, and over sand/gravel, with salinity of 0.3 ppt. The second ammocoete (92.5 mm TL) was collected (16-V-1997) in the sandy bottom of the Arroyo San Antonio, ca. 45 km upstream from the mouth of the Arroyo Santo Domingo, at salinity of 0.2 ppt. Ecological derivation.—Diadromous. Conservation status.—Special concern. Comments.—The specimen UABC-597 is the second known fish species (after Oncorhynchus M. nelsoni) in the Sierra San Pedro Martir. It is syntopical with the endemic trout, in the Arroyo San Antonio ca. Rancho San Antonio. The two findings of Pacific lamprey in the fresh waters of Baja California confirm once again the strong ichthyo-geographical affinity of the northwestern Baja California region with that of southern California (Swift et al. 1993). The presence of am- mocotes in the middle Arroyo San Antonio suggests a connection of this stream with the ocean during high winter floods, when anadromous adults penetrate to the stream to spawn. 68 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Order Clupeiformes Family Engraulidae Anchoa compressa (Girard, 1858). Deepbody anchovy Distribution.—Morro Bay, California (U.S.A.) to Bahia Todos Santos, Baja California, México (Miller and Lea 1972; Fitch and Lavenberg 1975). Previous records.—None. Recent records.—Mouth of the Arroyo La Misi6n [= Guadalupe] (UABC-864 [1]). Bioecological data.—The only specimen was collected along with a barred surfperch near the mouth of the stream, during the arrival of high tide flows (20 March 1995). The deepbody anchovy is commonly found in southern California bays and estuaries, where it prefers inshore and channel habitats (Horn and Allen 1985; Horn 1988). Ecological derivation.—Sporadic. Conservation status.—Stable. Comments.—The specimen registered here constitutes the first continental oc- currence in the peninsula of Baja California. Order Salmoniformes Family Salmonidae Oncorhynchus mykiss nelsoni (Evermann, 1908). San Pedro Martir rainbow trout Distribution.—Endemic to the Rio Santo Domingo (= San Antonio de Murillos or San Ramon), Sierra San Pedro Martir (SSPM), Baja California, México (Ev- ermann 1908; Nelson 1921; Snyder 1926; Needham 1938; Smith 1991). Previous records.—Arroyo Santo Domingo ca. Rancho San Antonio (type lo- cality) in June 1902 (Meek 1904), 30 July 1905 (Evermann 1908; Nelson 1921), 24-27 April 1925 (Snyder 1926), 17 May 1936, 23 May 1937 (Needham 1938), and 14 May 1938 (Needham 1955). Recent records.—Arroyo Santo Domingo ca. Rancho San Antonio (UABC-097 [11], 144 [10]), Arroyo La Zanja ca. junction with Arroyo San Antonio (UABC- 143 [3]), Arroyo El Potrero at Rancho El Potrero (UABC-145 [4], 735 [1], 834 [8]), Arroyo La Grulla at La Grulla meadow (UABC-069 [7], 157 [17], 835 [21], 859 [6], 860 [3]; UANL-5679 [2]), Arroyo San Rafael at Rancho Mike’s Sky (UABC-098 [1], 099 [4], 102 [30], 103 [43], 150 [1]), 841 [15], 842 [13], 843 [33], 844 [17], 845 [12], 846 [12], 847 [28], 848 [15], 849 [8], 850 [31], 851 [11], 852 [32], 853. [14],. 854 [26], 855 [9], 856 [45], 857 [10}; 858 {19} neG8 [58]) and Arroyo San Rafael at Rancho Garet (UABC-148 [3], 149 [7], 151 [1], 152 [3]). Bioecological data.—This rainbow trout is non-migratory and short lived (<5 years), and is distributed in the streams of the western slope of the Sierra San Pedro Martir at elevations from 540 to 2,030 m. Preferred habitats are pools with depth >30 cm, heavy riparian and aquatic vegetation (Ceratophyllum demersum and Potamogeton natans), sandy bottoms, high availability of prey and salinities of 0.1 to 0.3 ppt (Ruiz-Campos and Pister 1995). The species’ spawning period occurs between January and March and it is sexually mature at 103 mm standard length [SL] and after | year of age (Ruiz-Campos 1993). Newly emerged trout enter the population from May to June (Ruiz-Campos et al. 1997). O. mykiss CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA 69 nelsoni is sympatric with Pacific lamprey in the Arroyo Santo Domingo (Rancho San Antonio) ca. 45 km upstream from its mouth at the Pacific Ocean. Ecological derivation.—Diadromous. Conservation status.—Stable. Comments.—The original distribution of this subspecies was a section of the Arroyo Santo Domingo from the Rancho San Antonio to 24 km upstream (Ev- ermann 1908; Nelson 1921; Snyder 1926; Needham 1938, Smith 1991; Ruiz- Campos and Pister 1995). It was introduced into other streams of the western slope of the Sierra San Pedro Martir between 1929 and 1941, such as La Grulla, La Zanja, La Mision [of San Pedro Martir], El Potrero [= Valladares] and San Rafael (Ruiz-Campos and Pister 1995). Recent genetic analysis (mtDNA) con- firmed the relationship of O. mykiss nelsoni with anadromous coastal trout (steel- head) from southern California (Nielsen et al. 1996; Nielsen 1998). Order Atheriniformes Family Atherinidae Atherinops affinis (Ayres, 1860). Topsmelt Distribution.—Vancouver Island [6.4 km W Sooke Harbour], British Columbia, Canada to Gulf of California (Miller and Lea 1972). Previous records.—None. Recent records.—Lower parts of the coastal streams of La Misi6n (UABC-074 P12). '127 [25], 198 [21], 431 (Sy, 482 [16t, SOT [19], 596 (ol; UANL-IS7Zr 4 ise- San Miguel (UABC-210 [9], 212 [5], 361 [6]), Santo Tomas (UABC-453 [7], 538 [2]) and El Rosario (UABC-101 [1], 465 [2], 593 [29]). Bioecological data.—Topsmelts are found in small aggregations in main stream channels near their mouths. Gravid adults were observed from middle March to late May. This species was found in salinities ranging from 1.0 a 26.2 ppt. The most abundant populations were detected in the lower La Mision, San Miguel [= El] Carmen o San Antonio de las Minas] and El Rosario streams. Ecological derivation.—Sporadic. Conservation status.—Stable. Comments.—All records referred above constitute the first occurrence of the species in the inland waters of the peninsula of Baja California. This species is known to enter inland waters of low salinity for spawning (Swift et al. 1993). Atherinopsis californiensis Girard, 1854. Jacksmelt Distribution.—Yaquina, Oregon, U.S.A. to Bahia Santa Maria, Baja California, México (Roedel 1953; Miller and Lea 1972). Previous records.—None. Recent records.—Mouth of the streams of San Rafael (UABC-173 [35]) and La Mision (UABC-866 [11]). Bioecological data.—This species was represented by juveniles that were cap- tured along with longjaw gobies in two isolated hypersaline ponds (38.8 and 51.9 ppt) at the mouth of Arroyo San Rafael, which is blocked of the sea by a wide bar of boulders. Ecological derivation.—Sporadic. Conservation status.—Stable. Comments.—The finding of jacksmelt in the mouths of the streams of La Mi- 70 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES sidn and San Rafael, represents the first mainland records in the peninsula of Baja California. Leuresthes tenuis (Ayres, 1860). California grunion Distribution.—San Francisco, California, U.S.A. to Bahia Magdalena, Baja California Sur (Miller and Lea 1972). Previous records.—None. Recent records.—Mouths of the streams of San Miguel (UABC-142 [121]) and La Misi6n (UABC-867 [1]). Bioecological data.—Two adults and 119 juveniles were caught (30 June 1995) in a small lagoon near the mouth of the stream at San Miguel, which is blocked from the ocean by a sandy bar. Juveniles of this taxon have been reported from rocky tide pools near the collecting site (Ruiz-Campos and Hammann 1987). Ecological derivation.—Sporadic. Conservation status.—Stable. Comments.—An adult specimen (UABC-867) was collected on 8 June 1995 in the mouth of Arroyo La Mision during the entry of tidal flows (Cabrera-Santillan 1997). Family Fundulidae Fundulus parvipinnis parvipinnis Girard, 1854. California killifish Distribution.—Morro Bay, California, U.S.A. (Miller and Lea 1972) to Ojo de Liebre lagoon, Baja California Sur, México (De La Cruz-Agiiero et al. 1996). Previous records.—Lower parts of the coastal streams of Cantamar [= Mé- dano], La Mision and San Miguel (Miller 1943; Follett 1960). Recent records.—Lower parts of the coastal streams of Cantamar (UABC-350 [64], 437 [92], 446 [80], 469 [116], 479 [7], 595 [22]; UANL-13724 [94]), El Descanso (UABC-141 [66], 358 [4], 407 [2], 478 [16], 484 [12], 485 [34], 505 [4], 590 [14]), La Misi6n (UABC-072 [29], 128 [16], 155 [28], 360 [242], 418 [3], 432 [46], 447[160], 480 [4], 483 [1], 589 [1]; UANL-13719 [13]), San Miguel (UABC-213 [1], 221 [1]) and San Simén (UABC-316 [17], 587 [63]; UANL- 2536 [43]). This species was also recorded in a slough adjacent to the mouth of Arroyo El Descanso (UABC-434 [2], UANL-13722 [1]). Bioecological data.—This euryhaline and sporadic killifish prefers the littoral habitats of sandy or muddy bottom such as marsh pools and inshores. It was registered within a wide range of salinity (1.0 to 88 ppt). Sexually ripe individuals were detected between April and May. California killifish is very abundant in the northern streams of the study area (e.g., Cantamar, La Mision and El Descanso) but absent from south of Arroyo San Miguel to Arroyo Santo Domingo. Three age-classes (O—2 years) were identified according to Fritz’s (1975) criterion: Ju- venile (< 44 mm SL), 1 year (44-79 mm SL) and 2 years (> 79 mm SL). Juveniles were observed from March to November. Ecological derivation.—Sporadic. Conservation status.—Stable. Comments.—This taxon is one of the most typical and abundant species of marshes and esturies of southern California (Horn 1988) and some coastal lagoons of the peninsula of Baja California (Ojo de Liebre and Guerrero Negro; De La CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA S41 Cruz-Agiiero et al. 1996). Its euryhaline capacity allows it to be the dominant species at mixohaline systems (mouths) subject to flooding by high tides. Order Gasterosteiformes Family Gasterosteidae Gasterosteus aculeatus microcephalus Girard, 1854. Partially armored threespine stickleback Distribution.—Bering Strait, Alaska (Eigenmann 1886) to Arroyo El Rosario, Baja California, México (Follett 1960). Previous records.—*‘Tia Juana Hot Springs”? [= Manantiales Agua Caliente] (Smith 1883), Wild Cat stream [= Arroyo Gato Bronco] (Smith 1883), lower parts of the coastal streams of Cantamar, El Descanso, Guadalupe [= Matanyonal or La Mision], Santo Tomas, San Vicente, Seco [tributary of Arroyo San Rafael] (Miller and Hubbs 1969), El Salado (= San Antonio del Mar) (Rutter 1896), Santo Domingo (Myers 1930; Swift et al. 1993) and El Rosario (Follett 1960). Recent records.—Mouth of the coastal streams of El] Descanso (UABC-070 [12], 410 [18]), Santo Domingo (UABC-165 [39], 167 [1], 168 [37]) and El Rosario (UABC-113 [1], 163 [174], 307 [22], 459 [1], 583 [77], 585 [1]). An additional record is that of a slough near the mouth of Arroyo El Descanso (UABC-199 [5], 200 [23], 436 [52], UDANL-13723 [36]). Bioecological data.—Threespine sticklebacks inhabit those sites with marginal emergent (bulrush, Scirpus californicus and cattail, Typha domingensis) or sub- mergent aquatic vegetation, with sandy and silty bottoms. This species was found at salinities of 1.0 to 15.6 ppt (mean= 6.7). It is sympatric with exotic mosqui- tofish (Gambusia affinis). Ripe adults were observed from November to April, and newly transformed juveniles between March and May. The population of the slough near the mouth of Arroyo El Descanso (Fig. 2a) makes up the most abun- dant and permanent stock in northwestern Baja California. Three age-classes were recognized (O—2 years old) according to Carlander’s (1969) criterion: juvenile (< 28 mm TL), 1 year (28—60 mm TL) and 2 years (> 60 mm TL). Juveniles were distinguished from February to June. Ecological derivation.—Diadromous. Conservation status.—Threatened. This taxon was considered rare by SEDE- SOL (1994) based on old collecting records. Its population is being reduced. Comments.—This subspecies once widely distributed in the coastal streams of northwestern Baja California is now confined to three localities. This distributional reduction is associated to alteration of habitats by man-made impacts (e.g., ur- banization, pollution, livestock grazing and siltation), being most evident along the Tijuana-Ensenada tourist corridor and the agricultural valleys of San Quintin and Colonet. Order Scorpaeniformes Family Cottidae Leptocottus armatus australis Hubbs, 1921. Pacific staghorn sculpin Distribution.—Morro Bay, California, U.S.A. (Hubbs 1921) to Bahia San Quin- tin, Baja California, México (Bolin 1944; Follett 1960; Miller and Lea 1972). Previous records.—Arroyo Rosarito (Smith 1883) and Arroyo Guadalupe (La Mision) (Follett 1960). 72 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Recent records.—Lower parts of the coastal streams of Cantamar (UABC-209 [12]), La Misi6n (UABC-067 [1], 868 [8]), San Miguel (UABC-082 [1]) and Santo Tomas (UABC-219 [1]). Bioecological data.—The presence of this sculpin in the coastal streams of the study area is concomitant to the opening of their mouths by high freshwater flows. Adult specimens (90.1—191 mm TL) were collected in salinities ranging of 0.8 to 2.2 ppt. Ecological derivation.—Sporadic. Current status.—Stable. Comments.—Our record of L. armatus australis in the lower Arroyo Santo Tomas, extends approximately 66 km southward the previously known freshwater range (Arroyo La Mision, cf. Follett 1960). Order Perciformes Family Kyphosidae Girella nigricans (Ayres, 1860). Opaleye. Distribution.—Otter Rock [Lincoln county], Oregon, U.S.A. (Bond 1985) to Punta Entrada, Bahia Magdalena, Baja California Sur, México (Norris 1963). Previous records.—None. Recent records.—Mouths of the coastal streams of La Mision (UABC-871 [1]) and San Miguel (UABC-197 [1], 214 [1], 200 [6]). Bioecological data.—Subadult fish were collected in the mouth of the stream during intromision of tidal flows, at salinities of 6.3 to 7.3 ppt. Juveniles are common in the rocky tide pools near the mouth (Ruiz-Campos and Hammann 1987). Ecological derivation.—Sporadic. Conservation status.—Stable. Comments.—The finding of this coastal species in the streams of La Misién and San Miguel constitute their first inland records in the Baja California pen- insula. Family Mugilidae Mugil cephalus Linnaeus, 1758. Striped mullet Distribution.—Circumtropical species, also distributed in many temperate re- gions (boundary of 15 °C-surface isotherm). In the Eastern Pacific Ocean it occurs from Monterey, California (Miller and Lea 1972) to Chile (Puerto Montt), in- cluding Gulf of California and Galapagos Islands (Harrison 1995). Previous records.—Arroyo La Mision 1.6 km E Pacific Ocean (Follett 1960) and Arroyo San Sim6n ca. 4 km W Lazaro Cardenas (Ruiz-Campos and Con- treras-Balderas 1987). Recent records.—Lower parts of the streams of Cantamar (UABC-450 [2]), El Descanso [adjacent slough] (UABC-208 [1]), 957 [1], La Mision (UABC-118 [1], 449 [2]), San Miguel (UABC-083 [11]), Santo Tomas (UABC-211 [3], 451 [6]), El Salado (UABC-467 [1], 549 [2]), San Rafael (UABC-548 [2]), San Telmo (UABC-170 [5], 313 [16]), Santo Domingo (UABC-112 [136]), San Sim6n (UANL-2538 [19]), and El Rosario (UABC-120 [294], 139 [2], 159 [46], 161 [3], 315 [2], 448 [19], 461 [12], 594 [3]). Bioecological data.—This euryhaline species (0.3 to 48.3 ppt) prefers the main CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA T3 channels of streams near their mouths, where high dynamics exist due to tidal inflows. Subadult striped mullets (<150 mm TL) were seen 20 km upstream from the mouth of Arroyo Santo Tomas (21 June 1998). Young-of-the-year (YOY) individuals were collected in February. Two adults (460 and 535 mm TL) were netted in an isolated slough near the mouth of Arroyo El Descanso (Fig. 2a), which is separated from the ocean by a wide bar of sand and boulder that can hardly be surpassed by high tides. Both specimens had abundant mesenterial fat and degenerate gonads that suggest suppression of breeding migration because of the spatial isolation. Ecological derivation.—Diadromous. Current status.—Stable. Comments.—It is one of the most widespread species in the study area (Table 2) with abundant populations in the lower parts of La Misi6n and El Salado streams. Family Embiotocidae Amphistichus argenteus Agassiz, 1854. Barred surfperch Distribution.—Bodega Bay, California, U.S.A. to mouth of Arroyo La Misi6n, Baja California, México (Tarp 1952). Previous records.—Mouth of Arroyo La Mision (Tarp 1952). Recent records.—Mouth of Arroyos La Misi6n (UABC-863 [1]) and El Rosario (UABC-466 [13]). Bioecological data.—Juveniles and adults (131-346 mm TL) were captured in the main channel of Arroyo El Rosario ca. 80 m above mouth, during tidal inflow (salinity of 24.6 ppt). This surfperch is commonly caught by hook and line in the sublittoral adjacent to the collecting site. Ecological derivation.—Sporadic. Current status.—Stable. Comments.—The record of the species in the mouth of Arroyo El Rosario, represents its southernmost locality. Hyperprosopon argenteum Gibbons, 1854. Walleye surfperch Distribution.—Vancouver Island, British Columbia, Canada to Punta San Ro- sarito, Baja California, México (Tarp 1952; Miller and Lea 1972). Previous records.—None. Recent records.—Mouth of the Arroyo El Rosario (UABC-457 [1], cf. com- ments, infra). Bioecological data.—The only specimen registered here (197 mm TL) was captured along with adult and juvenile barred surfperch near the mouth of the stream, during the inflow of tidal currents (salinity of 24.6 ppt). Ecological derivation.—Sporadic. Current status.—Stable. Comments.—The specimen reported here represents the first finding of the spe- cies in the continental waters of the peninsula of Baja California. Micrometrus minimus Gibbons, 1854. Dwarf perch Distribution.—Bodega Bay, California, U.S.A. (Tarp 1952) to Isla de Cedros, Baja California, México (Miller and Lea 1972). 74 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Fig. 4. (A) Livestock grazing in the riparian biotopes in the lower part of Arroyo Santo Tomas. (B) Modification of sites adjacent to the lower part of Arroyo San Rafael for intensive agriculture practices. CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA i Le. Previous records.—None. Recent records.—Mouth of Arroyo San Miguel (UABC-081 [1]). Bioecological data.—The only specimen was captured on March 3 1994, in the mouth of the Arroyo El Carmen, which is blocked from the ocean by a sandy bar. This species was detected in salinity of 1.1 ppt. Ecological derivation.—Sporadic. Conservation status.—Stable. Comments.—The specimen reported here is the first occurence of this species in the continental waters of the peninsula Baja California, and at strictly oligo- haline conditions. Family Gobiidae Clevelandia ios (Jordan & Gilbert, 1882). Arrow goby Distribution.—Vancouver Island, British Columbia, Canada to Gulf of Califor- nia (Miller and Lea 1972). Previous records.—None. Recent records.—Mouth of Arroyo San Rafael (UABC-175 [8], 176 [3]). Bioecological data.—Juvenile arrow gobies were found in two isolated hyper- saline ponds (51.9 ppt) with dense submergent macrophytes near the mouth of the stream. Ecological derivation.—Sporadic. Current status.—Stable. Comments.—This goby has not been previously reported in the mainland Baja California. Ilypnus gilberti (Eigenmann & Eigenmann, 1889). Cheekspot goby Distribution.—Walker stream, Tomales Bay (California, U.S.A.) to Gulf of Cal- ifornia (Miller and Lea 1972). Previous records.—None. Recent records.—Mouth of Arroyo Santo Domingo (UABC-164 [1]). Bioecological data.—The only specimen was collected in a remnant pond (sa- linity of 2.6 ppt) on the stream’s dry bed, which is located ca. 600 m above mouth. It is syntopic with longjaw mudsucker, threespine stickleback and mos- quitofish. Ecological derivation.—Sporadic. Current status.—Stable. Comments.—In spite of the presence of this goby in Bahia San Quintin (Ro- sales-Casian 1996), it had not been previously reported from the continental wa- ters of Baja California. Gillichthys mirabilis Cooper, 1864. Longjaw mudsucker Distribution.—Tomales Bay, California, U.S.A. to Gulf of California (Miller and Lea 1972). Previous records.—Mouth of Arroyo San Simon, ca. 4 km W Lazaro Cardenas (Ruiz-Campos and Contreras-Balderas 1987). Recent records.—Lower parts of the Arroyos La Misi6n (UABC-068 [1], 126 [1], 215 [11], 406 [14], 429 [1], 486 [1], 489 [3], 869 [1]), El Salado (UABC- 454 [98], 464 [5], 537 [11]), San Rafael (UABC-171 [16], 172 [36], 174 [6], 470 76 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES [23], 539 [25]), Santo Domingo (UABC-598 [3]) and San Simon (La Pinta: UABC-319 [159], 460 [252], 456 [7], 586 [3]; and Papalote: UABC-314 [11], 588 [4], UANL-2539 [427]). Bioecological data.—This euryhaline species (salinity range = 4.9 to 88 ppt) was commonly found on muddy bottoms of ponds and channels with abundant submerged vegetation. Most of the collected specimens were YOY (< 127 mm TL) and > 1 year old (152-178 mm TL). Ecological derivation.—Sporadic. Current status.—Stable. Comments.—Five new localities are added to the inland distribution of the species in Baja California. Order Pleuronectiformes Family Paralichthyidae Hippoglossina stomata Eigenmann & Eigenmann, 1890. Bigmouth sole Distribution.—Monterey Bay, California, U.S.A. to Gulf of California, includ- ing Isla Guadalupe (Miller and Lea 1972). Previous records.—None. Recent records.—Mouth of Arroyo San Miguel. Bioecological data.—The only specimen reported here was caught on April 29 1996 in a remaining pond (salinity of 6.8 ppt) near the mouth of the stream, which is closed by a sandy bar. The specimen was identified in the field in ac- cordance with Miller and Lea (1972) and then released there. Ecological derivation.—Sporadic. Current status.—Stable. Comments.—This record represents the first occurence of the taxon in the in- land waters of the peninsula of Baja California. Family Pleuronectidae Hypsopsetta guttulata (Girard, 1856). Diamond turbot Distribution.—Cape Mendocino, California, U.S.A. to Bahia Magdalena, Baja California Sur, México, with an isolated population in the Gulf of California (Miller and Lea 1972). Previous records.—None. Recent records.—Mouths of the streams of La Mision (UABC-433 [1], 468 [1]) and El Salado (UABC-463 [3]). Bioecological data.—This euryhaline species was collected in the lower parts of streams with sandy bottoms during conditions of closing (8.4 ppt) or opening (48.2 ppt) of the mouth. In the lower Arroyo El Salado, three diamond turbots were collected | km above mouth. Ecological derivation.—Sporadic. Current status.—Stable. Comments.—Our records of H. guttulata in the streams of La Misi6n and El Salado, constitute the first findings of the taxon in the continental waters of the State of Baja California. CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA qa Exotic Taxa Order Atheriniformes Family Poeciliidae Gambusia affinis (Baird & Girard, 1853). Mosquitofish Previous records.—Rio Tijuana (3.2 km E Tiuana), Arroyo Guadalupe (= La Mision) in the Valle de Santa Rosa and town of La Mision (4.8 km E highway), and Arroyo San Simon S San Quintin (Follett 1960). Recent records.—Mouth of Arroyo El Descanso (UABC-409 [14], 411 [710], 435 [7], 481 [6]); lower Arroyo La Mision (mouth: UABC-216 [2], 487 [7], UANL-13720 [8]; town: UABC-050 [3], 073 [9]; and Rancho Santa Rosa: UABC-376 [65]); mouth of Arroyo San Miguel (UABC-201 [10], 488 [99]); Arroyo Santo Tomas at Ejido Ajusco (UABC-605 [2]); Arroyo Seco ca. Colonet (UABC-317 [56]); mouth of Arroyo San Telmo (UABC-169 [61], 312 [315], 471 [26]), Arroyo Santo Domingo (ca. 600 m above mouth: UABC-166 [1], 310 [9]; and at rancho El Divisadero ca. Misi6dn Santo Domingo: UABC-455 [112], 592 [30]); and lower Arroyo El Rosario (UABC-160 [2], 162 [30], 309 [14], 320 [56], 458 [130], 462 [12], 584 [32]). Bioecological data.—This exotic poeciliid is widely distributed along the study area, including some localities in the Sierra de Juarez (Laguna Hanson and Arroyo Neji). It prefers lentic and shallow habitats with abundant submergent and emer- gent plants, and of sandy-muddy bottoms. In the lower parts of streams, this species is found at salinities ranging from 0.2 to 15.6 ppt. Comments.—This ubiquitous taxon may be a current or potential competitor to the native fish, Gasterosteus aculeatus microcephalus, since both are syntopical in the lower parts of the streams of El Descanso, Santo Domingo and El Rosario. Order Perciformes Family Centrarchidae Lepomis cyanellus Rafinesque, 1819. Green sunfish Previous records.—Rio Tijuana, 3.2 km E Tijuana; a stream entering to the southwestern corner of Valle de Santa Rosa, 32.2 km S [sic] Ensenada; and Ar- royo San Miguel (Follett 1960). Recent records.—An slough adjacent to the mouth of Arroyo El Descanso (UABC-177 [1]); Arroyo La Mision at its mouth (UABC-865 [1]), at Rancho Tierra Santa (UABC-665 [33]) and at Rancho Santa Rosa (UABC-377 [4]); Ar- royo San Carlos at Rancho Alamitos (2 ripe males and 2 juveniles collected but not preserved, on 1 May 1995), Arroyo Santo Tomas near the mouth (UABC- 452 [1]) and at Ejido Ajusco (UABC-224 [2]); mouth of Arroyo San Telmo (UABC-311 [6]), and Arroyo Santo Domingo at Rancho El Divisadero (G. Ruiz- Campos, pers. obs.). Bioecological data.—Green sunfish prefer ponds with abundant submergent macrophytes (Ceratophyllum demersum) and sandy bottoms. Ripe adults were observed between April and May. It is coexisting with mosquitofish in many localities of the study area, within a salinity range of 0.4 to 6.9 ppt. Comments.—The Follett’s (1960) record from Valle de Santa Rosa corresponds to a personal communication by Dr. Carl L. Hubbs, who referred it to 32.2 km S Ensenada instead of 32.2 km N Ensenada. 78 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES The following two exotic species were captured in localities not considered for the spatial and temporal fish monitoring. These localities are within the study area and period: Lepomis macrochirus Rafinesque, 1819. Bluegill Previous records.—None. Recent records.—Laguna Hanson, Sierra de Juarez (UABC-077 [4]) and Emilio Lopez Zamora reservoir near Ensenada (UABC-415 [2]). Comments.—The specimens from Laguna Hanson were reported incorrectly by Ruiz-Campos and Contrears-Balderas (1987) as L. megalotis instead of L. ma- crochirus. Micropterus salmoides (Lacépéde, 1802). Largemouth bass Previous records.—None. Recent records.—Emilio L6pez Zamora reservoir near the city of Ensenada (UABC-413 [4]) and Laguna Hanson at Sierra Juadrez (G. Ruiz-Campos, pers. obs.). Comments.—This game fish has been recently stocked in several small bodies in the region in order to promote sport fishing. Ecological Composition The spatial and temporal composition of the ichthyofauna was evaluated during an annual cycle (February 1996 to March 1997) along twelve coastal streams of the study area (Fig. 1). Two species (Mugil cephalus and Gambusia affinis) were recorded from most coastal streams of the area, occurring in ten and seven streams, respectively (Table 2). Other species with wide distribution were: Fundulus p. parvipinnis (5 streams), Gillichthys mirabilis (5), Lepomis cyanellus (5), Atherinops affinis and Leptocottus armatus australis (4 each). The rest of the taxa were restricted to less than four streams in the study area. The Arroyo San Vicente (lower part) was the only sampled locality that no had fish. In relationship to the temporal occurrence of the species, eight (34.8%) were permanent residents: Oncorhynchus mykiss nelsoni, Fundulus p. parvipinnis, Gas- terosteus aculeatus microcephalus, Mugil cephalus, Gambusia affinis, Lepomis cyanellus, Lepomis macrochirus, and Micropterus salmoides; nine (39.1%) were tidal visitors: Atherinops affinis, Atherinopsis californiensis, Leuresthes tenuis, Leptocottus armatus australis, Girella nigricans, Amphistichus argenteus, Clev- elandia ios, Gillichthys mirabilis, and Hypsopsetta guttulata; and six (26.1%) occasional visitors: Lampetra tridentata, Anchoa compressa, Hyperprosopon ar- genteum, Micrometrus minimus, Ilypnus gilberti, and Hippoglossina stomata. The most abundant fish species during the seasonal samplings were F. parvi- pinnis parvipinnis, Atherinops affinis, Gillichthys mirabilis, Mugil cephalus and Gasterosteus aculeatus microcephalus (Table 3). With the exception of G. micro- cephalus, a diadromous species, most of the abundant species are of sporadic and euryhaline type that penetrate the streams during high tides (Horn 1988; Zedler et al. 1992; Saiki 1997). The widest intervals of salinity were recorded for F. parvipinnis parvipinnis, Atherinops affinis, Mugil cephalus, Clevelandia ios, Gillichthys mirabilis, and 12 CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA ‘JQUOJOD ‘vd ODag OAOIIY AreINgGII sit Opnypouy , ‘pouIquIOS vIUIg PT pue djoledeg Jo sonpeoo’T xx. ‘ysnojs Jusoe[pe oy} opnyouUy .. € [eJOL Sn]JauvaAD stuodaT siuyffp visnquvy pvjnyns vyasdosdAy xX pIDUOo]s DuIssojsoddiyy x x x xX SIIQDAM SKYIYINLD xX ysaq ie snuda]] SO1 DIpuvD]aAaqD x xX OK snjpydao [1s6nyp SNUUIU SNAJIWOAILY unajuasiv UuodososdsadkY xX snajuasiv Ssnyoysiyduy xX SUDIIASIU DIJAALD Xx xX SIJDAJISND SNJOUAD snjjoIO|daT xX XK xX SNIDYAIIOAINIUA SNIDAINIVD SNAJSOAIISVH) SINUA] SAYJSAANIT SISUAIUAOJIJVI SISdOUulsAIYyIV siuyffp sdou1say1y xX X stuuidiaspd siuuidiaipd snjnpun.f x xX 1UOS]AU SSIYAU SNYIUAYAOIUC DssaAdwuod poyouy x DIDJUuapIA] DAJAMUVT ~ Ne) a) >) + ~ oy exe xx xx x x x rae x x xx KK SA ANHTANMNANANA ROR eH AAR HH * TROL roisl «SS ds a oS Sd AS LS JH WI *Ad WO BxeL sonteso'T] ‘ouesoy [dq = Yq pue ‘uous ues = Sg ‘osuTUIOG OURS = CS ‘OUaL, Ueg = AL ‘erjey ues = YS ‘operes Iq = Sq ‘U.IA UeS = AS ‘SRPUIO] OJURS = LS ‘UdUTIeD [q = OW ‘UOISI, PT = WT ‘osuvosag Iq = AC Jewrjuey = WD ‘suonerasiqqy ‘(potted /661-S661) OOIXa|I ‘eIUIOJTTeD eleg uIo}soMY}IOU Jo suTvaTS oY) JO syed JOMOT PUR I[PpIU oY} UT poJOoT[OO satoads ysy sy} Jo uONNQqMsIq “7 I9IQRL SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 80 L69 Ehe 6S I “Lt 807 [BIOL 2c 91 iL E C6 siuyfp pisnquvy 0 c I I pipjnyins vyjasdosday 6'€ LC I I ST SIJIQoANa SKYIYINPID I L I 4 C snjpydao jisnp Lo Lev LIZ cr 09 IZ stuffy sdouayly 8°67 807 I I Or O9I siuuidiaivd siuuidiaivd snjnpun4 % [BIOL L66I-II-61 9661-IX-€7 9661 -IIIA-17C 9661 -AI-87C exeL UOISIJ BT OAOLIY ‘ysnoy[s Juaoe[pe ay) apnyouy vOV 8el CEL c9 col [BIOL ©'0 I I snpjauvao snuoda] Li} 8 I L siuyfp pisnquvy a | 2 e I (6 snjpydao pisnpw €£6 €cv vl STI as 67I SN]DYdIIOAINUA SNJVA]NID SNAISOAIISVH) ve OT vl ré stuuidiaipvd stuuidiaapd snjnpunj % [RIOL L661 -I1-07 9661 -[X-CT 9661 -IIIA-1C 9661 -AI-L7 exeL ,osuvosoq [q OAOLIY ‘ysy JO douasqy = «~ 9S¢ * he S6l Se [RIOL ea 9 * 9 snjoydao pisnp sir g eT * I Tl sypajsnvo snjpuiiv snyovoidaT 906 LES xe L 881 TPE stuuidiaipd stuuidiaivd snjnpun4 % [BIOL L661 -III-O7 9661-IX-€7 9661 -IIIA-17é 9661-AI-LC BxeL Ieureyurd OAOLIY ‘OOIXd|] ‘PIUIOJTTLD eleg usd}saMyYLIOU JO suTvaS JO syed JOMOT OY} UT Pa}da][OO satoads ysy JO dduepuNqe [e1odway “¢ AqeRL 81 CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA a LE oT id [RIOL c8 t € vipjnyins vyjasdosd&y a4 91 i! ¢ SIIqvana SKYYINIIO 9'8P 81 g El snjpydad pjisnw % [RIOL Lo6l-l-6l 9661-XI-87 BxeL opryes [q oAOLIYy AS (4 cl v cl [PIOL t I I snyjauvao smumodaT L'69 tc S 3 SI snjoydao jlsnpw t I I SIJDAISND SNIDUAD snyoIojdaT € Ve 8 ¢ 9 siuyfo sdou1sayly % [BIOL Lool-1-81 9661-XI-97 9661 -III-Vc S66I-IA-Ot exeL SPUIOT, OJURS OAOLIYV SLI 66 LS 6l [BIOL ac9 601 66 Ol siuyffo visnquvy 9°0 I I vIpUOIS DUISsO]sodd1y eo | 1! snjoydas plsnpw 9°0 I I SNUMUIU SNAJIWOAIL o'V 8 8 SUDIIS1U DIJAAIO 9°0 I I SIDAISND SNyoUAD SnyOoIO|dIT VC CV OE 9 siuyffo sdouayly Et G (6 stuuidiaspd stuuidiaspd snjnpuny % [BIOL 9661 -TX-67 9661 -AI-6C vo6oI-II-c BxeL usuLIey [q OAOLIY ‘ponunuoy “¢ 91qeL, SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 82 ‘poquivans Alq = Sd 617 0) 0) O c8 LEI [BIOL SO I Sd sd Sd I siuyffo visnquvy Fal) 3 Sd Sd Sd 3 Sipiqoamad sKyIyouyIy SO I sd Sd sd I yaagis snuda]] 179 9€I sd Sd Sd 9€1 snjoydas [snp Ice WE, Sd Sd Sd ee sn]DYdaIOAINU SNJVA]NIVD SNajSOs2ISDH) c'0 I Sd Sd Sd I pDIDJuaplA] DAJadUyy] % [BIOL L661-1-0C 9661-X-Tl 9661 -IA-LT 9661-II-ST S66I-Il-6l exeL osullo0g ojuRg OAOLIYV ‘ysy JO s0uasqy = x 6CV 2 9 EEt 99 [RIOL | 9 * 9 snjjauvao snuoday] L’¢6 COV x 97 3 19 siuyffp pisnquvy 6v Ic *k | S snjpydao jisnpw % [BIOL L66I-L6l 966I-X-€l 9661 -IA-87C 9661 -II-97C eBxeL ouwlyjay ueg OAOIIY vol 6C tC cS [BIOL 8° 6C It SC 9 SIpIqvana SKYIYIN|ID 9OI i jai sol DIpUD]aAa]yD St 14 v snjpydag isn BSS 8S €T cE sisuausofiyypo sisdoumayly % [RIOL, L661-1-07 9661-XI-87é 966I-III-€7 eXeL Jovjey ueg OAOLIYV ‘ponunuoy “¢ 31qRL 83 CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA SIOl VCC SLI £9 CST C6C [BIOL COC 807 ce Ol vi Ce siuiffo pisnqupvy v6 OO & eC EC 6 V6C snjoydas jiénpy 10 I I unajuasiv uodosordsadky Vc Ic 6 snajuasav snyoysiyduy Pie CLE LL I CC bli if SNIDYAIIOAINU SNJVAINIVD SNAISOAAISVLH 801 Ol 801 C siuiuffp sdourayjy % [RIOL L661-III-8 966I-X-Ol 9661-IA-SC 9661-II-Ve C66l-II-81 exeLl ouesoy [q OAOLIY ‘pouIquIOS eUIg BT pue djo[edeg Jo So[edO] OY x 91S OL 6ST L81 [BIOL Svs 9EV £ 6SC OLI SIIQDANU SKYIYINIID ee a | O8 €9 LI stuuidiaspd siuuidiasipd snjnpun.z % [RIOL L66I-II-L 9661-X-CI 9661-IA-LT exeL ,UOUWTS UBS OAOLIY ‘ponunuoy “¢ I1qRL, 84 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Hypsopsetta guttulata, which are typical representatives of the euryhaline marine component (Castro-Aguirre 1978). Other species as Lampetra tridentata, Lepto- cottus armatus australis, Gambusia affinis and Lepomis cyanellus, were associated with low salinity levels. Species similarity among streams was significantly low in most of the cases (Table 4), with the exception of the Arroyos El Descanso and San Telmo that registered a similarity of 60%. The low similarity of species was associated to localities with high seasonal variation in the species composition. The ecological classification of the native continental fish species of north- western Baja California, which is based on their tolerance to salinity (Myers 1938; Follett 1960), includes 15 sporadic (78.9%) and four diadromous species (21.1%) (cf. synopsis). This demonstrates the complete dominance in inland waters by fish forms of marine derivation. This situation of dominance is typical of recently emerged geographical regions (e.g., Central America and Caribbean islands) (My- ers 1938, 1951; Miller 1966), which are colonized by marine species that enter the mouths of streams, and some of them as Lampetra tridentata and Mugil cephalus, can penetrate as far as 45 and 23 km upstream, respectively. Ichthyogeography Of 19 native taxa, 13 (68.4%) are of Californian affinity: Anchoa compressa, Fundulus p. parvipinnis, Atherinops affinis, Atherinopsis californiensis, Leures- thes tenuis, Leptocottus armatus australis, Girella nigricans, Amphistichus ar- genteus, Micrometrus minimus, Ilypnus gilberti, Gillichthys mirabalis, Hippog- lossina stomata, and Hypsopsetta guttulata, three (15.7%) are of the eastern Pa- cific of North America (Gasterosteus aculeatus microcephalus, Hyperprosopon argenteum and Clevelandia ios), one Holarctic (5.3%, Lampetra tridentata), one Endemic (5.3%, Oncorhynchus mykiss nelsoni) and one Circumtropical (5.3%, Mugil cephalus). The number of fish species registered in the present study is quite lower than that reported for the continental waters of southern California (Swift et al. 1993), where a greater quantity of perennial streams exist. Two main causes explain the low richness of fish species in the northwestern Baja California (Follett 1960): (1) its great aridity that results in few perennial streams; and (2) a paleohydro- logical discontinuity between the streams of southern California and those of northern Baja California. In our region of study, there are seven taxa that reach their southernmost con- tinental ranges (cf. Tarp 1952; Follett 1960; Miller and Lea 1972): Lampetra tridentata, Oncorhynchus mykiss, Fundulus p. parvipinnis, Atherinopsis califor- niensis, Gasterosteus aculeatus microcephalus, Leptocottus armatus australis, and Amphistichus argenteus. The presence of holarctic diadromous taxa (L. tridentata, O. mykiss and G. aculeatus) as far south as Arroyo El Rosario supports Nelson’s (1921) hypothesis that the vicinity of El Rosario is the southern boundary of the San Diegan faunal district. Four exotic species were registered in this study (Gambusia affinis, Lepomis cyanellus, L. macrochirus and Micropterus salmoides), of which G. affinis is of wide distribution in the region and coexists with the native threespine stickleback (G. aculeatus microcephalus) in the lower parts of El Descanso (slough), Santo Domingo and El Rosario streams. 85 CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA ‘(LL61 ‘IeZ pue JomMo1g) suredijs yjOq UI poreys satoads Jo Joquinu = ,.9,, pue ‘AToAT}Oedsol ‘,.g,, pue ..v,, SUTRAS oY) UT saIoads Jo Joquinu ae ..q,, pue ..e,, aIYM *[9 — q + B]/9 = [DD x ‘%09 ueY) IaysIY Io Tenbo sonyea IO} ALLIeTIUITS JURIIUSIS OO! olesoy [q ) OO UOUITS *§ SZ Te OOT osulluogd ‘§ SZ 0 CLE OOT owyaL ‘S 781 er Or 9°87 OOT jaeyey ‘S I ot SZ Ca 07 9°87 OO! operes Iq Ce 0 07 Or [a L9Ol OOT SPUIOL “S CEE Or eel 07 vl 16 O¢ OO! usulIeD [A L:97 pS COC [eZ LOC IE 8°O€ L9v OOT UOISI| PT 16 LO ma 09 Ge al 9°87 ELT 9°87 OOT osuvoseqd TI SZ OI 07 earaii 07 Or ECE 1€¢ EEE OO! TeUIeyUe Olesoy [H uOUTS “°§ osuIWwIOg Ss OW [OT aS [oejyeyd oS opeles TH SseuoL aS usuIe,) [A UOISTJ[A] am | OSUBDSOC] Jeurejyue’) sulvals [e1seod ‘AVWPLOO] YORO IOJ POUTQUIOD BUNdI[OD Jo sayep ITV (L66I-S66I :poted) oorxaypy ‘eruIOsITeD eleg usosoMy}ioU Jo (syed JoMOT) SUIRATS [eJSvOD SUOWR (,,XOPUT S,pIeddKL) AlLIe[IUIS satoads Jo JUDIIEg “py IQRL 86 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Conservation Status Based on the fish samplings in the study area, most of collected species are determined to have a stable conservation status. However, three diadromous spe- cies were determined to have the following statuses: (1) Lampetra tridentata, was determined as special concern due to its recent records in the freshwater waters of Baja California (Ruiz-Campos and Gonzalez-Guzman 1996). In addition, this taxon has been also categorized as of Special Concern in southern California (Williams et al. 1989; Swift et al. 1993). (2) Gasterosteus aculeatus microceph- alus, was placed in the category threatened due to its significant population de- crease along the northwestern region of Baja California (Ruiz-Campos et al. 1998). That is, of eleven localities where it was historically registered (Smith 1883; Eigenmann 1892; Rutter 1896; Myers 1930; Follett 1960; Miller and Hubbs 1969), it still occurs in only three of them (El Descanso, Santo Domingo and El Rosario streams). And (3) Oncorhynchus mykiss nelsoni, whose conservation sta- tus was previously determined as stable in the two main drainages of its distri- bution (San Rafael and Santo Domingo; Ruiz-Campos and Pister 1995). Several types of anthropogenic disturbances were detected in the aquatic and riparian habitats of the study area (Figures 4a-b). All streams presented some type of disturbance, depending on their nearness to the adjacent urban and agricultural areas. The recreational activities, especially the use of these sites for camping, generate the garbage proliferation that affects the quality of the habitats. These types of disturbance are evident in those streams located between Rosarito and Ensenada, where increased urbanization exists. In addition, the streams situated south of Ensenada are subject to progressive alteration of their aquatic and riparian habitats due to agricultural and livestock practices, which promote siltation. Recommendations on Conservation and Management Some recommendations for conservation and management of the native fish fauna and their habitats in the northwestern Baja California, which are derived from the present study, are as follows: (1) strictly prohibit the use and transfor- mation of the estuarine-riverine ecosystems for building of marinas and other tourist facilities, which may cause significant alterations on their hydrological, physicochemical, and biological attributes; (2) prevent the discharge of urban sewage into the streams as well as the use of their riparian ecosystems for de- positing garbage; (3) prohibit the deforestation of lands adjacent to streams for expansion of agriculture practices, since it promotes the erosion and siltation of streams’ channels; (4) restrict the use of the riparian habitats as grazing sites by livestock as it deteriorates the aquatic habitats and increases the siltation of the streams; (5) periodically monitor the levels of coliform bacteria and pesticides in the coastal streams of the region in order to evaluate the impact by urban pollution and agriculture practices; (6) strictly prevent the introduction of exotic fishes into the aquatic ecosystems of this region, which might harmfully interact with the native fish fauna; and, (7) design a program of holistic conservation at level of basins for the protection of the aquatic and riparian biota. Acknowledgements Many individuals participated along the different stages of the present study. We thank Alejandro Gerardo, Manuel Villalobos, Faustino Camarena, Lorenzo CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA 87 Quintana, Carlos Marquez, Sara Cabrera, Victor Salceda, Federico Cota, Yanet Guerrero, Enrique Sanchez, Marcos Lizarraga, and Sergio Sanchez, for their valu- able assistance in the fish samplings. Also we thank Walter Zufiga for drawing the map of the study area. This research was mainly derived from the project 431100-5-1993PN: Estatus Ecolégico y Distributivo de los Peces Continentales del Noroeste de Baja California: Distrito San Dieguense, which was supported by the Consejo Nacional de Ciencia y Tecnologia of México. E. P. Pister and two anonymous reviewers made useful comments on the manuscript. Literature Cited Archibold, O. W. 1995. Ecology of world vegetation. Chapman and Hall, London. 510 pp. Bancroft, G. 1926. The faunal areas of Baja California del Norte. 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Common ocean fishes of the California coast. California Department of Fish and Game, Fish Bulletin, 91:1—184. Rosales-Casian, J. A. 1996. Ictiofauna de la Bahia de San Quintin, Baja California, México, y su costa adyacente. Ciencias Marinas, 22:443—458. Ruiz-Campos, G. 1993. Bionomia y ecologia poblacional de la trucha arcoiris, Oncorhynchus mykiss nelsoni (Evermann), de la Sierra San Pedro Martir, Baja California, México. Tesis Doctoral, Facultad de Ciencias Biol6gicas, Universidad Autonoma de Nuevo Leén. Monterrey, México. 223 pp. + 1 appendix. Ruiz-Campos, G., S. Contreras-Balderas, M. L. Lozano-Vilano, S. Gonzalez-Guzman, and J. Alaniz- CONTINENTAL FISH OF NORTHWESTERN BAJA CALIFORNIA 89 Garcia. 1998. Estatus ecoldgico y distributivo de los peces continentales del noroeste de Baja California, México: distrito San Dieguense. Informe Técnico Final Proyecto 431100-5-1993PN, Consejo Nacional de Ciencia y Tecnologia, México. 150 pp. + 4 appendices. Ruiz-Campos, G., and S. Contreras-Balderas. 1987. Ecological and zogeographical check-list of the continental fishes of the Baja California peninsula. Proceedings of the Desert Fishes Council, 17:105—117. Ruiz-Campos, G., and G. Hammann. 1987. A species list of the rocky intertidal fishes of Todos Santos Bay, Baja California. Ciencias Marinas, 13:61—69. Ruiz-Campos, G., and M. Rodriguez-Meraz. 1993. Notas ecolégicas sobre la avifauna de Laguna El Rosario, Baja California, México. The Southwestern Naturalist, 38:59—64. Ruiz-Campos, G., and E. P. Pister. 1995. Distribution, habitat, and current status of the San Pedro Martir rainbow trout, Oncorhynchus mykiss nelsoni (Evermann). Bulletin of the Southern Cal- ifornia Academy of Sciences, 94:131—148. Ruiz-Campos, G., and S. Gonzalez-Guzmdan. 1996. First freshwater record of Pacific lamprey, Lam- petra tridentata, from Baja California, México. California Fisha and Game, 82:144—146. Ruiz-Campos, G, E. P. Pister, and G. A. Compean-Jiménez. 1997. Age and growth of Nelson’s trout, Oncorhynchus mykiss nelsoni, from Arroyo San Rafael, Sierra San Pedro Martir, Baja Califor- nia, Mexico. The Southwestern Naturalist, 42:74—85. Rutter, C. 1896. Notes on freshwater fishes of the Pacific slope of North America. Procedings of the California Academy of Sciences, Serie 2, 6:245—267. Saiki, M. K. 1997. Survey of small fishes and environmental conditions in Mugu lagoon, California, and tidally influenced reaches of its tributaries. California Fish and Game, 83:153—167. SEDESOL [Secretaria de Desarrollo Social]. 1994. Norma oficial mexicana NOM-059-ECOL-1994, que determina las especies y subespecies de flora y fauna silvestres terrestres y acudaticas en peligro de extinci6n, amenazadas, raras y las sujetas a protecci6n especial, y que establece especificaciones para su proteccién. Diario Oficial de la Federaci6n. Tomo CDLXXXVIII Num. 10, México, D.F, Lunes 16 de Mayo de 1994. 60 pp. Smith, R[osa]. 1883. Notes on the fishes of Todos Santos Bay, Lower California. Proceedings of the United States National Academy of Sciences Museum, 6:232—236. Smith, R. H. 1991. Rainbow trout, Oncorhynchus mykiss. Pages 304—322 In Trout (J. Stolz y J. Schnell, eds.). The Wildlife series, Stackpole Books, Harrisburg (Pennsylvania). Snyder, J. O. 1926. The trout of the Sierra San Pedro Martir, Lower California. University of California Publications in Zoology, 21:419—426. Swift, C. M, T. R. Haglund, M. Ruiz, and R. N. Fisher. 1993. The status and distribution of the freshwater fishes of southern California. Bulletin of the Southern California Academy of Sci- ences, 92:101—167. Tamayo, J. L., and R. C. West. 1964. The hydrogeography of middle America. Pages 84—121 In Handbook of middle America (I. R. Wauchope, de.). Vol I. University of Texas Press, Austin. Tarp, E H. 1952. A revision of the family Embiotocidae (the surfperches). California Department of Fish and Game, Fish Bulletin, 88:1—99. Wiggins, I. L. 1980. Flora of Baja California. Stanford University Press, Stanford. 1025 pp. Williams, J. E., J. E. Johnson, D. A. Hendrickson, S. Contreras-Balderas, J. D. Williams, M. Navarro- Mendoza, D. E. McAllister, and J. E. Deacon. 1989. Fishes of North America endangered, threatened, or of special concern: 1989. Fisheries, 14(6):2—20. Zedler, J. B., C. S. Nordby, and B. E. Kus. 1992. The ecology of Tijuana Estuary, California: national estuarine research reserve. NOAAA Office of Coastal Resource Management, Sanctuaries and Reserves Division, Washington, D.C. 151 pp. Accepted for publication 1 June 1999. SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 90 M eS Le SION ,8 80%6P Oe INI OIpsd ueg eLaIg ‘efueZ ey] OAOLY [ap eIOUaNyUOoS “ed OTUOJUY URg OAOLIY—6Z M 70 8c LE2S1l NiO:CIE6r OE INR] OIpad ueg euatg ‘efuezZ ey] OAOLIY—gZ NO TELY LEST INGE SP 8P OE INV OIPsd Ue BLIDIG ‘OlUOJUY URg OYSURY Je SOT[LN] ap OluOjUY Ug OAOLIY—/Z M 0°00 ,67 oSIT “(N ,O'O€ ,€S .O€ IMIR, O1P9d UL BLIDIG ‘MOPROU LI[NID eT 3 LI[NID ey CAOLIW—97 M ,O'SV .8€ SIT “N ,0°00 .SS .O€ IMR O1Psd URS BLIDIG ‘OlaNOg [q OYoueY ye o1aNog [q OAOLIY—"¢Z M ,0°S0 ,9€ SIT “N ,0°SZ ,vO WIE INR OIP9g UBS BLIDIC ‘JoIRH OYouLY Ie [avjey ueg OAOLIY—fPZ M ,0'SO ,8€ SIT “N OSE ,90 IE IMR OIPSd UBS BLIDIC ‘AAS S,dyxIA OyouryY ye javjey ueg OAOLIY—¢Z M ,0'00 ,TE TT “N ,0°00 ,9F IE ‘epeuosug ‘(7 Aemysiy q MW ¢'p) soWWeElY OYouRY Je sojIeD ueg OAOLIY—ZZ M 0°00 .vS .STT “N 0°00 ,ZO cE ‘epeuosug ‘Zolene eLIaig ‘uosue] eUNnSe]—[Z M .0°00 ,61 IT ‘N ,0°00 ,€7 CE ‘aqeoay, ‘en opify “eo any OAOLIW—"Q7Z NO Siete eSEL “NGS Ce ic OF ‘epeuasug ‘Olesoy [q OAOLTY vUuRDOg—6] Mar titiw ts oll Na IeVCuve OC ‘epeuosuq ‘(eIUIg BT] [9}OH 9AOGR WY |) UOWIG Ueg OAOLTY BURDIOg—g] Wie Oe es e501 “Neal POLS .0€ ‘epeuosug ‘(a10[edeg opifg ‘eo) uoUIIg URg OAOLIY PURDOg—/| NOS OT-.7S SSL N W159 OE ‘epeuosug ‘(UOIST] “B9) OLOpRSIAIG [q OYSuRY Je OSUTUIOG OJULG OAOLIY—9] Me OS COOL aN vOeS CV OE ‘epeuosuy ‘UuQUIeY Ug “vd OSUTWOG OJURg OAOLIY BURDOg—‘C| NM 9'LS vl YIT 'N «S67 9S OC ‘epeuosug ‘Oujay, Urs BUN “eo OUTTay, Ueg OAOLITY vUR.Og—+F] M ,8'67 ,9T YIT “N «180 .8S O€ “epeuosug ‘JOUO[OD eIUNg ‘vO JavjeYy ueg OAOLIY BURDIOg—¢] MG Re OT s9ET "N-al'9S SO TE ‘epeuasug “JOUOTOD “wd (JavjeYy uLg OAOLIY Jo AreyNGLN) Odag OAOLIY—TZ] Me WOE FEL OTL GN 3S'Se 190 Ie ‘epeuosuy ‘(epury eUIOT “ed) Opeyesg [q OAOLIY eUuRDOg— |] Mad ES) Ce so E NG VSuST-oLS “epeuosug ‘ayus0I1A ueg OAOLTY eURDIOg—"(| NEO 00,80 49 LT “N 70'00%,5E oI ‘epeuasug ‘oosnfy opifq ie sero], ojurg OAOLTY—6 NO 8c 6 10 mm length). The left testis, vas deferens and part of the left kidney were removed from males; the left ovary was removed from females for histological examination. Tissues were em- bedded in paraffin and cut into sections at 5 wm. Slides were stained with Harris’ hematoxylin followed by eosin counterstain. Testes slides were examined to de- termine the stage of the male cycle; ovary slides were examined for the presence of yolk deposition. Vasa deferentia were examined for sperm. Slides of kidney sexual segments were examined for secretory activity. Because some of the spec- imens were road-kills, not all tissues were available for histological examination due to damage or autolysis. In road-killed males, the kidneys typically underwent autolysis before the reproductive organs. Number of specimens examined by re- productive tissue were: testis = 57, vas deferens = 38, kidney = 50, ovary = 42. Testicular histology was similar to that reported by Goldberg and Parker (1975) for the colubrid snakes, Masticophis taeniatus and Pituophis catenifer (= P. me- lanoleucus) and the viperid snake, Agkistrodon piscivorus reported by Johnson et al. (1982). In the regressed testes, seminiferous tubules contained spermatogonia and Sertoli cells. In recrudescence, there was renewal of spermatogenic cells char- acterized by spermatogonial divisions; primary and secondary spermatocytes and spermatids were occasionally present. In spermiogenesis, metamorphosing sper- matids and mature sperm were present. Males undergoing spermiogenesis were found April—September; regressed tes- tes were found March-June; testes in recrudescence were found March—August 101 102 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Monthly distribution of conditions in seasonal testicular cycle of Crotalus mitchellii. Values shown are the numbers of males exhibiting each of the three conditions. Month N Regressed Recrudescence Spermiogenesis March 3 2 1 6) April 11 4 5 2 May 25 3 11 11 June 9 3 3 3 July - 0) 2 2 August - 0) 1 3 September 1 O 0) 1 (Table 1). The smallest spermiogenic male measured 512 mm SVL. This was the smallest male included in the study. Sperm were present in the vasa deferentia of the following males: March 2/2 (100%); April 8/8 (100%); May 15/15 (100%); June 7/8 (88%); July 2/3 (67%); August 1/1 (100%); September 1/1 (100%) sug- gesting C. mitchellii has the capacity to breed March-September. Kidney sexual segments were enlarged and contained secretory granules in 16/17 (94%) of males undergoing spermiogenesis; 11/11 (100%) of males with regressed testes and 14/20 (70%) of males with recrudescent testes. On a monthly basis enlarged sexual seg- ments with secretory granules were found in males in the following proportions: March 3/3 (100%); April 8/9 (89%); May 19/23 (83%); June 6/7 (86%); July 2/ 3 (67%); August 3/4 (75%); September 1/1 (100%). Mating coincides with hy- pertrophy of the kidney sexual segment (Saint Girons 1982). Because of insufficient sample sizes from summer and autumn, it is difficult to compare the testicular cycle of C. mitchellii with that of other crotalids. The observation of 44% of May males undergoing spermiogenesis may suggest that spermiogenesis occurs primarily in the spring in C. mitchellii. This is in contrast to the western rattlesnake, Crotalus viridis, the western diamondback rattlesnake, Crotalus atrox, the Mojave rattlesnake, Crotalus scutulatus and the tiger rattle- snake, Crotalus tigris in which the major period of spermiogenesis occurs in summer-autumn (Aldridge 1979a, Jacob et al. 1987; Goldberg 1999). Since the peak of C. mitchellii activity occurs in May-June in southern California (Klauber 1931) collections of summer-autumn samples to describe the testicular cycle would be difficult. One male (LACM 28018) was found in copulation by G. Ahern near Cabazon on the west slope of the San Jacinto Mountains, Riverside County, California at 1800 hours on 11 June 1964. J. W. Warren (c.f. Brattstrom 1965) found a pair of C. mitchellii mating in the afternoon at Afton, San Bernardino County on 18 April 1953. Mating in Arizona occurs in April-May (Lowe et al. 1986). Additional field observations are needed before the period in which mating occurs under natural conditions is known. During the months of female reproductive activity (April—June) (Table 2) 15/34 (44%) C. mitchellii showed evidence of reproductive activity (early yolk deposition, enlarged follicles or oviductal eggs). This is slightly higher than the value (35%) reported for C. tigris females (Goldberg 1999). Females with enlarged follicles (> 10 mm length) were found April-June (Table 2). Females in early yolk deposition (i.e., secondary vitellogenesis sensu Aldridge RESEARCH NOTE 103 Table 2. Monthly distribution of conditions in seasonal ovarian cycle of Crotalus mitchellii. Values shown are the number of females exhibiting each of the three conditions. Enlarged follicles Early yolk (> 10 mm length) Month N Inactive deposition or oviductal eggs March 1 1 0) 0) April 12 8 3 1 May 14 8 Z 4} June 8 3 0) 5 July 1 1 0 0 August 3 3 0) 0) September 2 2 0) 0 November 1 1 0) 0) ' Only 1 follicle (17 mm length) measured from damaged ovary. 1979b) were found in April—May. The “‘small eggs’’ reported 10 June in a female C. mitchellii by Cunningham (1959) were likely undergoing early yolk deposition. The smallest reproductively active female (follicles > 10 mm length) measured 552 mm SVL. Mean litter size for 9 females from Table 3 was 5.78 + 1.79 SD (3-8 range). This value is close to the mean litter size 5.77 + 2.47 SD (1-10 range) calculated for 22 C. mitchellii listed in Klauber (1972). According to Fitch (1985) C. mitchellii litter sizes are largest in the north and decrease in southern (Mexican) populations. Crotalus mitchellii appears to follow a biennial reproductive cycle in which yolk deposition (secondary vitellogenesis sensu Aldridge 1979b) commences in summer followed by ovulation the next year which is similar to that reported in other North American rattlesnakes (see Goldberg, 1999). However, Crotalus atrox females are believed to bear litters each year in Oklahoma (Fitch and Pisani 1993) as do southern populations of the western rattlesnakes, Crotalus viridis (c.f. Fitch 1985). Furthermore, there are reports of different populations of the timber rat- tlesnake, Crotalus horridus following biennial, triennial or quadrennial reproduc- tive cycles (Ernst 1992). Additional reproductive data on C. mitchellii from dif- ferent parts of its range will be needed before the timing of the female reproduc- tive cycle can be ascertained for this species. Table 3. Litter sizes for Crotalus mitchellii. SVL Date (mm) Litter size Locality Source 28 April 762 i, Riverside Co., CA LACM 104878 7 May 352 3 San Bernardino Co., CA LACM 19894 28 May 760 8 Riverside Co., CA LACM 104866 10 June 763 / San Bernardino Co., CA LACM 19981 14 June 652 4 Riverside Co., CA LACM 134441 15 June 762 5 San Bernardino Co., CA LACM 104938 23 June 683 7 Riverside Co., CA LACM 104926 3 Sept. 634 he Maricopa Co., AZ UAZ 43945 16 Sept. 656 4? Maricopa Co., AZ UAZ 44316 ' Gave birth to 5 live young and 2 still born in captivity on 3 September. ? Gave birth to 4 live young in captivity on 16 September. 104 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES I thank Robert L. Bezy (Natural History Museum of Los Angeles County), Michael E. Douglas (Arizona State University) and Charles H. Lowe (The Uni- versity of Arizona) for permission to examine C. mitchellii. Michelle Zamora assisted with histology. Literature Cited Aldridge, R. D. 1979a. Seasonal spermatogenesis in sympatric Crotalus viridis and Arizona elegans in New Mexico. J. Herpetol., 13:187—192. . 1979b. Female reproductive cycles of the snakes Arizona elegans and Crotalus viridis. Her- petologica, 35:256—261. Brattstrom. B. H. 1965. Body temperatures of reptiles. Amer. Midl. Nat., 73:376—422. Cunningham, J. D. 1959. Reproduction and food of some California snakes. Herpetologica, 15:17—19. Ernst, C. H. 1992. Venomous reptiles of North America. Smithsonian Institution Press, Washington, D.G.,; ix -+.-236- pp: Fitch, H. S. 1985. Variation in clutch and litter size in New World reptiles. Misc. Pub. Mus. Nat. Hist., Univ. Kansas, 76:1—76. . and G. R. Pisani. 1993. Life history traits of the western diamondback rattlesnake (Crotalus atrox) studied from roundup samples in Oklahoma. Occas. Pap. Mus. Nat. Hist., Univ. Kansas, 156:1-24. Goldberg, S. R. 1999. Reproduction in the tiger rattlesnake, Crotalus tigris (Serpentes: Viperidae). Texas J. Sci., 51:31-36. . and W. S. Parker. 1975. Seasonal testicular histology of the colubrid snakes, Masticophis taeniatus and Pituophis melanoleucus. Herpetologica, 31:317—322. Jacob, J. S., S. R. Williams and R. P. Reynolds. 1987. Reproductive activity of male Crotalus atrox and C. scutulatus (Reptilia: Viperidae) in northeastern Chihuahua, Mexico. Southwest. Nat., 32:273-276. Johnson, L. F, J. S. Jacob and P. Torrance. 1982. Annual testicular and androgenic cycles of the cottonmouth (Agkistrodon piscivorus) in Alabama. Herpetologica, 38:16—25. Klauber, L. M. 1931. A statistical survey of the snakes of the southern border of California. Bull. Zool. Soc. San Diego, No. 8, 93 pp. . 1936. Crotalus mitchellii, the speckled rattlesnake. Trans. San Diego Soc. Nat. Hist., 8:149—184. . 1972. Rattlesnakes. Their habits, life histories, and influence on mankind. 2nd ed. Vol. 1, Univ. California Press, Berkeley, xlvi + 740 pp. Lowe, C. H., C. R. Schwalbe and T. B. Johnson. 1986. The venomous reptiles of Arizona. Arizona Game and Fish Department, Phoenix, ix + 115 pp. Saint Girons, H. 1982. Reproductive cycles of male snakes and their relationships with climate and female reproductive cycles. Herpetologica, 38:5—16. Stebbins, R. C. 1985. A field guide to western reptiles and amphibians. Houghton-Mifflin, Boston, Masachusetts, xiv + 336 pp. Accepted for publication 15 June 1999. Appendix: Specimens of C. mitchellii examined from the herpetology collections of Arizona State University, Tempe (ASU), Natural History Museum of Los Angeles County, (LACM) and The Uni- versity of Arizona, Tucson (UAZ). ARIZONA: LA PAZ COUNTY, LACM 107219; UAZ 50218. MARICOPA COUNTY, ASU 1606, 3200, 3583, 3585, 9073, 24342. LACM 112475. UAZ 27594, 42974-42976, 43945, 44316, 49264 YUMA COUNTY, ASU 15834-15836; UAZ 27589, 35672, 35710, 35816, 43976. CALIFORNIA: INYO COUNTY, LACM 36696, 104871. KERN COUNTY, LACM 134440; UAZ 35814, 35996, 35997. ORANGE COUNTY, LACM 104872—104874 SAN BERNARDINO COUNTY, LACM 19981, 19894, 63974, 104935—104939, 104941, 104945, 104946, 104949, 104951, 104954, 104955, 134443, 138218; UAZ 35813. RIVERSIDE COUNTY, LACM 28018, 52592, 104866, 104878, 104879, 104881—104883, 104885, 104887, 104890, 104892, 104894, 104895, 104898, 104899, 104901—104903, 104905—104909, 104911, 104913, 104915—104917, 104919, 104921— 104923, 104925, 104926, 104928, 104929, 134441, 134442, 138217, 19996-19998 SAN DIEGO COUNTY, LACM 52593, 52594. NEVADA: CLARK COUNTY, UAZ 27597. NYE COUNTY, LACM 134038, 134039. Bull. Southern California Acad. Sci. 99(2), 2000, pp. 105—109 © Southern California Academy of Sciences, 2000 Research notes Reproduction in the Glossy Snake, Arizona elegans (Serpentes: Colubridae) from California Stephen R. Goldberg Department of Biology, Whittier College, Whittier, California 90608, U.S.A. The glossy snake, Arizona elegans Kennicott 1859 is a wide-ranging species that occurs in the southwestern United States from southwestern Nebraska and east Texas to central California, southern Utah to southern Baja California, south- ern Sinaloa and San Luis Potosi, México from below sea level to 1830 m; it inhabits desert, sagebrush flats, grassland, chaparral and woodland (Stebbins 1985). Aldridge (1979a; 1979b) reported on reproduction in A. elegans in New Mexico. There are other anecdotal reports on reproduction in A. elegans by Burt and Hoyle (1934); Reynolds (1943); Cowles and Bogert (1944); Wright and Wright (1957); Tennant (1984); Degenhardt et al. (1996). Fitch (1970) summa- rized information on reproduction in A. elegans. Biology of the snake genus Arizona is summarized in Dixon and Fleet (1976). It is of interest to compare reproduction in populations from different areas of the geographic range of snakes to determine variation in the reproductive cycle. The purpose of this note is to present the first detailed information on the ovarian and testicular cycles of A. elegans from California and to provide information on clutch sizes. Reproduction of the California population of A. elegans is compared with reproduction of a population of A. elegans from New Mexico (Aldridge 1979a; 1979b). A sample of 111 specimens of A. elegans (31 females, mean Snout-Vent Length, SVL = 723.2 mm + 96.2 SD, range = 562—918 mm); 80 males, mean SVL = 610.3 mm = 118.2 SD, range = 367-958 mm) from California was examined from the herpetology collection of the Natural History Museum of Los Angeles County (LACM) (Appendix). Snakes were collected in 1937-1977. Counts were made of enlarged follicles (> 10 mm length) or oviductal eggs. The left testis, vas deferens and part of the left kidney were removed from males; the left ovary was removed from females for histological examination. Tissues were embedded in paraffin and cut into sections at 5 wm. Slides were stained with Harris’ hematoxylin followed by eosin counterstain. Testes slides were examined to determine the stage of the male cycle; ovary slides were ex- amined for the presence of yolk deposition (i.e., secondary vitellogenesis sensu Aldridge 1979a). Vasa deferentia were examined for sperm. Slides of kidneys were examined for secretory activity in the sexual segments. Because some of the specimens were road-kills, not all tissues were available for histological ex- amination due to damage or autolysis. Number of specimens examined by repro- ductive tissue were: testis = 80, vas deferens = 55, kidney = 38, ovary = 31. Testicular histology was similar to that reported by Goldberg and Parker (1975) for the colubrid snakes, Masticophis taeniatus and Pituophis catenifer (= P. me- lanoleucus). In the regressed testes, seminiferous tubules contained spermatogonia 105 106 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Monthly distribution of conditions in seasonal testicular cycle of Arizona elegans from California. Values shown are the numbers of males exhibiting each of the three conditions. Month N Regressed Recrudescence Spermiogenesis April 11 10 1 0 May 50 46 + 0) June 14 10 3 1 July 4+ 0 3 1 September 1 0) 0) 1 and Sertoli cells. In recrudescence, there was renewal of spermatogenic cells char- acterized by spermatogonial divisions. Primary and secondary spermatocytes and spermatids were occasionally present. In spermiogenesis, metamorphosing sper- matids and mature sperm were present. In the spring (April—June), 66/75 (88%) of males contained regressed testes (Table 1). Testes in 11/80 (14%) were undergoing recrudescence. Spermiogenesis was occurring in the following males: 1/14 (7%) June; 1/4 (25%) July; 1/1 (100%) September. Vasa deferentia in 55/55 (100%) A. elegans males collected in the spring contained sperm (5/5 April; 42/42 May; 8/8 June) suggesting that mating occurs during this period. Ball (1990) reported A. elegans males and females collected 13 and 16 May in Oklahoma courted and mated when placed in captiv- ity. The only September male (which was undergoing spermiogenesis) contained sperm in the vas deferens. It is not known whether A. elegans mates during autumn. The A. elegans testicular cycle appears to fit the “‘aestival spermatogen- esis D”’ as described by Saint Girons (1982) (spermatogenesis from June to Oc- tober; ovulation in the beginning of June). Kidney sexual segments of males: 2/2 (100%) April; 27/28 (96%) May; 7/7 (100%) June; 1/1 (100%) September were enlarged and contained secretory granules. Mating coincides with hypertrophy of the kidney sexual segment (Saint Girons 1982). There were no A. elegans males collected in August and only one from Sep- tember (Table 1). This is a reflection of the seasonal activity cycle of A. elegans in southern California in which this species is mainly active during the spring. Of 34 reports of A. elegans in San Diego County (Klauber 1931), 28 (82%) were from winter-spring; only 6/34 (18%) were from August-September. The smallest mature male (sperm in the vas deferens, LACM 102083) measured 367 mm SVL. Males smaller than this size were excluded from the study to avoid including immature males in analysis of the testicular cycle. The timing of the testicular cycle of A. elegans in California is similar to that of A. elegans in New Mexico (Aldridge 1979b) and M. taeniatus and P. catenifer (Goldberg and Parker 1975) in which testes are regressed in spring with sper- miogenesis occurring later in the year. However, the A. elegans testicular cycle is distinctly different from that of the sympatric western shovelnose snake, Chion- actis occipitalis, which also has a spring activity period in California during which time spermiogensis occurs (Goldberg 1997). Arizona elegans females with enlarged follicles (> 10 mm length) or oviductal eggs were found May—June (Table 2). One May female was undergoing yolk deposition (= secondary vitellogenesis sensu Aldridge 1979a). One June female RESEARCH NOTE 107 Table 2. Monthly distribution of conditions in seasonal ovarian cycle of Arizona elegans from California. Values shown are the number of females exhibiting each of the three conditions. Enlarged follicles Yolk (> 10 mm length) or Month N Inactive deposition oviductal eggs March 1 1 0 0 April 4 4 0) 0) May 11 5 1 5 June 7 4* 0) 3 July 4 4 0) 0 August é: 3 0 0 September 1 l 0 0) * Corpora lutea present in one female; eggs had been recently deposited. (LACM 102023) collected 16 June contained corpora lutea but no oviductal eggs indicating a recent ovulation. Aldridge (1979a) reported A. elegans females from New Mexico to also ovulate in June. The smallest reproductively active A. elegans female (follicles > 10 mm length, LACM 122093) measured 562 mm SVL. Fe- males smaller than this size were excluded from the study to avoid including immature females in analysis of the ovarian cycle. Mean clutch size for 8 females with enlarged follicles (> 10 mm length) or oviductal eggs was 7.5 + 3.2 SD, range = 2-11 (Table 3). This value may be slightly higher than what actually occurs since clutch sizes for 7 of the 8 females (Table 3) came from counts of follicles > 10 mm length. There is a chance that not all enlarged follicles would have completed development. There was no ev- idence (yolk deposition in progress in a female with oviductal eggs) to suggest females produce more than one clutch per year. Fourteen A. elegans clutches from the literature (Fitch 1970) from different locations averaged 8.5, range = 3-23. Aldridge (1979a) reported potential fecundity (enlarged follicles or oviductal eggs) of 8.4 + 0.7 SE, range 6-12 for 6 A. elegans from New Mexico. There was no significant difference between the clutches of Aldridge (1979a) for A. elegans from New Mexico and clutches from California A. elegans presented herein (t = 0.925, p > 0.30). Comparisons of larger numbers of clutches will be Table 3. Clutch sizes for Arizona elegans from California estimated from counts of yolked follicles > 10 mm length or oviductal eggs. SVL Date (mm) Clutch size County LACM # 4 May 918 11 Riverside 102034 11 May 562 2 Riverside 122093 20 May 897 8 San Diego 52460 24 May 745 9 Riverside 102109 11 June 823 ig San Diego 102137 15 June 745 9 Riverside 102026 16 June 784 i Riverside 102027 18 June 699 2 San Bernardino 102124 * Oviductal eggs; other clutches are enlarged follicles. 108 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES needed to ascertain differences in fecundity between New Mexico and California populations of A. elegans. Only 9/23 (39%) snakes were reproductively active (enlarged follicles > 10 mm length or oviductal eggs) during March—June. This is within the range of 7— 70% found for annual percentages of breeding females per year in their survey of 85 snake species (Seigel and Ford 1987). In conclusions, the reproductive cycle of A. elegans from California appears similar to that of A. elegans from New Mexico, ca. 870 km apart (Aldridge 1979a, 1979b) as testes are regressed in both populations in spring; spermiogenesis occurs in late summer. Yolk deposition began in spring in California and New Mexico A. elegans with ovulation in June. Additional reproductive studies between widely separated populations of A. elegans will be required to ascertain the amount of geographic variation in reproduction in this widely distributed species. I thank Robert L. Bezy (Natural History Museum of Los Angeles County) for permission to examine A. elegans. Michelle Zamora assisted with histology. Literature Cited Aldridge, R. D. 1979a. Female reproductive cycles of the snakes Arizona elegans and Crotalus viridis. Herpetologica, 35:256—261. . 1979b. Seasonal spermatogenesis in sympatric Crotalus viridis and Arizona elegans in New Mexico. J. Herp., 13:187—192. Ball, R. L. 1990. Captive propagation of the Kansas glossy snake Arizona e. elegans. Pp. 6—12 In: A. W. Zulich (ed.), Proceedings of the 14th International Herpetological Symposium on Captive Propagation and Husbandry. International Herpetological Symposium, Inc., Dallas-Ft. Worth, Texas, June 20-23, 1990. Burt, C. E., and W. L. Hoyle. 1934. Additional records of the reptiles of the central prairie region of the United States. Trans. Kansas Acad. Sci., 37:193-—216. Cowles, R. B., and C. M. Bogert. 1944. A preliminary study of the thermal requirements of desert reptiles. Bull. Amer. Mus. Nat. Hist., 83:261—296. Degenhardt, W. G., C. W. Painter and A. H. Price. 1996. Amphibians and reptiles of New Mexico. University of New Mexico Press, Albuquerque, xix + 431 pp. Dixon, J. R., and R. R. Fleet. 1976. Arizona Kennicott Glossy Snake. Cat. Amer. Amphib. Rept. 179.1-179.4. Fitch, H. S. 1970. Reproductive cycles in lizards and snakes. The University of Kansas Museum of Nat. Hist. Misc. Publ. 52:1—247. Goldberg, S. R. 1997. Reproduction in the western shovelnose snake, Chionactis occipitalis (Colu- bridae), from California. Grt. Bas. Nat. 57:85—87. , and W. S. Parker. 1975. Seasonal testicular histology of the colubrid snakes, Masticophis taeniatus and Pituophis melanoleucus. Herpetologica, 31:317—322. Klauber, L. M. 1931. A statistical survey of the snakes of the southern border of California. Bull. Zool. Soc. San Diego, No. 8, 93 pp. Reynolds, EF A. 1943. Notes on the western glossy snake in captivity. Copeia 1943:196. Saint Girons, H. 1982. Reproductive cycles of male snakes and their relationships with climate and female reproductive cycles. Herpetologica, 38:5—16. Seigel, R. A., and N. B. Ford. 1987. Reproductive ecology. Pp. 210-252 in Snakes: ecology and evolutionary biology. (R. A. Seigel, J. T. Collins, and S. S. Novak, eds.), Macmillan Publishing Company, New York. Stebbins, R. C. 1985. A field guide to western reptiles and amphibians. Houghton Mifflin Company, Boston, xiv + 336 pp. Tennant, A. 1984. The snakes of Texas. Texas Monthly Press, Austin, 561 pp. Wright, A. H., and A. A. Wright. 1957. Handbook of snakes of the United States and Canada. Com- stock Publ. Assoc., Cornell University Press, Ithaca, New York, vol. 1, xviii + 564 pp. Accepted for publication 2 March 2000. RESEARCH NOTE 109 Appendix Specimens of A. elegans from California examined from the herpetology collection of the Natural History Museum of Los Angeles County, (LACM). IMPERIAL COUNTY, LACM 2178. KERN COUNTY, LACM 101994, 101995, 123758. LOS AN- GELES COUNTY, LACM 20392, 20395, 20396, 74056, 74057, 126187, 126190. RIVERSIDE COUNTY, LACM 20436, 52461-52463, 52467, 52468, 52470, 52472, 101993, 102000, 102001, 102003, 102010, 102021—102023, 102026, 102027, 102030, 102032, 102034—102036, 102038, 102040, 102043, 102044, 102046, 102049, 102050, 102054, 102056, 102057, 102062, 102065, 102067—102069, 102072, 102083, 102084, 102086—102088, 102091, 102099, 102101, 102103, 102104, 102106, 102109, 102110, 115764, 122093—122096. SAN BERNARDINO COUNTY, LACM 20440-20444, 20447, 68831, 68832, 102112, 102114, 102115, 102117, 102119—102122, 102124, 102126, 102127, 102130, 102133, 122455, 125989, 138134. SAN DIEGO COUNTY, LACM 27675, 27676, 27678, 27680, 52460, 59071, 66929, 76285, 102136, 102137, 102140, 102146, 102153, 102154, 102156, 102164, 102165, 123756, 126291. Bull. Southern California Acad. Sci. 99(2), 2000, pp. 110-113 © Southern California Academy of Sciences, 2000 New occurrences of the endemic labrisomid fish Paraclinus walkeri Hubbs, 1952 in Bahia de San Quintin, Baja California, Mexico. Jorge A. Rosales-Casian Grupo de Ecologia Pesquera, Depto. Ecologia, Div. Oceanologia Centro de Investigaci6n Cientifica y de Educaci6n Superior de Ensenada, B.C. Km 107 carretera Tijuana-Ensenada, A. P. 2732. Ensenada, Baja California, México. — Paraclinus walkeri (family Labrisomidae) is a small, cryptic species that, since their first collections in 1949 (Hubbs 1952, Rosenblatt and Parr 1969) has been reported only from Bahia de San Quintin, Baja California (México). A total number of eleven individuals of the Paraclinus walkeri, were collected from January to December 1994 in Bahia de San Quintin, as a part of a larger study of the fishes of nearshore environments that included Bahia de Todos San- tos, Estero de Punta Banda, and the Bahia de San Quintin and its adjacent coastal waters (Rosales-Casiadn 1997b). The Bahia de San Quintin (30°24’—30°30' N, 115°57'—116°01’ W) is located 300 km south of California border, and is one of the most important lagoons in Baja California (Ibarra-Obando 1990); it has a total area of 4,000 ha, communicates with the sea through a narrow mouth (<1000 m) that is 2—7 m depth, and is divided into two arms: the western arm is called Bahia Falsa and the eastern, Bahia de San Quintin (Fig. 1). The channel bottoms are muddy with fine sediment towards the head, and coarser sand near the mouth (Gorsline and Steward 1962). This bay is classified as an antiestuary, with salinity and temperature values that increase from the mouth towards the head (Chavez-de-Nishikawa and Alvarez-Borrego 1974). It is a protected habitat characterized as a high productivity zone due to the presence of seagrass beds of Zostera and Spartina (Ballesteros-Grijalva and Garcia-Lepe 1993; Poumian-Tapia 1995), and phytoplankton. In San Quintin, an almost permanent upwelling has been reported close to the mouth (Dawson 1951), and the most intense period was ob- served during the months of April and May (Rosales-Casian 1997b). A report by Hubbs (1952) mentioned that the species P. walkeri was found only in San Quintin Bay, Baja California, and that it is probably found nearer to the head of the bay than to the mouth. Under natural conditions, the fish live in sponges found on sand bottom, and they were collected from these same sponges which were attached to the pilings of an old pier that Hubbs (1952) assumed to be optimal for this species. The name walkeri is attributed to Boyd W. Walker, and the first individual was collected on an expedition of the Stanford Natural History Club on March 24, 1949, from a mud flat. The genus Paraclinus (Per- ciformes: Labrisomidae) currently contains 19 species of which eleven are found in the eastern Pacific (Eschmeyer 1998; Rosemblatt and Parr 1969). In Bahia de San Quintin, the first published check-list of the fish species re- ported 69 species belonging to 56 genera and 34 families, including the species P. integripinis and P. walkeri (Rosales-Casidn 1996). The geographic range of P. integripinis is from Bahia Almejas, Baja California, México to Santa Cruz Island, 110 RESEARCH NOTE 1s \,. Molino Viejo Kenton Hill : de Mt.Ceniza e \ San Quintin > | r J 10m e ~— OTTER - TRAWL e— BEAM - TRAWL 30°25'N Mt Mazo _-Pta Entrada 0 500 1000 2000 Ss METROS 16°50 W Figure 1. Location of the sampling sites in Bahia de San Quintin, B.C. México. California (Miller and Lea 1972). A comparison of the collected fishes with a beam-trawl gear from the Estero de Punta Banda and Bahia de San Quintin is presented in Rosales-Casian (1997a). In this last study, the most important fish species in Punta Banda (5m-depth) were the California halibut (Paralichthys cal- ifornicus), the kelp bass (Paralabrax clathratus), and the barred sand bass (P. nebulifer); in San Quintin the catches were dominated by the bay pipefish (Syng- nathus leptorhynchus), P. californicus, and the California tonguefish (Symphurus atricauda). In Bahia de San Quintin, the labrisomid P. walkeri was collected with two of the five gears during monthly sampling in 1994. These were beam-trawl (1.6 m x 0.4 m, 3-mm mesh), and an otter-trawl (opening of 7.5 m headrope, with 19 mm of body mesh, and 6 mm mesh cod-end), both towed at a velocity of 1.5 knots for five minutes. The beam-trawl collected six individuals at a depth of 5m, b12 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Data of Paraclinus walkeri collected in Bahia de San Quintin, B.C., México. Collections were made in 1964. TL: Total length, ST: Standard length, W: Total weight. Month Gear Depth (m) TL (mm) ST (mm) W (g) September Otter-trawl 10 87 7S 7.0 September Beam-trawl 10 87 73 8.1 September Beam-trawl 10 82 69 tt September Beam-trawl 10 86 aS 9.8 October Beam-trawl = 45 39 0.9 October Beam-trawl 5 45 39 1.1 October Beam-trawl 5 46 39 1.1 October Beam-trawl 5 40 35 0.7 October Beam-trawl a 47 40 1.3 November Beam-trawl 5 57 50 22 November Otter-trawl 5 46 38 3.6 and three individuals at a depth of 10m. Two more specimens were collected by otter-trawl, one individual at a depth of 5 and 10m. The collection of specimens occurred from August (n = 1), September (n = 3), October (n = 5), to November (n = 2). The specimens from 5m were captured on the muddy bottom in the channel and were associated with seagrasses (Z. marina). P. walkeri from 10 m were associated with remains of the same eelgrass during fall (August-November). The collection sites in Bahia de San Quintin are presented in Fig. 1. Paraclinus walkeri in almost all features of external morphology fits the di- agnosis of P. integripinnis. The diagnosis is based upon an increase in the number of branchiostegal rays that is 7, rarely 6; body usually with a uniform brown coloration and with 5-7 darker bars; opercular spine with an acute tipe, rarely with two points (Hubbs 1952; Rosenblatt and Parr 1969). For P. integripinis a diagnosis is six branchiostegals rays, rarely five and never seven; opercular spine is sharp to blunt or rounded, and may bear as many as three points; the color pattern does not include a barred phase (Rosenblatt and Parr 1969). The sampling of the 1994 study was not directed to the pier pillings or the sponges that are the habitats for this labrisomid, thus my data cannot be used to estimate population size in Bahia de San Quintin. Its relative abundance from the total fish community (10,079 individuals) in the bay during 1994 was less than 0.11%. In the same period, a total number of 22 specimens of P. integripinnis was collected with same gears and depths. The total and standard length and the weight of the collected P. walkeri are shown in Table 1; the range of total length was 40 to 87 mm, and the range of the total weight was 0.7 to 9.8 grams. Paraclinus walkeri seems to behave as a good biological species that is ripe for further research. However it is difficult to conceive how this tiny population, restricted to a small bay and embedded in the range of another very similar species, is able to maintain its genetic integrity (Rosenblatt and Parr 1969). Nevertheless, it does appear that P. walkeri may indeed be restricted to one, relatively small, coastal lagoon because in a similar system, Estero de Punta Ban- da, it was not collected. How might this species maintain itself and be unable to disperse from that point? First, P. walkeri is a very small species, apparently evolved to take advantage of lagoon environments. These systems are quite rare along the Baja California coast and dispersal from these isolated environments RESEARCH NOTE 113 may be difficult if a species cannot live along the open coast. Moreover, larval dispersal from Bahia de San Quintin may also be difficult. In a study of DNA of seven populations of an economically important serranid, the kelp bass (Parala- brax clathratus), from Baja California (México) and California (USA), Grothues (1994) found that the San Quintin population is an isolated one. Grothues spec- ulated that San Quintin lies in an area of upwelling, and that this may act as a barrier to larval drift, causing larvae moving along shore to be entrained seaward. This coastal lagoon remains as an almost pristine place and makes a special environment for study and comparison with other highly impacted sites from the California coast. Acknowledgements The funds for this study were obtained from CICESE and from the BENES Program (Calif. Dept. Fish and Game) by way of Larry G. Allen of California State University in Northridge (#FG-2052MR). Thanks to Richard Rosenblatt and Cynthia Klepadlo for identifying the first five P. walkeri. Thanks to the Programa SUPERA (ANUIES) for the scholarship during my graduate program. Literature Cited Ballesteros-Griyalva, G. and Garcia-Lepe, M. G. 1993. Produccién y Biodegradacioén de Spartina foliosa en Bahia San Quintin, B.C., México. Ciencias Marinas, 19:445—459. Chavez de Nishikawa, A. and Alvarez-Borrego, S. 1974. Hidrologia de la Bahia de San Quintin, Baja California en invierno y primavera. Ciencias Marinas, 1(2):31—62. Dawson, E.Y. 1951. A further study of upwelling and vegetation along Pacific Baja California. Jour. Mar. Res. 10(1):39—58. Eschmeyer, W.N. 1998. Catalog of fishes. Volume 2: Species of fishes (M-Z). California Academy of Sciences. San Francisco, Ca, USA. pp. 959-1820. Gorsline, D.F and Stewart, R.L. (1962). Benthic marine exploration of Bahia San Quintin, Baja Cal- ifornia: Marine and quaternary geology. Pacific Nat., 2:275—280. Grothues, T.M. 1994. An investigation into the population genetic structure and larval dispersal pat- terns of the kelp bass (Paralabrax clathratus). Masters thesis, California State University of Northridge. 42 p. Hubbs, C.L., 1952. A contribution to the classification of the blennioid fishes of the family Clinidae with a partial revision of the eastern Pacific forms. Stanford Ichthyol. Bull. 4(2):41—165. Ibarra-Obando, S.E. 1990. Las lagunas costeras de Baja California. Ciencia y Desarrollo. 16(92):39—49. Poumian-Tapia, M. 1995. Sobre la cuantificacién de la biomasa de Zostera marina L. en Bahia de San Quintin, B.C. durante un ciclo anual. M.Sc. thesis. Ecologia, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada. 152 p. Miller, D.J. and R.N. Lea. 1972. Guide to the coastal marine fishes of California. Calif. Dept. Fish and Game, Fish Bull. 157. 235 p. Rosales-Casian, J.A. 1996. Ichthyofauna of Bahia de San Quintin, Baja California, México, and its adjacent coast. Ciencias Marinas 22:443—458. Rosales-Casian, J.A. 1997a. Inshore soft-bottom fishes of two coastal lagoons on the northern Pacific coast of Baja California. CalCOFI Rep. 38:180—192. Rosales-Casidn, 1997b. Estructura de la comunidad de peces y el uso de los ambientes de bahias, lagunas y costa abierta en el Pacifico norte de Baja California. Ph.D. thesis. Ecologia, Centro de Investigaci6n Cientifica y Educaci6n Superior de Ensenada, B.C. (CICESE). 201 p. Rosenblatt, R.H. and Parr T:D. 1969. The Pacific species of the Clinid fish genus Paraclinus. Copeia, No. 1:1—20. Accepted for publication 17 May 1999 Bass e -cps : gassing. I in > 2} The ‘spelen, we Fe5 vin euerttineth en cia Ty Perth Path’ Bln Wrest pace ease! ey antinn,? AMES ih ash; cnts ghia Ty ds BOW NOR we rait13 17 Meee peronsiy mF suis Hy ht Sei oe gic Riedie a ap c.6 ae ¥*. ety i - phba ll ek } WAG eh rawierehigndigie) ot!’ iar iis abl ; ¢ ' 4 _ pre’ “4 Yeo eee yf wotduW! jt nan d : t \ 7. ‘ Wiss. ate ee A rahi are ipa oirelngeg’ ait ' r 2 s ! ss 4 Pi anit © th, Cheat AT rien “< 7 the anit phat 1d AR RM siete: 74), , Aas 2 A if Shak i Ppa et ah oP ies AA neg ast 1 wk & y@ f X -9 itn en VS MARAT. Winds oteaed. Wie hee et ‘) ier votes n ’ Mit igis Caw ops > Mis ¢ pir i) ] a! { 4? ; ‘ , i 4 + , ’ ® i ‘ “ A * s i * re ‘ ; ¢ ‘ ' py in Fee te Arh Se ct ante ei sagt, be ot nih of ah af ste hing, j anim ya p Diet iwaht as uf a rae Beiete, mons ton ihe» ‘ + ol T 7? 4 Biter _ ~ th ae = 4 * of enn sh dies ¢ BEN at “ ‘~ , ng Pitre ash ti AA ‘iso INSTRUCTIONS FOR AUTHORS The BULLETIN is published three times each year (April, August, and Decernber) and includes articles in English in any field of science with an emphasis on the southern California area. 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Goldbere n-ne ee ee New occurrences of the endemic labrisomid fish Paraclinus walkeri Hubbs, 1952 in Bahia de San Quintin, Baja California, Mexico. Jorge A. eae a ee ee J he 59 91 101 105 ISSN 0038-3872 Pee rHEeRN CALIFORNIA "ACADEMY «OF °SCIENCES BOLLETIN Volume 99 Number 3 BCAS-A99(3) 115-178 (2000) DECEMBER 2000 Southern California Academy of Sciences Founded 6 November 1891, incorporated 17 May 1907 © Southern California Academy of Sciences, 2000 OFFICERS Daniel Pondella, President Ralph Appy, Vice-President Susan E. Yoder, Secretary Daniel A. Guthrie, Treasurer Daniel A. Guthrie, Editor David Huckaby, Past President Hans Bozler, Past President BOARD OF DIRECTORS 1998-2001 1999-2002 2000-2003 Kathryn A. Dickson Ralph G. Appy James Allen Donn Gorsline Jonathan N. Baskin John Dorsey David G. Huckaby John W. Roberts Judith Lemus Robert F. Phalen Tetsuo Otsuki Martha and Richard Daniel Pondella Gloria J. Takahashi Schwartz Susan E. Yoder Membership is open to scholars in the fields of natural and social sciences, and to any person interested in the advancement of science. Dues for membership, changes of address, and requests for missing numbers lost in shipment should be addressed to: Southern California Academy of Sciences, the Natural History Museum of Los Angeles County, Exposition Park, Los Angeles, California 90007-4000. Profemsional Bierahore | eee ee a he) OR ee, a iE ea re minthonl Were ee ee OR aS NO SAN a) Se es Be ea Memberships in other categories are available on request. Fellows: Elected by the Board of Directors for meritorious services. The Bulletin is published three times each year by the Academy. Manuscripts for publication should be sent to the appropriate editor as explained in “Instructions for Authors” on the inside back cover of each number. All other communications should be addressed to the Southern California Academy of Sciences in care of the Natural History Museum of Los Angeles County, Exposition Park, Los Angeles, California 90007-4000. Date of this issue 5 December 2000 © This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper). a MALICORALIIA y : — ' : CALIFORNIA | 7 e { Af. PVETAR AS SAE NAIA OO. ff ACADEMY OF SCIENCES | pee er DEC 24 avin | 2ARY SOUTHERN CALIFORNIA ACADEMY ii parA OF SCIENCES CALL FOR PAPERS 2001 ANNUAL MEETING May 4-5, 2001 CALIFORNIA STATE UNIVERSITY AT LOS ANGELES Contributed Papers & Posters: Both professionals and students are welcome to submit abstracts for a paper or poster in any area of science. Abstracts are required for all papers, as well as posters, and must be submitted in the format described below. Maximum poster size is 32 by 40 inches. Symposia: The following symposia are planned at the present time. If you wish to participate or to organize any additional symposia, please contact the organizer or the Academy Vice President, Ralph Appy (310 732 4643) rappy @portla.org. Organizers should have a list of participants and a plan for reaching the targeted audience. Marine Ecology of Rocky Reefs and Areas of Special Biological Significance Organizers: Dan Pondella (pondella@oxy.edu) and Bob Grove (Robert.Grove @ sce.com) The Puente-Chino Hills Wildlife Corridor and Wildlife Corridors in the Los Angeles Basin. Organizers: Dan Guthrie (dguthrie @jsd.claremont.edu) and Dan Cooper (dcooper! @ pacbell.net) Neuronal Degeneration, Growth and Repair Throughout the Lifespan Organizer: Amelia Russo-Neustadt, CSU, Los Angeles. (323) 343 2074 arusson@ calstatela.edu Spatially Explicit Ecology Organizer: Carlos Robles, CSU Los Angeles. (323) 343 2067 crobles@calstatela.edu Environmental Pollution and Environmental Justice Organizer: Carlos Robles, CSU Los Angeles. (323) 343 2067 crobles@calstatela.edu Dealing with Contaminated Runoff Organizer: John Dorsey, City of Los Angeles, Stormwater Management Division (213) 847 6347 jdorsey@san.lacity.org There will be additional sessions of Invited Papers and Posters and of papers by Junior Academy members. Student Awards: Students who elect to participate are eligible for best paper or poster awards in the following categories. Biology: ecology and evolution, biology: genetics and physiology, physical sci- ence. A paper by any combination of student and professional co-authors will be considered eligible provided that it represents work done principally by student(s). In the case of an award to a co-authored paper, the monetary award and a one year student membership to the Academy will be made to the first author only. For further information on posters, abstracts, registration and deadlines, see the Southern California Academy of Science web page at: www.lam.mus.ca.us/~scas/ Student Award Winners The Annual Meeting of the Southern California Academy of Sciences was held May 19-20 at the University of Southern California. Student award winners were as follows. Best Poster in Ecology/Evolution Kelly M. O’Reilly, Dept. of Biological Science, California State University, Fullerton Meristic and Morphological Variation among California Populations of the Marine Silverside Fish Atherinops affinis (Teleostei: Atherinopsidae) Best Oral Presentation in Ecology/Evolution Matthew Edwards, Dept. of Biology, University of California, Santa Cruz El Nino 1997-98: Large-scale Patterns of Disturbance and Recovery in Giant Kelp Forests Best Poster in Physiology/Genetics Gerald Lopez, Dept. of Biological Science, California State University, Fullerton High Creatine Phosphokinase Activity in the White Muscle of the Endothermic Mako Shark Best Paper in Physiology/Genetics Jennifer Jarrell, Dept. of Marine Science, University of South Florida Use of a Synthetic Polypeptide to Determine the Sex and Reproductive Status of Field-caught Red Grouper, Epinephelus morio American Institute of Fisheries Research Biologists; Best Oral Presentation Darryl Smith, Dept. of Biological Science, California State University, Fullerton Trophic Position of Southern California Estuarine and Island Populations of the Silverside Fish Atherinops affinis (Teleostei: Atherinopsidae): Analyses of 15N and 13C Stable Isotopes and Dietary Items American Institute of Fisheries Research Biologists; Best Poster Kristina Louie, Dept of Organismic Biology, Ecology and Evolution, UCLA Genetic Variation of the Eastern Pacific Bay Pipefish, Syngnathus leptorhynchus (Gasterosteiformes: Syngnathidae) Research Training Program Based on their oral presentation at the Annual Meeting and the written paper on their research, the following students will attend the National Associated Academy of Sciences meeting, held in con- junction with the American Association of Sciences Meeting in San Francisco in February, 2001. Heath Gibson, Troy High School Analysis of a Newly Identified Variable Star in Aquarius Christel Miller, Calif. Acad. of Math. and Science and Division of Endocrinology, Harbor, UCLA Medical Center Research and Education Institute Localization and Confirmation of Glycogen Synthase Kinase-3 Beta in the Mouse Testes by Im- munohistochemistry Natalie Sanchez Biological Science, California State Univ. Fullerton Position of Red Myotomal Muscle in Tunas and Sharks Ying Jiang Arcadia High School and Dept. of Pathology, USC School of Medicine Feathered Scales in Silkie Chickens: a Molecular Study Ronald Solarzano, Alhambra High School: Norris Cancer Center, U.S.C. Association of Alcohol Dehydrogenase Genotype with Risk of Colon Cancer in Humans Bull. Southern California Acad. Sci. 99(3), 2000, pp. 115-127 © Southern California Academy of Sciences, 2000 On the Wildlife of Wetlands of the Mexican Portion of the Rio Colorado Delta E. Mellink and V. Ferreira-Bartrina Centro de Investigacion Cientifica and de Educacion Superior de Ensenada, B.C. Apartado Postal 2732. Ensenada, B.C., Mexico Intl. mailing address: CICESE. P.O. Box 434844, San Diego, CA 92143, U.S.A. Abstract.—The delta of the Colorado River, praised for its wealth of wildlife, has been dramatically altered by agriculture. In this article we provide a basic over- view of the status of the aquatic wildlife of this area. Overall there is a great lack of knowledge on the status of the different aquatic species in the area, but negative impacts include the disappearance of the massive riparian forests, a reduction in the populations of native fish (very severe), a number of birds, two mammals, and possibly one amphibian and two reptiles. Conversely, habitat transformation might have benefited some amphibians, some birds, and one mammal. Alien aquatic taxa that have been introduced to the area or have colonized it include some plants, 4 invertebrates, more than 20 fish species, 3 amphibians, 3 reptiles, and 1 bird. We conclude that the area is far from being biologically intact, and that it does not meet the legal criteria for being a Biosphere Reserve, as it has been declared. Listing of some of the species as at risk is unsupported. Although the area is biologically very modified, it can provide important opportunities for the conservation of wetland taxa. Resumen.—E| delta del rio Colorado, afamado por la riqueza de su fauna silvestre ha sido dramaticamente alterado por la agricultura. En este articulo presentamos ona revisi6n basica del estado de la fauna acuatica en esta area. En general existe un gran desconocimiento del status de las diferentes especies acuaticas, pero los impactos negativos incluyen la desaparici6n de los bosques riparios masivos, una reduccion en las poblaciones de peces nativos (bastante severa), de algunas aves, dos mamiferos y, posiblemente, un anfibio y dos reptiles. Por lo contrario, la transformacion del habitat ha beneficiado a algunos anfibios, algunos reptiles y un mamifero. Especies ex6genas que se han introducido al area, o que la han colonizado, incluyen algunas plantas, 4 invertebrados, mas de 20 especies de pecas, 3 anfibios, 3 reptiles y 1 ave. Concluimos que el area esta lejos de ser biol6gicamente intacta y que no reune los criterios para ser una reserva de la Bidsfera, como ha sido declarada. El listado de algunas de las especies como en riesgo carece de sustento. Aunque el area se encuentra biol6gicamente muy mod- ificada puede proveer oportunidades importantes para la conservaci6n de taxa acuaticos. During the early 20th century, sportsman and scientists praised the delta of the Rio Colorado for its wealth of wildlife (Leopold 1949, 1953; Murphy 1917). Earlier, the area had been an attraction for beaver trappers (Mearns 1907; Pattie 1831; Sykes 1937a). However, the biological integrity of the area was dramaticaly altered when agriculture was established at the turn of the century, first in the Lis 116 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES United States’ Imperial Valley, and, shortly thereafter, in Mexico’s Valle de Mex- icali. This area has become one of Mexico’s prime agricultural areas (Sanchez- Ramirez 1990). This conversion resulted in “‘the lower Rio Colorado . . . [having] . one of the most highly modified channels in western North America. The most characteristic feature of aquatic habitats in arid zones, extreme variability in time and space, has been surpressed .. .”’ (Minckley 1982). In this rendering of the river, the extent of wetland habitats has been greatly reduced. Only a few wetland areas remain, including those associated with the Rio Hardy, the Cienega de Santa Clara and the Cienega del Doctor (Glenn et al. 1996). The Cienega del Rio Hardy was a large wetland fed by water from the Hardy and the Colorado. The large water discharge of the mid-1980s eroded the natural dam that created it and lead to its draining (J.M. Payne, pers. comm.). The Cienega de Santa Clara, the largest wetland in the Mexican portion of the delta, is fed mainly by brackish agricultural drain water from Arizona, U.S.A. (Glenn et al. 1992, 1996; Zengel et al. 1995). Its vulnerability was evidenced by an 8-month interruption in water flow, due to channel repair (Zengel et al. 1995). Moreover, if the Yuma Desalting Plant, in southern Arizona, becomes operational it will have very deleterious effects on the emergent vegetation of this wetland (Glenn et al. 1992, 1996; Zengel et al. 1995). The Cienega del Doctor owes its existence to the artesian springs along the Cerro Prieto fault, to the east of the delta, which have high plant richness (Ezcurra et al. 1988; Zengel et al. 1995). Other wetlands in the area include irrigation canals and agricultural drainages, and ephemeral wetlands produced by irrigation water spillover and tailwaters. On the other hand, fishing activities in the Upper Gulf of California allegedly caused the reduction of totoaba (Totoaba macdonaldi), an endemic large sea bass, and vaquita (Phocoena sinus), an endemic porpoise. These reductions, and the importance of the area as a shrimp hatchery, have promoted several management and conservation actions by the Mexican government, including designation of the delta’s marine part as well as the Cienega de Santa Clara as a Biosphere Reserve, in 1993. This category requires that the area be, to a large extent, well preserved. Also, several wildlife species that occur or previously occurred in the area have been listed by the Mexican Federal Government as endangered or threatened. However, both the species that have been listed and the biological character- istics of the area included in the Biosphere Reserve have remained largely un- studied. It is our intention in this paper to provide a basic overview of the wildlife components of the wetlands of the Mexican portion of the Rio Colorado delta. We do not restrict this review to the area included in the Biosphere Reserve, but refer to the total Mexican portion of the delta. A cautionary note: the descriptions of the early 20" century are often used as a model of the pristine conditions of this area. However, the large amounts of sediments recorded in the river by Sykes (1937b) reflected a major anomaly. Intensive trapping of beavers along the Colorado and its tributaries in the 19" century promoted an increase in the flow of sediments downriver (Dobyns 1978, 1981). The effects that such sediments had on the biota of the lower Rio Colorado delta are unknown. WILDLIFE OF THE DELTA OF THE RIO COLORADO jy Vegetation Up to the early 20" century, the area had a vegetation pattern clearly associated with the river. Plant communities in this area were probably similar to those currently found immediately north of the U.S. -Mexico border (Ohmart et al. 1988; see Nelson 1921 and Sykes 1937b for photographs). Cottonwoods (Populus fremontii) and willows (Salix gooddingii) along the banks, with shrub seepwillow (Baccharis salicifolia) and coyote willow (Salix exigua) as understory plants. Cattail (Typha spp.), bulrush (Scirpus spp.) and reed (Phragmites australis) formed emergent communities. Honey mesquite (Prosopis glandulosa) occured at a slightly higher level (“‘second bottom” sensu Ohmart et al. 1988), while screwbean mesquite (Prosopis velutina) was found along the drier banks. Arrow- eed (Tessaria sericea), salt bush (Atriple polycarpa, A. canescens), inkweed (Suaeda torreyana) and quail bush (Atriplex lentiformis), creosotebush (Larrea divaricata var. tridentata), ocotillo (Fouquieria splendens), palo verde (Cercidium floridum) and smoke tree (Psorothamnus spinosus) where found in the desert, away from the river. Additionally, both an Indian-cultivated and a wild form of the grass Panicum sonorum occured on the flats that were annually inundated by the river (Nabhan and de Wett 1984), and the Sonoran Desert endemic Ammob- roma sonorae occured on sand dunes in the area. In all, the Rio Colorado delta is thought to have included 200-400 species of wetland vascular plants, most of which have disappeared (Ezcurra et al. 1988). Currently, most of the massive riparian forests have disappeared, although some patches and isolated trees remain. Other plants, like cachanilla (Pluchea sericea) and salt bush, are widely found, even along irrigation ditches and drains. The local wild and domesticated forms of Panicum sonorum are “... for all practical purposes ... now extinct ...”’ in this area (Nabhan and de Wett 1984). Alien plants, especially tamarisks (Tamarix spp.), are widespread. Tamarisks colonized the lower Colorado around 1920 from the Gila River, where they had been introduced (Ohmart et al. 1988). These trees cause several problems. Due to their high evapotranspiration rate they can dry out smaller water bodies, af- fecting fish such as the endangered pupfish (Cyprinidon spp.). Also, due to its aggressiveness, they outcompete cottonwoods and willows, reducing the value of the habitat for several animals, including the endangered Yuma Clapper Rail (Ral- lus longirostris yamanensis; Dudley and Collins 1995), and beavers (Mellink and Luevano 1998). Fresh water invertebrates Very little is known about aquatic invertebrates either before the large-scale management of the river or after it. Grinnell (1914) reported that there were no aquatic molluscs in the Lower Colorado. This seems an underestimate as, although in large erosive fluvial systems there are few bentic and sessile invertebrates, some groups are well represented, especially in areas with little water flow (Ohmart et al. 1988). Murphy (1917) found exoskeletons of Planorbis tumens, a fresh water mollusc, and Certhidea sacrata, a brackish water species, in the dry bed of La- guna Salada. Suggestions for other species likely to occur or to have occurred in the area can be obtained from stocks in adjacent United States (Minckley, and Marsh and Minckley, in Ohmart et al. 1988). 118 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES On the other hand, at least four introduced aquatic invertebrates occur in the area: Asiatic clam (Corbicula fluminea), paper floater mussel (Anodonta imbecil- lus), crayfish (Procambarus, probably P. clarki), and freshwater shrimp (Palae- monetes paludosus). The asiatic clam was introduced into the region probably in the 1950s (Bequaert and Miller 1973; Dundee and Dundee 1958; Ingram 1959; Ingram et al. 1964). This species is a good disperser (Ingram et al. 1964) and currently is very common in the area (Fox 1970; Guardado-Puentes 1975; Mellink and Luevano unpublished data). In addition to troubling irrigation systems (Ohmart et al. 1988), this species can negatively impact native benthic inverte- brates (Dudley and Collins 1995). In southern California and Arizona, however, it is an important prey of exotic fishes (Minckley 1982) and in the Mexican portion of the delta, it appears to be an important food for racoons (Procyon lotor, Mellink and Luevano unpublished data). The paper floater mussel is an alien that has been reported from the U.S. portion of the Rio Colorado. We collected shells of this species in the Mexican portion of the delta (Identifyied by Jerry Landye). A similar species, the California floater (A. californiana), is severely endangered in the area, very likely due to the extir- pation of one of the local endemic fish species, that was obligate host for its swimming stage (Bequaert and Miller 1973). Crayfish were introduced in the lower Colorado in the 1930s (Dill 1944) and have dispersed widely through the area since then, being abundant in the Cienega de Santa Clara (Mellink and Luevano unpublished data). Crayfish are omnivores that reduce aquatic plants and algae, invertebrates, frogs, and even some fish, and in some places have eliminated most aquatic invertebrates (Dudley and Collins 1995; Hobbs et al. 1989). Dudley and Collins (1995) considered it as one of the invasive species posing high environmental risks on the U.S. side of the lower Colorado. However, crayfish have been found to be an important food item for large, alien, carnivorous fish species and for the soft-shelled turtle (Apalone spi- nifera), garter snakes (Thamnophis marcianus), Yuma Clapper Rail, and some mid-sized mammals in the U.S. portion of the area (Minckley 1982; Ohmart 1988). Freshwater shrimps are common in the lower Colorado, both in the U.S. (Minckley 1982) and, in Mexico, at least in the Cienega de Santa Clara (Abarca et al. 1993). Its actual or potential effects on the system are unknown, but some exotic fish and, to a lesser degree, American Coot (Fulica americana) feed on them (Eley and Harris 1976; Minckley 1982). Fresh water fish Thirty-seven species of fish have been reported from the U.S. side of the delta, of which only 11 are native. Ten of the native species have been extirpated or are extremely localized. Sixteen additional alien species have been introduced, but their introductions have failed (Ohmart et al. 1988). The first known alien in the lower Colorado was the carp (Cyprinus carpio), which was introduced before the turn of the century. By 1942 there were already 11 introduced fish in this area (Dill 1944; Gilbert and Scofield 1898). The fish assemblages in the mexican portion of the delta before the construction of dams are not known, but it is clear that most native species are not faring well. A recent collection from the confluence of the Rio Colorado and the Rio Hardy WILDLIFE OF THE DELTA OF THE RIO COLORADO 149 produced 13 species of fish, 11 of them alien. The two native fish were the striped mullet (Mugil cephalus), and the machete (Elops affinis), both typical of brackish waters (Valle-Rios 1997). The modification of aquatic habitat, especially through damming, and the pre- dation by alien fish on larvae are thought to be the principal causes of the demise of the native species of fish (Ohmart et al. 1988). Alien fish can also predate on very localized spring snails (Hydrobiidae), amphibians, and the endangered pup- fish (Dudley and Collins 1995). However, alien fish are not the only ones that feed on native pupfish, as the native machete also does so (Dill 1944). Icthyological research in the area has focused on the local pupfish (C. macu- larius), mostly in the Cienega de Santa Clara and in the artesian wells along the Cerro Prieto fault (Abarca et al. 1993; Hendrickson and Varela-Romero 1989). This species is adapted to variable environments and is a good colonizer of new habitats, and the delta populations are reasonably healthy (Hendrickson and Var- ela-Romero 1989). However, changes in the quality of the water reaching the Cienega and the abundance of alien fishes are imminent threats to their survival (Abarca et al. 1993; Glenn et al. 1992; Hendrickson and Varela-Romero 1989; Ohmart et al. 1988; Rinne and Guenther 1980). The following alien fish species have been found in the Cienega de Santa Clara (Abarca et al. 1993): Notropis lutrensis, Poecilia latipinna, Gambusia affinis, Tilapia sp. In addition to some of those species, the artesian wells have also Oreochromis spp., Cyprinus carpio, and [ctalurus punctatus. Striped mullets and other estuarine fishes are found in the main body of the Cienega as well as in channels that have some influx of seawater. Amphibians Limited collecting effort has been made to document the amphibians on the Mexican side of the delta, and the list of potential species must be extrapolated from nearby Arizona and California (Bury and Luckenbach 1976; Grismer 1994; Ohmart et al. 1988; Vitt and Ohmart 1978; Zeiner et al. 1988). There is even less information on the status of the different species in the area. Six native species of amphibians could have occurred in the area (Mayhew 1962; Ohmart et al. 1988; Van Denburg and Slevin 1913; Vitt and Ohmart 1978): Couch’s spadefoot (Scaphiopus couchi; of which no specimens exist from the Mexican side of the Rio Colorado), Great Plains toad (Bufo cognatus), red-spotted toad (B. punctatus), Woodhouse toad (B. woodhousii), Sonoran Desert toad (B. alvarius; of which only one specimen has ever been collected - Brattstrom 1951) and lowland leopard frog (Rana yavapaiensis, of the R. pipiens complex). None of them requires running water, although two prefer it, but they all require stagnant water during the breeding season. The species that depend less on water are Couch’s spadefoot, Great Plains toad, red-spotted toad, and Woodhouse toad. Ex- cept for the red-spotted toad, agriculture could have benefited these species, at least at some time (Ohmart et al. 1988). In fact, the Great Plains toad commonly occurs in irrigation channels (Vitt and Ohmart 1978). The two other species, Sonoran Desert toad and lowland leopard frog, prefer permanent or semipermanent water, although they are found in a variety of hab- itats and can use ephemeral reservoirs (Zeiner et al. 1988). It is possible that the reduction in flow in the Rio Colorado has impacted negatively these two species. 120 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES The lowland leopard frog has not been recorded recently in the U.S.-Lower Rio Colorado but its rarity or, perhaps, extirpation from southern California has been linked to the introduction of bullfrogs (Rana catesbeiana) to the area, rather than to river modification (Vitt and Ohmart 1978). The Rio Grande leopard frog (R. berlandieri) could also be responsible for the status of the lowland leopard frog (see Platz et al. 1990). The bullfrog has been introduced to many areas for its commercial production. In California, it diseminated rapidly through the whole state (Jennings 1983; Sto- rer 1922). It was introduced to the Lower Colorado in the 1920s (Dill 1944), where it is currently abundant (Grismer 1994; Vitt and Ohmart 1978), and it is raised on a farm adjacent to the Rio Hardy. The bullfrog is the introduced am- phibian with largest biological impact because of its aggressive, generalist, and predatorial behavior (Bury and Luckenbach 1976; Dudley and Collins 1995). In one case its diet included crayfish, wolf spiders (Lycosidae), insects (including a scorpion), abundant coleoptera, and also muskrats, snakes, soft-shelled turtles, and Asiatic clam (Clarkson and De Vos 1986). The introduction of bullfrogs has caused the disappearance of native amphibians (Clarkson and De Vos 1986; Ham- merson 1982; Moyle 1973). Rio Grande leopard frog and Tiger salamander (Ambystoma tigrinum) have also been introduced to the area. The Rio Grande leopard frog exists in the U.S. portion of the Lower Colorado (Ohmart et al. 1988, Platz et al. 1990), and very likely also in adjacent Mexico. Its effects have not been studied, but it could affect native amphibians (Platz et al. 1990). The tiger salamander is commonly used as fishing bait, and it is often released in fishing areas. So far two specimens from near Yuma are known (Vitt and Ohmart 1978). Their larvae compete with those of native amphibians (Zeiner et al. 1988). Reptiles Only two native species of aquatic reptiles occurred in the Lower Colorado: the Sonoran mud turtle (Kinosternon sonoriensis), which has never been collected on the Mexican side of the border, and the checkered garter snake (Thamnophis marcianus). Records of yellow mud turtle (K. flavescens) have been dismissed as invalid (Funck 1974; Jennings 1983; Van Denburg and Slevin 1913; Vitt and Ohmart 1978). Ohmart et al. (1988) also include Mexican garter snake (T. eques) as present in the area, but we have not been able to find any suportive records, and likely this was based on a misidentification. The Sonoran mud turtle could have been extirpated from the area, and the checkered gartner snake diminished in its numbers, due to the reduction of riparian habitat (Jennings 1983; Ohmart et al. 1988). Garter snakes occur in some irrigation ditches, but there they are killed by locals, children and pets. At least three species of alien reptiles have been introduced into the Lower Colorado: the soft-shelled turtle (Apalone spinifera), the painted turtle (Crysemys picta) and the American alligator (Alligator mississipiensis). Soft-shelled turtles were introduced into the Lower Colorado probably at the turn of the century (Bury and Luckenbach 1976; Dill 1944; Miller 1946; Webb 1962). This species was abundant throughout Valle the Mexicali, but, according to local inhabitants, hunting for human consumption has reduced its populations. Painted turtles were not reported for California by Bury and Luckenbach WILDLIFE OF THE DELTA OF THE RIO COLORADO 121 (1976), but recently they have been found in the Mexican portion of the Colorado River (L. Grismer, pers. com.), as well as in southwestern California (Dudley and Collins 1995). Free-living painted turtles surely derive from released pets. The potential threats of this species are undocumented, although it may have threat- ened native frogs and the southwestern pond turtle (Clemmys marmorata pallida) in southwestern California (Dudley and Collins 1995). American alligators were released during the late 1930s and early 1940s in at least two occasions in the U.S. portion of the Lower Colorado, by a traveling circus, and at the railroad station at Needles where they had been kept as pets (Hock 1954). The name ‘El Caiman” (the Alligator) for a ranch along the Rio Pescaderos, in Baja California, suggests that at least one of them traveled south through the riverine system. Birds Ohmart et al. (1988) considered both fish and birds as the animals most im- pacted by the transformation of the lower Rio Colorado Valley, in the U.S.A. For the Mexican side of the area little is known about the birds. Even Nelson’s (1921) description of the peninsula largely overlooks the aquatic birds of this area. The early century synthesis by Grinnell (1928) is the most comprehensive review. A later synthesis (Wilbur 1987) has been criticized (Everett 1988), and recently only a few, localized observations have been published (v.gr. Mellink et al. 1996, 1997; Palacios and Mellink 1992, 1993; Patten et al. 1993; Peresbarbosa and Mellink 1994; Price 1899; Ruiz-Campos and Rodriguez-Meraz 1997). As an alternative, the information from the U.S. side of the delta is a useful complement in many cases. One of the birds that has conservation problems is the Large-billed Savannah Sparrow (Ammodramus sandwichensis rostratus). This subspecies breeds solely in marshes of the delta of the Rio Colorado and, perhaps, in some marshy areas of northwestern Sonora (Van Rossem 1947). During the non-breeding season it used to disperse widely, becoming very abundant even in San Diego, California. Currently, it is almost absent from that city, a fact that has been linked to the modifications of the delta (Unitt 1984). The species still nests on Isla Montague, at the mouth of the river (Peresbarbosa and Mellink 1994), but its nesting habitat elsewhere appears very reduced. Formerly, the delta supported important colonies of nesting waders, especially of Snowy Egrets (Egretta thula) and Great Egrets (Ardea alba). There was a strong reduction of these colonies early in the century due to their hunting, al- though recently some new colonies have formed (Kathy Molina, pers. com.; Mora 1989, 1997), and others are found on Isla Montague (Palacios and Mellink 1992, 1993; Peresbarbosa and Mellink 1994). The most common waders in the area currently are Black-crowned Night-heron (Nycticocorax nycticorax), Green Heron (Butorides striatus), Snowy Egret, Great Egret, and Great Blue Heron (A. hero- dias). Only one alien species of waterbird has colonized the area: the Cattle Egret (Bubulcus ibis), which breeds in Valle de Mexicali since the early 1970s (Mora 1997), and which is increasing in numbers in the region (Garrett and Dunn 1981; Rosenberg et al. 1991). Nothing is known about the current occurrence of more sporadic species like the Roseate Spoonbill (Ajaia ajaja) documented and collected early in the century 122 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES at Laguna Salada (Grinnell 1926; letters of E.W. Funcke to J. Grinnell, of 17 December 1925, 31 December 1925, and 5 January 1926 at the Museum of Ver- tebrate Zoology, University of California, Berkeley). Similarly, there are no recent records of Wood Storks (Mycteria americana), but they have likely been over- looked in the area (Wilbur 1987). Waterfowl intensively use Valle de Mexicali and some species could have in- creased populations as a result of agriculture (Anderson and Ohmart 1982; Mel- link et al. 1997; Ohmart et al. 1985). The waterfowl have been described by several authors (A. Leopold 1949, 1953; A.S. Leopold 1959; Kramer and Migoya 1989; Payne et al. 1991; Saunders and Saunders 1981), and their discussion is beyond the scope of this article. We will comment only on the Fulvous Whistling- duck (Dendrocygna bicolor). This species was recorded from the area in 1922 (Bancroft 1922). It is currently a fairly common but declining, summer resident with some winter records at some locations on the U.S. side of the lower delta (Garrett and Dunn 1981; Rosenberg et al. 1991), but there are no modern records of it in the Valle de Mexicali. Shorebirds are an important part of the fauna of the delta, especially on the extensive intertidal mudflats south of Isla Montague (Mellink et al. 1997). Within the delta there are some large mudflats to the south of the Cienega de Santa Clara which also support large amounts of shorebirds (Abarca 1993; Mellink et al. 1997; Morrison et al. 1992). The abundance of shorebirds in the entire delta has pro- moted recognition of the area by the Western Hemisphere Shorebird Reserve Network. It is unknown whether original conditions of the area supported more or less shorebirds than today, and of which species. One of the most sensitive birds of the delta is the Yuma clapper rail (Rallus longirostris yumanensis), whose population in Cienega de Santa Clara is almost 50% of the known population of the subspecies (Abarca et al. 1993; Eddleman 1989). Some minor populations of this rail may occur in some vegetated agri- cultural drains throughout the valley (Robert Henry, pers. comm.). Mammals The three aquatic mammals of the lower delta, river otter (Lutra canadensis), beaver (Castor canadensis), and muskrat (Ondatra zibethica), have been consid- ered at risk due to the modification of the water streams (Ceballos and Navarro 1991). Huey (1964) did not report river otters in Baja California, and Ohmart et al. (1988) considered that they had never been abundant in the Lower Colorado (U.S. portion). However, Sandez (in Herrera-Carrillo 1932) indicated that they were abundant in Valle de Mexicali sometime during the 19" century, a statement that Mellink (1995) found difficult to qualify. Later, Onesimo Gonzalez (Campo Flores, Rio Hardy) described and positively identified river otters in a field guide, and indicated that they had been abundant in the Hardy river until about 1955, when they disappeared (Mellink and Luevano unpublished data). There are no river otters currently in the area, and the habitat seems not suitable to them. One of the most typical and abundant species of the Lower Colorado was the beaver (Huey 1964; MacDougal 1906; Pattie 1931; Stone and Rhoads 1905). Currently its populations on the Mexican side of the delta are largely reduced, and highly variable. They expand and contract with the amount of free water in the area, and some years the species probably disappears altogether, or almost so. WILDLIFE OF THE DELTA OF THE RIO COLORADO 123 When the system receives water (i.e. when large amounts of water are released from U.S. dams), large colonies can again establish, either from animals that have survived in localized water pockets or from animals carried from the U.S. by the sudden river current (Mellink and Luevano 1998). Muskrats seem to have been rather uncommon in the Lower Colorado early in the century (Mellink 1995). Muskrats require still waters and were favored by the establishment of agriculture in the area (Dixon 1922; Grinnell 1914; Mellink 1995). Their maximum populations in the area occurred probably during the 1960s, when cultivated land was at its largest, and the water conduction system was inefficient with many seeps. Although the lining of channels with concrete surely reduced the populations of this species, the species does not seem to face any conservation problem (Mellink 1995), despite its listing by Mexico as a spe- cies at risk. Concluding remarks The basic premise for protecting the area was its alleged “‘pristinity”’. However, it is clear that the area is far from biologically intact. Even the Cienega de Santa Clara, touted as one of the last remnants of Rio Colorado Delta wetlands, owes its condition to the recent discharge of brine water from the Wellton Mohawk Irrigation District, in Arizona, through the Wellton Mohawk Main Outlet. The biological composition of the area’s wetlands includes several alien species and is quite different from that of turn-of-the-century. Clearly, the conditions that make an area legally suitable for being a Biosphere Reserve, under the Mexican Environmental Law, do not exist in the Rio Colorado Delta. On the other hand, several species of animals from the area are considered as rare, threatened, or endangered in a Baja California state government brochure, a poster from the local university, the official list of species at risk, and a list in a recent hunting calendar. Some species in the area undoubtedly face conservation problems, like the pupfish. However, the listing of several other species seems to be based either on wrong perceptions of their local conditions or based on their status elsewhere. For example, the soft-shelled turtle, although it could have a problem in northeastern Mexico, is alien to the delta and should not be listed for it. Also, the listing of muskrats for this area is not consistent with its present status. Legal protection actions have been focused on the two marine species, totoaba and vaquita, which are perceived as at greater risk. They have been protected by multiple measures, including restrictions in the type of fishing gear and its use in the delta area. The decree of a large area as a Biosphere Reserve has meant stricter enforcement of such existing fishing restrictions. This stricter enforcement and the establishment of a small research station, have been the only actions toward biological conservation in the area. No management measures have been taken for any other species at risk, including such flag-species as the pupfish and Yuma Clapper Rail, except for listing them and prohibiting their hunt. Indeed, there hasn’t even been a serious effort to evaluate the current status of the regional Species and subspecies presumably at risk. Although the area is biologically very modified, it can provide important op- portunities for the conservation of wetland taxa. The first step should be a thor- ough evaluation of the status of the species or subspecies presumed to be at risk, 124 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES and the determination of the factors that affect them. Only then can adequate management actions be taken. Acknowledgements We thank Dan Guthrie and Lee Grismer for their careful and critical review of this article. 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Crooks?* ‘Department of Biology, San Diego State University, San Diego, CA 92182 2Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0218 Abstract.—A twenty-year dataset on the subtidal benthic macrofauna within Mis- sion Bay, San Diego, reveals distinct differences in community structure along a back-bay/front-bay gradient. Assemblages in the extreme back bay are character- ized by low diversities and abundances, and are dominated by an exotic mussel, Musculista senhousia. Species richness increases toward the mouth, and because of the very high densities of M. senhousia at a station intermediate in the spatial gradient, total abundance and biomass show sharp peaks in this region. Despite the dramatically increased dominance M. senhousia has achieved in the bay, few negative effects of this invasion on subtidal macrofauna are evident. Coastal bays, estuaries, and lagoons located within cities are subject to a wide variety of anthropogenic influences, including habitat loss or alteration, pollution, and the invasion of exotic species (e.g. Conomos 1979; Essink and Beukema 1986; Cohen and Carlton 1998). Many coastal embayments within southern Cal- ifornia have been particularly affected by urbanization (Marcus 1989; Schoenherr 1992; Anderson et al. 1993). Yet, these systems are vital as their remnant natural habitats support several endangered species and are the sites of active restoration and conservation efforts (Zedler 1996). One of the most highly modified systems in southern California is the 1862- ha coastal lagoon, Mission Bay, in San Diego (Fig. 1). Over the last 150 years, the bay has been extensively altered by river diversion, dredging, and filling, and it now is the largest aquatic park on the west coast of the United States (Chapman 1963; California Coastal Commission 1987; Crooks 1998a). The physical and hydrographic characteristics of the bay produce a flushing gradient, with relatively high water exchange near the mouth (San Diego City Planning Department 1957; Taylor 1982; Marcus 1989; Largier et al. 1997). In the back bay, flushing is more sluggish due to the increased distance from the ocean and the presence of a large, artificial island (Fiesta Island) which creates two narrow, dead-end channels (San Diego Water Utilities Department 1978). Drift tube and fluorescene dye studies also suggest higher retention times for this region (Levin 1983). Compounding circulation problems in the back bay is the input of organic-rich urban runoff from two creeks in this area (San Diego Water Utilities Department 1978; Marcus 1989). Mission Bay is seasonally hypersaline, with warmer waters and slightly * Corresponding Author Present Address: Smithsonian Environmental Research Center 647 Contees Wharf Road Edgewater, MD 21037 phone: 301-261-4190 ext. 416 fax: 301-261-7954 crooks @serc.si.edu 128 MISSION BAY BENTHOS 129 <0 1970-1 976 ny -J™ 1977-1996 fe a o 3) Oo © =| 2 oO Fig. 1. Mission Bay, San Diego, California (32°47'N, 117°14’W), showing sample sites in this and a previous study (Dexter 1983). higher salinities in the back bay during the summer months (Levin 1983). Such conditions, which are typical of systems in regions with Mediterranean climates, may further serve to reduce bay-ocean mixing (Largier et al. 1997). During winter months, salinities in the back bay can be periodically decreased after heavy rains, but the salinity of the entire bay often is near full seawater (Levin 1982). One of the most dramatic changes in the biotic nature of coastal systems within California has been the invasion of exotic species (Carlton 1979; Cohen and Carlton 1998; Crooks 1998a). Although marine systems in San Diego appear less heavily invaded than in San Francisco Bay, there are approximately 60 non-native Marine species recognized from the region (Crooks 1998a). One of the most conspicuous of these invaders is a mat-forming mytilid, Musculista senhousia (Benson in Cantor) (Crooks 1992, 1996). Within Mission Bay, the presence of this accidentally-introduced mussel was first noted in a salt marsh creek in the mid-1960’s (MacDonald 1969). Since then, the short-lived, fast-growing mussel has become abundant in both intertidal and subtidal soft sediments (Dexter 1983; Crooks 1996, 1998b), and has been reported to have both positive and negative effects on macrofauna and eelgrass (Crooks 1998a; Reusch and Williams 1998). The goal of this paper is to describe long-term spatial and temporal trends in the subtidal benthic communities of Mission Bay. Within the bay, regular sam- pling of the subtidal, soft-bottom benthos, conducted in conjunction with a course in Biological Oceanography at San Diego State University, began in 1970. During the first 8 years, sampling was carried out close to the entrance of Mission Bay (Dexter 1983). Beginning in 1977, sampling began around Fiesta Island at sites situated increasing distances from the mouth and ending at the dead-ends of the two passages (Fig. 1). We will use these data to 1) identify dominant species in the bay and assess spatial and temporal trends in these taxa, 2) characterize dif- ferences in community structure (including species richness, total biomass, total abundances, and representation of suspension and deposit feeders) along the back- bay/front-bay gradient, 3) describe the population dynamics of Musculista sen- 130 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES housia in the subtidal of the bay by examination of size-frequency data, and 4) identify changes in biotic communities potentially attributable to this invader. Methods Field and Laboratory Procedures In 1977, seven stations were established at locations around Fiesta Island (Fig. 1). One of these, Station B, was an original station (Dexter 1983). Stations were located at least 500 m apart and were identified with reference to shoreline po- sitions, and all samples were taken within a ca. 15-m radius at each station. Sampling was conducted on 16 dates from 1977 to 1996, occurring primarily in the late summer or winter. Stations A,B,C, and F were sampled on every date (16 times), Station E was sampled on 14 dates, and Stations D and G were sampled 11 times each. On each sampling date, four to seven replicate grab sam- ples of approximately 0.1 m?* surface area were taken at the stations. Although the number of replicate sub-samples (i.e. grabs) varied between years, the same number of replicates were taken at all stations sampled on a given date. The Hayward orange-peel grab used for sampling penetrated approximately 15 cm into the substrate. A total of 463 grabs were collected, and the mean sample volume was 4.501. Collected sediment was wet sieved through 750-j1m mesh, and material retained on the sieve was stained with rose bengal and preserved in 5% buffered formalin. Samples were sorted under a dissecting microscope, and all macrofauna were transferred to alcohol, counted, and identified to the lowest taxonomic level pos- sible. All collected specimens from each core were wet-weighed together to pro- vide a total biomass of the sample. This information was used to characterize macrofaunal communities in terms of species richness, total density of individuals, densities of major macrofaunal taxa, and total biomass. In addition, feeding modes of species were determined from the literature (Fauchald and Jumars 1979; Morris et al. 1980). As the mesh size used in this study (750 pm) was larger than that often used for collecting macrofauna (300-500 wm), the values in this study represent underestimates of macrofaunal densities and species richnesses. How- ever, consistent spatial and temporal comparisons of sampled communities are possible as the same mesh size was used throughout the study. Certain species were identified as community dominants, and their distribution and abundances were selected for further analysis. The following criteria were applied to determine community dominants. The species 1) was present at one or more stations on at least 90% of the sample dates between 1977 and 1996, 2) comprised at least 5% of the individuals, and 3) was present on at least 40% of the sample dates at any single station. In order to investigate the population dynamics of M. senhousia, lengths of the mussel were measured to the nearest 1 mm using vernier calipers on all intact specimens, unless very large numbers were collected. In these cases, a plankton splitter was used to subdivide large samples to obtain an unbiased representative subsample of 100—200 individuals. Data Analyses In this study the sampling unit was a station, and station means were used for spatial and temporal comparisons. For calculations of means and standard errors, MISSION BAY BENTHOS 13 data were log (x+1) transformed and subsequently back-transformed for graphical presentations. Spearman rank correlations were performed to examine relation- ships among the dominant species, and were calculated using means from each station on each sampling date (n = 100 for each correlation). To detect only highly significant relationships and to take into account the number of comparisons made (twenty-eight), only correlations with a P < 0.001 are reported. Similarities of communities were calculated using Bray-Curtis coefficients of community simi- larity (Krebs 1989). Both the spatial variation among replicates within a station at any one time (i.e. within-sampling unit variability) and temporal variation at a station over time (i.e. comparisons of communities at a station among years) were examined. Also, paired t-tests were used to compare coefficients of variation of densities of suspension and deposit feeders. In order to investigate general relationships between the communities at the sites, an ordination technique, non-metric multi-dimensional scaling (MDS), was used (Clarke and Warwick 1994; ter Braak 1995). In this technique, Bray-Curtis similarities were calculated comparing the community at each site to that at each other site. Using this matrix of similarities, the MDS technique provided the best two-dimensional configuration for each station relative to all other stations. This technique also yielded a stress value to indicate the level of fit of this two-di- mensional representation (values less than 0.1 typically are considered good). The first MDS plot compared all stations, with data averaged across all years (using only dates in which all stations were sampled). The second compared the five most frequently sampled stations, using the averages of samples from summer months and the averages of samples from winter months. Data for MDS analyses were non-transformed and non-standardized. SIMPER (similarity percentage) analyses (Clarke and Warwick 1994), a resampling technique, also were per- formed to determine the contribution of individual species to community dissim- ilarities. Results Dominant Species The macrofauna (<750 wm) of Mission Bay were dominated primarily by molluscs and polychaetes; the two groups combined accounting for 75 to 91% of all fauna at the stations. Station A, closest to the mouth, had the most distinctive representation of these taxa, with 84% polychaetes and 4% molluscs. All other stations had between 32—45% molluscs and 30—55% polychaetes. Eight species (or species complexes) were identified as community dominants (Fig.’s 2 and 3). These included three suspension feeders, one carnivorous poly- chaete, and four polychaete deposit feeders. Averaged over all sampling dates, the eight dominants together accounted for 92% of all individuals at Station B, 82% at Station C, and 65-70% at the other stations. The deposit-feeding poly- chaete Lumbrineris sp., which was identified as the community dominant in the earlier studies of Mission Bay (= L. minima in Dexter (1983)), was still widely distributed throughout the bay, with consistently high population densities at Sta- tion A (Fig. 2). Another deposit-feeder, the maldanid Praxillella pacifica Berkeley, a large, head-down conveyor belt feeder, was rare at most stations but attained high densities at Station A. Tharyx sp. was present at low densities at most sta- 132 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Diplocirrus sp. Lumbrineris sp. Praxillella pacifica Tharyx sp. 9.2 100 1(14.0) (36.6) (9.2) (3.3) “aa l (12.7) (0.1) (0.2) Station A Station B ee oO =) 3 : S : S S S & o = a 2 ay RS Station E Station D Station C 1004 (2-) "| : 1 100 7 (9-4) (10.1) (0.2) (10.5) 1 100 7(1.5) (14.7) (0.8) (2.2) | 1 100 76 80 84 88 92 9676 80 84 88 92 96 76 80 84 88 92 96 76 80 84 88 92 96 No. individuals + 1 / 0.1 m2 Station G Station F All stations Year Fig. 2. Mean abundances (+ | s.e.) of the dominant deposit-feeding species. Numbers in paren- theses represent contribution of the species to total number of individuals at the station, averaged across all sampling dates. tions, and reached highest densities at Stations D and FE The flabelligerid Diplo- cirrus sp. (=Pherusa neopapillata in Dexter (1983)) occured at low densities at all stations except Station A. The suspension-feeding sabellid Euchone limnicola Reish was present at all stations, although it occured infrequently and at low densities at Stations D and E (Fig. 3). The populations of the phoronid Phoronis sp. fluctuated widely; highest densities occured at Station B and lowest densities at Station A. The invasive mussel, Musculista senhousia, showed a general pattern MISSION BAY BENTHOS 133 Musculista senhousia Phoronis sp. Euchone limnicola Nereis arenaceodentata 1004(0.3) (4.5) (0.8) 10 7 a Station A (43.6) (25.9) (5.9) (1.1) ._ 22 SS tes Station B (43.3) (10.7) (9.0) (0.6) - Oo So: = Station C (34.6) 8.6) (2.3) (PAE No. individuals + 1 / 0.1 m2 a ssa. Sy 2 eee ‘ s c ) Station E Station D (42.1) (1.3) (8.0) 1000) (18.8) (21.4) (1.7) (2.5) a 100 s 3S 10 7) 1 1000 (41.8) (2.3) (3.3) (2.0) 10 1 76 80 84 88 92 96 76 80 84 88 92 9676 80 84 88 92 96 76 80 84 88 92 96 Year an aa a3 Fig. 3. Mean abundances (+ 1 s.e.) of the dominant suspension-feeding and carnivorous (Nereis arenaceodentata) species. Numbers in parentheses represent contribution of the species to total number of individuals at the station, averaged across all sampling dates. of increased abundance over time at all Stations except A, where it was rare. Densities of the predatory polychaete Nereis arenaceodentata Moore were gen- erally the lowest of all the dominant species, but it was persistent throughout most Stations with less frequent occurence at Station A. There were significant Spearman rank correlations (P<0.001) among the dis- 134 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES tribution of some of the community dominants. Musculista senhousia correlated negatively with the suspension-feeding polychaete E. limnicola (r = —0.36) and the deposit-feeding polychaete Diplocirrus sp. (tr = —0.29), and positively with the predatory polychaete N. arenaceodentata(r = 0.42). The deposit-feeding mal- danid Praxillella pacifica correlated negatively with Phoronis sp. (r = —0.36) and positively with Lumbrineris spp. (tr = 0.44). These relationships may represent possible interspecific interactions as well as differences in habitat utilization. For example, the negative correlation between Phoronis sp. and Praxillella pacifica may represent different habitat preferences as the former was rare at Station A whereas the latter was most abundant there (Fig.’s 2 and 3). These correlations also reflect temporally disjunct species occurences at the same station, such as is evident between M. senhousia and the polychaetes E. limnicola and Diplocirrus sp. (Fig.’s 2 and 3). Occasionally, other species were abundant in the benthos (i.e. comprising great- er than 20% of the individuals at a station). These included the gastropod Acteo- cina inculta (Gould) (Stations C and F in 1977; Station D in 1979), the poly- chaetes Leitoscoloplos pugettensis (Pettibone) (= Haploscoloplos elongatus in Dexter (1983); Station E in 1980), Chaetozone corona Berkeley and Berkeley (Stations F and G in 1980), and Armandia brevis (Moore) (Station E in 1991), an unidentified turbellarian flatworm (Station E in 1981), the amphipod Aoroides columbiae Walker (Station E in 1981), and the isopod Paracerceis gilliana (Rich- ardson) (Station D in 1985). Back Bay—Front Bay Gradient Examination of dominant species and community characteristics reveal differ- ences in the stations (Table 1; Fig.’s 2 and 3). From this information, Stations A, B, and E can be identified as being relatively distinct. Station E, the poorly-flushed site at the mouth of Tecolote Creek, had the lowest species richness, biomass, and total density (Table 1). Suspension feeders (primarily M. senhousia) and de- posit feeders were in comparable abundances at this station (Fig. 4). Replicate grabs at this station displayed low similarities, indicating high within-sampling date spatial variability (within-year similarities, Table 1). Similarly, the average similarity of communities across time also was the lowest of all stations, sug- gesting high temporal variability in this part of the bay (between-year similarities, Table 1). Station B, at the northern end of Fiesta Island, had the highest averages of biomass, macrofaunal density, and species richness (Table 1). Spatial variation within sampling dates was relatively low, but temporal variation at the station was larger (Table 1). Station A, closest to the entrance, had the most distinct representation of the dominant benthic macrofauna (Fig.’s 2 and 3). Species rich- ness at the station was relatively high, biomass relatively low, and density inter- mediate (Table 1). Also, deposit feeders (e.g. Diplocirrus sp. and Lumbrineris spp.) consistently outnumbered suspension feeders (Fig. 4). The communities at this station displayed relatively low spatial and temporal variability, with the high- est averages of within-year (along with Station B) and between-year coefficients of similarities (Table 1). MDS of the average species compositions provides another perspective on re- lationships of communities at the stations, and reveals patterns in community structure which correspond to the back-bay/front-bay gradient (Fig. 5A). The two 135 =. Oe ee Se ee $00 + PEO S0';0 + 870 S0';0 + 170 S00 + vO'O + 9F'0 £00 + + L1+ TO! 60 + Sv + OOT Lv + OCE + 966 19T + bro 90°0 + O£€ 0 £00 + ye OT + 6Pf LO + 601 C+ €l VI + Lv8 vel + 6Le 681 + P70 SOO + €€0 10°0 = ZE0 r0'0 ¥ IS'0 reak-usoMmjog v0) | ='@0 4.550 €0'0 ¥ 950 ZO'0 ¥ 9S°0 eak-Uly AA SONLE[MUTS UoNeIs-uTMIM (q 16 60 = 08 80 = STI Col ae TT (W/ou) ssauyor sarsedg LY le see TE + HIT C= (,wu/(3) 1Y3I9EM JOM) sseWOTg 706 Ot F 698 ETIF 99IZ Orl + 16 (wou) Aysusq sonsuajovieyg AyunuU0D (Vv ————— a OS SS eS D d S| d 2) dq V soONsajovIeyD — SSS SE EE Eee es ee ee eee ee SUOT}EIS SO DLSuw«(<( — O_ —e_“$0a0— ‘O'S | } SUBOUT ore ILC ‘SONLE[MUTS UOTe]S-UTYIIM puUk SONSLIa}OvIeYyS AJTUNUIWOS OIMUSG “T 2IQRI. MISSION BAY BENTHOS 136 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Station A Station C Number +1 / m2 1975 1980 1985 1990 1995 Date 10000 Station D —tO— Deposit feeders (DF) sesO-ees Suspension feeders (SF) 1975 1980 1985 1990 1995 Date Fig. 4. Average densities of suspension feeders and deposit feeders over time. Coefficients of variation (COV) also are provided. most distant stations, A and E, appear most distinct. The other stations cluster in the middle, with Station B most similar to Station A. Stations G and D, which both reside in small coves on different sides of Fiesta Island, also appear relatively similar to each other. The analysis of five stations in summer and winter months reveals seasonality in the faunal communities, but the back-bay/front-bay gradient observed in the overall MDS (Fig. 5B) is evident in both seasons. Station A had the highest similarity between the summer and winter months, while Station E had the lowest similarity. SIMPER analyses between stations A, B, and E (Table 2) demonstrate how differences in abundances of dominant species (Fig.’s 2 and 3) drive seasonal community dissimilarities. In summer months, M. senhousia is most important in driving differences among the three stations, and Praxillella pacifica distinguishes Stations A from both B and E. The polychaete Lumbrineris sp. was responsible for differences among all stations in both summer and winter. In winter, Diplo- cirrus sp. distinguishes the front-bay from the back-bay stations, and Phoronis sp. distinguishes Stations B from A and E. Examining all stations together, some general patterns emerge. The average within-year and between-year similarities (Table 1) were correlated (R? = 0.68 using exponential regression), indicating that stations that were spatially variable at any one time also were variable over time. Also, suspension feeders showed relatively large temporal variability (Fig. 4), with an average coefficient of vari- MISSION BAY BENTHOS 137 A) B) O Summer A Winter Fig. 5. Results of non-metric multi-dimensional scaling (MDS) analyses for A) each station av- eraged across all dates (stress = 0.01), and B) Stations A,B,C,E, and F for summer and winter samples (stress = 0.05). ation across stations that was over 50% greater than that for deposit feeders (P<0.001; t, = 9.68, paired t-test). Musculista senhousia The number of recognized exotic species found in these samples is relatively low, but include a Japanese clam (Theora lubrica Gould) and a Mediterranean mussel (Mytilus galloprovincialis Lamarck). However, this count is certainly an underestimate due to limits of taxonomic resolution and the relatively poor char- acterization of marine invaders within the Californian biogeographic province (Crooks 1998a). Within the last 15 years, one exotic species, the mussel Muscu- lista senhousia, has come to dominate the back of Mission Bay. Densities of the mussel reached a peak around 1988, dropped off dramatically over the following three years, and have subsequently increased again in the 1990’s (Fig. 3). Musculista senhousia in the subtidal of Mission Bay is short-lived and fast- 138 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 2. Average dissimilarities of communities in the summer and winter samples. Also shown are the three species that contribute most to the differences in communities, as well as their contribution to the total dissimilarity (from SIMPER analyses). Stations Summer Winter A vs. B Dissimilarity = 86% Dissimilarity = 70% Musculista senhousia (32%) Phoronis sp. (17%) Lumbrineris sp. (15%) Lumbrineris sp. (16%) Praxillella pacifica (10%) Diplocirrus sp. (12%) Avs. E Dissimilarity = 93% Dissimilarity = 92% Musculista senhousia (23%) Lumbrineris sp. (33%) Lumbrineris sp. (20%) Diplocirrus sp. (17%) Praxillella pacifica (10%) Praxillella pacifica (8%) B vs. E Dissimilarity = 76% Dissimilarity = 90% Musculista senhousia (49%) Lumbrineris sp. (18%) Neanthes arenaceodentata (10%) Phoronis sp. (18%) Lumbrineris sp. (8%) Euchone sp. (13%) growing; the size-frequency histograms of M. senhousia display unimodal or bimodal distributions, suggesting the presence of only one or two year classes at any given time (Fig. 6). Modal sizes of mussels can change rapidly. For example, in January of 1983 there was a unimodal peak at 21.5 mm, with few small individuals present. Eight months later, the modal size of that cohort was 25.5 mm, and another cohort is evident with a mode of 15.5 mm. Four months later, the modal size of this second cohort was 21.5 mm. Growth in 1992 was less rapid, as the modal size did not change from January to June. The mean size of individuals, however, increased by 5 mm. There appears to be consid- erable variability of recruitment events of the population. Generally, the mean size of individuals is smaller in August and September, and larger in January and February. To investigate relationships between the abundance of M. senhousia and species richness and total macrofaunal densities, regressions were performed on means of each station (excluding Station A, as the mussel was rarely found at this site) across all years (Fig. 7). Despite the increased dominance of M. senhousia in the bay, neither relationship was negative. There is no significant relationship between density of all other organisms combined and density of M. senhousia (Fig. 7A), and there is a significant positive relationship between number of other species present at a station and the density of the mussel (Fig. 7B). Since M. senhousia is most abundant at Station B, and this station has been sampled on 21 dates between 1970 and 1996, it is possible to investigate longer- terms patterns that may emerge in relation to the increased abundance of this invader. Since 1970, there is no evidence of reduction in density or species rich- ness at the station (Fig. 8A). The abundant invertebrate macrofaunal organisms (e.g., Lumbrineris sp., and Diplocirrus sp., and E. limnicola) present in the early Stages of invasion by this mussel were still present in 1996, although there were negative correlations (across all stations from 1977—1996) for both Diplocirrus sp. and E. limnicola. There is also a possible negative relationship between the mussel and the deep-dwelling bivalve Solen rostiformis Dunker (= S. rosaceus), which was identified as a dominant at this station in the early studies (Dexter MISSION BAY BENTHOS 139 35 7 Sept. 1981 Jan. 1987 June 1992 30 4 Mean = 17.8 + 0.3 Mean = 17.4 + 0.5 Mean = 17.8 + 0.2 95 | N= 208 N=214 N = 636 Jan. 1983 Aug. 1988 June 1993 304 Mean = 19.0 + 0.3 Mean = 8.3 + 0.2 Mean = 15.4+0.4 N = 164 N = 424 N = 321 Sept. 1983 Aug. 1989 Jan. 1996 307 Mean = 16.3 + 0.6 Mean = 11.1 +0. 2 Mean = 14.85 + 0.3 25 N=92 N = 438 N = 261 Relative frequency (%) = Yi Oo See eas Jan. 1984 Jan. 1991 30 4 Mean = 13.8 + 0.6 Mean = 20.1 + 0.8 5 N= 93 N= 76 Sept. 1985 304 Mean = 13.6 + 0.4 w «om ny wm iV ay a) wm wo ey a) a) ny —D —W nw a) —Oe tn CNS en t= o=< Im, LGN 4 } S ¥ Size (mm) Fig. 6. Length-frequency distribution of Musculista senhousia. N = number of mussels measured. Mean sizes (+ | s.e.) also are shown. 1983). Its average density between 1970 and 1987 (294 individuals collected) was 40/m’, but had declined to 2.5/m* between 1988 and 1996 (6 individuals col- lected). One obvious change that has occurred is a shift from a primarily deposit- feeding community prior to 1980 (7 of 8 dates) to a suspension-feeding com- munity thereafter (10 of 13 dates), which is due to the increased dominance of the suspension-feeding M. senhousia (Fig. 8B). 140 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES AD 1000 100 Total macrofauna + 1 / 0.1 m2 1 10 100 1000 B) Number of species +1 / 0.1 m? 1 10 100 1000 Number Musculista senhousia+1 / 0.1 m2 Fig. 7. Musculista senhousia vs. A) total number of individuals and B) total number of species. Data points are station means (excluding Station A). Calculations of total macrofaunal densities and species richnesses exclude Musculista senhousia. Discussion Within Mission Bay, there are distinct differences in community structure which appear to arise from gradients in the physical properties in the bay. Although Mission Bay is a lagoon with limited freshwater input and salinities often close to full seawater, salinity in the back bay is most variable and after heavy rain can be as low as 10 ppt (Levin 1982). Urban runoff, which is the primary source of freshwater in the system, is rich in organic matter (e.g. yard waste and leaf litter). Because the sources of runoff in this system are concentrated in the poorly-flushed areas of the back bay, conditions in this area are often considered degraded due to organic enrichment (San Diego Water Utilities Department 1978; Marcus 1989). Locations closer to the mouth of the bay, however, receive greater tidal flushing and are further away from the principal sources of runoff. This pattern of flushing and organic input likely have effects on sedimentary properties com- parable to those reported in other systems (Pearson and Rosenberg 1978). Al- though quantitative sediment data for Mission Bay are limited, recent data are MISSION BAY BENTHOS Total Macrofauna (#+1/m2) A) . . # 1 2 10000 Musculista senhousia (#+1/m~) Number of Species (# / station) PODS arr) Sesreereery pet). Farr ea RS Op ee ae ed ee i ate a A 100 10 : 1 uw st 10000 ———_ Deposit Feeders (#+1/m7) i ore aane Suspension Feeders (#+1/m7) : ‘ 1000 Pty ihell ies ths Nine erect ay : “Ne? ‘ * Nes é r) D 3 fi We oO 1 a 1 A ‘ Oe . 1 00 ‘ re Pe oy 10 1970 1975 1980 1985 1990 1995 Year Fig. 8. Station B from 1970-1996. A) Average total densities (number m~’), total number of Musculista senhousia (number m~?), and species richness (number per station). B) Average densities of suspension and deposit feeders characteristic of the reported flushing regimes (Fairey et al. 1997). In the back bay, combustible organic matter is high (2.5—2.6%) and sediment grain sizes are small (78-93% fine sediments < 63m). Nearer the entrance of the bay, there is less organic matter (0.61%) and grain sizes are larger (33% fines) (Fairey et al. 1997). Gradients in physical conditions such as those reported in Mission Bay can affect benthic assemblages, and organic enrichment (both natural and anthropo- genic) are particularly important in structuring these communities (Pearson and Rosenberg 1978; Long and Chapman 1985; Jensen 1986; Brown et al. 1987; Friligos and Zenetos 1988; Heip 1995). Typically, communities in areas with low flushing and sources of organic input have low diversities and are dominated by opportunistic species (Pearson and Rosenberg 1978; Weston 1990). Such char- acteristics are found at Station E (nearest the mouth of Tecolote Creek), where species richness is low and the fauna is dominated by the exotic Musculista sen- housia (Table 1; Fig. 3). Nearer the front of the bay, species richnesses increase 141 142 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES as organisms that are absent or rare in the back bay become more common (e.g. E. limnicola and P. pacifica; Fig.’s 2 and 3). Total abundance and biomass both exhibit sharp peaks at Station B, which can be accounted for by the very high abundances of large-bodied M. senhousia in this area (Table 1; Fig. 3). The abun- dance of this invader drops dramatically nearer the mouth (Station A), even though known sedimentary properties from the area (Fairey et al. 1997) are within the reported range for the species (Crooks 1992, 1998b). Feeding modes of species within estuarine systems also are reported to respond to environmental gradients, with deposit feeders replacing suspension feeding in areas of low flushing and finer sediments (Sanders 1958; Franz 1976; Pearson and Rosenberg 1978). However, this generalization has been questioned (Snel- grove and Butman 1994), and this pattern does not currently hold in Mission Bay. Station A, closest to the mouth, is typically dominated by deposit feeders (Fig. 4). In an earlier study of Mission Bay, Dexter (1983) found that the finer-sediment locations near the back bay (including Station B) also typically were characterized by deposit feeders (although occasionally suspension feeders such as E. limnicola and Phoronis sp. were abundant). However, M. senhousia, which has the ability to achieve high abundances in fine sediments (Morton 1974), has changed the representation of feeding modes near the back bay and created a community dominated by suspension feeders (Fig. 8). Another reported pattern related to feeding modes, that of greater variability in suspension- than deposit-feeding pop- ulations (Levinton 1972) was observed in Mission Bay (Fig. 4). One striking feature of the faunal composition in the bay is the increased dom- inance by the mussel M. senhousia (Figs. 3 and 8). Musculista senhousia is well suited as an estuarine invader. It has anatomical adaptations to living in and pro- cessing fine sediments, broad temperature tolerances, and plastic habitat require- ments (Morton 1974; Crooks 1992, 1996). It also is known to tolerate some degree of organic enrichment (Tsutsumi et al. 1991). Musculista senhousia has life-his- tory characteristics typical of classic weedy, invasive species, as has been ob- served in this study and in shorter-term studies in the intertidal of Mission Bay (Crooks 1996) and in Asia (George and Nair 1974; Morton 1974; Tanaka and Kikuchi 1978). The species is short-lived (maximum of 2 years) and fast-growing, attaining sizes of 25 mm within 1 year. The mussel also has flexible reproduction and recruitment periodicity (Crooks 1996 and references therein) and temporally variable population densities (Fig. 3). The potential effects of this invader are varied. Despite its ability to dramati- cally alter benthic habitats through the construction of dense byssal mats, a variety of small macrofauna often exist in higher abundances in the presence of the mussel. In the intertidal of Mission Bay, species richness, total macrofaunal den- sities, and densities of taxa such as crustaceans, small gastropods, and insect larvae are higher within mussel mats (Crooks 1998b). Similar increased densities or species richnesses of small macrofauna also have been reported in Hong Kong (Hutchings and Wells 1992) and New Zealand (Creese et al. 1997), and are related to the structural complexity and biogenic habitat provided by mussel mats (Crooks 1998b; Crooks and Khim 1999). In this study, the positive relationship between species richness and abundance of M. senhousia (Fig. 7B) suggests a positive effect of the mussel, although this also could be accounted for by similar respons- es of M. senhousia and other species to environmental conditions. Nonetheless, MISSION BAY BENTHOS 143 no negative effects on either species richness or total densities were detectable (Fig. 7). Although positive effects of this species are common at one scale, animals not able to live within the matrix of the mussel mat may be negatively affected. Descriptive studies of bivalve abundances, as well as laboratory and field exper- iments, demonstrate negative effects of the mussel on abundance, growth, and survivorship of native clams (Sugawara et al. 1961; Anonymous 1965; Uchida 1965; Willan 1987; Crooks 1992; Creese et al. 1997; Crooks 1998a). Thick mats of M. senhousia also can inhibit vegetative propagation of the eelgrass Zostera marina L. (Reusch and Williams 1998). In the present study, bivalves with which M. senhousia may interact (such as Solen rostiformis, Tagelus californianus (Con- rad), or Laevicardium substriatum (Conrad)) were not sufficiently abundant to document negative correlations. However, there has been a substantial decrease in the Solen rostiformis in the same time frame as the increase of M. senhousia. In addition, negative correlations were reported between M. senhousia and the polychaetes E. limnicola and Diplocirrus sp. One possible explanation for this is that both these polychaetes live in tubes which protrude above the sediment sur- face, and could thus be negatively impacted by the dense byssal mats of M. senhousia. Similarly, densities of the intertidal, tube-building polychaete Pseu- dopolydora paucibranchiata Okuda were lower in experimental plots containing artificial mussel mats (Crooks and Khim 1999). However, this tube-builder was not found in lower abundances within natural, intertidal mussel mats (Crooks 1998). Experimental manipulations would be necessary to further evaluate the relative importance of competitive interactions and responses to environmental factors (both natural and anthropogenic) in shaping these benthic communities. The distribution of M. senhousia within Mission Bay, with decreased densities towards the mouth (Fig. 3), appears to be a general pattern that can be observed with exotics in other systems. For example, in San Francisco Bay the numbers of exotic species and their respective densities tend to increase dramatically to- wards the back of the bay (Carlton 1979; Hopkins 1986; Nichols and Pamatmat 1988). Such patterns seem to fit a positive relationship between a decline in habitat quality (as is often seen in back-bay locations) and the abundance of exotic species (Elton 1958; Orians 1986; Hobbs 1989; Pysek 1993; Kowarik 1995). However, this pattern is confounded by the fact that most transport mechanisms for estuarine exotics (e.g. ballast water movement, oyster transplantation, and ship fouling) are from one bay to another and bias against moving species adapted to open-ocean conditions (Carlton 1979; Ruiz et al. 1997). It is therefore difficult to quantita- tively distinguish the role of habitat quality from that of vectors of introduction in determining invasibility of estuarine ecosystems. Nonetheless, it is clear that the rate of introductions within these areas is rapidly rising (Cohen and Carlton 1998; Crooks 1998a), and that exotic species will become increasingly important in shaping biotic communities within urbanized coastal ecosystems. Acknowledgements We would like to acknowledge the 200+ students who have aided in the col- lection and processing of benthic samples taken in conjunction with the Biological Oceanography class at San Diego State University. 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Annu. Rev., 32:111—177. Sugawara, K., T. Ebihara, T. Ishii, K. Aoki, and A. Uchida. 1961. Outbreak of a mussel Brachidontes senhousia in Urayasu shellfish rearing ground. Rep. Chiba Prefecture Inner-Bay Fish. Exp. Stn., 3:83—92. (In Japanese) Tanaka, M., and T. Kikuchi. 1978. Ecological studies on benthic macrofauna in Tomoe Cove, Amakusa II. Production of Musculista senhousia (Bivalvia, Mytilidae). Publ. Amakusa Mar. Biol. Labor., 4(3):215-233. Taylor, E. 1982. Mission Bay hydraulic model. Senior Thesis, San Diego State University, San Diego, California, 10 pp. ter Braak, C. J. EF 1995. Ordination. Pp. 91—173 in Data analysis in community and landscape ecology. (R. H. G. Jongman, C. J. E ter Braak, and O. E R. van Tongeren, eds.). Cambridge University Press, England, 299 pp. Tsutsumi, H., T. Kikuchi, M. Tanaka, T. Higashi, K. Imasaka, and M. Miyazaki. 1991. Benthic faunal succession in a cove organically polluted by fish farming. Mar. Poll. Bull., 23:233-—238. Uchida, A. 1965. Growth of a mussel Musculista senhousia and the influence of Musculista senhousia on the clam Tapes philippinarum. Rep. Chiba Prefecture Inner-Bay Fisheries Exp. Stn 5:69— 78. (in Japanese) Weston, D. P. 1990. Quantitative examination of macrobenthic community changes along an organic enrichment gradient. Mar. Ecol. Prog. Ser., 61:233—244. Willan, R. C. 1987. The mussel Musculista senhousia in Australasia; another aggressive alien high- lights the need for quarantine at ports. Bull. Mar. Sci., 41(2):475—489. Zedler, J. B. 1996. Tidal wetland restoration: a scientific perspective and southern California focus. Report T-038. California Sea Grant College System, University of California, La Jolla, Cali- fornia, 129 pp. Accepted for publication 3 August 1999. Bull. Southern California Acad. Sci. 99(3), 2000, pp. 147-160 © Southern California Academy of Sciences, 2000 Investigations of Red Tides Along the Southern California Coast Dominic E. Gregorio and Richard E. Pieper Southern California Marine Institute 820 South Seaside Avenue Terminal Island, California 90731 Abstract.—Prior to 1976 red tides of the dinoflagellate Lingulodinium polyedra usually developed during the fall of the year. From 1976 until 1994 there was an hiatus of red tide blooms. In the winter of 1995 an extensive red tide, dominated by L. polyedra, developed along the entire Southern California Bight. This new pattern of winter and spring red tides continued through 1996 and 1997. In ad- dition, a localized red tide persisted at the Los Angeles River mouth from winter through summer. During post-bloom conditions, L. polyedra cells were observed erupting from their cell walls, taking on a naked amoeboid form. Algal blooms are called red tides when the cell densities are high enough to change water color, often to red. Such blooms have long been a common phe- nomenon within the Southern California Bight (SCB), with the earliest reported red tide occurring in 1746 (Brongersma-Sanders 1957). Red tides can occur in nearly any month of the year and are generally more prominent in nearshore waters (Oguri et al. 1975). Many reported red tides in the past were accompanied with observed mortality of fish and shellfish, while others resulted in no reported damage to the marine system. The specific causes and oceanographic conditions which set the stage for red tides are not completely known (Hardy 1993). Nutrients levels, water temperature, light availability, and zooplankton grazing are all involved in the determination of phytoplankton doubling rates. If these factors are optimized, rapid growth of one or several species can lead to natural blooms. In addition, nutrient enrichment due to agricultural runoff, urban storm drain runoff, sewage effluent and general inshore eutrophication can lead to enhanced algal growth. In the past, the dominant organisms responsible for red tides in the SCB have been the dinoflagellates Prorocentrum micans and Gonyaulax polyedra, and mor- tality of fish and invertebrates have been associated with red water of the latter (Brongersma-Sanders 1957). Spring blooms were usually associated with P. mi- cans, while the more intensive red tides of the late summer and fall were com- monly dominated by G. polyedra (Sweeney 1975). In 1967 Goodman et al. (1984) identified three distinct phytoplankton communities, two of which were dominated by diatoms and associated with upwelling conditions, and the third dominated by Gonyaulax polyedra. This Gonyaulax dominated community was correlated with a shallow pigment layer, low silicate, and high temperatures. This condition is the one usually correlated with red tide formation during the summer and fall months. The pattern of bloom development in the SCB has shown marked variations during the past several decades. Prior to 1975, blooms of the dinoflagellate Go- nyaulax polyedra usually developed during the fall of the year. The triggering 147 148 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Lingulodinium polyedra (Gonyaulax polyedra) red tides off southern California 1901— 1977 (Data from 1901 to 1962 from Brongersma-Sanders 1957, and Oguri 1964). Jan Feb Mar Apr May — Jun Jul Aug Sep Oct Nov Dec 1901 Torry (1902) mortality 1907 Kofoid (1911) mortality 1917 Allen (1921) mortality 1938 Allen Allen (1938) (1938) 1945 Pope Allen (1946) (1946) mortality 1952 Brongersma (1957) 1962 Oguri (1964) 1975 Pieper (unpubl.) 1976 1977 Gaines Gaines (1981) (1981) mechanism(s) for these blooms are unknown but natural causes are usually in- voked. Stratified conditions due to the lack of mixing or dispersion, coupled with nutrient availability, possibly from coastal upwelling, may have provided the set- ting needed for maximum dinoflagellate growth and aggregation. A seed popu- lation would have been needed for these blooms to develop. This seed population may have been present in the plankton in small numbers, or may have arisen from benthic cysts. These blooms failed to continue into the late fall and winter, presumably as light became limiting and storms mixed the water column. This seemingly stable pattern culminated in the fall of 1975 when the area experienced a bight-wide bloom. Then, from 1975 until 1994 there was a hiatus of red tide blooms, except for localized red tides in Los Angeles Harbor in 1976 and 1977 (Morey-Gaines 1981). See Table 1 for a summary of red tide blooms of Gonyaulax polyedra. Gonyaulax polyedra was reclassified as Lingulodinium polyedra by Dodge (1989). Although Steidinger and Tangen (1997) refer to Lingulodinium polyedra as Lingulodinium polyedrum, it will be referred to as Lingulodinium polyedra henceforth. The pattern again changed abruptly in 1995 when an extremely large precipi- tation event occured early in January of 1995, followed by Santa Ana wind con- ditions (warm, dry, sunny). Concurrent with this meteorological sequence an ex- tensive red tide condition developed along the entire coast of the SCB. This large scale bloom persisted from January through April, and was recorded from Santa Barbara to San Diego, and offshore as far as San Clemente Island. Cell concen- RED TIDES ALONG THE SOUTHERN CALIFORNIA COAST 149 trations were measured at La Jolla in excess of 2 million cells 1~! (Hayward et al 1995). In the vicinity of Los Angeles Harbor the red tide peaked and crashed on March 11, leaving dissolved oxygen levels of 3.5 mg/l. This depressed dis- solved oxygen concentration is lower than the minimum regulatory objective of 5.0 mg/l for the Los Angeles and Long Beach Harbors complex as determined by the California Regional Water Quality Control Board. Analysis performed by the California Department of Health Services in March of 1995 determined that Lingulodinium polyedra was the dominant dinoflagellate in the bightwide red tide. Sporadic localized red tides persisted through the spring of 1995, including a red tide condition stretching from the Los Angeles River mouth eastward to Belmont Pier, Long Beach. Continued sampling by the authors during this period confirmed that these subsequent smaller red tides were also dominated by Lingulodinium. Other dinoflagellate genera present in the mainland coastal samples included Prorocentrum, Protoperidinium, and Ceratium. Imme- diately following the crash of the bightwide red tide event, naked dinoflagellate cells were observed in plankton samples. These naked dinoflagellates were sus- pected to be an unarmored form of Lingulodinium. Smith (1995) has proposed 1985 as a boundary year in terms of oceanographic conditions in the southern California Bight. Between 1985 and 1994 sardine lar- vae and sea surface temperatures have increased, while small plankton volume and anchovy larvae have decreased. The ecological system of the Southern Cal- ifornia Bight appears to have undergone some significant change, and this change may have included a shift in dinoflagellate bloom seasonality. These initial observations from early 1995 indicated more than just a shift in the seasonality of red tide blooms. Enrichment from urban runoff may have played a role in the bightwide red tide of 1995. Red tide conditions also persisted at the mouth of the Los Angeles River after the collapse of the bightwide red tide. The Los Angeles River is a major flood control channel for urban runoff. In addition, it receives a large component of its flow from sewage treatment plants. Field and laboratory studies were initiated to further investigate these red tide phenomena. Methods From Spring 1995 through Spring 1997 field measurements and samples were performed from ships of opportunity. Vertical plankton tows, to a depth of 10 meters, were performed using a phytoplankton net, 20 cm. in diameter and 1 meter long, with 80 micron mesh. Plankton was sampled at three locations: (a) the mouth of the Los Angeles River, located within the Los Angeles/Long Beach Harbor complex; (b) one mile outside of the Los Angeles Harbor breakwater; and (c) oceanic water near Bird Rock on the north side of Santa Catalina Island. Samples were analyzed at the Fish Harbor Laboratory for relative dinoflagellate population densities (by genus, given in percent of total dinoflagellates). Naked dinoflagellates were assigned their own category and were not identified to genus. Cell counts of diatoms were also performed for each sample to determine relative concentrations of diatoms to dinoflagellates. In addition, a count of zooplankton, excluding protozoans, was performed for each sample to determine the relative abundance of phytoplankton to zooplankton. During the same period several Secchi disc and Forel Ule color measurements were performed at the mouth of the Los Angeles River and outside the Los 150 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Angeles Harbor Breakwater to produce indicators of water transparency and rel- ative color. The light extinction (k) was calculated from the Secchi depth using the equation k = 1.7 / d, where d is the Secchi depth in meters (Raymont 1963). Nutrient analyses, for ammonia nitrogen, nitrate nitrogen, and orthophosphates were performed on samples collected at the mouth of the Los Angeles River from Spring 1995 through Summer 1996. Ammonia nitrogen was measured using the Salycilate Method (Reardon et al 1966). Nitrate nitrogen was determined using a modified Cadmium Reduction Method (modification of Eaton et al, Standard Method 4500-NO,-E 1995). Orthophosphates were tested using the Ascorbic Acid Method (modification of Eaton et al, Standard Method 4500-PE 1995). All results were read colorimetrically. Laboratory pure cultures of Lingulodinium polyedra and Prorocentrum micans were originally collected from southern California waters in the 1960’s and main- tained since then by the Provasoli-Guillard National Center for Culture of Marine Phytoplankton (CCMP), located at the Bigelow Lab for Ocean Sciences in West Boothbay Harbor, Maine. Sub-cultures were transported from CCMP to SCMI’s Fish Harbor Lab in 1995, then subjected to a series of assays to investigate some simple environmental parameters. Culture light conditions included a 12 hour photoperiod with broad spectrum cool white fluorescent lighting, 80 microeinstein intensity. For each experiment there were 5 replicates of each species in 40 ml screw top test tubes, 25 mm diameter, placed in racks with even access to light. The caps were left loose to allow diffusion of air into the tubes. The caps were tightened and the tubes in- verted on a daily basis. The stock culture media consisted of f/2 in sterile seawater. The seawater source was the Fish Harbor Laboratory seawater system. The sea- water was filtered through a 5 micron filter, f/2 added, and then autoclaved prior to use. Test cultures were inoculated from the stock culture of each species at the curve of optimum population growth. Cultures were inoculated by adding 50 ml of media per 10 ml of culture. The cultures for each variable and control replicate are derived from the same well mixed test tube. Control culture media was the same as for the stock cultures (1.e., f/2 in sterile Fish Harbor water). Cell counts are measured at the beginning of the experiment and at regular intervals through- out the experiments. Results Field Studies Extensive red tides were not observed during the summer and fall of 1995, except at the mouth of the Los Angeles River. Following the winter rains in 1996, patchy red tides developed in San Pedro Bay, both inside and outside of the harbor. One red tide occurred in late February and early March, and was domi- nated by Ceratium. Another red tide developed in late March and lasted into early May, and was dominated by Lingulodinium. Following winter rains in 1997 and a spring characterized by relatively high winds, a red tide once again developed throughout San Pedro Bay during early May. This red tide was reported in Santa Monica Bay as well (T. Tamminen, personal communication). This red tide was RED TIDES ALONG THE SOUTHERN CALIFORNIA COAST 151 dominated by Lingulodinium and culminated in a crash on May 10, 1997. See Table 2 for a summary of Lingulodinium red tide observations from 1995-1997. Aside from the wide-spread red tides, a localized red tide persisted at the mouth of the Los Angeles River during 1995 and 1996, from winter through summer months. These red tides were sometimes observed to extend eastward for as much as two miles along the Long Beach coastline. Regular plankton sampling at the Los Angeles River mouth was not conducted in 1997; however, the red tide of May 1997 in San Pedro Bay was observed and sampled at the Los Angeles River mouth. Nutrients were generally abundant at the Los Angeles River mouth, although values varied considerably between samples (see Table 3). For the study period mean ammonia nitrogen was 15.4 wg-atoms/L, mean nitrate nitrogen was 24.8 y.g-atoms/L, and mean inorganic phosphorus was 2.6 wg-atoms/L. As expected, the concentrations were greater during the winter rainy season. Measurements of the coefficient of light extinction (k) at the river mouth yield- ed results between 0.57 and 3.4. Outside of the harbor the k values were lower (i.e., the water was less turbid), between 0.16 and 0.49 (Figure 1). At the river mouth, the Forel Ule scale readings were between XII and XVIII (..e., ranging from yellow to red). Outside of the harbor the Forel Ule color results were be- tween III and X (i.e., generally blue-green to green; Figure 2). Armored Lingulodinium was the most abundant dinoflagellate taxa in a majority of the samples, regardless of location. At the river mouth armored Lingulodinium was the dominant dinoflagellate, followed by naked dinoflagellates. When counts from all samples at this location were combined, 48% of all dinoflagellate cells were armored Lingulodinium, and 28% were naked dinoflagellate cells (Figure 3). Throughout the study the two most common of the naked cells were identified as Gymnodinium and an amoeboid cell hypothesized to be a life stage of Lingu- lodinium. In many of these samples, the dominant naked cells were of the latter form. During the crash of the May 1997 red tide, samples were observed, from the Los Angeles River mouth as well as other locations, with naked cells erupting from Lingulodinium thecae. This confirmed that the naked cells in the May 1997 samples were in fact Lingulodinium. This also gave more credence to the idea that some of the naked cells observed in previous samples, both at the river mouth and elsewhere, may also have been an amoeboid life stage of Lingulodinium. This phenomena was videotaped, using light microscopy, and digitized into still mi- crographs (Figure 4). Outside of the harbor breakwater, armored Lingulodinium was again the dom- inant dinoflagellate. For all samples at this location combined, 45% of all dino- flagellate cells were armored Lingulodinium, 22% were Ceratium, and 16% were naked dinoflagellate cells (Figure 3). For all samples at Catalina combined, ar- mored Lingulodinium represented 31% of all dinoflagellate cells, 26% were Cer- atium, and 24% were naked dinoflagellate cells. The ratio of phytoplankton to zooplankton was noticeably different at these sampling stations. Generally, the phytoplankton to zooplankton ratios decreased with distance from the river mouth out to less impacted offshore waters. At the river mouth, the median was 1425:1, immediately outside of the harbor the median was 503:1, and at Catalina the median was only 159:1. At the river mouth, only 22% of the samples had phytoplankton to zooplankton ratios of less than 999:1; SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 152 eee ee Se eS SS en nnn ym JOATY “W'T ‘Arg oIpeg pues Aeg eomoyy eyUes L661 Ydwn keg WS keg WS d1OYSJJO a10YSJJO SULIO}Ie[d qteH Ysty qreH Ysty qteH Ysty TOATY VI TOATY VT ToATY VI JOATY VI TOATY VI ToATY VI JOATY VI 9661 Yudn ToATY VI yuOW[9q qreH YSt4 Aeg WS BIOL eT S66! OE EE EEE ———————————EE rae anata a as 90q AON 190 das sny Ine une AeW idy IRA qo uef ‘(pueys] eUTTeIeD BJURS O} JNO JoUULYD OIPsd Uk 9} O} SIOfoI SIOYSJJO ‘keg Oipog ues jo uoriod 19yno 9y} Ul poyeoo] sre SULIOPe]d ‘Aoy joqd euuryy = YAW ‘eouopy eyueg = WS ‘sopesuy soy = VT) 966I-S66I “BMUAOJTED UTSYINOS JFO sop pol ‘(papakjod xpjnpkuoy) vapasjod wniuIpojnsuly “TZ I3QeL RED TIDES ALONG THE SOUTHERN CALIFORNIA COAST 153 Table 3. Nutrient concentrations, Los Angeles River mouth, all results in pg-at/l. Maximum Mean, Standard Mean, Standard Mean, Stan. dev., measure- rainy dev., rainy dry dev., dry _ study study ment season season season season period period ammonia nitrogen 42.8 21.2 14.4 6.0 aT 15.4 13.8 nitrate nitrogen 214.2 36.9 70.6 Sui 6.6 24.8 58.0 inorganic phosphorus 242.7 | 3.1 L7 re 20 260 the remainder (78%) had ratios between 1,000:1 and 9,999:1. Immediately outside of the harbor, a majority of the samples, 74%, had a ratio of less than 999:1. At Catalina, 91% of all samples had phytoplankton to zooplankton ratios of less than 999:1 (see Table 4). The ratios of dinoflagellates to diatoms were also noticeably different at the three sampling stations. Generally, there were decreasing ratios of dinoflagellates to diatoms from the eutrophic river mouth out to less impacted waters. At the river mouth, the median was 39:1, and 89% of the samples had a ratio of greater than 9 dinoflagellates per every 1 diatom. Immediately outside of the harbor the median was 17:1, with 59% of the samples having ratios greater than 9:1. At Catalina the median ratio of dinoflagellates to diatoms was only 6:1, and a ma- jority (63%) of the samples had ratios less than 9:1 (see Table 5). Laboratory Studies Lingulodinium polyedra and Prorocentrum micans, the two dominant species in the 1995 red tide, were subjected to salinity assays. Test salinities were 15, 25 and 35 parts per thousand. Both cultures displayed a tolerance for depressed salinity levels. L. polyedra grew well in both 35 and 25 ppt salinity water, but perished at a lower salinity of 15 ppt (Figure 5). P. micans grew well at all three salinities of 35, 25, and 15 ppt. P. micans also grew at a faster rate than L. polyedra under identical water quality conditions (Figure 6). These results indicate that P. micans has an even higher tolerance to stressful water quality conditions (i.e., depressed salinity) than L. polyedra. This is not surprising, since P. micans is known as a euryhaline species, with its range of tolerance between 15 and 40 ppt, and an optimum salinity of 25 ppt (Kain and Fogg 1960). Laboratory pure cultures of L. polyedra were also grown in water from the mouth of the Los Angeles River in two experiments. In one experiment these cultures were subjected to summer dry season (35 ppt) water quality, and in the other experiment the salinity was depressed (32 ppt) by the presence of winter storm water runoff. For both of these assays, reference cultures in f/2 nutrient Table 4. Phytoplankton to zooplankton ratios. Categories represent ranges of ratios grouped by orders of magnitude. Values are percentages of all samples that fall into the respective categories. Ranges of phytoplankton to zooplankton ratios 0.1-9 10-99 100-999 > 1,000 L.A. River (% of samples) 0) 22 0) 78 Outside Harbor (% of samples) 0) 5 69 26 S. Catalina Island (% of samples) 14 18 59 9 154 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES & 4 Outside of L.A. Harbor 1 L.A. River Mouth Extinction Coeffiecient (k) meine 4 0 +———__4+—__+——___+___} — $$ __}——___}—________+_ ___} Mar-95 Jun-95 Sep-95 Dec-95 Apr-96 Jul-96 Oct-96 Feb-97 May-97 Aug-97 Fig. 1. Coefficient of light extinction (k) at the Los Angeles River mouth and outside of the Los Angeles Harbor breakwater. media were maintained simultaneously to the test cultures. In the dry season experiment, L. polyedra did poorly, actually declining in population size. This may have been due to the absence of some limiting nutrient, or the presence of some toxicant in the river runoff. In the second experiment, evaluating the impact of storm water runoff conditions, L. polyedra experienced a 143 percent increase in population size in a 23 day period compared to a culture of L. polyedra grown in offshore water (from near Catalina Island) which had only a 12 percent increase (Figure 7). Discussion Red tide reports associated with the dinoflagellate L. polyedra (previously Go- nyaulax polyedra) from 1901 through 1977 were from the summer and fall sea- sons. There were no reported red tides in the SCB from 1978 through 1994, a sixteen year period. Then, between 1995 and 1997 the red tide blooms of Lin- gulodinium in the Southern California Bight were observed during the late winter and spring periods of the year. This marked a major shift in the seasonality of A Outside of L.A. Harbor 7 Wi L.A. River Mouth “ a | Vict i | 3 = 8 & w t B Oo _ £4174 = Am A ry A A bie A 6 7 & A a 1+ ' t t ——| + ———{ hs nl Mar-95 Jun-95 Sep-95 Dec-95 Apr-96 Jul96 Oct-96 Feb-97 May-97 Aug-97 Fig. 2. Forel Ule Color at the Los Angeles River mouth and outside of the Los Angeles Harbor break water. RED TIDES ALONG THE SOUTHERN CALIFORNIA COAST 155 O Dinophysis Prorocentrum 90%+ § S RR eed somt | ' Protoperidinium | “a Ceratium a, a il 30% ‘0 naked dinoflagellates 20% // 7 Lingulodinium 10% 0%. WJ5ed Wa Percent of All Samples on ro) > 4 Los Outside Off Santa Angeles L.A. harbor Catalina River breakwater Island mouth Fig. 3. Dinoflagellate community composition. dinoflagellate blooms, which coincided with other significant changes in the eco- logical system of the Bight, such as increased temperature, decreased small plank- ton volume, and a shift in larval abundance from anchovy to sardines. Beyond its coincidence with these other ecological changes, the ultimate reason for the change in the seasonal pattern of red tide development is not obvious. Even the causes of these bightwide red tides in general are still elusive. Potential causes may be related to wind and/or coastal runoff. The largest red tides during the years 1995 to 1997 followed windy periods. Wind blowing over the ocean can cause an increase in the mixed layer and/or coastal upwelling, thereby en- riching the euphotic zone with nutrients. There is also some indication that river and storm drain output, providing abundant nitrogen (including the forms of am- monia or urea), may be an important stimulus for bloom formation. Available nitrogen is often the limiting macronutrient in marine systems, with ammonia and urea being the preferred forms for algal uptake. The present study shows that both L. polyedra and P. micans are tolerant of depressed salinities associated with river runoff. Coastal southern California experiences appreciable rain and asso- ciated runoff only during the winter season, and during the present study period large scale red tides only occurred during the winter and early spring periods. The higher nutrient availability in the runoff may be exploited by dinoflagellates because of the coincidental availability of organic complexing agents (i.e., humic acids) found in river and terrestrial runoff. These organic complexing agents bind with manganese and copper. Under offshore conditions (i.e., upwelling rather than runoff) manganese and copper result in mortality to dinoflagellates (Dempster 1955; Loeblich 1967; Anderson and Morel 1978). Organic complexing agents are suggested as important agents for the development of red tides (Prakash and Rashid 1968; Collier et al. 1969; Doig and Martin 1974). The persistent, localized red tide condition at the Los Angeles River mouth is likely due to eutrophication resulting from urban runoff. Dinoflagellate blooms have been documented in other polluted, eutrophic water bodies along the east coast of the U.S., such as Chesapeake Bay, New York Bight, and Long Island Sound. These waters are characterized by having elevated ammonium:nitrate ra- 156 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES => : Fig. 4. Naked cells erupting from Lingulodinium polyedra thecae. The following series represents the emergence of amoeboid cells from intact Lingulodinium polyedra. Each frame is of a different cell, but from the same sample. The figure in the upper left shows an intact cell. The figure in the lower right shows the fully emerged amoeboid cell and the empty theca. Although all cells were the same size, some appear smaller due to the manipulation of the images to fit within these frames. The top panel is composed of digital photographs. The bottom panel is composed of line drawing inter- pretations of the digital photographs. RED TIDES ALONG THE SOUTHERN CALIFORNIA COAST 7 Table 5. Dinoflagellate to diatom ratios. Categories represent ranges of ratios grouped by orders of magnitude. Values are percentages of all samples that fall into the respective categories. Ranges of phytoplankton to zooplankton ratios 0.1-9 10-99 100-999 1,000-—9,999 >10,000 L.A. River (% of samples) ti 45 bi 11 Ze Outside Harbor (% of samples) 41 27 9 23 0 S. Catalina Isl. (% of samples) 63 3 aD 0 0 tios and high concentrations of dissolved organic compounds (McCarthy et al. 1977; Paasche and Kristiansen 1982). Within the study area, the Los Angeles River, flowing into the Los Angeles/ Long Beach Harbor complex, contains sewage plant effluent throughout the year and significant urban storm drain runoff during the rainy season. Elevated nutrient levels during 1996 were measured in association with the winter and early spring peak runoff period. Runoff flows into the harbor where the lack of mixing is conducive to dinoflagellate bloom development. The dinoflagellates decrease in abundance, in relation to diatoms, with distance from the mainland harbor com- plex. The dinoflagellate community composition also changes with distance away from the harbor complex, with Lingulodinium occupying a less dominant role in the less impacted offshore water. This is further supported by the laboratory as- says, in which L. polyedra cultures grew more favorably on wet season Los Angeles River mouth water as compared to cleaner offshore seawater. The life history of Lingulodinium, in terms of its amoeboid stage, brings up interesting ecological questions. The amoeboid stage occurs during stressful post bloom conditions. It is possible that this stage has an adaptive advantage with regard to mobility or reproduction. Possibly the amoeboid stage is a better pred- ator than the armored stage. There may also be a relationship between this stage and the benthic (dormant) cyst stage. The amoeboid stage may be more vulnerable to predation, unless this stage has built-in toxic safeguards that are as yet un- cell count /ml » gig st ae —f- ee es a ———e 4 0 1 2 5 7 8 10 12 day Fig. 5. L. polyedra response to three different salinities. 158 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 1200 1000 cell count/ml fo?) 8 day Fig. 6. P. micans response to three different salinities. known. Possibly there are fewer zooplankton organisms in post bloom conditions, thereby reducing the risk of predation. Past data on red tide events off southern California are, at best, sporadic. Many of these are largely a function of reports which originate only when investigators were in the field, rather than as a result of consistent sampling strategies. Simi- larly, the results reported herein were, due to budget constraints, largely obtained through the use of ships of opportunity. The occurrence of Lingulodinium red tides and other harmful algal blooms in the Southern California Bight deserves further study. A consistent field sampling plan and additional laboratory investi- gations are recommended to examine further the nature of red tides off southern California. Acknowledgments We wish to thank the Algalita Marine Research Foundation, and the Surfrider Foundation, Long Beach and North Orange County Chapter, for their generous contributions. Technical assistance and algal cultures were provided by the Pro- 250 ————= river mouth 32ppt ee ee es Catalina 35ppt = = /2 35ppt ‘ cell count/ mi Fig. 7. L. polyedra response to urban runoff vs. offshore water and ideal culture media. RED TIDES ALONG THE SOUTHERN CALIFORNIA COAST 159 Table 6. Lingulodinium polyedra (Gonyaulax polyedra) red tides off Southern California. Jan Feb Mar Apr May — Jun Jul Aug Sep Oct Noy « Dec 1901 xX 1907 ty XX XX 1938 XX XX 1945 x HE 1952 XX 1962 x 1975 ~@. 1976 XX 1977 xx er res Pe ee 1 EXT HEX eX a eee SCF Senha ex 1997 XX vasoli-Guillard National Center for Culture of Marine Phytoplankton. Crystal Brandt, Matt Sullivan, and Carrie Wolfe of the Southern California Marine Insti- tute also provided valuable assistance. Also, many thanks to Dr. Francis McCarthy and Bill Wilson for their helpful comments on this paper. Literature Cited Anderson, D. M., and EK M. Morel. 1978. Copper sensitivity of Gonyaulax tamarensis. Limnology and Oceanography. 23:283-—295. Brongersma-Sanders, M. 1957. Mass mortality in the sea. Chapter 29 In: Hedgpeth, J. W. ed., Treatise on Marine Ecology and Paleoecology, Volume 1. Pp. 941-1010. Mem. 67. Geological Society of America, New York. California Regional Water Quality Control Board, Los Angeles Region. 1994. Water Quality Control Plan, Los Angeles Region, Dissolved Oxygen Objectives. Pp. 3-11. Collier, A., W. B. Wison, and M. Borkowski. 1969. Responses of Gymnodinium breve Davis to natural waters of diverse origin. J. Phycology. 5:168—172. Dempster, R. P. 1955. The use of copper sulfate as a cure for fish diseases caused by parasitic dino- flagellates of the genus Oodinium. Zoology (N.Y.). 40:133-138. Department of Health Services. 1995-1996. Marine biotoxins in shellfish and toxigenic marine phy- toplankton. Technical Reports 95—25 through 96—21. State of California, Health and Welfare Agency, Sacramento, California. Dodge, J. D. 1989. Some revisions of the family Gonyaulacacae (Dinophycae) based on a scanning electron microscope study. Botanica Marina. 32:275—298. Doig, M. T. WI and D. EF Martin. 1974. The effect of naturally occurring organic substances on the growth of the red tide organism. Water Res. 8:601—606. 160 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Eaton, A. D., L. S. Clesceri, and A. E. Greenburg (eds). 1995. Standard Methods for the Examination of Water and Wastewater. 19th Edition. American Public Health Association. Washington, D.C. Goodman, D., R. W. Eppley, and E M. H. Reid. 1984. Summer phytoplankton assemblages and their environmental correlates in the Southern California Bight. J. Mar. Res. 42(4):1019—1050. Hardy, J. T. 1993. Phytoplankton. Chapter 3 Jn: M. D. Dailey, D. J. Reish and J. W. Anderson eds., Ecology of the Southern California Bight. Pp. 233—265. University of California Press, Berke- ley. Hayward, T. L., D. R. Cayan, P. J. S. Franks, R. J. Lynn, A. W. Mantyla, J. A. McGowan, P. E. Smith, F S. Schwing, and E. L. Venrick. 1995. The state of the California Current in 1994-1995: a period of transition. Calif. Coop. Oceanic Fish. Invest. Rep. 36:19-—39. Kain, J. M. and G. E. Fogg. 1960. Studies on the growth of marine phytoplankton. III. Prorocentrum micans Ehrenberg. J. Mar. Bio. Assoc. UK. 39:33—50. Loeblich, A. R. 1967. Aspects of the physiology and biochemistry of the Pyrrhophyta. Phykos. 5: 216-255. McCarthy, J. J., W. R. Taylor, and J. L. Taft. 1977. Nitrogenous nutrition of the plankton in Chesapeake Bay. I. Nutrition availability and phytoplankton preferences. Limnology and Oceanography. 22: 996-1011. Morey-Gaines, G. 1981. The ecological role of dinoflagellate blooms in the Los Angeles-Long Beach harbor. Ph.D. Dissertation. Department of Biological Sciences, University of Southern Califor- nia. Los Angeles. USC Sea Grant Publication No. USCSG-TD-01-81. Oguri, M. 1964. The relationship between red tide and sewage discharges into the marine environment. Allan Hancock Foundation Harbors Environmental Project, University of Southern California. unpublished report. Oguri, M., D. Soule, D. M. Joge, and B. C. Abbott. 1975. Red tides in Los Angeles-Long Beach harbors. Jn: LoCicero, V. R. ed., Proceedings of the First International Conference on Toxic Dinoflagellate Blooms. Pp. 41—46. Mass. Sci. Tech. Foundation, Wakefield, Massachussetts. Paasche, E., and S. Kristiansen. 1982. Nitrogen nutrition of the phytoplankton in the Oslofjord. Es- tuar.coast.shelf Sci. 14:237-—249. Prakash, A., and M. A. Rashid. 1968. Influence of humic substances on the growth of marine phy- toplankton: Dinoflagellates. Limnology and Oceanography. 13:598—606. Raymont, J. E. G. 1963. Plankton and Productivity in the Oceans. Pp. 201—202. Pergamon Press, London, UK. Reardon, J., J. A. Foreman, and R. L. Searcy. 1966. New reactants for the colorimetric determination of ammonia. Clinica Chimica Acta. 14:403—405. Smith, P. E. 1995. A warm decade in the southern California bight. Calif. Coop. Oceanic Fish. Invest. Rep. 36:120-126. Steidinger, K. T. and K. Tangen. 1997. Chapter 3, Dinoflagellates. In: Tomas, C. R. ed., Identifying Marine Phytoplankton. Pp. 509-510. Academic Press, Harcourt Brace and Company, San Di- ego. Sweeney, B. M., 1975. Red tides I have known. Jn: LoCicero V. R. ed., Proceedings of the First International Conference on Toxic Dinoflagellate Blooms. Pp. 225—234. Mass. Sci. Tech. Foun- dation. Wakefield, Massachussetts. Tamminen, T. Santa Monica Baykeeper. 1997. personal communication. ACCEPTED FOR PUBLICATION 28 SEPTEMBER 1999. Bull. Southern California Acad. Sci. 99(3), 2000, pp. 161-170 © Southern California Academy of Sciences, 2000 The Influence of Bay versus Coastal Habitats on Development and Survival of Striped Shore Crab Larvae (Pachygrapsus crasstpes Randall 1840) Claudio DiBacco Marine Life Research Group, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, California, 92093-0218 phone (858) 534-3579, Fax: (858) 822-0562, cdibacco@ucsd.edu Abstract.—The striped shore crab, Pachygrapsus crassipes, lives in both protected embayments and exposed nearshore coastal habitats and larvae may develop in either setting. This study compared survivorship and development of Pachygrap- sus crassipes zoeae brooded in two southern California embayments and an ex- posed coastal habitat and cultured in corresponding waters under laboratory con- ditions. Larvae cultured in nearshore coastal seawater experienced higher survi- vorship during zoeal development, exhibited a higher percentage of stage VI zoeae surviving to the post-larval megalopal stage, and yielded a larger percentage of viable megalopae than larvae reared in seawater collected from either San Diego Bay or Mission Bay. This study suggests that brood site and culture water source will influence P. crassipes’ rate of development and survivorship. The early life history of many nearshore benthic invertebrate species involves the release of planktonic larvae (meroplankton) that remain in the water column until ready to settle as juveniles or adults (reviewed by Levin & Bridges 1995). The planktonic phase provides a vehicle for larval dispersal, gene flow between populations, and colonization of new habitats (Thorson 1950; Mileikovsky 1971; Scheltema 1971). Larval dispersal strategies vary; some larvae are retained within estuaries, other species are preferentially exported to coastal waters (Epifanio 1988), while others are spawned offshore and must migrate onshore (reviewed by Shanks 1995). The trade-off between nutrition, predation, and physiological stress have been offered as explanations for why certain larvae may be preferentially exported from estuaries while others are retained throughout their development. Estuaries are considered to be more productive than coastal waters (Ferguson et al. 1980) and may provide more food. However, the higher productivity of estuaries also sup- ports more predators (Weinstein 1979) and certain taxa may favor reduced pre- dation pressure associated with coastal waters (Morgan 1987a). Physiological stress is usually greater in estuaries due to larger temperature and salinity fluc- tuations depending on the size of embayments and freshwater input (Morgan 1987b). Most studies that have addressed the adaptive significance of larval develop- ment in bays versus coastal waters have focused on species that inhabit bays as adults and show a clear preference for being exported to coastal waters or retained within embayments through larval development. However, a number of marine benthic invertebrate species inhabit both estuarine and exposed coastal habitats 161 162 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES during larval and adult stages of development. Gaines and Bertness (1992) have shown for the Narragansett Bay region that acorn barnacle larvae, Semibalanus balanoides, develop and recruit within bay or coastal habitats and that rainfall- driven bay flushing largely controls the exchange of larvae between these habitats. Embayments and open coastal environments can differ considerably with respect to physical (light, temperature, salinity, flow), chemical (elemental contaminants), and biological (food availability, predation pressure) factors. Larvae that are brooded or released in these respective habitats may experience developmental differences that ultimately affect population success. In southern California, adults and larvae of the striped shore crab, Pachygrap- sus crassipes, are widely distributed in low-energy bay habitats and exposed coastal habitats. The majority of adult crabs found in embayments inhabit burrows built into the sides of tidal creeks in high intertidal marshes, while inhabitants of the high-energy rocky intertidal occupy predominantly high and mid-level crev- ices and tidepools (Hiatt 1948). Fertilized eggs are extruded, attached to the fe- males pleopods on the abdomen, and brooded for 26 to 31 days prior to hatching (Hiatt 1948). Following hatching, larval development of P. crassipes is thought to include 6 zoeal stages (Jose Cuesta, pers. comm.) followed by a post-larval megalopal stage. Schlotterbeck (1976) reported a mean duration of 115 d for zoea reared to the fifth stage of development under laboratory conditions. This study examined the effects of brood site (site of origin) and culture water source on the survival and rate of development of P. crassipes larvae. Newly released larvae originating from three sites were reared in the laboratory in waters from each site through to the megalopal stage. The null hypothesis was that there are no differences in the development rate or survival of zoeae brooded in or developing in waters of southern Californian embayments when compared with zoeae developing in a nearby exposed coastal environment. Methods Culturing experiments A laboratory experiment was conducted to examine the effects of site of larval origin and culture water on larval mortality and development. Ovigerous crabs, Pachygrapsus crassipes, were collected from three sites in southern California, USA, including two embayments (1) Sweetwater Marsh, San Diego Bay (SDB)(Chula Vista, California), and (2) the Northern Wildlife Preserve, Mission Bay (MB) (Pacific Beach, California), and one open coastal site (3) Dike Rock (DR), La Jolla Shores Beach (La Jolla, California) (Fig. 1). Sweetwater Marsh is located in the inner half of SDB, 17 km from the bay’s entrance. The Northern Wildlife Preserve is located in the northeast corner of MB, 5 km from the bay entrance. Dike Rock is a coastal rocky intertidal habitat, located on the open coast, 24 km north of the entrance to SDB. Ovigerous females were collected between 29 June and 29 July 1996 (Table 1) and transported back to the lab in plastic coolers containing local, ambient temperature seawater within 1-2 hours of col- lection. Females were transferred to a temperature controlled culture room (20 °C-22 °C) and held in a 14 h light/10 h dark schedule simulating in situ conditions. Each ovigerous female was placed into an acid-washed, high-density polyethylene (HDPE) bow] filled with 4 L of 5-ym filtered seawater collected at the same sites LARVAL CRAB DEVELOPMENT AND SURVIVAL 163 i 10'N Mission a5 20'N U.S.A. Mexico 329 30'N 117°21' W 117°07 W Fig. 1. Location of three collection sites for ovigerous shore crabs, Pachygrapsus crassipes, and culture water in southern California. Sites include two embayments, Sweetwater Marsh, San Diego Bay and the Northern Wildlife Preserve, Mission Bay, and one open coastal site, Dike Rock, La Jolla Shores Beach. and times as crabs (SDB, 34.3 + 1.4 psu (practical salinity units, average + SD); MB, 32.2 + 1.5 psu; DR, 32.8 + 1.4 psu). All containers were aerated using standard aquarium air pumps and were covered to avoid evaporation and changes in salinity. Laboratory culture water was collected by pumping subsurface (> 0.5 m) seawater through a filter bag and into prewashed (10% Nitric Acid, rinsed in 18 mQ water), 20-L HDPE carboys for transport back to the lab. Once in the laboratory, all water was passed through a 5-ym filter. Filtered seawater was maintained in the dark at a temperature of 18 °C and replaced every week. Ovig- erous females were not fed. Zoeae hatching within 36 h of the female collection date were used to provide larvae for culturing experiments (Table 1). A total of 12 females, 4 from each of three sites, were used in this study (Table 1). Zoeae hatched from individual females were sub-sampled into 3 groups of 200 individuals. The three groups were reared in source water collected from SDB, MB or DR, respectively. Larvae in each treatment were reared under static conditions in 4 L of seawater in HDPE bowls at 200 individuals per bowl (50 zoeae L™') on a diet of newly hatched brine shrimp nauplii (Artemia sp.) at a density of 4000 nauplii L~'. All larvae were fed freshly hatched brine shrimp (Artemia sp.) nauplii that had been reared in seawater corresponding to the re- spective culture water treatment. In addition to maintaining culture water tem- perature (20 °C-22 °C) and salinity (33.28 + 1.13 psu; mean + SD) at ambient conditions, oxygen concentration and pH were monitored to ensure that they were 164 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Collection site, date collected and date hatched for ovigerous crabs, Pachygrapsus cras- sipes, employed in larval culturing experiments. Collection site Individual Date collected Date hatched Sweetwater Marsh, 1 29 June 1996 30 June 1996 San Diego Bay, CA 2 1 July 1996 2 July 1996 5 29 July 1996 30 July 1996 4 29 July 1996 30 July 1996 Northern Wildlife Preserve, 5 1 July 1996 2 July 1996 Mission Bay, CA 6 1 July 1996 3 July 1996 7 15 July 1996 16 July 1996 8 15 July 1996 16 July 1996 Dike Rock, La Jolla Shores 9 1 July 1996 3 July 1996 Beach, La Jolla, CA 10 13 July 1996 14 July 1996 M4 13 July 1996 15 July 1996 12 29 July 1996 30 July 1996 maintained close to ambient conditions, thus minimizing their effect on zoeal survivorship and development. Larvae were transferred to clean culture bowls with fresh seawater every 48 h; food rations were replenished daily. Larval cultures were monitored every second day. Dead individuals were tallied and removed while live zoeae were transferred to fresh seawater. Larvae were examined under a dissecting microscope and considered dead when no body movements or a beating heart were visible. Cultures were maintained until all larvae had either died or metamorphosed into post-larval megalopae. Magalopae were held individually in containers identical to those used to culture zoeae. They were supplied with fresh seawater every second day and fed newly hatched brine shrimp nauplii and commercial brine shrimp flakes daily. Statistical analysis The following parameters were evaluated: (1) zoeal survivorship, (ii) zoeal du- ration (number of days from hatching to stage VI for surviving larvae) expressed as average time to megalopa (ATM sensu Epifanio et al. 1998), (111) percentage of stage I zoeae surviving to the megalopal stage of development, (iv) percentage of zoeae that molted from stage VI zoea to the megalopal stage, and survival time of megalopae reared in this experiment. One-way and two-way analysis of vari- ance (ANOVA) models were used to evaluate site of larval origin (SDB, MB, DR) and source water (SDB, MB, DR) effects on larval survivorship and rates of development. A repeated measures analysis, using a two-way ANOVA model, was used to test site of origin and source water effects on zoeal survivorship independent of time. Two-way ANOVA models were used to assess brood site and culture water effects only when no significant interactions were observed. If an interaction term was significant, each factor was analyzed independently using a l-way ANOVA model. All post-hoc multiple comparisons were conducted with the Student-t statistic, using a Bonferroni correction (Type I error) where multiple comparisons were made. Percent data were arcsine transformed prior to analysis. LARVAL CRAB DEVELOPMENT AND SURVIVAL 165 100 ® » A. SDB Brood = 20 ae . ioe 0 all e® ° e cathy Se e evs HD 2- eee ey rrr vv vvyvy 100 @ e B. MB Brood S804 vx 2 Tux = 60-4 e Vv Y eo” Ot ° RR RUBS iS begae © ee SEEUY i COocccccccecocessig: ” 20-4 0+ = —— ———+ ————— 100 @ s, C. DR Brood Z 0} %. = @ = 60 + us ) ey = 40 e - 5 Cte. ” 20- oes e TTY YY YY vVyy athe vooegococ00C” 0 5 10: Abo 20-4425. 6 Z0us Sabian!) 45. < ep Time (days) Culture Water: @ SDB O MB v DR Fig. 2. Culture water effects on laboratory cultured crab larvae, Pachygrapsus crassipes, expressed as percent survivorship. Mean survivorship estimates within each plot (A-C) are independent of larval origin since larvae were brooded in (A) Sweetwater Marsh, San Diego Bay (SDB), CA, (B) Northern Wildlife Preserve, Mission Bay (MB), CA, or (C) Dike Rock (DR), La Jolla, CA. All curves are terminated at day 50, but cultures lasted an average of 98 + 7 d (SD). Error bars are not shown for the sake of clarity. Statistical comparisons among sites are given in the text. Results Zoeal Survivorship Zoeae in culture survived an average of 98 + 7 d (mean + SD). Larval brood site (Repeated Measures Analysis, 2-way ANOVA model; F,,, = 11.261, p<0.001) and culture water (F,,,=3.745, p=0.037) both had a significant effect on zoeal survivorship. The interaction term was not significant (F,,,.=0.121, p=0.974). Zoea cultured in DR seawater had 14% higher survivorship than those reared in SDB seawater (Student-t; £9 95,2)2;=2-080, p=0.0211)(Fig. 2). Zoeae reared in MB seawater did not differ significantly from zoeae reared in either DR (Student-t; 9 952) 22= 2-074, p=0.247) or SDB seawater (Student-f; £9 95,2) 2; =2-080, p=0.229). Zoeae brooded in MB experienced 21% and 24% higher survivorship than those brooded in either SDB (Student-tf; £0 95,2) 2; =2.080, p=0.004) or the DR habitat, respectively (Student-t; 1 95;2).2;=2.080, p<0.001). Zoeae brooded in SDB and the DR habitat exhibited similar survivorship (Student-t; £9 95:2) 2.=2-074, p=0.420). 166 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Nh on ie ie fy a % Surviving to Megalopae rs a b a lia aa ul 301 a a a 25 | Rid San Diego Bay Mission Bay Dike Rock % Surviving Molt Survival Time (days) 5 Culture Seawater Brood Site: Mmm SDB (7Z1 MB Cc DR Fig. 3. Culture water and brood site effects on (A) the mean percentage of stage I zoeae, Pach- ygrapsus crassipes, surviving to the megalopal stage of development, (B) the mean percentage of stage VI zoeae, Pachygrapsus crassipes, which molted from the sixth zoeal stage to the megalopal stage, and (C) the survival time (days) for laboratory cultured crab megalopae, Pachygrapsus crassipes since molting from the sixth zoeal stage of development. Error bars indicate +1 SE. MB= Mission Bay, SDB= San Diego Bay, DR= Dike Rock. Culture water treatments sharing the same letter (a, b) are not significantly different. Brood site results are given in the text. Development Time Laboratory-based estimates of ATM (mean zoeal duration, stages I through VI) for individual P. crassipes larvae ranged from 68 d to 108 d. There were no significant differences in ATM for P. crassipes zoeae as a function of brood site (2-way ANOVA, F, ,.=0.287, p=0.754) or culture water (F, ,,=0.021, p=0.979; interaction term, F, ,,=0.294, p=0.878). Survival to Megalopae Source water had a significant effect on the percentage of zoeae surviving to the megalopal stage of development (2-way ANOVA, F, ,.=8.578, p=0.002), while differences due to the site of larval origin were not significant (F, ,.=3.306, p=0.060; interaction term, F, ,,=0.681, p=0.614) (Fig. 3A). Cultures reared in SDB seawater yielded a significantly lower percentage of megalopae (3.6 + 1.9%; mean + SD) than those reared in DR seawater (14.5 + 5.5%; Student-t; LARVAL CRAB DEVELOPMENT AND SURVIVAL 167 10.05(2),16= 2-120, p=0.002) or MB water (10.5 + 5.5%; Student-t; £9 952) 16=2-120, p=0.040). The percentage of megalopae produced from zoeae cultured in DR or MB seawater did not differ statistically (Student-f; 1 95,2) ;,=2.120, p=0.125). The percentage of stage VI zoeae that successfully molted to the megalopal stage of development ranged from 10.2% to 61.1% across brood site and culture water treatments (Fig. 3B). Culture water had a significant effect on the survival of stage VI zoeae molting to the megalopal stage of development (2-way ANO- VA, F,s = 5.400, p=0.013) while brood site did not (F,,=2.162, p=0.141; in- teraction term, F, ,=0.923, p=0.470). Stage VI zoeae reared in MB seawater ex- perienced significantly lower molting success (11.3 = 8.5%; mean + SD) than those reared in DR (37.9 + 22.0%; Student-t; 1 95:2) ;7=2-110, p=0.005) or SDB seawater (30.7 + 24.0%; Student-t; t9 95(2) ;7=2-110, p=0.030). Megalopal Duration The majority of larvae reaching the larval megalopal stage (474 of 481 indi- viduals) did not metamorphose (i.e., settle) to the juvenile stage of development. Pachygrapsus crassipes megalopae settle and then metamorphose in intertidal or high intertidal habitats (e.g., mussel beds, seagrass) (Hiatt 1948; DiBacco, un- published data). The lack of any settlement substrate in culture containers em- ployed in this study may have inhibited metamorphosis to the juvenile stage. The length of time that megalopae survived (Survival Time, Fig. 3C) is interpreted here as a measure of their overall fitness in culturing conditions. Megalopae that successfully metamorphosed to the juvenile stage are not considered here since they represent only 5.1% (n=26 ind.) of total megalopal observations. A 2-way ANOVA on survival time revealed an interaction between culture water and brood site (F, ,=2.661, p=0.142); therefore these factors were analyzed separately with l-way ANOVA. Site of larval origin (l-way ANOVA, F,,,=11.089, p<0.001) had a significant effect on survival time, but source water did not (F,,,=2.017, p=0.157). Megalopae originating from MB survived significantly less time (2.3 + 7.6 d) than those originating from the DR site (10.0 + 17.4 d, Student-t; to.05(2),14= 2-145, p=0.002) or from SDB (7.2 + 14.3 d; Student-t; fo 95.2) 4=2.145, p=0.004). Megalopal survival time in SDB and the DR site did not differ (Stu- dent-t; 9 952), 16= 2-120, p=0.636). Discussion Our results suggest that P. crassipes zoeae cultured or brooded in bay seawater (SDB or MB) experienced lower survivorship and produced fewer megalopae than zoeae brooded or reared in coastal (DR) seawater, with the exception of MB brooded zoeae which had higher survivorship than larvae brooded in either SDB or DR. These results have implications for the source of individuals recruiting to adult populations. If larvae originating from SDB are less likely to survive and ultimately settle than those from other bays, other sites may be responsible for maintenance of SDB populations. Reduced survivorship of larvae in SDB habitats with no change in development time would favor recruitment by larvae that were brooded and which develop in coastal waters. Organisms which either inhabit both bay and coastal habitats, or whose larvae can be found in both environments during all stages of development, may experience preferential recruitment than larvae brooded and/or developing in coastal water. If bay populations are self- 168 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES seeding, reduced availability of recruits could result in reduced population size and ultimately local extinction. Residence time estimates for SDB seawater, in the region of the Sweetwater Marsh, are on the order of 100 days (Chadwick et al. 1996, Chadwick & Largier 1999). Planktonic larvae that disperse passively would spend most or all of their time in the bay. Pachygrapsus crassipes zoeae sampled in SDB during consec- utive ebbing and flooding tides exhibited tidally timed, vertical migratory behavior (DiBacco 1999). They concentrate in surface waters during nighttime ebbing tides and on or near the sediment surface (<1 meter above bottom [mab], including the sediment-water interface) during flood conditions (DiBacco 1998). This mi- gratory behavior, which has been observed for other grapsid crabs (Christy and Stancyk 1982), should promote transport out of SDB and drastically reduce the residence time of zoeae within the bay. Larvae leaving SDB for open coastal waters should experience increased probability of surviving to the megalopal stage (Fig. 3A). The survivorship estimates reported in this study are comparable to those of grapsid crab larvae in other studies. Survivorship through the last stage of zoeal development of P. crassipes in the present study ranged from 3 % to 15 % at relatively constant temperatures (20 °C-22 °C) and salinities (31 %-32 %) selected to mimic ambient conditions. Schlotterbeck (1976) reported 0 % survivorship for P. crassipes with no zoeae surviving through the fifth zoeal stage (V) of devel- opment reared under similar temperature, salinity and food conditions in the lab- oratory. Other laboratory studies have reported survivorship estimates between 0 % and 60 % for grapsid crab larvae reared under comparable temperature and salinity conditions (Armases cinereum, formerly Sesarma cinereum, see Costlow et al. 1960; Hemigrapsus sanguineus, see Epifanio et al. 1998). The ATM for P. crassipes zoeae (from hatching to the megalopal stage of development) observed in this study (84 d from stage I to megalopa) was shorter than estimates reported by Schlotterbeck (1976) for the same species (86 d from stage I to stage IV). The duration of zoeal development reported for zoeae of other grapsid crab species can be considerably shorter; e.g., 15 to 55 d for Hemigrapsus sanguineus (Epi- fanio et al. 1998) and 20 to 28 d for Armases cinereum (Costlow et al. 1960). The longer duration of P. crassipes zoeal development seems to reflect a char- acteristic difference in development rate among the species mentioned above. Since P. crassipes zoeal development time is much greater than that of other grapsid crabs, survivorship differences due to brood site or culture water may be especially important in determining the source of successful recruits to adult pop- ulations. Site of larval origin (i.e., brood site) as well as subsequent dispersal and trans- port are important in determining exposure times to potentially toxic environ- ments. One factor not controlled in this study was anthropogenic pollutants. Sig- nificantly higher mean trace element concentrations were found in stage I zoea originating from SDB (Cu=25.3 pg-kg™'!, Al=34.1 wg-kg~', Zn=25.8 pg-kg~') when compared with larvae collected from coastal habitats (Cu=1.0 pg-kg"', Al=8.9 pg-kg', Zn=3.4 wg-kg~')(DiBacco & Levin, in press). Elevated body burden estimates and seawater composition suggest that trace elements could con- tribute to reduced survivorship observed in SDB brooded and cultured larvae. Trace elemental toxicants are sources of physiological stress and can account for LARVAL CRAB DEVELOPMENT AND SURVIVAL 169 reduced survivorship and development in marine invertebrate larvae (Kennish 1992). San Diego Bay, which has been heavily impacted by industrial, commercial and military development, has been ranked as one of the most contaminated urbanized coastal areas in the nation (O’Connor 1990). San Diego Bay pollutants include nutrient enrichment via organic wastes (sewage, fertilizers), hydrocarbons (PAHs), chlorinated hydrocarons (PCBs, pesticides), and heavy metals (copper, aluminum, zinc). These contaminants are introduced to the marine coastal envi- ronments directly through industrial, commercial, and military activities or by way of rainwater runoff (non-point source) from thousands of acres of urban development in the SDB watershed (McCain et al. 1992; Flegal & Safiudo-Wil- helmy 1993; SWRCB & NOAA 1996; Kennish 1998). Although elevated con- centrations of toxicants in SDB are likely to have an effect on the survivorship and development of P. crassipes larvae, the experimental design employed here does not allow us to isolate effects due to elemental toxicants and other sources of pollution. The exposure of larvae to pollutants in situ may fluctuate as a result of inter- mittent additions of polluting substances or due to the dispersal and transport of larvae between regions of an embayment or between bay and coastal environ- ments. The ability of P. crassipes to migrate vertically and enhance transport out of SDB to more pristine coastal environments could reduce harmful developmen- tal effects associated with SDB water. Ringwood (1992) showed that larvae of a bivalve, Isognomon californicum, exposed to ambient concentrations of selected trace elements initially suffered severe adverse effects. However, these effects were reversible if the toxicant was removed from the larva’s environment prior to permanent damage. Ringwood’s (1992) results and those presented here for P. crassipes suggest that both larval source and larval trajectories in bay and coastal settings can have a major influence on the dynamics of the larval phase, and potentially on the structure of populations. Methods that reveal larval site of origin or transport pathways and rates will contribute significantly to understanding the dynamics of estuarine and coastal species. Acknowledgments Field and laboratory assistance was provided by Jeffrey Crooks, Zoe Lieber- man, Matthew Luoto, Christopher Martin, Robin Oleata, Anthony Rathburn, Drew Talley, Theresa Talley, Mari Tashiro. Lisa Levin, A. Rathburn and J. Crooks reviewed earlier drafts of this manuscript. The Office of Naval Research (NO0014- 96-1-0025) supported this work. CDB was also supported by a Natural Sciences and Engineering Research Council of Canada Postgraduate Fellowship, a Mildred E. Mathias Graduate Student Research Grant, and a University of California Toxic Substance Research and Teaching Program Graduate Student Fellowship. Literature Cited Chadwick D. B., Largier J. L., and R. T. Cheng. 1996. The role of thermal stratification in tidal exchange at the mouth of San Diego Bay. pp. 155-174 In: Bowman MJ, Mooers CNK (eds.) Coastal and Estuarine Studies, Buoyancy Effects on Coastal and Estuarine Dynamics. American Geophysical Union, Washington D.C. Chadwick, D. B., and J. L. Largier. 1999. Tidal exchange at the bay-ocean boundary. J. Geophysical Res. 104:29901-—29924. Christy, J. H., and J. E. Stancyk. 1982. Timing of larval production and flux of invertebrate larvae in 170 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES a well-mixed estuary. pp. 489-503 In: Kennedy VS (ed.) Estuarine Comparisons. Academic Press, New York. Costlow, J. D. Jr., G. C. Bookhout, and R. Monroe. 1960. The effect of salinity and temperature on larval development of Sesarma cinereum (Bosc) reared in the laboratory. Biol. Bull. 118:183— 202. DiBacco, C. 1998. Temporal and vertical distributions of crab larvae in San Diego Bay, California. Eos 79:145. DiBacco, C. 1999. Bay-ocean exchange of crab larvae: the roles of larval behavior, origins, distribution and physical processes. University of California, San Diego. Ph.D. Dissertation. 196 pp. DiBacco, C. and L. A. Levin (in press). Development and Application of Elemental Fingerprinting to Track the Dispersal of Marine Invertebrate Larvae. Limnology and Oceanography. Epifanio, C. E. 1988. Transport of invertebrate larvae between estuaries and the continental shelf. Amer. Fish. Soc. Symp. 3:104-114. Epifanio, C. E., A. I. Dittel, S. Park, S. Schwalm, and A. Fouts. 1998. Early life history of Hemigrapsus sanguineus, a non-indigenous crab in the Middle Atlantic Bight (USA). Mar. Ecol. Prog. Ser. 170:23 1-238. Ferguson, R. L., G. W. Thayer, and T. R. Rice. 1980. Marine primary producers. pp. 9-69 In: Vernberg FJ (ed.) Functional Adaptations of Marine Organisms. Academic Press, New York. Flegal, A. R., and S. A. Saftudo-Wilhelmy. 1993. Comparable levels of trace metal contamination in two semi-enclosed embayments: San Diego Bay and South San Francisco Bay. Environ. Sci. Technol. 27:1934—1936. Gaines, S. D., and M. D. Bertness. 1992. Dispersal of juveniles and variable recruitment in sessile marine species. Nature 360:579-580. Hiatt, R. W. 1948. The biology of the lined shore crab, Pachygrapsus crassipes Randall. Pacific Science 2:135—213. Kennish, M. J. 1992. Ecology of Estuaries: Anthropogenic Effects. CRC Press, Boca Raton. Kennish, M. J. 1998. Pollution Impacts on Marine Biotic Communities. CRC Press, Boca Raton. Levin, L. A., and T. Bridges. 1995. Pattern and diversity in reproduction and development. pp. 1—48 In: McEdwards L (ed.) Marine Invertebrate Larvae. CRC Press, Boca Raton. McCain, B. B., S. L. Chan, M. K. Krahn, D. W. Brown, M. S. Myers, J. T: Landahl, S. Pierce, R. C. Clark Jr, and U. Varanasi. 1992. Chemical contamination and associated fish diseases in San Diego Bay. Environ. Sci. Technol. 26:725-—733. Mileikovsky, S. A. 1971. Types of larval development in marine bottom invertebrates, their distribution and ecological significance: a re-evalution. Mar. Biol. 10:119—213. Morgan, S. G. 1987a. Morphological and behavioral antipredatory adaptations of decapod zoeae. Oecologia 73:393—400. Morgan, S. G. 1987b. Adaptive significance of hatching rhythms and dispersal patterns of estuarine crab larvae: avoidance of physiological stress by larval export? J. Exp. Mar. Biol. Ecol. 113:71—78. O’Connor, T. P. 1990. Coastal environment quality in the United States. 1990. A special National Oceanic and Atmospheric Administration 20” Anniversary Report; U.S. Department of Com- merce: Rockville, MD. Ringwood, A. H. 1992. Effects of chronic cadmium exposures on growth of larvae of an Hawaiian bivalve, Isognomon californicum. Mar. Ecol. Prog. Ser. 83: 63—70. Scheltema, R. A. 1971. Larval dispersal as a means of genetic exchange between geographically separated populations of shallow-water benthic marine gastropods. Biol. Bull. 140:284—322. Schlotterbeck, R. E. 1976. The larval development of the lined shore crab, Pachygrapsus crassipes Randall, 1840 (Decapoda, Brachyura, Grapsidae) reared in the laboratory. Crustaceana 30:184—200. Shanks, A. L. 1995. Mechanisms of cross-shelf dispersal of larval invertebrates and fish. pp. 323-367 In: McEdwards L (ed.) Marine Invertebrate Larvae. CRC Press, Boca Raton. SWRCB and NOAA. 1996. Final Report. Chemistry, toxicity and benthic community conditions in sediments of the San Diego Bay region. State water resources control Board and National Oceanic and Atmospheric Administration. Sate water Resources Control Board. Division of Water Quality. Sacramento, CA. Thorson, G. 1950. Reproductive and larval ecology of marine bottom invertebrates. Biol. Rev. 25:1—45. Weinstein, M. P. 1979. Shallow marsh habitats as primary nurseries for fishes and shellfish, Cape Fear River, North Carolina. Fish. Bull. 77:339—357. Accepted for Publication 13 January 2000 Bull. Southern California Acad. Sci. 99(3), 2000, pp. 171-173 © Southern California Academy of Sciences, 2000 Research Report New Geographical Records of Nine Species of Crustaceans from Southern Baja California, Mexico Ricardo T. Pereyna and Carlos A. Sanchez Universidad Aut6noma de Baja California Sur, Departamento de Biologia Marina, Proyecto Fauna Arrecifal, Apdo. Postal 19-b, La Paz, B.C.S. México C.P. 23080. Phone (112) 8-08-01; RP:rtimon@ hotmail.com CS:csanchez@ calafia.uabcs.mx Surveys on Baja California coasts allow us to report new geographical records of 9 species of crustaceans (1 stomatopod, 5 caridean shrimps and 3 brachyuran crabs). The new records update those of Wicksten & Hendrickx (1992), Hendrickx (1995) and Hendrickx & Landa-Jaime (1997). The following abbreviations are used: total length, TL; carapace width, CW; carapace length, CL. Order Stomatopoda Family Squillidae Squilla tiburonensis Schmitt 1940 Previous distribution.—From Consag Rock to Espiritu Santo and Punta Piaxtla Gulf of California, Mexico (Hendrickx & Salgado-Barragan 1991). New records.—3 males (TL 77—87 mm) and 6 females (TL 60—84 mm), taken on December 21, 1997 during shrimp trawling operations, depth 58.7 m, Asuncion Bay, 27°06'45” N, 114°15'43” W, west coast of Baja California, Mexico. Order Decapoda Family Alpheidae Synalpheus biunguiculatus (Stimpson 1860) Previous distribution.—Guaymas, Gulf of California, Mexico to Colombia; Clarion, Clipperton and Malpelo Islands; Hawaii (Wicksten & Hendrickx 1992). New records.—1 ovigerous female (TL 24.8 mm), March 3, 1998, collected in lobster larvae traps, depth 6 m, Punta Abreojos, 26°45’40" N, 113°30'58” W, west coast of Baja California, Mexico. Family Hippolytidae Hippolyte williamsi Schmitt 1924 Previous distribution.—Puerto Pefiasco, Gulf of California, Mexico to Mejil- lones Bay, Chile; Galapagos Islands (Wicksten & Hendrickx 1992). New records.—4 males (TL 14.7—18.9 mm), 5 females (TL 13.2—18.6 mm) and 12 ovigerous females (TL 15.8—19.4 mm), March 3, 1998, collected in lobster larvae traps, depth 6 m, Punta Abreojos, 26°45’40” N, 113°30'58" W, west coast of Baja California, Mexico. 171 172 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Thor cordelli Wicksten 1996 Previous distribution.—Rocas Alijos and Clarion Island, Mexico; Punta Alta, Colombia (Wicksten 1996). New records.—1 ovigerous female, (TL 14.1 mm), March 3, 1998, collected in lobster larvae traps, depth 6 m, Punta Abreojos, 26°45'40"” N, 113°30’58” W, west coast of Baja California, Mexico. Family Palaemonidae Neopontonides dentiger Holthuis 1952 Previous distribution.—Baluarte River, Sinaloa, Mexico to Cabo San Francisco, Ecuador (Wicksten & Hendrickx 1992). New records.—1 male (TL 24.6 mm) and 2 ovigerous females (TL 27.2—27.7 mm), March 3, 1998, collected in lobster larvae traps, depth 6 m, Punta Abreojos, 26°45'40” N, 113°30'58” W, west coast of Baja California, Mexico. Palaemonetes hiltoni Schmitt, 1921 Previous distribution.—San Pedro, U.S.A; Guaymas and Caimanero Lagoon, Gulf of California, Mexico (Wicksten & Hendrickx 1992). New records.—7 males (TL 22—32.5 mm), 12 females (TL 22—30.7 mm) and 3 ovigerous females (TL 33.7—34.9 mm), March 3, 1998, collected in lobster larvae traps, depth 6 m, Punta Abreojos, 26°45’40” N, 113°30'58” W, west coast of Baja California, Mexico. Remarks.—Wicksten (1989) remarked that this species “‘has not been reported from Southern California since its description in 1921.’’ Palaemonetes hiltoni is rare on the Pacific coast of Baja California, existing predominantly in the Gulf of California: Sonora and Sinaloa, Mexico (Holthuis 1952). Family Epialtidae Acanthonyx petiveri H. Milne Edwards 1834 Previous distribution.—From Santa Maria Bay, west coast of Baja California, La Paz and Mazatlan, Gulf of California, Mexico to Valparaiso, Chile; Revilla- gigedo and Galapagos Islands; Western Atlantic (Hendrickx 1995). New records.—2 males (CW 9.8—10.5 mm, CL 12.8—14 mm) on February 28, 1998, intertidal under rocks at Punta Abreojos, 26°42'30” N, 113°34’'30" W, west coast of Baja California, Mexico. Epialtus minimus Lockington 1877 Previous distribution.—From 28°12'N, west coast of Baja California, and throughout the Gulf of California to Acapulco, Mexico (Hendrickx 1995). New records.—1 male (CW 9.5 mm, CL 10.5 mm) on February 28, 1998, intertidal, under rocks at Punta Abreojos, 26°42'30” N, 113°34'30" W, west coast of Baja California, Mexico. Remarks.—The presence of this species outside the Gulf of California was considered an extralimital record (Garth 1958). Therefore, the record provided herein confirms the presence of Epialtus minimus on the west coast of Baja Cal- ifornia. RESEARCH NOTE 173 Family Parthenopidae Parthenope johngarthi Hendrickx & Landa-Jaime 1997 Previous distribution.—From Tenacatita Bay, Jalisco to Manzanillo, Colima, Mexico (Hendrickx & Landa-Jaime 1997). New records.—1 male (CW 43 mm, CL 34 mm) and 1 female (CW 39 mm, CL 29 mm) taken on May 23, 1999 collected by J. Fiol with baited traps, depth 75 m, at La Ventana, 24°05’59” N, 109°57’'08” W, La Paz, Gulf of California, Mexico. Remarks.—This species has been recently described, the northern-most record of which was from Tenacatita Bay, Jalisco, Mexico. This is the first report in the Gulf of California and constitutes the northern-most record. Acknowledgements We thank M. C. José Salgado Barragan (ICMyL-UNAM), who confirmed the identification of the stomatopod. We also thank Dr. Mary K. Wicksten and Dr. Joel W. Martin for their comments, donors of the Birch Aquarium at Scripps, M. C. Jess Fiol, Ms. Miriam Reza and Alexander Sanchez. The collecting trips were supported by the “‘Reef Fauna”’ and ‘“‘Salitrales de San Ignacio’’ projects, the latter from Exportadora de Sal, S. A. (ESSA). Literature cited Garth, J. S. 1958. Brachyura of the Pacific coast of America, Oxyrhyncha. Allan Hancock Pac. Exp., 21: 1-584. Hendrickx, M. E. 1995. Checklist of brachyuran crabs (Crustacea: Decapoda) from the eastern tropical Pacific. Bull. Inst. r. Sci. nat. Belg., 65: 125-150. & J. Salgado-Barragan. 1991. Los estomato6podos (Crustacea: Hoplocarida) del Pacifico mex- icano. Inst. cienc. del mar y Limn., Univ. nal. aut6n. México, Publ. Esp., 10: 1—200. & V. Landa-Jaime. 1997. A new species of Parthenope Weber (Crustacea: Brachyura: Par- thenopidae) from the Pacific coast of Mexico. Bull. Inst. r. Sci. nat. Belg., 67: 95-100. Holthuis, L. B. 1952. A general revision of the Palaemonidae (Crustacea Decapoda Natantia) of the Americas. II. Occ. Pap. Allan Hancock Found., 12: 1—332 pp. Lockington, W. N. 1877. Remarks on the Crustacea of the Pacific coast, with descriptions of some new species. Proc. Calif. Acad. Sci., 7: 28—36. Milne Edwards, H. 1834. Histoire naturelle des Crustacés, comprenant l’anatomie, la physiologie et la classification de ces animaux. Paris, vol. 1, 468 pp. . 1924. The Macrura and Anomura collected by the Williams Galapagos Expedition, 1923. Zoologica, 5(15): 161-171. . 1940. The stomatopods of the west coast of America based on collections made by the Allan Hancock Expeditions, 1933—38. Allan Hancock Pac. Exp., 5 (4): 129-225. Stimpson, W. 1860. Prodromus descriptionis animalium evertebratorum, quae in Expeditione ad Oceanum Pacificum Septenetrionalem, a Republica Federata missa, D. Ringgold et J. Rodgers, Ducibus, observatit et descripsit. Proc. Acad. Nat. Sci. Philad., 22—48. Wicksten, M. K. 1989. A key to the Palaemonid Shrimp of the Eastern Pacific Region. Bull. south. Calif. Acad. Sci., 88 (1): 11-20. . 1996. A new species of hippolytid shrimp from Rocas Alijos. Pp. 295-298 in Rocas Alijos. (R. W. Schmieder, ed.), Kluwer Academic Publishers, 481 pp. & M. E. Hendrickx. 1992. Checklist of Penaeoid and Caridean Shrimps (Decapoda: Penaeo- idea, Caridea) from the Eastern Tropical Pacific. Proc. Biol. Soc. San Diego, 9:1-9. Accepted for publication 28 September 1999. Bull. Southern California Acad. Sci. 99(3), 2000, pp. 174-176 © Southern California Academy of Sciences, 2000 Potential Impacts of Pogonomyrmex rugosus on Larrea tridentata in southern California Simon A. Lei Department of Biology, Community College of Southern Nevada 6375 West Charleston Boulevard, Las Vegas, Nevada 89146 The seed harvester ant (Pogonomyrmex rugosus) occurs in arid and semiarid plant communities throughout much of the southwestern United States (Carlson and Whitford 1991). Pogonomyrmex rugosus discs (nests) are often surrounded by conspicuous clearings from which the ants have actively removed the vege- tation. Pogonomyrmex rugosus colonies are located preferentially near creosote bush (Larrea tridentata), and P. rugosus may cause mortality of L. tridentata by defoliation in southern Nevada (Rissing 1988). Shrubs may initially provide valu- able shade to establishing ant colonies; yet, later in colony ontogeny, shrubs com- pete with ants for water in southern Nevada (Rissing 1988). From casual obser- vations, size of and proximity to a P. rugosus colony appear to influence viability of L. tridentata in southern California. The xerophytic L. tridentata-Ambrosia dumosa (white bursage) shrubland is a common vegetation type in the Mojave Desert of southern California. In a 5-ha site, viability of L. tridentata appears to be greatly reduced by the presence of numerous ant colonies. The objectives of this study are two-fold: 1) Are the P. rugosus nests in the 5-ha site located closer to the nearest L. tridentata than expected based upon an assumption of random distribution? 2) Are more L. tri- dentata plants found to be dead in proximity to ant nests? The study site, predominated by evergreen L. tridentata shrubs, was near Baker, California (roughly 35’05°N, 115’55°W; elevation 715 m). Other woody species are sparsely distributed in this vegetation zone, including white bursage (A. du- mosa), ratany, (Krameria parvifolia), Mojave yucca (Yucca schidigera), golden- head (Acamptopappus shockleyi), indigo bush (Psorothamnus fremontii), and brit- tle bush (Encelia virginensis). Soils are sandy in texture, and are calcareous with abundant loose rocks on the surface. Soils are derived from limestone-dolomite mountains and hills (Rowlands et al. 1977). The spatial distribution of P. rugosus nests and the nearest L. tridentata shrubs was examined at a 5-ha site. All 206 ant nests in the site were identified. Each ant colony had multiple nest entrances, with a construction of subterranean cham- bers (cavities) and runways. Diameters of the exposed soil surface (disc) at each ant colony were measured in centimeters by computing the average of length and width of the nest. A farthest point was established at a 4-m radius from the center of each ant nest. Condition of the L. tridentata shrub closest to the center of each P. rugosus colony was recorded as either live or dead. Shrubs with green leaves on secondary branches were considered alive. The distance (cm) from the center of the ant colony to the center of the nearest L. tridentata was measured. The numbers of live and dead shrubs within the 4-m radius zones (plots) centered on 174 RESEARCH NOTE 175 SO a T WM Live shrub Dead shrub SO = 20 - = 10 = |g | O Z Zz 7) A O-1 1-2 2-3 3— 4 PERCENT LIVE AND DEAD LARREA DISTANCE OF LARREA FROM ANT NESTS (m) Fig. 1. Condition of L. tridentata (live and dead) in plots of 4-m radius centered on P. rugosus colonies near Baker, California. ant nests were recorded and were converted into percentages. These zones were subdivided into four, 1-m radius increments. Mean distance between the centers of ant colonies and nearest shrub was ob- tained for observations. The ratio of the observed mean distance to the expected mean distance (R-value) served as a measure of departure from randomness (Clark and Evans 1954). The nearest neighbor method (Clark and Evans 1954) was used to determine whether the P. rugosus colonies were randomly distributed in the habitat with respect to L. tridentata. The significant difference in the value of R for these two populations was tested at the 0.05 level by the Student-Fisher t distribution (McClave and Dietrich 1991). Pogonomyrmex rugosus colonies and the nearest L. tridentata shrubs were strongly aggregated, with an R value of 0.23. The mean distance between the centers of ant colonies and nearest shrubs was 179.7 = 10.5 cm. The mean di- ameter of ant colonies (disc) was 81.8 + 8.2 cm (n = 206). The greatest percentage of live L. tridentata shrubs was found between 3 to 4- m radius plots from the center of P. rugosus nests (Fig. 1). Conversely, the per- centage of dead shrubs, with no green leaves on secondary branches, was highest within the 1-m radius plots centered on ant nests. Percentages of live and dead shrub were nearly equal within the 1-m radius plot (Fig. 1). The centers of ant nests were generally clear of L. tridentata plants. Although many shrubs were considered alive, a substantial leaf defoliation by ants was evident, especially L. tridentata establishing within the 2-m radius plots from the center of ant nests. Pogonomyrmex rugosus colonies and the nearest L. tridentata shrubs exhibited strong aggregation. For the spatial distribution in this study, R = 0.23, indicating a significant departure from random expectation in the direction of aggregated spacing by the c test. According to the distance to nearest neighbor as a measure of spatial distribution in populations, R = O in a maximum aggregation, since all of the individuals occupy the same locus and the distance to nearest neighbor is therefore 0. In contrast, R = 2.1491 in a maximum uniformity, since individuals 176 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES will be distributed as evenly and widely as possible in a hexagonal pattern (Clark and Evans 1954). The ratio of observed to expected mean distance to nearest neighbor provides a measure of the degree to which the distributional pattern of the observed population deviates from random expectation (Clark and Evans 1954). Subterranean Pogonomyrmex rugosus are located preferentially near L. triden- tata shrubs in some microhabitats at a Mojave Desert site (Rissing 1988), which is in agreement with this study. Pogonomyrmex rugosus may select nesting sites in consideration of proximity to nearby shrubs. In this study, a higher mortality rate was observed for L. tridentata shrubs near ant nests than those distributed randomly. The interaction is potentially detrimental for shrubs; shrubs nearest ant nests have significantly reduced viability, and defoliation of leaves by ants may cause mortality of shrubs in southern Nevada (Rissing 1988). Rissing (1988) saw P. rugosus defoliating leaves of surrounding L. tridentata. Pogonomyrmex ru- gosus probably are attempting to reduce nest shading by removing leaves through time. Most ant colonies in the genus Pogonomyrmex require high temperatures for brood development (Clark and Comanor 1975). The ‘“‘disc”’ is a visually obvious nest structure, but the limits of the nest itself may extend below the soil surface at a distance beyond the ‘“‘disc’’ (Lei 1999). The subterranean P. rugosus colony also has influences on the soil surface beyond the limits or physical structure of the nest disc (Lei 1999). Although the total area covered by active P. rugosus nests was relatively small, subterranean P. rugosus greatly reduced the viability of L. tridentata beyond the nest discs. Pogonomyrmex rugosus preferentially established nests near L. triden- tata. A substantial L. tridentata mortality within the 2-m radius plots centered on ant nests was observed, primarily due to multiple nest entrances with extremely high social activities. Despite a considerable leaf defoliation by ants, L. tridentata plants had the greatest percentage of green leaves on their branches when estab- lishing away from the nest discs near Baker, California. Acknowledgments I gratefully acknowledge Steven Lei, David Valenzuela, and Shevaun Valen- zuela for providing valuable field assistance. Careful reviews of the manuscript by David Charlet and Leslie Thomas are also gratefully appreciated. Literature Cited Carlson, S. R. and W. G. Whitford. 1991. Ant mound influence on vegetation and soils in a semiarid mountain ecosystem. Amer. Mid. Nat. 126:129-—139. Clark, W. H. and P. L. Comanor. 1975. Removal of annual plants from the desert ecosystem by western harvester ants, Pogonomyrmex occidentalis. Envir. Entomology 4: 52—56. Clark, P. J. and F C. Evans. 1954. Distance to nearest neighbor as a measure of spatial relationships in populations. Ecology 35: 155-162. Lei, S. A. 1999. Ecological impacts of Pogonomyrmex on woody vegetation of a Larrea-Ambrosia shrubland. Great Basin Naturalist 59: 281—284. McClave, J. T. and EF H. Dietrich. 1991. Statistics, Fifth Edition. Dellen Publishing Company, San Francisco, California, 629 pp. Rissing, S. W. 1988. Seed-harvester ant association with shrubs: competition for water in the Mojave Desert? Ecology 69: 809-813. Rowland, P. G., H. Johnson, E. Ritter, and A. Endo. 1977. The Mojave Desert. In: M. Barbour and J. Major, (eds.) Terrestrial Vegetation of California. John Wiley and Sons, New York, 1002 pp. Accepted for publication 28 September 1999 Bull. Southern California Acad. Sci. 99(3), 2000, pp. 177-178 © Southern California Academy of Sciences, 2000 INDEX TO VOLUME 99 Alaniz-Garcia, Jorge, see Ruiz-Campos, Gorgonio Brattstrom, Bayard: The Range, Habitat Requirements, and Abundance of the Orange-throated Whioptail, Cnemidophorus hyperythrus beldingi, 1 Bursey, Charles R., see Stephen R. Goldberg Cheam, Hay, see Stephen R. Goldberg Contreras-Balderas, Salvador, see Ruiz-Campos, Gorgonio Crooks, Jeffrey A., see Deborah M. Dexter Dexter, Deborah M. and Jeffrey A. Crooks: Benthic Communities and the Inva- sion of an Exotic Mussel in Mission Bay, San Diego: A Long-Term History, 128 DiBacco, Claudio, The Influence of Bay versus Coastal Habitats on Development and Survival of Striped Shore Crab Larvae (Pachygrapsus crassipes Randall 1840), 161 Ferreira-Bartrina, V., See E. Mellink Gobalet, Kenneth W.: Has Point Conception been a Marine Zoogeographic Boundary throughout the Holocene? Evidence from the Archaeological Re- cord, 32 Goldberg, Stephen R., Reproduction in the Speckled Rattlesnake, Crotalus mitch- ellii (Serpentes: Viperidae), 101 Goldberg, Stephen R., Reproduction in the Glossy Snake, Arizona elegans (Ser- pentes: Colubridae) from California, 105 Goldberg, Stephen R., Charles R. Bursey and Hay Cheam: Helminths of the Channel Islands Slender Salamander, Batrachoseps pacificus pacificus (Cau- data: Plethodontidae) from California, 55 Gonzalez-Guzman, Salvador, see Ruiz-Campos, Gorgonio Gregorio, Dominic E. and Richard E. Pieper: Investigations of Red Tides Along the Southern California Coast, 147 Hernandez, Luis, see Mary K. Wicksten Lei, Simon A.: Age and Size of Acacia and Cercidium Influencing the Infection Success of Parasitic and Autoparasitic Phoradendron, 45 Lei, Simon A.: Potential Impacts of Pogonomyrmex rugosus on Larrea tridentata in southern California, 174 Longino, John T., see James K. Wetterer Lozano-Vilano, Maria de Lourdes, see Ruiz-Campos, Gorgonio Mellink, E, and V. Ferreira-Bartrina: On the wildlife of wetlands of the Mexican portion of the Rio Colorado delta, 115 Miller, Scott E., see James K. Wetterer 177 178 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Pereyna, Ricardo T. and Carlos A. Sanchez: New Geographical Records of Nine Species of Crustaceans from Southern Baja California, Mexico, 171 Pieper, Richard E., see Dominic E. Gregorio Rosales-Casian, Jorge A.: New occurrences of the endemic labrisomid fish Par- aclinus walkeri Hubbs, 1952 in Bahia de San Quintin, Baja California, Mex- ico, 110 Ruiz-Campos, Gorgonio, Salvador Contreras-Balderas, Maria de Lourdes Lozano- Vilano, Salvador Gonzaélez-Guzmaén and Jorge Alaniz Garcia: Ecological and Distributional Status of the Continental Fishes of Northwestern Baja Cali- fornia, Mexico, 59 Sanchez, Carlos A., see Ricardo T. Pereyna Trager, James C., see James K. Wetterer Wicksten, Mary K. and Luis Hernandez: Range Extension, Taxonomic Notes and Zoogeography of Symbiotic Caridean Shrimp of the Tropical Eastern Pacific (Crustacea: Decapoda: Caridea), 91 Ward, Philip S., see James K. Wetterer Wetterer, Andrea L., see James K. Wetterer Wetterer, James K., Philip S. Ward, Andrea L. Wetterer, John T. Longino, James C. Trager and Scott E. Miller: Ants (Hymenoptera: Formicicae) of Santa Cruz Island, California, 25 - ey “newt

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(ComisgeaDemapeds Caicte ae 21.” o . ae i: = > SS 9 sab PRP SS ee fare KOM: coo ee eT a | Whetecw, Andree 1..; tee. da: - ' ~ A r 7 r y - os 7 id aes wal 7 ’ os : 7 A e 4 a a> e oe »” yy 7 1 k ‘ - r A - - . _ : ‘ * ; r 9 Pg ' - + lees ee ‘ ad ov, - 2 > \ v : Z ~ = oa a _ -» —_ : >. e& * a » i = i ; 4 7. a { pie - f - ' \ uJ . - a, % ‘ 7 4 Lf %. 7% a a j i / ‘ - = Ala - 7 < a 1 na ’ we - ~ INSTRUCTIONS FOR AUTHORS The BULLETIN is published three times each year (April, August, and December) and includes articles in English in any field of science with an emphasis on the southern California area. Manuscripts submitted for publication should contain results of original research, embrace sound principles of scientific investigation, and present data in a clear and concise manner. The current AIBS Style Manual for Biological Journals is recommended as a guide for contributors. Consult also recent issues of the BULLETIN. 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He or she should promptly and carefully read the proof sheets for errors and omissions in text, tables, illustrations, legends, and bibliographical references. He or she marks corrections on the galley (copy editing and proof procedures in Style Manual) and promptly returns both galley and manuscript to the Editor. Manuscripts and original illustra- tions will not be returned unless requested at this time. All changes in galley proof attributable to the author (misspellings, inconsistent abbreviations, deviations from style, etc.) will be charged to the author. Reprint orders are placed with the printer, not the Editor. CONTENTS On the Wildlife of Wetlands of the Mexican Portion of the Rio Colorado Delta.. E.:-Mellink and V. Ferreira-Bartrina ........_ _ eee Benthic Communities and the Invasion of an Exotic Mussel in Mission Bay, San Diego: A Long-Term History. Deborah M. Dexter and Jeffrey A. Crooks: 5 Investigations of Red Tides Along the Southern California Coast. Dominic E. Gregorio and Richard E. Pieper: ......_.... 2 The Influence of Bay versus Coastal Habitats on Development and Survival of Striped Shore Crab Larvae (Pachygrapsus crassipes Randall 1840). Claudio DiBbatco 8 New Geographical Records of Nine Species of Crustaceans from Southern Baja California, Mexico. Ricardo T. Pereyna and Carlos A. Sanchez Potential Impacts of Pogonomyrmex rugosus on Larrea tridentata in southern Cahfornia. Simon A. Lei ee INDEX to Volume 99. its 128 147 161 171 COVER: Long-billed Curlew, a common bird in the Rio Colorado Delta. Photograph by Daniel A. Guthrie