All North Carotina State Library w. a number 7 July 1982 EDITORIAL STAFF John E. Cooper, Editor Alexa C. Williams, Managing Editor John B. Funderburg, Editor-in-Chief Board Alvin L. Braswell, Curator of David S. Lee, Chief Curator Lower Vertebrates, N.C of Birds and Mammals, N.C. State Museum State Museum John C. Clamp, Associate Curator William M. Palmer, Chief Curator (Invertebrates), N.C. of Lower Vertebrates, N.C. State Museum State Museum Martha R. Cooper, Associate Rowland M. Shelley, Chief Curator (Crustaceans), N.C. Curator of Invertebrates, N.C. State Museum State Museum James W. Hardin, Department of Botany, N.C. State University Bnmleyana, the Journal of the North Carolina State Museum of Natural His- tory, will appear at irregular intervals in consecutively numbered issues. Con- tents will emphasize zoology of the southeastern United States, especially North Carolina and adjacent areas. Geographic coverage will be limited to Alabama, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia. Subject matter will focus on taxonomy and systematics, ecology, zoo- geography, evolution, and behavior. Subdiscipline areas will include general in- vertebrate zoology, ichthyology, herpetology, ornithology, mammalogy, and paleontology. Papers will stress the results of original empirical field studies, but synthesizing reviews and papers of significant historical interest to southeastern zoology will be included. Suitability of manuscripts will be determined by the Editorial Board, and ap- propriate specialists will review each paper adjudged suitable. Final ac- ceptability will be decided by the Editor. Address manuscripts and all cor- respondence (except that relating to subscriptions and exchange) to Editor, Bnmleyana, N. C. State Museum of Natural History, P. O. Box 27647, Raleigh, NC 27611. In citations please use the full name — Bnmleyana. North Carolina State Museum of Natural History North Carolina Department of Agriculture James A. Graham, Commissioner CODN BRIMD 7 ISSN 0193-4406 Terrestrial Drift Fences With Pitfall Traps: An Effective Technique for Quantitative Sampling of Animal Populations J. Whitfield Gibbons and Raymond D. Semlitsch Savannah River Ecology Laboratory, Drawer E, Aiken, South Carolina 29801 ABSTRACT. — The terrestrial drift fence with pitfall traps is a com- monly used technique to collect and quantitatively sample populations of certain vertebrate and invertebrate species. However, a variety of limitations, advantages, biases, and contingencies must be considered to use the method most effectively. The best materials to use for these fences and traps have been aluminum flashing and plastic 20-liter buckets. Aluminum flashing is rigid and does not deteriorate with age. Large plastic buckets permit the capture of many species that can escape from small can traps. Maintenance, such as filling cracks or holes along the fence, bailing water from traps, and mowing vegetation alongside fences, are necessary for continued effectiveness. Initial cost of construction is high, both in time and money; however, drift fences are cost effective for most ecological studies. Biases result primarily from variation in morphology, ecology, and behavior of species, or as a consequence of design and the manner in which the drift fence is checked and maintained. INTRODUCTION The terrestrial drift fence and pitfall trap technique has been used for many years for field sampling a variety of vertebrate and inverte- brate species (e.g. Imler 1945; Gloyd 1947; Woodbury 195 1, 1953; Storm and Pimentel 1954; Packer 1960; Husting 1965; Shoop 1968; Hurlbert 1969; Gibbons 1970; Gibbons and Bennett 1974; Briese and Smith 1974; Randolph et al. 1976; Collins and Wilbur 1979; Bennett et al. 1980; Brown 1981; Wygoda 1981). The use of pitfall traps (without drift fences) in the study of invertebrates was reviewed by Mitchell (1963) and Greenslade (1964); however, no thorough assessment of the drift fence technique has been presented (but see Storm and Pimentel 1954). Our purpose is to discuss the advantages as well as the limitations of the approach, using examples from 13 years of data taken on reptiles and amphibians collected on the U. S. Department of Energy's Savan- nah River Plant (SRP) near Aiken, South Carolina. CONSTRUCTION OF DRIFT FENCES Basic design for a terrestrial drift fence is a straight fence extending slightly below ground and up to 50 cm high, with pitfall traps placed Brimleyana No. 7:1-16. July 1981. 1 2 J. Whitfield Gibbons and Raymond D. Semlitsch alongside the fence and buried flush with the ground at prescribed intervals (Fig. 1 A). The intent is to intercept animals traveling overland so that upon encountering the drift fence they turn left or right and continue along the fence until they fall into a trap. Fences and traps used on the SRP have undergone a 13-year evolu- tion of construction materials and design (Fig. 1B,C,D). The earliest drift fences, constructed in 1968 of chicken wire, were intended only for cap- ture of turtles moving overland. Twenty-liter (5-gallon) metal paint buckets served as pitfall traps. From 1969 to 1971, hardware cloth (!4- inch mesh) was used for fencing material. We have subsequently found the most effective material to be 50 cm high aluminum flashing, of which approximately 10 cm is placed below the surface of the ground. This has the advantage of preventing small animals from passing under or through the fence, or larger ones from using the mesh to climb over. The flashing is also considered to be superior to various plastic fencing materials used by other investigators (Storm and Pimentel 1954; Packer 1960; Husting 1965; Shoop 1974; Gill 1978; Wygoda 1979; Douglas 1979; Collins and Wilbur 1979) in that it is not easily torn or pushed down by larger vertebrates such as turtles, alligators, feral pigs, or deer. Furthermore, aluminum flashing does not rust or deteriorate with age as do many other commonly used fence materials. Twenty-liter plastic buckets have proved to be the most effective pitfall traps. These containers are relatively permanent, whereas metal buckets begin to deteriorate within two years, making them less useful for long-term studies. Although smaller volume traps (# 8 cans) have been used effectively for certain species (Shoop 1965; Gill 1978; Douglas 1979), larger traps permit the capture of many species that can easily escape from a shallow can. MAINTENANCE Once drift fences and pitfall traps have been constructed, mainten- ance is required for continued effectiveness. Vegetation growing along- side the fence should be mowed or cut to prevent animals from using it to climb over, as well as to assure visibility in checking traps and fence margins. Mowing chores can be reduced in some situations by placing a heavy layer of sand alongside the fence, extending out 5-10 cm. Cracks or crevasses may develop along the fence or around buckets following construction, particularly after heavy rainfalls. They should be filled to prevent animals from using them as tunnels under the fence. Pitfall traps often fill and overflow with water after heavy rains or from rises in groundwater. Holes drilled in the bottom or sides will prevent water accumulation in some instances, although on certain occasions bailing may be necessary. Terrestrial Drift Fences with Pitfall Traps • C g ^ c ex E § 1/3 r ■> .11 ■o o i! * — ' ex . o 2P *"' 4 J. Whitfield Gibbons and Raymond D. Semlitsch In addition to the hazards of too much water, traps must be checked at frequent intervals to avoid desiccation, predation, and other problems that can arise. In sampling amphibians, desiccation can be avoided at most times of the year by a daily checking schedule. A more frequent checking routine, or use of wet sponges in the bottom of traps, can prevent desiccation or lessen heat stress during summer. Reptiles and mammals are typically more resistant to desiccation and can remain in pitfall traps for longer periods of time than amphibians. The probability of predation on animals in pitfall traps increases the longer they go unchecked, hence checking at several day intervals would not be desirable in most instances. Daily checking is recom- mended under most circumstances, although more frequent checking (i.e., two or three times a day) may be necessary during mass migration of amphibians from breeding ponds, or when prolonged disruption of the animals' activity is detrimental. Use of an electric wire system designed to safeguard each pitfall trap is effective in deterring most mammalian predators except shrews (C. R. Shoop, pers. comm.). TIME, COST, AND EFFORT TO CONDUCT A STUDY Drift fences with pitfall traps yield a wealth of biological informa- tion, often providing ecological perspectives that could be obtained in no other manner. However, the cost in labor and materials can be great. The time investment in an effective drift fence operation can be parti- tioned into construction, maintenance, and operation (Table 1). Initial cost of construction is high, both for materials and in time required for installation. After construction, the cost for materials is small; however, the time investment can become onerous if the traps are checked in an effective manner, such as daily (Table 1). Although the time and effort put into drift fence construction, maintenance, and operation are high, data accumulation is often super- ior to any other form of collecting for a wide variety of terrestrial anim- als, particularly amphibians (Fig. 2; Table 2). The technique is highly cost effective once the critical investment level has been reached. This is especially true for long-term ecological studies where continuous daily hand sampling is impractical. INTERPRETATION OF RESULTS Drift fences with pitfall traps yield large amounts of data on numbers (often total population sizes), seasonality, migration patterns, diversity, and distribution patterns of many animals (see references in Introduction; Table 2). Some species are collected in high numbers that closely represent the actual population size, whereas the proportional capture of others is below that of their actual abundance. However, as Terrestrial Drift Fences with Pitfall Traps 5 Table 1. Categorization of time, labor, and expenses for materials for various stages of drift fence construction, maintenance and operation for two study sites on the Savannah River Plant. Category Sites Rainbow Bay Sun Bay September 1978 February 1979 440 450 88 90 168 119 $660 $682 0 0 0 0 $10 $10 $80 $80 Date constructed Circumference (m of fencing) Number of pitfall traps Construction costs: total labor (man hours) aluminum flashing (@$22/roll) buckets (obtained at no cost) stakes (180/ fence obtained at no cost) plastic cable ties (400/ fence) shovels, axes, sledge hammer Maintenance costs (hr/yr): cut grass around fence 5 5 check and fill cracks and holes, replace sponges, renumber pitfall traps, and other routine maintenance 4 4 Operation (hr/yr): daily checking of pitfall traps and processing animals (not including transportation) 365 365 with any sampling technique, certain biases and limitations must be taken into account in the interpretation of data. Biases are primarily due to variation in morphology, ecology, and behavior of species, or are a consequence of fence design and the manner in which it is checked and maintained. A species' morphology is an obvious factor in determining the effectiveness of the technique in capturing certain animals. The large body size of some snakes and mammals permits ready escape from the pitfall traps, as does an ability to climb or jump over the fence. Climb- ing or burrowing adaptations, such as toepads on treefrogs or the dig- ging limbs of moles, can reduce the proportion of the population that is actually sampled. Behavior can also influence the capture of certain species. For example, although many specimens of the eastern box turtle, Terrapene J. Whitfield Gibbons and Raymond D. Semlitsch ex ~ o ,«J ON ■5"S c ca o — c m ^2 ON S- — ' "O — 5< X 3 & < OQ C 3 CO 4> ca C ca •5b .S "g 2 w ca T3 U 5 3 CL O g «■ U X >> 3 « < O X) 2 S* c < >i 33 > ca ca <~ c/3 ° u c -5 6 § 2 » o ca 6 °° <~ C O 3 C "3 O T3 o ca <-. >» •- ca D OQ Cu 1/3 c»ONTto- ©o — w>oooo© oo — r-> »0 (N °- ^ voo ON — oo on o ONfnfNONONTfO^OO ^ NO Tt — NOCJOtNOOOO «o Tt so m — ON OOOONW-iW-jtNO^t — «n oo — oo on Tf u-> © — < f*% O On O — — ro — o . >^ ^ >^ .be Terrestrial Drift Fences with Pitfall Traps oo © © r-- r- © OnCn?© — ©© — © rn © t-» esi r- — ©©©©© © © on — — tj- iraamooooo ON OO (N ^ Tfr — — « r»-> oo — oo v-> — so r- © © © so © — — © © OnOO — Tf©©©© — oo — — — T* SO OO OO O O t O ©©sO© — On r- o o o — — oooooo — ooooooo oooooo — o 0\(^0 OOOOOOOOO — *0v0rn^fr*^f*^0 Tf — — OOOOOOOO o — «so«/-ir--oo— ■ o fee © M I -s « 05 1 • r w R Si fc C •St O ^£ ^ Q 5 years). For some species they provide the only effective sampling technique, and for many it is highly cost effective. However, variation in morphology, ecology, and behavior of each species must be considered. If the limitations and biases of the drift fence and pitfall trap technique are considered, population sizes, seasonality, migration patterns, diversity, and distribution of many spe- cies of animals can be effectively determined. ACKNOWLEDGMENTS.— We are grateful to the more than 400 individuals who have worked at or visited the Savannah River Ecology Terrestrial Drift Fences with Pitfall Traps 15 Laboratory and helped install, maintain, and check drift fences and pit- fall traps. Special debts of gratitude go to L. B. Wright, D. H. Bennett, D. H. Nelson, J. W. Coker, T. M. Murphy, K. L. Brown, L. A. Briese, S. H. Bennett, J. L. Greene, K. K. Patterson, G. B. Moran, C. A. Shoe- maker, J. P. Caldwell, and many others. Data for comparing the drift fence technique with that of conventional hand-collecting methods was made possible through field notes contributed by R. D. Aldridge, J. R. Harrison III, D. W. Herman, D. W. Tinkle, and L. J. Vitt, as well as our own. We thank S. H. Bennett, K. L. Brown, A. C. Lamb III, and C. R. Shoop for constructive comments on the manuscript. Research was conducted under contract EY-76-C-09-0819 between the U. S. Department of Energy and the University of Georgia, and under NSF Grant NO. DEB 7904758. LITERATURE CITED Bennett, David H., J. W. Gibbons and J. C. Franson. 1970. Terrestrial activity of aquatic turtles. Ecology 5/(4):738-740. Bennett, Stephen H., J. Glanville and J. W. Gibbons. 1980. Terrestrial activity, abundance, and diversity of amphibians in differently managed forest types. Am. Midi. Nat. /0J(2):412-416. Briese, Linda A., and M. H. Smith. 1974. Seasonal abundance and movement of nine species of small mammals. J. Mammal. 55(3):6 15-629. Brown, Kent L. 1981. An analysis of species diversity along a temporal gradient of loblolly pine stands in South Carolina. Unpubl. M.S. Thesis, Texas Christian Univ., Fort Worth. 44 pp. Collins, James P., and H. M. Wilbur. 1979. Breeding habits and habitats of the amphibians of the Edwin S. George Reserve, Michigan, with notes on the local distribution of fishes. Occas. Pap. Mus. Zool. Univ. Mich. 686A-34. Douglas, Michael E. 1979. Migration and sexual selection in Ambystoma jef- fersonianum. Can. J. Zool. 57(1 2):2303-23 10. Gibbons, J. Whitfield. 1970. Terrestrial activity and the population dynamics of aquatic turtles. Am. Midi. Nat. #5(2):404-414. , and D. H. Bennett. 1974. Determination of anuran terrestial activity patterns by a drift fence method. Copeia 1974(1 ):236-243. , and K. K. Patterson. 1978. The reptiles and amphibians of the Savannah River Plant. SRO-NERP-2, Aiken, SC. 24 pp. , J. W. Coker and T. M. Murphy, Jr. 1977. Selected aspects of the life history of the rainbow snake {Farancia erytrogramma). Herpetologica 53(3):276-281. Gill, Douglas E. 1978. The metapopulation ecology of the red-spotted newt, Notophthalmus viridescens (Rafinesque). Ecol. Monogr. 48(2): 145-166. Gloyd, Howard K. 1947. Some rattlesnake dens of South Dakota. Chicago Nat. 9:87-97. Golley, Frank B. 1962. Mammals of Georgia. Univ. Georgia Press, Athens. 218 pp. 1966. South Carolina Mammals. Charleston Museum, Charleston. 181 pp. 16 J. Whitfield Gibbons and Raymond D. Semlitsch Greenslade, P. J. M. 1964. Pitfall trapping as a method for studying populations of Carabidae (Coleoptera). J. Anim. Ecol. 3J(2):301-310. Hurlbert, Stuart H. 1969. The breeding migrations and interhabitat wandering of the vermilion-spotted newt Notophthalmus viridescens (Rafinesque). Ecol. Monogr. 39(4):465-488. Husting, E. L. 1965. Survival and breeding structure in a population of Ambystoma maculatum. Copeia 1965(3):352-362. Imler, Ralph H. 1945. Bullsnakes and their control on a Nebraska wildlife refuge. J. Wildl. Manage. 9(4):265-273. Mitchell, B. 1963. Ecology of two carabid beetles, Bembidion lampros (Herbst) and Trechus quadristriatus (Schrank). II. Studies on populations of adults in the field, with special reference to the technique of pitfall trapping. J. Anim. Ecol. 52(3):377-392. Nelson, David H., and J. W. Gibbons. 1972. Ecology, abundance, and seasonal activity of the scarlet snake, Cemophora coccinea. Copeia 1972(3):582-584. Packer, Wayne C. 1960. Bioclimatic influences on the breeding migration of Taricha rivularis. Ecology 4/(3):509-5 17. Patterson, Karen K. 1978. Life history aspects of paedogenic populations of the mole salamander, Ambystoma talpoideum. Copeia 1978(4):649-655. Randolph, J. Collier, P. A. Randolph and C. A. Barlow. 1976. Variation in energy content of some carabid beetles in eastern Canada. Can. J. Zool. 54(1):10-18. Semlitsch, Raymond D. 1981. Terrestrial activity and summer home range of the mole salamander (Ambystoma talpoideum). Can. J. Zool. 59(2):3 15-322. , and M. A. McMillan. 1980. Breeding migrations, population size structure, and reproduction of the dwarf salamander, Eurycea quadridigi- tata, in South Carolina. Brimleyana 3:97-105. K. L. Brown and J. P. Caldwell. 1981. Habitat utilization, seasonal activity, and population size structure of the southeastern crowned snake Tantilla coronata. Herpetologica 57(l):40-46. Shoop, C. Robert. 1965. Orientation of Ambystoma maculatum: movements to and from breeding ponds. Science 749(3683):558-559. 1968. Migratory orientation of Ambystoma maculatum: movements near breeding ponds and displacements of migrating individuals. Biol. Bull. 735:230-238. 1974. Yearly variation in larval survival of Ambystoma maculatum. Ecology 55(2):440-444. Storm, Robert M., and R. A. Pimentel. 1954. A method for studying amphibian breeding populations. Herpetologica 10(3): 161-166. Woodbury, Angus M. 1951. Symposium: a snake den in Tooele County, Utah. Introduction — a ten year study. Herpetologica 7(1):4-14. 1953. Methods of field study in reptiles. Herpetologica 9(2):87-92. Wygoda, Mark L. 1979. Terrestrial activity of striped mud turtles, Kinosternon baurii (Reptilia, Testudines, Kinosternidae) in west-central Florida. J. Herpetol. /5(4):469-480. 1981. Notes on terrestrial activity of the crayfish Procambarus alleni (Faxon) in west-central Florida. Fla. Sci. 44:56-59. Accepted 22 April 1982 Marine and Freshwater Fishes of the Cape Fear Estuary, North Carolina, and Their Distribution in Relation to Environmental Factors Frank J. Schwartz Institute of Marine Sciences, University of North Carolina, Morehead City, North Carolina 28557 William T. Hogarth Carolina Power and Light Company, New Hill, North Carolina 27562 AND Michael P. Weinstein Department of Biology, Virginia Commonwealth University, Richmond, Virginia 23284 ABSTRACT.— A survey of the saline lower Cape Fear River watershed, conducted from 1973 through 1980, yielded 12,612,022 fishes of 249 species in 85 families. This list is supplemented by an additional three families and seven species reported in the literature. A mixture of Virginian, Carolinian, Caribbean, resident, transient, and estuarine-dependent fishes seasonally occupied the study area, which included parts of the Northeast Cape Fear River, the Cape Fear River downstream of Lock 1, and the adjacent Atlantic Ocean off Baldhead and Oak islands. Collections were made with beach seine, rotenone, gill net, plankton net, otter trawl, and traveling screens of a nuclear steam electric power plant located 2.4 km upstream of Southport, North Carolina. Fish presence and abundance were recorded and related to water temperature, dissolved oxygen, and salinity. Resident or seasonal status of each species was also related to spatial habitat distribution, substrate preference, freshwater and marine intrusion, or geographic province origin. The river serves as a nursery area for many estuarine-dependent fishes. Although industrial and domestic pollution enter the river, primarily at Wilmington, North Carolina, they have not as yet seriously affected its vitality for fish survival. INTRODUCTION Early ichthyological studies by Lawson (1714), Catesby (1771), and Smith (1907) largely ignored the marine fish fauna of the lower Cape Fear River, North Carolina. By contrast, the freshwater fishes of the system have been well documented by Fowler (1945) and Menhinick et al. (1974). Brimley (1935) and Gudger (1948) reported strandings and Brimleyana No. 7:17-37. July 1981. 17 18 Frank J. Schwartz, William T. Hogarth, Michael P. Weinstein occurrences of the whale shark. Rhincodon typhus, and the basking shark, Cetorhinus maximus, respectively, from the river near its mouth. Attempts to survey the estuarine tributaries to the lower river were made by Bayless (1963) and Louder (1963). Lawler (1975) sampled the river to near Campbell Island (Buoy 42) and others have reported spo- radic occurrences of marine or freshwater fishes within the estuary (Lindquist et al. 1977; Lindquist et al. 1978; Martin and Shipp 1971; Tucker and Hodson 1976; Wade 1962). Myers (1925) described the freshwater minnow Notropis cummingsae from the Cape Fear River at Wilmington. Commercially important species, such as the shads, were studied by Davis and Cheek (1967), Nichols and Louder (1970), and Walburg and Nichols (1967), usually in relation to Lock 1 on the main Cape Fear River northwest of Wilmington. Huish and Benedict (1977) tracked the movements of several sonic tagged dusky sharks, Carchar- hinus obscurus, near Buoy 19 in the lower river. Jenkins (1970) cor- rected the systematics and occurrences of suckers reported by Bayless (1963) for the lower river. Copeland and Birkhead (1973) and Birkhead et al. (1977, 1979) focused their studies primarily in the Dutchman Creek area west of Southport, North Carolina. Environmental impact studies associated with the operation of a nuclear steam electric power plant on the Cape Fear River near South- port permitted the first extensive survey of the marine and freshwater fish fauna of the saline portions of the Cape Fear watershed. The sur- vey was conducted between 1973 and 1980. Some results were docu- mented by Schwartz and Dahlberg (1978), Schwartz et al. (1979, 1979), Sulak et al. (1979), and Weinstein et al. (1980, 1980). Additional results are reported here. Fish presence and abundance were related to water temperature, dissolved oxygen, and salinity (see Schwartz et al. 1979, 1979). Additional data on tidal movements, periodicity, and flow strength, which would be experienced by fishes once they are in or near the system, were documented by Carpenter and Yonts (1979), Schwartz and Chestnut (1973), and Welch and Parker (1979). We review and cor- rect information on occurrences of several fishes in the system (Table 1). STUDY AREA The Cape Fear River lies entirely within North Carolina and is the largest Atlantic river drainage system in the state. It is about 528 km long with a drainage basin of about 14,553 km2. The estuarine portion accounts for 880 km2 of the system. Spring runoff varies from lows of 0.5 to highs of 3.1 m/sec (Schwartz and Dahlberg 1978; Schwartz et al. 1979, 1979) and is often influenced by tropical hurricanes, inland storms, rain, and snow melt from inland rivers. All or most of the estu- ary is subject to tidal excursions of ±2 m, as a result of strong tides and Fishes of Cape Fear Estuary 19 southwest winds during nine months of the year. The estuary is 0.3 km wide at Wilmington, widens to 2.1 km at Snows Cut and 2.0 km at its mouth. River discharge, which once passed through Corn Cake Inlet, has been diverted via a dredged channel to enter the sea between Baldhead Island and Caswell Beach, just east of Southport (Carpenter and Yonts 1979). The present dredged river chan- nel varies from 7.6 to 13.6 m deep between the estuary mouth and Wil- mington. North and west of Wilmington, the Northeast Cape Fear and Cape Fear rivers shoal to 3.7 and 3.6 m, respectively. The main ship channel has a mud-clay substrate throughout most of its length, with silting occurring north of Wilmington. Shoals exist on either side of the ship channel. From Wilmington south to Buoy 42 the narrow east and west shoals, on either side of the channel, are composed of sandy-mud. South of Snows Cut eastern shoals are typically sandy while mud domi- nates western shoals. Extensive mud flats are present in the vicinity of the mouth of the river at Caswell Beach. A Pleistocene sandstone and the porous Castle Hayne formation creates a series of rock ledges that pass from southwest to northeast across the river at Buoy 18 and pro- duce a sill on the east side of the river near the buoy. Our study area included all major tidal tributaries and the North- east Cape Fear River from 36 km north of Wilmington to near Buoy 46; the main Cape Fear River from Lock 1 (63 km northwest of Wilming- ton); and the main river south of Wilmington (including the man-made Snows Cut channel), 24 km south of Wilmington on the east side of the river to its junction with the Atlantic Ocean (Fig. 1). The south- western boundary of the study area was Dutchman's Creek, 3.6 km west of the Intracoastal Waterway at Southport. The seaward boundary was the Atlantic Ocean and encompassed an area from the eastern tip of Baldhead (Smith) Island on the east, westward to Long Beach, North Carolina, and for 8 km offshore to depths of 12 m. MATERIALS AND METHODS Schwartz et al. (1979, 1979) employed 91.4 m gill nets to sample pelagic species during January through November 1973-1980. Otter trawls of 7.6 and 12.2 m were used to sample all other fishes at shoal, channel, power plant intake canal, and ocean stations during the same period. Weinstein et al. (1980b) employed rotenone and beach seines at tidal creek stations throughout the saline portion of the Cape Fear. Details of sampling methodology were cited in Weinstein et al. (1979). One excellent and efficient continuous sampling device was the traveling screens located at the head of an intake canal at the power plant, which were cleaned several times daily. Three species were obtained by North Carolina State University (Copeland et al. 1979) and Carolina Power 20 Frank J. Schwartz, William T. Hogarth, Michael P. Weinstein Fig. 1. Fish sampling sites, Cape Fear River and adjacent Atlantic Ocean, 1973- 1980. Fishes of Cape Fear Estuary 21 and Light Company personnel using meter (505/u mesh) plankton sam- pling efforts conducted throughout the study area. Voucher specimens are deposited in the curated collection of the Institute of Marine Sciences, University of North Carolina. Specific fish names follow Robins et al. (1980). Exceptions are: Dawson's (1979) sub- specific designation for the opposum pipefish as Oostethus brachyurus lineatus, and Tyler's (1980) definition of Monocanthus and the family Monocanthidae. Deckert's (1973) and Miller's (1976) revisions of Diap- terus are adopted. Contrary to Fahay and Obenchain (1978), we follow McCosker's (1977) placement of the genus Pisodonophis in Ophichthus. We also recognize Ophidion welshi (Nichols and Breder 1922) rather than Rissola marginata (= Ophidion marginatus, Cohen and Nielsen 1978) as the most abundant cusk-eel inhabiting the river. Rare, common, and abundant fishes are defined as species known from 1, 2 to 10, or more than 10 specimens, respectively. The terms Virginian, Carolinian, and Caribbean refer to geographic provinces along the western Atlantic coast (Briggs 1974). Virginian is that area usually located north of Cape Hatteras; Carolinian is the Continental Shelf area adjacent to the coast between Cape Hatteras and the tip of Florida; and Caribbean is that offshore area seaward of the Carolinian area and located over warm waters of great depths adjacent to the Gulf Stream. Substrate designations are considered sand, mud, clay, muddy- sand or sandy-mud, depending on visual inspection of the amount of mud or sand comprising a Shipek grab at each study station. RESULTS AND DISCUSSION Physical and Chemical Parameters. — Water temperatures and salinities usually ranged from 4-26° C and 0-8 ppt in the river near Buoy 42, 3.7-29° C and 3-30 ppt southward of Wilmington to Snows Cut, 5-31.8° C and 10-34 ppt from Snows Cut to Buoy 19 (5.5 km north of Southport), and 5.6-30.7° C and 20-36 ppt in the river south of Buoy 19 and including the nearby Atlantic Ocean (Schwartz 1979, 1979). Waters in the Intracoastal Waterway west of Southport, which are of lower river origin, mirrored water temperatures and salinities usually noted for the river near Southport. Oxygen content was usually more than 4 ppm. On only one occa- sion was 0 ppm oxygen content noted — for a patch of water that extended from the Intracoastal Waterway side of Caswell Beach, around the island, and along the outer beach southwestward for 2 km. Fishes.— During 1973-1980, 12,612,022 fishes of 249 species and 85 families were collected throughout the lower Cape Fear estuary (Table 2). Additional fishes recorded in the literature supplement our list by three families and seven species. As expected, several of these 22 Frank J. Schwartz, William T. Hogarth, Michael P. Weinstein species were freshwater fishes that had been flushed or moved into the river usually following extensive rain and freshwater incursions. Schwartz (1981) provided a list of such fishes. Anadromous fishes ascending the river to spawn in inland freshwaters were: American shad, Alosa sapidissima; alewife, Alosa pseudoharengus; blueback herring, Alosa aestivalis', and hickory shad, Alosa mediocris. The diadromous Americal eel, Anguilla rostrata, was widely distributed within the estu- ary, whereas the conger eel, Conger oceanicus, was usually collected in its higher saline parts. The bulk of the fishes collected were estuarine- dependent forms (Clark et al. 1974), such as spot, Leiostomus xanthu- rus; Atlantic croaker, Micropogonias undulatus; weakfish, Cynoscion regalis\ flounders, Paralichthys spp.; mullets, Mugil spp., and others that usually spawned offshore but used various areas of the estuary as a nursery ground (Weinstein 1979; Weinstein et al. 1980, 1980). Adults of many species overwintered within the system (Atlantic menhaden, Brevoortia tyrannus; spot; etc.), or passed north and south (cownose ray, Rhinoptera bonasus; cobia, Rachycentron canadum), during spring and fall migrations. The scalloped hammerhead, Sphyrna lewini, and spiny dogfish, Squalus acanthias, also exhibited inshore or offshore seasonal migrations. A few fishes (gobies; blennies; bay anchovy, Anchoa mitchilli; killifishes, Fundulus spp.; and silversides, Menidia spp.) were residents. Several species were sporadic captures that either entered the river in association with sargassum (yellow chub, Kyphosus incisor; Bermuda chub, Kyphosus sectatrix; planehead file- Table 1 . Species incorrectly reported from the Cape Fear River estuary. Species Achirus fascia tus Achirus lineatus Calamus leucosteus Dasyatis violacea Diapterus olisthostomus Etheostoma nigrum Etropus microstomus Eucinostomus lefroyi Fundulus notti Gerres cinereus Gobionellus oceanicus Moxostoma pappillosum Rissola marginata Probable Species Trinectes maculatus Trinectes maculatus Calamus sp. * Dasyatis sabina Diapterus auratus Etheostoma olmstedi Etropus crossotus Eucinostomus argenteus Fundulus lineolatus Diapterus auratus Gobionellus boleosoma Moxostoma anisurum Ophidion welshi Reference Smith 1907 Louder 1963 Smith 1907 Lawler 1975 Birkhead et al. 1977, 1979 Bayless 1963; Louder 1963; Smith 1907 Lawler 1975 Lawler 1975 Bayless 1963; Copeland and Birkhead 1973 Lawler 1975 Louder 1963 Bayless 1963; Smith 1907; Jenkins 1970 Lawler 1975 * Mounted specimen at N. C. State Museum, fell apart 24 September 1975; identification doubtful. Fishes of Cape Fear Estuary 23 fish, Stephanolepis hispidus; and gray triggerfish, Balistes capriscus) or with intrusion of offshore waters (bearded brotula, Brotula barbata; margined snake eel, Ophichthus cruentifer; and offshore tonguefish, Symphurus civitatus). The O. cruentifer was a larva that, like menhaden larvae (Nelson et al. 1977), apparently had been carried inshore by cur- rents from off the edge of the Continental Shelf, where the species has been reported by Fahay and Obenchain (1978). A limited number of species, such as the pink wormfish, Microdesmus longipinnis, were range extensions from nearby southern habitats (Hammond 1973). Most common or abundant fishes occurred over wide expanses of the estuary and within wide ranges of water temperatures, dissolved oxygen, and salinity regimes (Table 2). Schwartz (1981) recorded 77 marine fishes that often remained for up to six weeks in 0 ppt salinity intrusion waters. Weinstein et al. (1980) attributed postlarval population oscillations of three fishes — spot, Atlantic croaker, and flounder — to rapid salinity changes in the Buoy 42 area. As waters warmed during summer, southern warm-water Caroli- nian or Caribbean province species were collected (Spanish mackerel, Scomberomorus eavalla; etc.). Conversely, northern smooth and spiny dogfish, Mustelus canis and Squalus acanthias, of Virginian affiliation were present in the river south of Buoy 18 and especially off Caswell Beach as waters cooled. The only cold-related fish kills occurred during the severe winters of 1976 and 1977 (January-February), when many striped mullet, Mugil cephalus; weakfish; and red drum, Sciaenops ocel- latus, were found dead or dying in the power plant intake canal or on shoals that had iced over. Gobies, blennies, and the clingfish, Gobiesox strumosus, were usu- ally associated with mud-oyster habitats of higher saline areas of the river. The crested cusk-eel, Ophidion welshi, was most commonly col- lected in dense mud substrates in the dug intake canal, especially during 1973-1976, although it was also collected from the mud-clay main chan- nel and occasionally in sandy habitats. The star drum, Stellifer lanceola- tus, was most abundant in late summer in the mud-clay substrate of the main channel, from Buoy 19 southward. The banded drum, Larimus fasciatus, was a high-saline form associated with sandy substrates at ocean stations and in the river south of Buoy 18. The pink wormfish was found only in the intake canal and at the lower river channel Buoy 18 and sandy shoal 18E stations. The white catfish, Ictalurus catus, rarely strayed southward from freshwater mud habitats near Buoy 42. Most of the remaining species were broadly distributed and exhibited no preference for specific substrates. The estuarine part of the Cape Fear River possesses a large variety of Virginian, Carolinian, and Caribbean province fishes that are resident, 24 Frank J. Schwartz, William T. Hogarth, Michael P. Weinstein V5 c 3 c o 4J c cO _!> 1> <*- 1) X) 3 CO CO E C/J + td 3 E C >> X) CD c cO x 3 "O co E X c 03 — ■3 •a c co E CO C/3 c 3 E a CO C/3 _o C/i _a> 2 'E >> 'o a. > 1- .3 "3 c o c/) 1* X X < c/j "cO '5 CO X c o t/3 t/5 CO X E o c 1> 3 O £ > o c/3 _£0 o' 00 ON a. x cO ID CD X 1 Q. c 2 -a CD Ov o 2 o o cO 3 5 c CD cd o o 1h c o o ? a CO 1) ■5 c X c co u X •a U on o a t/) t/2 * 0> x X '■5 V >> 1/5 CO X ■^ •o a> c c CO CO c CD £ a. J3 Q. > a. ^ CO 3 c co 3 c o C/3 E o 1- cO "5 u c a: a: u u u < zc u 2 c/5 i/J^ c« W5 C/f C/5 C/3 (/)* C/5 3 u as CO W3 00 C/3* u «: u CO CO* CO u u sl si j= s: en on en on en 3 cn cn v»/ cn M o o" d o" 6 6 d o 3 d d 3 cn cn 3 O" O H H C/3 H H H f- H Q. en H* H H H H D, cn H* H H* bu H H o. ^ LL tu u. co* ci. U. £ PL, £ cn* o. tu cyn in U. 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Weinstein Oast* aL U<< aJU U« >■>•>- ^^w^^^^ww^^^w U U U >> U >">>>' U >>>>' U U c3 U O; >n q 9; oo * oo - N » * i; oo p <*> w-i O m in 1/1 O0 hi oo sO © 00 as © - - os' ~ ~ ~ OS iri ov __ sO p p p _ __ sO m «n m" /"> p O p «/"> O o p © © ■<*' — ' © r-i © — < cn o o i^- 0-* OOO >^ o ri M rn<^io o>^so r--i^or^or~r-ooooor~- «->oor^ r-' odsdsb osr-' <^ >> UUU UU >>>> > oo vim i^ m © r- T o> rs» o V-N fi Tt en "*' ci c4 Tt >/-> q o o o oo o © /-> CO U > CO U > CO u > CO U > CO U > CO U > CO u > CO U > CO U > 3 > CO U > U U U U u co' U SO sO -* 00 — 0 sO rsi r^ On' Os - od d On' "**| d *~] ■* O0 r-- q m rn sO 00 00 M rs sd R r--' 00 d d ro sd »n d sd O q q O O o q o q q OO in "♦ rn r^ * t' d d — d c-i sO sd 1 o «N — — *N Tf Tt O o >d <5 >> — _ i ■ I f*& f * j? 1 « \n in i! ■ Jin - n nimiii * j i « 2 3 II 1 I 1 | J I £ 1 'B- 2 3* I §.! 1 "5 J | I 3 3^ § Igsl-sl-sM 511 si s o-| ajj 3-^1 1 II a i s § .i 32 Frank J. Schwartz, William T. Hogarth, Michael P. Weinstein uu < & < u uu u u>>uu u >>>>u>>>>> > u> u oo >o r~ oo ^ oo oq oo oo oo so so oo oo> oo © O «rt so ^f O *0 oo «r> © •* © © © r-_ ~ © CO fO f*l f*} fO fO "■• <*"i fO fO fO sd * SO d d o ■<* O VO »n SO O p p so Ov' — d d>o^:^«wrsiso^ S -s = ^ -3 00 T3 3 3 C C O -^ - I sis | ■ I'siao T3 «9 ii O C 1> sllliii I ii 1 3 1 |15 1 1 1 S 8.1 S II -2 1 s # I S. i §• | Is | II S I J '5 I 1 I . I I 1 1 1 It . 11 1 3 I 1 1 I I I . ? 1 I I S 1 1 I 11X4* allllsllf |l||l|'i1llll|l|lil | C/3W?C/5h- Qco C^UOQ Fishes of Cape Fear Estuary 33 u u u on "is U on u u w OC U U a: ae: a: S w 2 S — — 00 H H H" on on 2 s s on s s s on C/5 c« on" S C/5 u u on on o" d - H H H *. W u u eB CO u u U CO u U U U CB* U u CB* u Ca,Ci V,Ca, Ca,Ci CN V-l v» «/-> CM o o © q o OS sb sa > C 35 3 CM > 03 1 "o a: a. c o '3 c T3 C C CQ m u 3 u. a I —> J J < & u Q LU til 6 s 2 C c« on to S ft y 5 s 06 yj H D 00 C/5 « E E on 'i. on on E " on 34 Frank J. Schwartz, William T. Hogarth, Michael P. Weinstein transient and estuarine-dependent (Schwartz et al. 1979, 1979). It thus serves as an important avenue for seasonal migrations of many species along, into, or away from the area, and is vital as a nursery area for the many fishes that depend on estuaries for growth and survivial for part or all of their lives. Although industrial and domestic pollution enter the river, primarily at Wilmington, and may have an indirect effect on fishes such as herrings (Schwartz 1979), they have not as yet seriously affected its vitality for fish survival. ACKNOWLEDGMENTS.— We thank the field and laboratory per- sonnel of the University of North Carolina, Institute of Marine Scien- ces; Carolina Power and Light Company; and Lawler, Matusky, and Skelly for their aid with many aspects of this project. Dr. R. Hodson of North Carolina State University provided several larval specimens. The comments of several anonymous reviewers are appreciated. Funding for the project was provided by Carolina Power and Light Company, Raleigh, North Carolina, for which we are grateful. Brenda Bright typed the manuscript. Jane Law and William Link of the Institute of Marine Sciences provided Figure I. LITERATURE CITED Bayless, Jack D. 1963. Survey and classification of the Northeast Cape Fear River and tributaries, North Carolina. N. C. Wildl. Resour. Comm., Raleigh. 15 pp. + appdx. 30 pp. Birkhead, William A., C. R. Benett, E. C. Pendleton and B. J. Copeland. 1977. Nursery utilization of the Dutchman Creek estuary, N. C. 1971-1976. Carol. Power & Light Co. Rep. 77-2. 1 16 pp. , B. J. Copeland and R. G. Hodson. 1979. Ecological monitoring in the lower Cape Fear River estuary 1971-1979. Carol. Power & Light Co. Rep. 79-1. 292 pp. Briggs, John C. 1974. Marine Zoogeography. McGraw-Hill Book Co., N.Y. 475 pp. Brimley, H. H. 1935. Notes on the occurrence of a whale shark (Rhincodon typus) in the Cape Fear River, near Southport, N. C. J. Elisha Mitchell Sci. Soc. 57:160-162. Carpenter, James H., and W. L. Yonts. 1979. Dye tracer and current meter studies, Cape Fear estuary, N. C. 1976, 1977, and 1978. Carol. Power & Light Co. BSEP Studies, vol. 1. 331 pp. + appdx. 227 pp. Catesby, Mark. 1771. The natural history of Carolina, Florida, and the Bahama Islands. 2 vol. 3rd ed. London. Clark, John, W. G. Smith, A. W. Kendall, Jr. and M. P. Fahay. 1974. Studies of estuarine dependence of Atlantic coastal fishes. Data Rep. 2, Southern Section: New River Inlet, N. C. to Palm Beach, Florida, RV DOLPHIN Fishes of Cape Fear Estuary 35 cruises 1967-68; zooplankton, volume, surface meter net collections, temperatures, and salinities. Tech. Rep. Bur. Sport Fish. Wildl. 59. 97 pp. Cohen, Daniel M., and J. G. Nielsen. 1978. Guide to the identification of genera of the fish order Ophidiiformes with a tentative classification of the order. NOAA Tech. Rep. NMFS Circ. 417. 72 pp. Copeland, Billy J., and W. S. Birkhead. 1973. Baseline ecology of the lower Cape Fear River estuary and ocean off Oak Island, N. C. 1971-72. Contr. 33 Pamlico Mar. Lab. N. C. State Univ. 391 pp. , R. G. Hodson and R. J. Monroe. 1979. Larvae and postlarvae in the Cape Fear River estuary, N. C. during operation of the Brunswick Steam Electric Plant, 1974-78. Rep. 79-3 N. C. State Univ., Raleigh. 226 p. Davis, James R., and R. B. Cheek. 1967. Distribution, food habits, and growth of young Clupeids, Cape Fear River system, North Carolina. Proc. 20th Annu. Conf. Southeast Assoc. Game Fish Comm. 1966:250-258. Dawson, Charles E. 1979. Review of the polytypic Doryrhamphine pipefish Oostethus brachyurus (Bleeker). Bull. Mar. Sci. 29(4):465-480. Deckert, Gary D. 1973. A systematic review of the genera Diapterus and Eugerre: with the description of a new genus, Schizopterus (Pisces: Gerrid- ae). Unpubl. M.S. Thesis, Northern 111. Univ., Dekalb. 74 pp. Fahay, Michael P., and C. L. Obenchain. 1978. Leptocephali of the Ophichthid genera Ahlia, Myrophis, Ophichthus, Pisodonophis , Callechelys, Lethar- chus, and Apterichtys on the Atlantic Continental Shelf of the United States. Bull. Mar. Sci. 25(3):442-486. Fowler, Henry W. 1945. A study of the fishes of the southern Piedmont and Coastal Plain. Monogr. 7 Acad. Nat. Sci. Phila. 408 pp. Gudger, Eugene W. 1948. The basking shark Cetorhinus maximus on the North Carolina coast. J. Elisha Mitchell Sci. Soc. 64(\):4\-44. Hammond, Donald D. 1973. A record of Microdesmus longipinnis (Weymouth) (Pisces: Microdesmidae) from South Carolina waters. J. Elisha Mitchell Sci. Soc.59(l-2):72-73. Huish, Melvin T., and C. Benedict. 1977. Sonic tracking of dusky sharks in the Cape Fear River, North Carolina. J. Elisha Mitchell Sci. Soc. 93(l):21-26. Jenkins, Robert E. 1970. Systematic studies of the Catostomid fish tribe Mox- ostomatini. Unpubl. Ph.D. dissert., Cornell Univ., Ithaca. 799 pp. Lawler, John. 1975. Environmental impact assessment of alterations for the maintenance of Wilmington harbor, North Carolina, pp. A1-A242, Aquatic Ecology Studies Cape Fear River Estuary, North Carolina, September 1972 to August 1973, appdx. A. Lawler, Matusky, Skelly Engineers, Tappan, NY. Lawson, John. 1714. The history of Carolina; containing the exact description and natural history of that country: etc. London. 258 pp. Reprinted 1903 by Observer Printing House, Charlotte, NC. 172 pp. Lindquist, David G., J. R. Shute and P. W. Shute. 1977. Record of bluefin killifish Lucania goodei in North Carolina. J. Elisha Mitchell Sci. Soc. 95(1): 19-20. , and Recent record of the banded killifish, Fundulus diaphanus (Lesueur) in southeastern North Carolina. J. Elisha Mitchell Sci. Soc. 94(2): 113. 36 Frank J. Schwartz, William T. Hogarth, Michael P. Weinstein Louder, Darrell E. 1963. Survey and classification of the Cape Fear River and tributaries of North Carolina. N. C. Wildl. Resour. Comm., Raleigh. 20 pp. + appdx. 95 pp. Martin, James R., and R. L. Shipp. 1971. Occurrence of juvenile snook, Centro- pomus undecimalis, in North Carolina waters. Trans. Am. Fish. Soc. 700(1): 131-132. McCosker, John E. 1977. The osteology, classification, and relationships of the eel family Ophichthidae. Proc. Calif. Acad. Sci. Ser. 4, 41(1): 1-123. Menhinick, Edward F., T. M. Burton and J. R. Bailey. 1974. An annotated checklist of the freshwater fishes of North Carolina. J. Elisha Mitchell Sci. Soc. 90(1):24-5O. Miller, Robert R. 1976. Geographical distribution of Central American fresh- water fishes, pp. 125-156 in T. B. Thorson (ed.). Investigation of the Ich- thyofauna of Nicaraguan lakes. Univ. Nebraska, Lincoln. 663 p. Myers, George S. 1925. Notropis cummingsi, a new minnow from Wilmington, North Carolina. Am. Mus. Novit. 168. 4 pp. Nelson, William R., M. C. Ingham and W. E. Schaaf. 1977. Larval transport and year-class strength of Atlantic menhaden, Brevoortia tyrannus. Fish. Bull. 75(1):23-41. Nichols, John T., and C. M. Breder. 1922. Otophidium welshi, a new cusk eel, with notes on two others from the Gulf of Mexico. Proc. Biol. Soc. Wash. 55:13-15. Nichols, Paul R., and D. E. Louder. 1970. Upstream passage of anadromous fish through navigation locks and use of the stream for spawning and nursery habitat Cape Fear River, N. C, 1962-66. U. S. Fish Wildl. Serv. Circ. 352. 12 pp. Robins, Charles R., R. M. Bailey, E. E. Bond, J.R. Brooker, E. A. Lachner, R. N. Lea and W. B. Scott. 1980. A list of common and scientific names of fishes from the United States and Canada. Am. Fish. Soc. Spec. Publ. 12. 4th ed. 174 pp. Schwartz, Frank J. 1979. Caudal peduncle droop in blueback herring, Alosa aestivalis, from Cape Fear River, North Carolina. ASB Bull. 26(2):34. Abstract. 1981. Effects of freshwater runoff on fishes occupying the freshwater and estuarine coastal watersheds of North Carolina, pp. 282-294 in R. Cross and D. Williams (ed.). National Symposium on Freshwater Inflow to Estuaries. U. S. Fish Wildl. Serv. Off. Biol. Serv. FWS/OBS-81/04. , and A. F. Chestnut. 1973. Hydrographic atlas of North Carolina estuaries and sound water, 1972. Univ. N. Carol. Sea Grant Publ. SE 73-12. 132 pp. , and M. P. Dahlberg. 1978. Biology and ecology of the Atlantic sting- ray, Dasyatis sabina (Pisces: Dasyatidae) in North Carolina and Georgia. Northeast Gulf Sci. 2(1): 1-23. , P. Perschbacher, M. McAdams, L. Davidson, K. Sandoy, C. Simpson, J. Duncan and D. Mason. 1979. An ecological study of fishes and invertebrate macrofauna utilizing the Cape Fear River estuary, Carolina Fishes of Cape Fear Estuary 37 Beach Inlet, and adjacent Atlantic Ocean. Summary Rep. 1973-1977. Inst. Mar. Sci. Univ. N. Carol., Morehead City. 568 p. and J. Tate. 1979. An ecological study of fishes... Annual Report for 1978. Inst. Mar. Sci. Univ. N. Carol., Morehead City. 326 pp. Smith, Hugh M. 1907. The Fishes of North Carolina. N. C. Geol. Econ. Surv., Raleigh. 453 pp. Sulak, Kenneth J., P. W. Perschbacher and F. J. Schwartz. 1979. Invasion of the Atlantic by Peprilus burti (Pisces: Stromateidae) and possible implica- tions. Copeia 1979(3):538-541. Tucker, John W., Jr., and R. G. Hodson. 1976. Early and mid-metamorphic larvae of the tarpon, Megalops atlanticus, from the Cape Fear River estu- ary, North Carolina 1973-74. Chesapeake Sci. 77(2): 123-125. Tyler, James C. 1980. Osteology, phylogeny, and higher classification of the fishes of the order Plectognathi (Tetraodontiformes). NOAA Tech. Rep. NMFS Circ. 434. 422 pp. Wade, Richard A. 1962. The biology of the tarpon, Megalops atlanticus, and the ox-eye, Megalops cyprinoides, with emphasis on larval development. Bull. Mar. Sci. Gulf Caribb. 72(4):545-622. Walburg, Charles H., and P. R. Nichols. 1967. Biology and management of the American shad and status of the fishes, Atlantic coast of the United States 1960. U. S. Fish Wildl. Serv. Spec. Sci. Rep. Fish. 550:35-38. Weinstein, Michael P. 1979. Shallow marsh habitats as primary nurseries for fishes and shellfish, Cape Fear River, N. C. Fish. Bull. 77(2):339-358. , S. L. Weiss and M. F. Walters. 1980. Multiple determinants of community structure in shallow marsh habitats, Cape Fear River estuary, North Carolina, USA. Mar. Biol. (Bed.) 55:227-243. , , R. G. Hodson and L. R. Gerry. 1980. Retention of three taxa of postlarval fishes in an intensively flushed tidal estuary, Cape Fear North Carolina. Fish. Bull. 78(2)'A 19-436. Welch, Joseph M., and B. B. Parker. 1979. Circulation and hydrodynamics of the lower Cape Fear River, North Carolina. NOAA Tech. Rep. NO580. 108 pp. Accepted 17 December 1981 Nesting of the Green Turtle, Chelonia mydas (L.), in Florida: Historic Review and Present Trends C. Kenneth Dodd, Jr. Office of Endangered Species U.S. Fish and Wildlife Service, Washington, D.C. 20240 ABSTRACT.— Except for accounts in the 1800s, which focused on the Keys and Cape Sable region, there are no reliable literature records for nesting of the green turtle, Chelonia mydas, in Florida. Two nests were reported prior to 1959, but the number recorded has steadily increased and at least 366 nests were confirmed in 1980. The majority were found from Merritt Island south to Key Biscayne, and most were laid on relatively undisturbed beaches. Five reasons can be advanced for this apparent increase in nest reports: better surveillance of nesting beaches; greater awareness of sea turtles and their problems; protective legislation; the success of a head-start program on Hutchinson Island; and the possibility that some turtles are immigrating from populations farther south. Although speculative, it is possible that the nesting pop- ulation of green turtles in Florida is increasing and results from a combination of the latter three reasons. A review of the level of histor- ical green turtle nesting, as well as a year-by-year record of nesting since 1959, are provided. INTRODUCTION The green turtle, Chelonia mydas (L.), may be the most familiar of sea turtles to mankind. It has been used as a source of food (meat, eggs, calipee) by indigenous peoples throughout the world (see Nietschmann 1972, 1976 for an example of how important the green turtle is to the Miskito Indians of coastal Nicaragua). The turtle also was the basis for gourmet turtle soup in markets formerly in the United States, and such markets still exist in Europe. While subsistence taking for local use probably has not seriously affected wild stocks, with the possible excep- tion of egg taking in certain areas (see Harrisson 1976), the commercial market has seriously depleted the turtles in many regions (Bacon 1975; Nietschmann 1972). In some parts of the world, green turtles are taken incidentally by trawlers (see Chin 1976). Habitat alteration, particularly of nesting beaches and feeding grounds, and predation by both natural and feral predators, have also combined to seriously deplete popula- tions. Pollution of the oceans, especially by petrochemical products, has a known but as yet unquantified effect on this species (Kleerekoper and Bennett 1976; Witham 1978). The green turtle is perhaps historically the most exploited of all marine turtles (Parsons 1962; King, in press), although the hawksbill, Eretmochelys imbricata (L.), may have that dubious distinction today. Chelonia mydas is considered either threa- Brimleyana No. 7:39-54. July 1 98 1 . 39 40 C. Kenneth Dodd, Jr. tened or endangered by most sea turtle biologists, depending on the breeding population involved (World Conference on Sea Turtle Conser- vation 1979). In the Caribbean, the green turtle has a long history of exploitation (see Parsons 1962 for extensive review), chiefly as a source of meat dur- ing colonial exploration, then for sale primarily to European markets. As a result, the remnant nesting populations, centered at Tortuguero, Costa Rica (Carr et al. 1978) and Aves Island, are believed to be but a fraction of a once huge population. Scattered nesting still occurs on many Caribbean and Gulf of Mexico beaches, but everywhere there is pressure on these populations. Indeed, although protected for many years, concern has been expressed about the survival and viability of the Tortuguero colony (Bjorndal 1980), and Aves Island is threatened by erosion. Because of the nesting site fixity of green turtles, it is likely that each nesting area constitutes a unique gene pool (Smith et al. 1978; William R. Rainey, pers. comm.), thus accentuating the importance of the conservation of each nesting population. In accordance with Section 7 of the U.S. Endangered Species Act of 1973, as amended, the U.S. Fish and Wildlife Service is responsible for the determination of Critical Habitat for listed Endangered and Threatened species. While I will not discuss the concept in detail, such a determination is a conservation tool that requires Federal agencies to insure that activities they authorize, fund, or carry out are not likely to jeopardize the particular habitat on which the species depends (see Dodd 1978 for a complete discussion of the concept as it applies to marine turtles). Since the Florida population of Chelonia mydas is listed as Endangered on the U.S. List of Endangered and Threatened Wildlife and Plants, the determination of its Critical Habitat might provide an additional important conservation measure. This paper, done in prepa- ration of background material for a proposal of Critical Habitat for the species, reports on the level of green turtle nesting in Florida. It is not an endorsement by the U.S. Fish and Wildlife Service of a proposal under the legal requirements of the Act. HISTORICAL BACKGROUND Prior to Carr and Ingle's (1959) first report of definite nesting by two turtles, there appears little in the literature to indicate that green turtles ever nested in significant numbers on Florida beaches. Indeed, there is some question whether any green turtles nested on the mainland at all, since references to them are largely confined to fisheries statistics or secondhand accounts. While Carr and Ingle (1959) provided a brief literature review, it would be well to reexamine these references. The first reference to green turtles in southeastern U.S. waters was Green Turtle Nesting in Florida 41 that of Catesby (1731-43). He implied that green turtles nested on the Florida coast when he stated that green turtles do not breed in the Bahamas but come from Cuba and the "Continent. " Bahamian turtlers were said to obtain their turtles in two ways and from two sources: by using a detachable spike mounted on a harpoon to spear turtles in local Bahamian waters, and by traveling to Cuba to turn female turtles as they nested. Catesby stated that Bahamians carried their turtles to the Carolinas (which at that time included all territory between Virginia and Florida) since they were esteemed as a "rarity." Catesby also reported that loggerhead sea turtles, Caretta caretta (L.), were not known from the Continent north of Cape Florida, where they are known to nest in abundance today. As the Florida coast was wild and little known during Catesby's time, it is not surprising that precise information regarding species and nesting areas could be confused, especially by one obtaining much information from secondhand sources. However, it is unlikely that Bahamian turtlers would have hazarded a long and arduous voyage to the remote coasts of Cuba had a large exploitable population of nest- ing green turtles been available so close to home. It seems more likely that if green turtles nested along the Florida coast, they nested in such relatively small numbers that turtling expeditions would have been unprofitable. Why loggerheads would go unnoticed north of Cape Flor- ida remains unknown, although it is possible that many of these beaches were never visited by Bahamian turtlers. The most reliable early accounts of green turtle nesting are the observations of John James Audubon. His account of "The Turtlers" (1926) clearly stated that the green turtle nested not only in the Tortu- gas, but "resorts either to the shores of the main, between Cape Sable and Cape Florida, or enters Indian, Halifax, and other large rivers or inlets, from which it makes its retreat as speedily as possible, and betakes itself to the open sea." The green turtle was said to approach the shores, enter bays, inlets, and rivers early in April, and deposit three clutches of eggs in May and June. Audubon further described a general- ized nesting sequence, a process he reportedly saw several times, which, while primarily based on loggerheads, may have been based in part on observations of the green turtle. Of particular interest was the notation that green turtles selected the wildest and most secluded nesting locations as opposed to loggerheads; similar observations have been noted by L. Ehrhart (1979, pers. comm.) on Merritt Island. Green turtles, as noted above, do enter lagoonal or river systems, but it is unclear from Audubon's account whether nesting took place on these shores. J. Fletemeyer (1980, pers. comm.) noted, however, that loggerheads rarely nest in such locations and the use of lagoonal areas 42 C. Kenneth Dodd, Jr. in eastern Florida as green turtle developmental habitat is also well known (Mendonc^ and Ehrhart 1982). Finally, both Ehrhart and R. Witham (pers. comm.) believe that most Florida green turtles nest two or three times per season. Each of these observations supplies credence to Audubon's notes, although it must be pointed out that he often gen- eralized and his species identifications may have been confused. His delimitation of the area of nesting, Cape Sable to Cape Florida (near Miami), may have been more a reflection of the extent of his travels than a known lack of nesting farther north (see Proby 1974 for a review of Audubon's travels in the Key West area). However, green turtles are not definitely recorded today from beaches of either the Tortugas or Cape Sable, although individuals are not uncommonly observed in off- shore waters. Holbrook's (1842) implication that green turtles nested on Florida beaches as well as the Tortugas may in fact have been based in part on Audubon's observations. True (1884) reported green turtles nesting in Florida, the Bahamas, and the West Indies, and stated that they may occur from Long Island Sound (uncommonly) south through the Gulf States. He said that the turtles were smaller in the north, indicating "young or dwarfed" indi- viduals, and repeated Holbrook's (1842) nesting description verbatim. Nesting was said to occur from April to July. It is clear in True's account, however, that much of his information came from secondhand sources, and he probably had no direct knowledge of green turtle nest- ing in Florida. The originality of this source is thus open to question. As Carr and Ingle (1959) noted, William T. Sherman (1889) recorded the importance of green turtles to the economy of eastern Flor- ida, where he was stationed in 1840. Sherman stated: "They were so cheap and common that the soldiers regarded it as an imposition when compelled to eat green turtle steaks instead of poor Florida beef or the usual mess-pork. I do not recall in my whole experience a spot on earth where fish, oysters, and green turtles so abound as at Fort Pierce, Flor- ida." He did not record, however, how the turtles were obtained or their sizes, which would have given an indication of whether nesting might have occurred in the area. Between 1840 and the mid- 1890s green turtles had clearly suffered a significant decline in the Indian River area of eastern Florida. Turtle fisheries were operated at Sebastian, Ft. Pierce, and Eden, although tur- tles were incidentally taken elsewhere. After reviewing available catch statistics, Wilcox (1896) stated: "There is no doubt that turtle fishing on the Indian River is much less productive than formerly. Mr. Charles Pearke, of Sebastian, who has followed the turtle business during the past ten years, reports a great decrease of turtles as compared with ear- Green Turtle Nesting in Florida 43 lier years. About 1886 he took 2,500 turtles with eight nets; in 1895 he secured only 60 turtles with six nets. The principal reason assigned for the decrease by Mr. Pearke is that the turtles have been frightened off by the steamboats and launches. The unusual cold of the winter of 1894- 95 is also known to have seriously affected the abundance of turtles. Several hundred turtles were then found floating on the surface in a numbed or frozen condition. On being warmed most of them survived and were soon on their way to the northern markets. Since the cold spell turtles have been much scarcer than ever." This quote has often been incorrectly attributed to Evermann and Bean (1896). Wilcox also noted that the fishery was a net fishery operating between November and March, and that although occasional turtles weighed 220 pounds, the average weight was 50 pounds in 1891 and 36 pounds in 1895. This would indicate that a juvenile rather than a nesting population was being exploited. Brice (1896) also noted a decline in green turtle abundance, this time in the Keys region, and said it was probably due to overfishing. He stated: "The fishermen comment upon the fact that for the past few years the green turtles have not been depositing their eggs on Key West and the adjacent keys. It is very probable that this is owing to the exces- sive hunting of this species, and that they now deposit their eggs on the more distant and inaccessible keys." It is clear that Brice was talking about a breeding population, since nesting was mentioned and the tur- tles ranged in size from 125 to 275 pounds, unlike those of the fisheries on Cedar Key and the Indian River. The turtle grounds were principally from Marquesas Key to Alligator Light on the east coast, the Bay of Florida, and the Gulf of Mexico, intervening between the western keys and the mainland. This is roughly the same area with which Audubon (1926) was most familiar. By the time of later turtle statistics (Ingle and Smith 1949; Rebel 1974), Key West and other Florida ports served as outlets for a turtle fishery throughout the Caribbean instead of one solely regionally based; the local green turtle breeding population had been decimated. Until the report of Carr and Ingle (1959), green turtles had not been reported as nesting in Florida since 1896. NESTING TRENDS SINCE 1959 The numbers of green turtle nests that can be documented since 1959 are provided by site in Table 1. The sources of data for this table are: Carr and Ingle (1959); Routa (1967); Gallagher et al. (1972); Ehrhart (1975, 1979); Worth and Smith (1976); Mann (1977); Ehrhart and Yoder (1978); Fletemeyer (1979, 1980); Stoneburner et al. (1979); Florida Department of Natural Resources (1979, 1980); Schwartz et al. 44 C. Kenneth Dodd, Jr. NC. \ j^i sc. GA. • P2 ATLANTIC OCEAN N t \? 160 km 1 Va FL. B5 r6 ■ 7 08 Cape Florida Cape Sable 10 ?© £e7s / 9 Fig. 1. Location of green turtle nesting sites in the southeastern United States. 1. Camp Lejeune 2. Jekyll Island 3. Merritt Island 4. Sebastian Inlet 5. Hutchinson Island 6. Hobe Sound National Wildlife Refuge 7. Highland Beach 8. Hillsboro Beach 9. John U. Lloyd State Park 10. Loggerhead Key. (1981); Litwin (1981); and personal communications from C. and M. Barsumian, G. Dalrymple, L. M. Ehrhart, J. Fletemeyer, T. W. Fritts, T. W. Martin, M. Murphy, J. Richardson, D. L. Stoneburner, and R. Witham. The locations of the major nesting areas, originally selected as possible areas of Critical Habitat, as well as two outlier nestings, are shown in Figure 1. Caution should be exercised when using the figures in Table 1. They indicate a number only, and not necessarily a year-to-year trend, with the exception perhaps of Hutchinson Island, Merritt Island, and Hobe Sound. This is because not every beach received the same inten- sity of survey from one year to the next, and because the same precise area may not have been covered. For instance, Sebastian Inlet North received intensive aerial and ground survey in 1980. However, surveys were not performed in 1981. A single night survey yielding four nests does not necessarily indicate a precipitous decline of nesting on this beach in 1981. Considering these limitations, it is evident that the Green Turtle Nesting in Florida 45 — I r^ t* o ■» r- so f¥3 — — ao — *_ oo so co sOI m c /""•v (U fN r- irT sd ir> © o TD "* so "3 cu »r> Z c 03 > cu o > c C/3 T3 03 CU 03 CU 3 3 C/3 c C CO DQ z C/3 c o en 3 O C/3 "3 O ' <_, 2 c C o 'Js o3 x CO H cu 0« X CU C/3 9J X) o x 00 SB X £ •a rr « «- ^ w w 5 J2 •* x 2 ^ « 03 OQ 2 CU 3 i C/3 3 ro o i i so X 3 O C/3 CU 3 timate, h Boca h, 1 on ./-> O © vO 1 ^ C/3 *J CJ 4> 3 o3 OO SO - O cU 1 <"**> d U based ests on mpano 1 °o T3 i— 03 > CU CQ *$& 1 r~- .2 C/3 _3 ?z* 1 — £ "g « 1 = O > s O i_ C/3 urner, pers. co Pompano Bea etal. 1981); g. 1- C/3 CU c Cm X C N o ^> o t: 1 — 1— CU Ston nests chwa so X B 3 C J .3 ^ aJ On rt 1 ^° C CU •a C/3 CU > L. Ehrhart orm tides; i a (Litwin 1 "5b CU km( ghst rolin 1 ^ 3 (N SP 1 *n •n "-S u — >, «/~> X) x i^H 1 <"^ e -g s rsi X ^— s 1 s &z B a^ CU U. C B 1 w*> U- C/3 O 1 rf o> figure is an esti outa 1967); d. 7 1977); f. 1 inGe CU CU s CU "cU E — j X c T3 C£ 3 O 03 CU CQ CU .5 C/3 03 CU 1— econ unt ( Man 00 X 1) CU C o CU CU i— ^ 13 2 03 CU 03 c« 1/3 CU C CU X o 03 cu o c/3 S cu C/3 43.4 actu on B "3 3 03 -J CU DQ £ CU X 6 O H 03 -I! £ 46 C. Kenneth Dodd, Jr. number of green turtle nests reported in Florida is increasing, and that a rudimentary cyclical pattern may be emerging. Of particular interest is the grouping of nestings from Merritt Island south to Key Biscayne. Early accounts, principally those of Audubon (1926) and Brice (1896), do not record nesting from these beaches, and there are no reliable modern reports of nesting in the Keys and the Cape Sable area. Since green turtle nesting is now confined to the southeast Atlantic coast, this area should receive major concern for sea turtle protection and education projects. The outlier nestings recorded in Georgia and North Carolina in 1980 are noteworthy in that they constitute the first reliable reports of nestings outside Florida. While green turtles have long been known to occasionally occur in coastal waters as far north as New England, only loggerheads nest occasionally as far north as New Jersey. In the North Carolina report (Schwartz et al. 1981), one turtle is known to have made all the nests; in the Georgia instance, only one nest was reported (Litwin 1981) and it is unknown if this female nested elsewhere in the vicinity. Since there are no beach patrols from Merritt Island north to the Georgia barrier islands, perhaps she deposited additional nests in this area. In 1979, personnel of the National Park Service (NPS) visited Log- gerhead Key in the Tortugas (Fig. 1). During their stay, one nest of what was believed to be a green turtle was located high up in the beach grass (R. Dawson, pers. comm.). Since the green turtle digs a character- istic body pit quite distinctive from that of the loggerhead, experienced personnel can distinguish the two types of nests. However, no way of verifying this record now exists, so nesting in the Tortugas should at best be considered only a possibility. No green turtle nests could be determined elsewhere during NPS surveys, although many juvenile green turtles were seen in waters off the Tortugas. HUMAN IMPACT ON FLORIDA NESTING BEACHES To illustrate potential problems facing green turtle nesting in Flor- ida, human use of selected important beaches is reviewed below. Merritt Island Ownership: U.S. Government Use: Recreational (day only); restricted access to military and National Aeronautics and Space Administration lands; no commercial activities or development. This area is entirely under the jurisdiction of various Federal agen- cies. The island is largely under the administrative auspices of Merritt Island National Wildlife Refuge, which is administratively superim- posed on the lands of Kennedy Space Center. Public access to the Cen- Green Turtle Nesting in Florida 47 ter is restricted at all times. The other beaches at Merritt Island are under the jurisdiction of the National Park Service (Canaveral National Seashore). Access to the most popular beach, Playalinda, and all south- ern beaches within the seashore, is restricted to daylight hours. The farthest south section of beach is under the jurisdiction of Cape Canav- eral Air Force Station, and public access is restricted. Hutchinson Island Ownership: Private, 15 km; St. Lucie and Martin counties, < 1.6 km Use: Recreation. Hutchinson Island is a 36 km barrier island in an area that is expe- riencing rapid development, primarily in the south. It has a dune system which rises to 5 m in some areas. Beaches are rather narrow and sup- ported by sand streaming toward the south. The island is experiencing erosion, which is most severe in the north and gradually tapers off to the south. As of 1979, 37.8 percent (13.6 km) of beachfront had been developed; development is interspersed with undeveloped land in private ownership and county recreation beaches. Sea turtle nesting is lowest in the north in areas of worst erosion and, in the south, most nesting occurs on undeveloped beaches (Gallagher et al., in press). Hobe Sound Ownership: U.S. Government, 5.15 km; City (Jupiter Island), 0.16 km; Private, 0.32 km Use: Recreation, wildlife protection; limited access, day only. Nearly all beaches in this area are located on Hobe Sound National Wildlife Refuge, where public use after dark is not allowed without spe- cial permission. The principal threats to green turtle nests are raccoon predation and beach erosion, primarily at the northern end of the refuge. John U. Lloyd State Park Ownership: State, 4.0 km Use: Recreation, day only. Much of the beach here has been renourished by the Corps of Engineers; the sand is derived from 80' - 90' of water from offshore areas. The last such effort occurred about five or six years ago, and extended 1.93 km south of the inlet. John Fletemeyer, Nova University, believes that about 10 years are required for a renourished beach to return to normal characteristics of compaction. Under normal regimes, renourishment is accomplished every 10 years or so. Silt is the big com- pacting problem, not only forming a physical barrier but probably also inhibiting gas exchange and affecting incubation temperatures. As part 48 C. Kenneth Dodd, Jr. of the renourishment project, the Corps of Engineers has been required by the Florida Department of Natural Resources to relocate nests. For this they have contracted with Fletemeyer to patrol the beach every morning. Since this beach has no night use, nest relocation probably involves no serious detriment to the turtles. Highland Beach Ownership: Private, 4.5 km Use: Recreation, restricted access. The only potential for public access to this beach is at a motel on the northern section. Like the other areas in private ownership, the resi- dents here are protective of the turtles and have taken measures to insure their continued survival. The measures include funding and par- ticipating in sea turtle beach patrols. Perhaps the main feature that accounts for green turtle nesting on the beaches indicated in Table 1 is restricted night use. Merritt Island, Hobe Sound, John U. Lloyd State Park, and Key Biscayne allow no night activities; Highland Beach and Hillsboro Beach have restricted public access and owners who are aware of the turtles and the impor- tance of protecting them from disturbance; Sebastian Inlet North, Juno Beach, N. Melbourne Beach, and Ft. Pierce-Sebastian are all presently little disturbed at night. Only at Hutchinson Island is development rather extensive, and here turtles often select what undeveloped beaches remain between high-rise buildings. Many buildings on Hutchinson Island lack bright outdoor lighting facing the ocean, lighting that may inhibit nesting females (R. Witham, pers. comm.). While disturbance may be a primary inhibiting factor to nesting, development of areas behind dunes may lead to increased night use of beaches, regardless of lighting or other building restrictions imposed as mitigation measures. Relatively undisturbed nesting beaches, especially those of Sebastian Inlet North, should remain undeveloped to insure the protection of green turtles. Where development has occurred, planting of trees behind beaches to obscure buildings, such as has been done at John U. Lloyd State Park, may aid in reducing factors disturbing to nesting turtles. Other mitigating measures are provided by Shabica (in press). The survival of Florida's nesting colony also depends on the survi- val of hatchlings from Florida nests. Since the hatchlings become diso- riented by bright night lights, development of nesting beaches becomes a severe problem, leading to mortality from desiccation and increased exposure to predators (Mann 1977). On developed beaches where green turtles (and loggerheads) are known to nest, it may be necessary to patrol just before sunrise to look for misdirected hatchlings. While this may prove difficult, the alternative is to ignore a potentially serious loss Green Turtle Nesting in Florida 49 to the population. In the long term, it may be impossible to sustain both viable turtle populations and extensive development, regardless of res- trictive legislation against take or harm. To adequately protect a popu- lation, all habitats used during each life stage must also be protected. IS THE POPULATION INCREASING? Despite the spurt of development along much of the southeast Florida coast, there can be little doubt that there are now more green turtles reported nesting than there were 20 years ago. A number of explanations are possible. Better surveillance. — The first reports of green turtle nesting in Florida (Carr and Ingle 1959; Routa 1967; Gallagher et al. 1971) were based on the observations of a few individuals, made either by chance or while working a limited stretch of beach. Since 1959, there has been a substantial increase in the number of sea turtle beach patrols and the extent of beach covered. In 1979, the Florida Department of Natural Resources listed 20 areas regularly surveyed, and 29 in 1980. As an example, intensive aerial surveys revealed significant nesting in the Seb- astian Inlet North area where only incidental observations had been made in the past. Better surveillance undoubtedly accounts for some of the increase in reported nests, and additional patrols will likely increase future estimates of the level of Florida nesting. Greater public awareness. — During the last several years, there has been increased publicity concerning sea turtles and the threats facing them. Articles have appeared in numerous newspapers and magazines, and some local governments have even begun to fund sea turtle beach patrols and adopt regulations designed to assist conservation efforts. R. Witham (pers. comm.) believes that greater public awareness may help to decrease poaching, since citizens alert law enforcement agencies of suspected illegal activity. The appearance of a "strange" turtle (as opposed to the numerous loggerheads) is likely to result in reports to appropriate authorities. Protective legislation. — The State of Florida has had laws protect- ing green turtles, and their eggs and nests, since 1953, although these laws applied only from May through August. In 1974, the Florida Legislature extended the laws to include year-round protection for sea turtles (Shelfer 1978). These laws are strictly enforced by the Florida Marine Patrol of the Department of Natural Resources. In 1978, the green turtle breeding population in Florida was listed as Endangered under provisions of the Federal Endangered Species Act of 1973, as amended (16 U.S. Code 1531-43). The turtles and all parts and pro- ducts, including eggs and shells, are fully protected. The U.S. Fish and Wildlife Service and National Marine Fisheries Service, working in con- 50 C. Kenneth Dodd, Jr. junction with State and local agencies, have responsibility for en- forcement. As a result of these laws, most nesting and coastal green turtles are now unmolested, except for incidental take in shrimp trawls and boat related injuries. Vandalism still occurs, however, and only the continued strict enforcement of protective laws, with the imposition of severe penalties, will deter such activity. Head-start program on Hutchinson Island. — Since 1960, Ross Witham, Florida Department of Natural Resources, has been raising green turtles and releasing them off Hutchinson Island, Florida, in one of the earliest head-start programs in the world. This activity has been supported since 1971 by the Marine Research Laboratory of the Florida DNR. Turtles are raised to a size where natural predation should be reduced (approximately 20 cm), after which they are tagged and released (see Witham and Futch 1977 for details). Head-starting is an experimen- tal technique, and not all sea turtle biologists are enthusiastic about its use as a management tool (see Pritchard 1979 for a discussion). How- ever, turtles released in this program are known to survive in the wild, and are found in the same developmental habitat off Florida's coast where similar-size "wild" turtles occur (Witham and Futch 1977; Witham, pers. comm.). While there is no proof that increased nesting along Florida's east central coast is due to this head-start program, it must be recognized as a possibility, at least in part. Immigration. — One final possibility is that turtles now nesting in Florida are immigrants from other green turtle populations. Perhaps such individuals represent an expanding population, or they may be less nest site specific than green turtles are supposed to be. Immigrants could follow the western edge of the Gulf Stream during favorable water conditions and nest on beaches adjacent to known developmental habitat. However, Caribbean green turtle stocks are depleted and are not likely to be subject to such population pressure as to force the sur- plus into Florida waters in exponentially increasing numbers. The idea that the Florida population is the result of offspring from a few random founder individuals cannot be easily dismissed. If such were the case, however, it is difficult to understand why nesting is not increasing in the Keys. If most female green turtles return to their natal beach to deposit their eggs, a few successful hatchings on normally unfrequented beaches might lead to range extension, although this would be difficult to determine. CONCLUSIONS While earlier authors accepted the idea that Florida beaches once supported a large nesting population of green turtles (Carr and Ingle Green Turtle Nesting in Florida 51 1959:317), little hard evidence supports this position. What is known is that green turtles have long used coastal waters and lagoons as devel- opmental habitat, and that such populations were appreciably larger than at present. Overharvest, perhaps in conjunction with occasional winter kills (Wilcox 1896; Ehrhart 1977; Ehrhart and Lee 1981), deci- mated these largely juvenile and subadult populations. Overharvest is also implicated in the demise of what may have been a substantial nest- ing population in the Keys and Cape Sable region. There can be little doubt, however, that green turtles are increasingly encountered on east Florida beaches. Due to variances in the amount of time spent in survey and the length of beach covered, it is difficult to estimate a population size; surely many individuals have been unnoticed. Therefore, the fig- ures in Table 1 are minimum numbers and cannot be used compara- tively (except very generally) or to indicate concrete trends. It should be noted that there do appear to be "good" years and "bad" years, a cycle that has been observed in Australian green turtle populations (Limpus 1980) and is very poorly understood. Only systematic, well coordinated, long term research, involving beach patrols, tagging, and correlation with environmental variables, can ultimately shed light on the status of the green turtle in Florida. The question remains as to whether the Florida nesting population is actually increasing. Better surveillance and greater publicity undoubt- edly account for some of our awareness of green turtle nesting. It is possible that this trend is not as new as Table 1 would make it appear. However, I believe the facts argue that the population is increasing, although I am skeptical that Florida ever had "great nesting assemb- lages" (Carr and Ingle 1959). Instead, I hypothesize that there at one time was a small but stable nesting population, perhaps only a few thousand breeding females, that was decimated by overharvest. Such a population could easily have been exploited, and the dearth of natural- ists in this area could account for the lack of definite records prior to more modern times. Green turtles still frequented offshore waters, but even there they were reduced. By the late 1890s, all nesting may have ceased. However, beginning in the mid-twentieth century, laws were enacted to at least partly protect turtles and their nests. With poaching pressure reduced, early head-starting could have increased the popula- tion somewhat and made it possible for some individuals to exploit a still largely undeveloped coastline. At the same time, immigrant turtles may have provided some new genetic input to the small population. Scientific research, and public awareness of turtles that perhaps resulted from legislation, in turn revealed more turtles nesting. No single explan- tion is deemed adequate, and the long term future of Chelonia mydas in Florida is yet to be determined. 52 C. Kenneth Dodd, Jr. In the scenerio presented above, many of the nesting beaches avail- able to the green turtle were undeveloped. Turtles were occasionally poached, run over by boats, and faced problems associated with natural beach erosion and predation. But today, regardless of whether the popu- lation is expanding, development of remaining habitat and the increas- ing human presence it entails threatens to permanently end green turtle nesting in Florida. Unless beaches can be preserved, there is no secure future for this remarkable species. ACKNOWLEDGMENTS.— I would like to thank the following individuals for the generous sharing of data and , in many cases, ideas: C. and M. Barsumian, A. Carr, G. Dalrymple, R. Dawson, L. Ehrhart, J. Fletemeyer, T. W. Fritts, T. W. Martin, M. Murphy, J. Richardson, D. L. Stoneburner, and R. Witham. I thank Archie Carr, Thomas Fritts, P. C. H. Pritchard, and Ross Witham for their comments on the manuscript, and Sheila Hulsey for her silent encouragement. LITERATURE CITED Audubon, John J. 1926. The turtlers. pp. 194-202 in Delineations of American Scenery and Character. G. A. Baker and Co., New York. 349 pp. Bacon, Peter R. 1975. Review on research, exploitation, and management of the stocks of sea turtles. FAO Fish. Circ. 334. 19 pp. Bjorndal, Karen A. 1980. Demography of the breeding population of the green turtle, Chelonia mydas, at Tortuguero, Costa Rica. Copeia 1980(3):525-530. Brice, John J. 1896. The fish and fisheries of the coastal waters of Florida. Rep. U. S. Comm. Fish Fish. 22:263-342. Carr, Archie F., and R. M. Ingle. 1959. The green turtle (Chelonia mydas) in Florida. Bull. Mar. Sci. Gulf Caribb. 9:315-320. ,M.H. Carr and A. B. Meylan. 1978. The ecology and migrations of sea turtles, 7. The west Caribbean green turtle colony. Bull. Am. Mus. Nat. Hist. 762:1-46. Catesby, Mark. 1731-1743. The Natural History of Carolina, Florida, and the Bahama Islands. 2 Vols. Author, London. Chin, Lucas. 1976. Notes on marine turtles (Chelonia mydas). Sarawak Mus. J. 25(44):259-265. Dodd, C. Kenneth, Jr. 1978. Terrestrial Critical Habitat and marine turtles. Bull. Md. Herpetol. Soc. 74:233-240. Ehrhart, Llewellyn M. 1977. Cold water stunning of marine turtles in Florida east coast lagoons: rescue measures, population characteristics and evidence of winter dormancy. Am. Soc. Ichthyol. Herpetol. mtg., Gainesville, Fl. Abstract. 1979. A survey of marine turtle nesting at the Kennedy Space Cen- ter, Cape Canaveral Air Force Station, North Brevard County, Florida. Rep. to Div. Mar. Resour., Fla. Dep. Nat. Resour. 122 pp. , and R.C. Lee. 1981. Hypothermic stunning of marine turtles in east- central Florida lagoons in 1981. Soc. Study Amphib. Reptiles and Her- petol. League mtg., Memphis, TN. Abstract. Green Turtle Nesting in Florida 53 , and R.G. Yoder. 1978. Marine turtles of Merritt Island National Wildlife Refuge, Kennedy Space Center, Florida. Fla. Mar. Res. Publ. 33:25-30. Evermann, B.W., and B.A. Bean. 1896. Indian River and its fisheries. Rep. U.S. Comm. Fish Fish. 22:227-248. Fletemeyer, John. 1979. Sea turtle monitoring project. 1979 Report. Rep. to Broward Co. Environ. Qual. Control Bd., Ft. Lauderdale. 64 pp. 1980. Sea turtle monitoring project. 1980 Report. Rep. to Broward Co. Environ. Qual. Control Bd., Ft. Lauderdale. 88 pp. Florida Department of Natural Resources. 1979. Summary of sea turtle activity in Florida, 1979. 20 pp. 1980. Summary of marine turtle activity in Florida, 1980. 39 pp. Gallagher, Robert M., M.L. Holling, R.M. Ingle and C.R. Futch. 1972. Marine turtle nesting on Hutchinson Island, Florida, in 1971. Fla. Dep. Nat. Re- sour. Res. Lab. Spec. Sci. Rep. No. 37. 1 1 pp. , J. O'Hara and D.F. Worth. In press. Characteristics of loggerhead turtles nesting on Hutchinson Island, Florida. Bull. Mar. Sci. 33(1). Harrisson, D.S.L.J.T. 1976. Green turtles in Borneo. Brunei Mus. J. 5:196-198. Holbrook, John E. 1842. North American herpetology; or a description of the reptiles inhabiting the United States. 2nd ed., Vol. 1. J. Dobson, Philadel- phia, xv + 152 pp. Ingle, Robert M., and F.G.W. Smith. 1949. Sea turtles and the turtle industry. Spec. Publ. Univ. Miami, Coral Gables. 107 pp. King, F. Wayne. In press. Historical review of the status of the green turtle, Chelonia my das, and hawksbill, Eretmochelys imbricata. In K.A. Bjorndal (ed.). Proc. World Conf. Sea Turtle Conserv., Smithson. Inst. Press, Washington. Kleerekoper, H., and J. Bennett. 1976. Some effects of the water soluble pollu- tion fraction of Louisiana crude on the locomotor behavior of juvenile green turtle {Chelonia my das) and sea catfish (Arius felis). Preliminary results. Rep. Contract 206-76 Am. Petrol. Inst. 7 pp. Limpus, Colin J. 1980. The green turtle, Chelonia mydas (L) in eastern Aus- tralia, pp. 5-22 in Management of Turtle Resources. James Cook Univ. North Queensland Res. Monogr. No. 1. 72 pp. Litwin, Salome C. 1981. Chelonia mydas mydas (Green turtle). Nesting. Her- petol. Rev. 72(3):81. Mann, Thomas M. 1977. Impact of developed coastline on nesting and hatch- ling sea turtles in southeastern Florida. Unpubl. M.S. thesis, Fla. Atlantic Univ., Boca Raton. 100 pp. Mendonc,a, Mary T., and L.M. Ehrhart. 1982. Activity, population size and structure of immature Chelonia mydas and Caretta caretta in Mosquito Lagoon, Florida. Copeia 1982(1): 161-167. Nietschmann, Bernard. 1972. Hunting and fishing focus among the Miskito Indians, eastern Nicaragua. Hum. Ecol. 7:41-67. 1976. Memorias de arrecife tortuga. Ser. Geograf. Natur. No. 2, Banco de America, Managua, Nicaragua. 258 pp. 54 C. Kenneth Dodd, Jr. Parson, James J. 1962. The green turtle and man. Univ. Fla. Press, Gainesville. 126 pp. Pritchard, Peter C.H. 1979. 'Head-starting' and other conservation techniques for marine turtles. Cheloniidae and Dermochelyidae. Int. Zoo Yearb. 79:38-42. Proby, K.H. 1974. Audubon in Florida. Univ. Miami Press, Coral Gables. 384 pp. Rebel, Thomas P. 1974. Sea turtles and the turtle industry of the West Indies, Florida, and the Gulf of Mexico. Rev. ed. Univ. Miami Press, Coral Gables. 250 pp. Routa, Robert A. 1967. Sea turtle nest survey of Hutchinson Island, Florida. J. Fla. Acad. Sci. 50:287-294. Schwartz, Frank J., C. Peterson, H. Passingham, J. Fridell and J. Wooten. 1981. First successful nesting of the green turtle, Chelonia my das, in North Carolina and north of Georgia. ASB Bull. 2#(2):96. Abstract. Shabica, Stephan V. In press. Planning for protection of sea turtle habitat. In K. Bjorndal (ed.). Proc. World Conf. Sea Turtle Conserv. Smithson. Inst. Press, Washington. Shelfer, L. 1978. Florida's enforcement of marine turtle conservation laws. Fla. Mar. Res. Publ. 55:65. Sherman, William T. 1889. Memoirs. Vol. I. D. Appleton and Co., New York. Smith, Michael H., H.O. Hillestad, M.N. Manlove, D.O. Straney and J.M. Dean. 1978. Management implications of genetic variability in loggerhead and green sea turtles. XHIth Congr. Game Biol.:302-312. Stoneburner, D.L., D. Gilmore, J. Hinesley, D. Gross, D. Hall and J.L. Richardson. 1979. Observations on Chelonia my das: a northerly extension of known nesting range. Herpetol. Rev. 10(3): 103-104. True, Frederick W. 1884. The useful aquatic reptiles and batrachians of the United States. Part II, Sect. I: The Fisheries and Fishery Industries of the United States. U.S. Comm. Fish Fish., Washington, pp. 141-162. Wilcox, William A. 1896. Commercial fisheries of Indian River, Florida. Rep. U.S. Comm. Fish Fish. 22:249-262. Witham, Ross. 1978. Does a problem exist relative to small sea turtles and oil spills? Proceedings Conference on Assessment of Ecological Impacts of Oil Spills. AIBS. pp. 630-632. , and C.R. Futch. 1977. Early growth and oceanic survival of pen- reared sea turtles. Herpetologica 55:404-409. World Conference on Sea Turtle Conservation. 1979. Sea Turtle Conservation Strategy. IUCN, Gland, Switzerland. 38 pp. Worth, Dewey F., and J.B. Smith. 1976. Marine turtle nesting on Hutchinson Island, Florida, in 1973. Fla. Dep. Nat. Resour. Mar. Res. Publ. 18:1-17. Accepted 29 March 1982 Thermal Preferenda and Diel Activity Patterns of Fishes from Lake Waccamaw W. W. Reynolds and M. E. Casterlin Biothermal Research Institute R. D. 3, Box 10, Wyoming, Pennsylvania 18644 and D. G. LlNDQUIST ' Department of Biology University of North Carolina, Wilmington, North Carolina 28406 ABSTRACT.— We tested seven fish species from Lake Waccamaw in Ichthyotron electronic shuttleboxes to determine their preferred temper- atures and diel activity patterns. All preferred temperatures between 25 ° and 31 ° C, which corresponded to water temperatures measured in the lake in August 198 1 . All species avoided temperatures below 20 ° or above 36° C. One species was diurnal, two were nocturnal, and four were crepuscular in diel activity pattern under the LD 14:10 August photoperiod. INTRODUCTION Lake Waccamaw, North Carolina, is one of the shallow "bay lakes" of the southeastern coastal plain of North America. It is unusual among these lakes in having significant calcareous buffering capacity, and thus a pH normally at or above neutrality. Another unusual feature of Lake Waccamaw is that it harbors three endemic fish species: Fundulus wac- camensis Hubbs & Raney, the Waccamaw killifish (Cyprinodontidae); Menidia extensa Hubbs & Raney, the Waccamaw silverside (Atherini- dae); and Ethe o stoma per longum (Hubbs & Raney), the Waccamaw dar- ter (Percidae, Etheostomatinae). An undescribed ictalurid, Noturus sp., the broadtail madtom, also occurs in the lake. In connection with a survey to assess the conservation status of the endemic species, we measured the thermoregulatory behavior (preferred and avoided temperatures) and diel activity patterns of several fish spe- cies. They included the three endemic and one undescribed species named above, and three others that had never been so tested — Lepomis margina- tus (Holbrook), the dollar sunfish (Centrarchidae); Enneacanthus chae- todon (Baird), the blackbanded sunfish (Centrarchidae); and Noturus gyrinus (Mitchell), the tadpole madtom (Ictaluridae). 1 Direct reprint requests to DGL Brimleyana No. 7:55-60. July 198 1 . 55 56 W. W. Reynolds, M. E. Casterlin, D. G. Lindquist MATERIALS AND METHODS The fishes (38-60 mm standard length) were captured by seine or hand net, either in the lake or in backwaters of the Big Creek tributary, and tested individually in Ichthyotron electronic shuttleboxes as described by Reynolds (1977). These devices permit a fish, by passing through an electronic gate (light beam), to control water temperatures by normal swimming movements, which are monitored automatically via photo- transistors. The fish were tested during the first half of August 1981, under a natural photoperiod of 14 h light: 10 h dark (LD 14:10). Final thermal preferenda, which are independent of thermal acclimation (Rey- nolds & Casterlin 1979, 1980), were measured, and hourly activity as registered by the phototransistors (mean light beam interruptions per hour) were used to characterize diel activity patterns (Table 1). In gen- eral, more precise behavioral thermoregulators will show greater activity. The relative amount of activity (light beam interruptions) during day, night, and crepuscular periods is used to determine the diel patterns. RESULTS All species exhibited mean final thermal preferenda between 25 ° and 30° C (Table 1). Various measures of central tendency failed to coincide for each species because of skewness in the distributions of occupied temperatures. Of these species, Lepomis marginatus was the most precise behavioral thermoregulator, exhibiting the smallest range and standard deviation, while Menidia extensa was the least precise. Thus, the former species also exhibited the highest hourly activity rate, while the latter was the least active. Noturus gyrinus preferred the warmest temperatures, and Enne acanthus chaetodon the coolest, in terms of mean value. Fundulus waccamensis was the only diurnal species as determined by maximal activity, while Etheostoma perlongum and Noturus sp. were nocturnally most active (Table 1). The other species were crepuscular, being most active around dawn and/ or dusk. Here there was a marked behavioral difference between the two Noturus species, which often share the same microhabitats and nesting sites (Lindquist, unpubl.). During the first half of August 198 1 , normally a time of warmest water, the temperatures in the lake ranged from 27.4 ° to 3 1 .0 ° C over all areas and depths. Warmest temperatures occurred near the mouth of Big Creek, the major tributary. In the creek and associated canals, tempera- tures ranged from 24.8 ° to 30.9 ° C during the same period. DISCUSSION Lake Waccamaw does not normally freeze completely over in winter, nor does it stratify thermally to any significant extent in summer, as its maximum depth is only about 3 m. The temperatures preferred by the Behavior of Lake Waccamaw Fishes 57 £ cd s 03 O o cd £ 4J M cd -J Cu o o cd _ o _4> X •3 BU "T3 ■»-> C cd C/3 3 00 >> 3 O < *-> cd _C 3 c« 00 X fe- o O X) S JJ c .9 cd C ed 2 « 2. °° a* c h cd 3 C cd • — (L> o\ os ^t o ^t cm' so o' cm" "^ m o o en oo o CM «n Tf sO «n sd CM © r-- so m oo oo — «' o «n o rfr" Os CO Os co sO iri 6 n «^ o r- r»" ©' ©" r- — o r- o cm CM ro CO CM CM CO m cm r-> rn so so oo CM CM CM CM CM CM CM «n »n «n © © «n o »n m — o co m ro co sO «n co m • cm os r» oo — •£} cm cm cm cm m CM Tt cm «n cm c-> so «n — «' rt cm" m" — I ci cm' Tt rn Tt r- so o p- so oo «n r- os os CM CM CM CM CM CM CM S 3 a« o 3- 3 •S bo v) v. v. 3 3 58 W. W. Reynolds, M. E. Casterlin, D. G. Lindquist fishes tested correspond fairly well to normal maximum summer temper- atures in the lake. This is a typical result, in that freshwater and marine fishes often prefer temperatures (final preferenda) that are normal sea- sonal maxima in their habitats and geographic ranges (Reynolds & Thomson 1974; Reynolds et al. 1977; Casterlin & Reynolds 1979a, 1982). Field observations of fish distributions and movements appeared lar- gely consistent with our laboratory measurements. For example, as inshore lake temperatures over a two-week period warmed from 27.4 ° to 29.4 °C at one location, fewer Fundulus and Menidia could be seen or captured by seine inshore during the day, although they moved inshore at night as some cooling occurred. Enne acanthus chaetodon was captured in the cooler depths of backwater canals, which had lower temperatures than occurred in the lake at that time. We did not see this species in the lake, where temperatures were above its mean final preferendum. A more dramatic field example of apparent behavioral thermoregula- tion occurred during the unusually dry and hot summer of 1980. Diurnal temperatures in the lake shallows reached 40 ° C, and all fish then vacated these lethally hot regions, at least during daylight hours (Lindquist and Yarbrough, unpubl.). We often found males of both Noturus species guarding nests under the same spawning cover, and their thermal preferenda (Table 1) appar- ently differ little. The striking difference in their diel activity patterns (one being nocturnal, the other crepuscular and mainly active at dawn) sug- gests a temporal niche partitioning between these otherwise closely sim- ilar species. The very high activity level of Lepomis marginatus (Table 1) is note- worthy. It apparently reflects territorial or reproductive aggression, which was occurring at that time, and may not be typical of other sea- sons. For example, intense agonistic interactions, with resultant body damage, was seen among individuals in holding tanks, although this could not occur during the testing of single individuals in the Ichthyo- tron. It is also interesting that L. marginatus preferred lower tempera- tures than Lepomis macrochirus Rafinesque, the bluegill sunfish, which prefers about 31 °C (Reynolds & Casterlin 1979) but ranges much farther north. Enneacanthus chaetodon prefers temperatures similar to those preferred by Enneacanthus gloriosus (Holbrook), the bluespotted sunfish (Reynolds & Casterlin 1980; Casterlin & Reynolds 1979b). Etheostoma perlongum is only the third darter species to have been successfully tested for thermoregulatory behavior in the laboratory. Hill & Matthews (1980) reported thermal preference data for Etheostoma spectabile (Agassiz) and Etheostoma radiosum (Hubbs & Black) from the Blue River in Oklahoma, and found a correlation between thermoregula- tory precision and the thermal stability of microhabitats occupied by Behavior of Lake Waccamaw Fishes 59 these species in nature. In our tests, E. perlongum exhibited a thermoreg- ulatory precision that was intermediate among the species tested. Lind- quist et al. (1981) observed seasonal onshore-offshore spawning migra- tions of E. perlongum, which might be cued by changes in water temperature. Although darters generally appear to be diurnal (see Adam- son & Wissing 1977; Cordes & Page 1980; Mathur 1973), our data sug- gest that E. perlongum is nocturnal. However, our results may not accu- rately represent the fish's activity pattern in nature, and further tests are necessary to resolve this apparent discrepancy. Enneacanthus gloriosus exhibits a crepuscular activity pattern (Caster- lin & Reynolds 1980), as does E. chaetodon (Table 1). Centrarchids generally tend to be diurnal or crepuscular (Reynolds & Casterlin 1976; L. marginatus in Table 1). In contrast, ictalurids such as Noturus (Table 1) tend to be nocturnal or crepuscular, as are the Ictalurus species (Rey- nolds & Casterlin 1977, 1978). Ictalurids and centrarchids are considered typical "warm-water" fish species (Reynolds 1979), in contrast to "cold- water" species such as salmonids that prefer temperatures below 20 °C. Percids are more variable, with various species preferring widely different temperatures (Reynolds 1979). ACKNOWLEDGMENTS.— We thank John McNeill for generously allowing us the use of his cabin at Lake Waccamaw, and John R. and Peggy W. Shute for help in capturing several of the species. This study was made possible by grant-in-aid funds provided under section 6 of the Endangered Species Act of 1973 (PL 93-205) to David G. Lindquist. These funds were administered by the North Carolina Wildlife Resources Commission. LITERATURE CITED Adamson, Scott W., and T. E. Wissing. 1977. Food habits and feeding periodicity of the rainbow, fantail, and banded darters in Four Mile Creek. Ohio J. Sci. 77:164-169. Casterlin, Martha E., and W. W. Reynolds. 1979a. Shark thermoregulation. Comp. Biochem. Physiol. 64 A AS 1-453. ,and 1979b. Thermoregulatory behavior of the bluespotted sunfish, Enneacanthus gloriosus. Hydrobiologia 64:3-4. , and 1980. Diel activity of the bluespotted sunfish, Ennea- canthus gloriosus. Copeia 1980 (2):344-345. , and 1982. Thermoregulatory behavior and diel activity of yearling winter flounder, Pseudopleuronectes americanus (Walbaum). Environ. Biol. Fishes 7: 177- 180. Cordes, Lynn E., and L. M. Page. 1980. Feeding chronology and diet composi- tion of two darters (Percidae) in the Iroquois River System, Illinois. Am. Midi. Nat. 104:202-206. 60 W. W. Reynolds, M. E. Casterlin, D. G. Lindquist Hill, Loren G., and W. J. Matthews. 1980. Temperature selection by the darters Etheostoma spectabile and Etheostoma radiosum (Pisces: Percidae). Am. Midi. Nat. 704:412-415. Lindquist, David G., J. R. Shute and P. W. Shute. 1981. Spawning and nesting behavior of the waccamaw darter, Etheostoma perlongum. Environ. Biol. Fishes 6:177-191. Mathur, Dilip. 1973. Food habits and feeding chronology of the blackbanded darter, Percina nigrofasciata (Agassiz), in Halawakee Creek, Alabama. Trans. Am. Fish. Soc. 702:48-55. Reynolds, William W. 1977. Fish orientation behavior: an electronic device for studying simultaneous responses to two variables. J. Fish. Res. Board Can. 54:300-304. (ed.). 1979. Symposium on thermoregulation in ectotherms. Am. Zool. 79:191-384. , and M. E. Casterlin. 1976. Locomotor activity rhythms in the bluegill sunfish, Lepomis macrochirus. Am. Midi. Nat. 9(5:221-225. , and 1977. Diel activity in the yellow bullhead. Prog. Fish- Cult. 59:132-133. , and 1978. Ontogenetic change in preferred temperature and diel activity of the yellow bullhead, Ictalurus natalis. Comp. Biochem. Physiol. 54/1:409-411. , and 1979. Behavioral thermoregulation and the 'final pref- erendum' paradigm. Am. Zool. 79:21 1-224. , and 1980. The role of temperature in the environmental physiology of fishes, pp. 497-518 in M. A. Ali (ed.). Environmental Physi- ology of Fishes. Plenum Press, New York. 723 pp. , and D. A. Thomson. 1974. Responses of young Gulf grunion, Leu- resthes sardina, to gradients of temperature, light, turbulence and oxygen. Copeia 1974(3):747-758. , and and M. E. Casterlin. 1977. Responses of young Califor- nia grunion, Leuresthes tenuis, to gradients of temperature and light. Copeia 1977(1):144-149. Accepted 19 May 1982 Helminths of Some Seabirds from North Carolina Ronald W. Mobley and Grover C. Miller Department of Zoology, North Carolina State University, Raleigh, North Carolina 27650 ABSTRACT. — Eighty-five birds of the orders Procellariiformes, Pelecaniformes, and Charadriiformes were examined for helminths between May 1977 and September 1979. At least nine species of helminths were recovered — one species of Digenea, at least six of Cestoda, one Nematoda, and one Acanthocephala. The following new host records were obtained: Opisthovarium elongation and Falsifilicollis altmani in the common tern; Tetrabothrius laccocephalus in the north- ern fulmar and Audubon's shearwater; T. minor in Cory's shearwater; T sp. in the red-billed tropicbird; and T. filiformis , Choanotaenia sp., and Contracaecum sp. in Wilson's storm petrel. Feeding habits of the hosts were directly reflected by their helminth fauna. Procellariiform and pelecaniform hosts showed a predominance of helminths that probably use fish or squid as intermediate hosts, whereas charadrii- form hosts contained helminths whose intermediate hosts are either snails or terrestrial crabs. INTRODUCTION Much literature is available on the helminths of sea birds. Most early studies were concerned primarily with morphology and taxonomy. The best pre- 1900 descriptions of these helminths are found in the works of Diesing (1850), Fuhrmann (1899), and Loennberg (1899) as reported by Baer (1954). The twentieth century marked the beginning of polar exploration and consequently provided increased access to sea birds for parasitological study. Earliest reports were by Linstow (1905) on the Russian Polar Expedition, 1900-1903; Raillet and Henry (1912) on the cestodes from the French Antarctic Expedition; and Leiper and Atkinson (1914, 1915) on helminths recovered from the British Antarc- tic (Terra Nova) Expedition, 1910-1913. Later reports included those of Fuhrmann (1921) on the German South Polar Expedition, 1901-1903; Johnston (1937) and Mawson (1953) on the Australian National Antarctic Research Expeditions; and Johnston and Mawson (1945) and Prudhoe (1967) on parasitic helminths collected by the British, Austral- ian and New Zealand Antarctic Research Expedition, 1929-1931. Cestodes have probably been the most studied helminths of sea birds and literature is abundant. Spatlich (1909), Ransom (1909), Nybelin (1916), and Szpotanska (1925, 1929) all made important descriptive con- tributions. Linton (1927) in America, Tseng (1932, 1933) in China, Yamaguti (1935) in Japan, and Joyeux and Baer (1935, 1939) in France described specimens from their respective countries. Later studies cen- Brimleyana No. 7:6 1 -68. July 1 98 1 . 61 62 Ronald W. Mobley and Grover C. Miller tered more on taxonomic revisions and included works by Johnston (1935), Lopex-Neyra (1943, 1952), Wardle et al. (1952, 1974), and Baer (1954). The trematodes of sea birds were extensively studied by Linton (1928), Yamaguti (1958, 1971) and Cable et al. (1960). Van Cleave (1918, 1934, 1939, 1947), Perry (1942), Reish (1950), and Petrotchenko (1958) provided excellent information of the taxonomy and biology of the acanthocephalans of these birds. Recent contributions to sea bird helminthology included those of Deblock (1966), Jones and Williams (1967, 1968, 1969), Threlfall (1971), Ellis and Williams (1973), Williams and Ellis (1974), Riley and Owen (1975), and Bourgeois and Threlfall (1979). A variety of literature on the identification and ecology of the bird hosts is available in publications by Bent (1921, 1922), Murphy (1936), Roberts (1940), Palmer (1941), Robertson (1964), and Watson (1966). The objectives of our study were to (1) determine the gastrointesti- nal helminth fauna of certain sea birds, and their prevalence and inten- sity ranges; and (2) correlate differences in helminth fauna with aspects of host biology such as feeding habits and geographical range. METHODS AND MATERIALS Eighty-five birds were collected between May 1977 and August 1979, including seven species of Procellariformes, one species of Peleca- niformes, and two species of Charadriiformes. All were collected from the Atlantic Ocean east of and adjacent to Oregon Inlet, North Caro- lina. Twelve- or sixteen-gauge shotguns and either No. 2 or No. 4 high velocity shot were used to collect the hosts. Wilson's storm petrels, Oceanites oceanicus, were attracted into range using "chum" consisting of poultry offal. Fulmars Fulmarus gla- cialis; shearwaters, Puffinus spp.; and gadfly petrels, Pterodroma spp., were generally unresponsive to chum slicks but were occasionally encountered in close proximity to commercial fishing vessels. Red-billed tropicbirds, Phaethon aethereus, were collected singly near the collect- ing vessel. Common terns, Sterna hirundo, and bridled terns Sterna anaethetus, were collected either on the wing or as they rested on flot- sam. After collection each bird was labeled with respect to time and date, placed in an individual plastic bag, and put on ice. Hosts were hard forzen within eight hours of collection and examined as soon as possible, usually within 48 hours. Bird identifications were based on Watson (1966). Each bird was incised midventrally from cloaca to sternum. The alimentary tract, from gizzard to rectum, was removed intact to a glass dish containing saline, where the tract was then longitudinally dissected. The gut contents were agitated, rinsed, and allowed to settle. The super- North Carolina Seabird Helminths 63 natant was decanted into another dish for examination with a stereo- scopic microscope. All original sediment was washed repeatedly and decanted as above. Gross examination of intestinal tissue was made in an attempt to find attached helminths. Trematodes, cestodes, and acan- thocephalans were fixed and stored in AFA (Alcohol-Formalin-Acetic Acid), stained with Semichon's acetocarmine, cleared in methyl salicy- late, and mounted in Kleermount. Nematodes were fixed in 70 percent alcohol, stored in glycerin-alcohol, cleared in glycerin, and mounted in glycerin jelly. RESULTS AND DISCUSSION Nine species of parasites were recovered (Table 1). One species of digenetic trematode and one species of acanthocephalan were recovered from the common tern; five species of cestodes were found in various species of procellariiforms, and one species in the red-billed tropicbird; and one species of nematode was found in two Wilson's storm petrels. No helminths were recovered from the one black-capped petrel, Ptero- droma hasitata, or the seventeen bridled terns, Sterna anaethetus, examined. Sea birds vary greatly in the degree to which they are associated with the open sea. Truly pelagic species may encounter land only during breeding periods, while others, such as some species of gulls and terns, may live and feed inshore except during migrations. Resulting differen- ces in habits will affect exposure to the helminth fauna. Although fish probably represent a major food item for most spe- cies examined, the coast-inhabiting terns also secondarily eat a variety of crustaceans, insects, worms, and molluscs (Watson 1966). The acan- thocephalans found in common terns probably used crustacean inter- mediate hosts (Reish 1950; McDonald 1969). In 2 individuals the number of acanthocephalans recovered exceeded 200, thus indicating extensive feeding on the intermediate host. The procellariiform and pelecaniform hosts are all pelagic and primarily consume fish and squid (Watson 1966, 1975). The tetrabo- thriid cestodes and the heterocheilid nematode, Contracaecum sp., were probably transmitted through fish or squid intermediate hosts (Baer 1954; Ellis and Williams 1973; Yamaguti 1959). However, the cestode, Choanotaenia sp., recovered from Wilson's storm petrel, is from a genus known to use insects as intermediate hosts (Yamaguti 1959). Infections may have occurred during breeding, perhaps by ingestion of infected insects associated with the nesting sites. A high prevalence of infection may best be explained by birds defe- cating in an area where suitable intermediate hosts are present and their ingestion is likely. A highly prevalent helminth might tend to be less 64 Ronald W. Mobley and Grover C. Miller Table 1 . Prevalence and intensity range of gastrointestinal helminths of sea birds from North Carolina. Taxon (No. examined) Prevalence of infection (%) Intensity range Order Procellariiformes northern fulmar (1) Cestoda: Tetrabothrius laccocephalus ' Tetrabothrius procerus Cory's shearwater (7) Cestoda: Tetrabothrius minor ' Tetrabothrius laccocephalus greater shearwater (3) Cestoda: Tetrabothrius laccocephalus Audobon's shearwater (5) Cestoda: Tetrabothrius laccocephalus ' South Trinidad petrel (2) Cestoda: Tetrabothrius sp. Wilson;s storm petrel (37) Cestoda: Tetrabothrius filiform is ' Choanotaenia sp. ' Unidentified fragments Nematoda: Contraceacum sp. ' Order Pelecaniformes red-billed tropicbird (2) Cestoda: Tetrabothrius sp. ' Order Charadriiformes common tern (11) Digenea: Opisthovarium elongatum ' Acanthocephala: Falsifilicollis altmani ' 100 >10 100 >10 29 1-5 15 10 100 40 100 6 8 11 1 ->10 1-2 1 1-4 50 2 9 3 pairs in copuh 45 2 - >200 1 New host record North Carolina Seabird Helminths 65 host specific and could thus be transmitted through a variety of hosts. Conversely, if the prevalence of a particular helminth is low, host speci- ficity would tend to be higher, definitive or intermediate host popula- tions may be sparse, or definitive-intermediate host interactions might be poorly developed. The prevalence of Falsifilicollis altmani in the common tern is rela- tively high. Correspondingly, the definitive host population is fairly dense in the coastal areas of North Carolina. While the intermediate host is unknown, a variety of crustacean species occurs in the area. The parasite demonstrates only limited specificity; it has been found in at least four other bird genera (Ehrhardt 1966, Yamaguti 1963). An example of low infection is that of Tetrabothrius filiformis in Wilson's storm petrel. Host population density is relatively low except on the breeding grounds, and even there the birds are far-ranging in feeding habits (Bent 1922). Again, the intermediate hosts are unknown, but populations of fish and squid vary from sparse in warm open waters to dense in the cold waters surrounding the breeding grounds (Watson 1975). Like other tetrabothriids, T. filiformis is probably transmitted through fish or squid, both of which seem to be secondary to fish oil slicks and krill in the diet of Wilson's storm petrel (Watson 1975). Krill may be an intermediate/ paratenic host. The levels of infection in the northern fulmar and the shearwaters reported here and elsewhere (Bourgeois and Threlfall 1979) at first seem high for birds of the open sea. The tetrabothriid species (T. laccocepha- lus, T. minor, and T. procerus) recovered from these hosts, however, are found in a variety of related hosts and over a wide geographical range (Baer 1954). This range would seem to indicate that the helminths can use a large variety of intermediate host species or an intermediate host with a wide range. These factors, combined with the hosts' habits of feeding almost exclusively on squid and fish (Watson 1966, 1975), seem to support the relatively high rates of parasitism in these birds. Most of the cestodes recovered constitute new locality records, and several cestode species were found in hosts coming from both north and south polar regions. In conclusion, it appears that the offshore waters of North Carolina provide an area of intergradation for northerly/ south- erly seabirds and their parasites. We are doing additional work on these hosts and their parasites. ACKNOWLEDGMENTS.— Appreciation is extended to David S. Lee, Steven P. Platania, and other members of the North Carolina State Museum of Natural History staff for providing hosts and host identifi- cations. Acknowledgment is due Micou M. Browne for his assistance and suggestions in the preparation of this material. 66 Ronald W. Mobley and Grover C. Miller This is Paper No. 7089 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina. LITERATURE CITED Baer, Jean G. 1954. Revision taxonomique et etude biologique des Cestodes de la famille des Tetrabothriidae, parasites d Oiseaux de haute mer et de mammiferes marins. Mem. Univ. Neuchatel Ser. inquarto 1:1-21. Bent, Arthur C. 1921. Life histories of North American gulls and terns; order Longipennes. U. S. Natl. Mus. Bull. 107. 345 pp. 1922. Life histories of North American petrels and pelicans and their allies: order Tubinares and order Steganopodes. U. S. Natl. Mus. Bull. 121. 343 pp. Bourgeois, C. E., and W. Threlfall. 1979. 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The nematode and acanthocephalan parasites of the sheathbill, Chionis alba (Gmelin), at Signey Island, South Orkney Islands, and a summary of host parasite relationships in the sheathbill. J. Helminthol. 43:59-61. North Carolina Seabird Helminths 67 Joyeux, C. H., and J. G. Baer. 1934. Sur quelques Cestodes de France. Arch. Mus. Nat. Hist. Nat. (Paris) 77:165-170. , and 1939. Sur quelques cestodes de Charadriiformes. Bull. Soc. Zool. Fr. 64:171-187. Leiper, R. T., and E. L. Atkinson. 1914. Helminths of the British Antarctic Expedition 1910-1913. Proc. Zool. Soc. London, pp. 222-226. , and 1915. Parasitic worms with a note on a free-living nematode. British Antarctic (Terra Nova) Expedition, 1910. Natural His- tory Report, Zoology 2: 19-60. Linstow, Otto von. 1905. Helminthen der Russichen Polar-Expedition 1900- 1903. Mem. Acad. Imp. Sci. St. Peterbs. Phys. Math. 75:1-17. Linton, E. 1927. Notes on Cestode parasites of birds. Proc. U. S. Natl. Mus. 70. 73 pp. 1928. Notes on trematode parasites of birds. Proc. U. S. Natl. Mus. 73. 1-11. Loennberg, E. 1899. Ueber einige cestoden aus dem Museum zur Bergen. Ber- gens Mus. Arb. 4: 1-23. Lopez-Neyra, Carlos R. 1942. Division del genero Hymenolepis Weinland (S.I.) en ostros mas naturales. Rev. Iber. Parasitol. 2:46-93, 1 13-256. 1952. Byrocoelia albaredai n. sp. relaciones con Tetrabothriidae y Dilepididae. Rev. Iber. Parasitol. 72:319-344. McDonald, Malcolm E. 1969. Catalogue of helminths of waterfowl (Anatidae). U. S. Fish Wildl. Serv. Spec. Sci. Rep. Wildl. 726. 692 pp. Mawson, Patricia M. 1953. Parasitic Nematoda collected by the Australian National Antarctic Research Expedition: Heard Island and Macquarie Island, 1948-1951. Parasitol. 45:219-297. Murphy, Robert C. 1936. Oceanic Birds of South America. Amer. Mus. Nat. Hist., New York. 2 vols. Nybelin, Orvar. 1916. Neue Tetrabothriiden aus Vogel. Zool. Anz. 47:297-301. Palmer, R. S. 1941. A behavior study of the Common Tern {Sterna hirundo hirundo L.). Proc. Boston Soc. Nat. Hist. 42:1-119. Perry, M. L. 1942. A new species of the acanthocephalan Filicollis. J. Parasitol. 25:385-388. Petrotchenko, Vladamir I. 1958. Acanchocephala of domestic and wild animals. Rabot. Gel Mintol. 80 Let. Skrjabin, Akad. Sel-Skokhoziaistv. Nauk. 7:10458. Prudhoe, Stephan. 1969. Cestodes from fish, birds and whales. Report of the B.A.N.Z. Antarctic Research Expedition, 1929-31 9:17:193. Railliet, A., and A. Henry. 1912. Helminthes recueillis par 1 expedition antarc- tique francaise du Pourquoi Pas I. Cestodes d Oiseaux. Bull. Mus. Nat. Hist. Nat.:35-39. Ransom, H. B. 1909. The teanioid cestodes of North American Birds. U. S. Natl. Mus. Bull. 69. 129 pp. Reish, Donald. 1950. Preliminary note on the life cycle of acanthocephalan, Polymorphus kenti Van Cleave, 1947. J. Parasitol. 56:496. Riley, John, and R. W. Owen. 1975. Competition between two closely related Tetrabothrius cestodes of the fulmar (Fulmarus glacia/is L.) Z. Parasitenk. D. 46(3):221-228. 68 Ronald W. Mobley and Grover C. Miller Roberts, B. 1940. The life cycle of Wilson's Petrel. British Graham Land Exped., Sci. Rep. 7:141-194. Robertson, W. B., Jr. 1964. The terns of the Dry Tortugas. Bull. Fla. State Mus. Biol. Sci. 5:1-14. Spatlich, Walter. 1909. Untersuchungen uber Tetrabothrien. Ein Beitrag zur Kenntnis des Cestoden-korpers. Zool. Jahrb. Anat. 25:539-594. Szpotanska, I. 1925. Etude sur les Tetrabothriides des Procellariiformes. Bull. Acad. Pol. Sci. Lt. Ser. B.:673-727. 1929. Recherches sur quelques Tetrabothriides d Oiseaux. Bull. Acad. Pol. Sci. Lt. Ser. B.: 129-152. Threlfall, William. 1971. Helminth parasites of alcids in the northwestern North Atlantic. Can. J. Zool. 49(4):46 1-466. Tseng, S. 1932. Studies on avian cestodes from China. Part I. Cestodes from Charadriiform birds. Parasitol. 24:87-106. 1933. Studies on avian cestodes from China. Part II. Cestodes from Charadriiform birds. Parasitol. 24:500-511. Van Cleave, Harley J. 1918. The Acanthocephala of North American birds. Trans. Am. Microsc. Soc. 37:19-47. 1934. Observations on the status of certain genera of Acanthoce- phala, chiefly from birds. J. Parasitol. 20:324. 1939. A new species of acanthocephalan genus Polymorphus and notes on the status of the name Profilicollis. J. Parasitol. 25:121-131. 1947. Analysis of distinction between the acanthocephalan genera Fillicollis and Polymorphus with descriptions of a new species of Polymor- phus. Trans. Am. Microsc. Soc. 6(5:302-313. Wardle, R. A., and J. A. McLeod. 1952. The Zoology of Tapeworms. Univ. Minn. Press, Minneapolis. 780 pp. Wardle, R. A., J. A. McLeod and S. Radinovsky. 1974. Advances in the Zool- ogy of Tapeworms, 1950-1970. Univ. Minn. Press, Minneapolis. 274 pp. Watson, George E. 1966. Seabirds of the Tropical Atlantic Ocean. Smithsonian Identification Manual. Smithsonian Press, Washington. 120 pp. 1975. Birds of the Antarctic and Sub-Antarctic. Am. Geophy. Union, Washington. 350 pp. Williams, I. C, and C. Ellis. 1974. The helminth parasites of the sheathbill, Chionis alba (Gmelin), and the diving petrels, Pelecanoides georgicus (Murphy and Harper) and P. urinatrix (Gmelin), at Bird Island, South Georgia. J. Helminthol. 48(3): 195-197. Yamaguti, Satyu. 1935. Studies on the helminth fauna of Japan. Part VI. Ces- todes of birds I. Jpn. J. Zool. 6:184-232. 1959. Systema Helminthum. Vol. II. Cestodes of Vertebrates. Interscience Publ., New York. 860 pp. 1961. Systema Helminthum. Vol. III. The Nematodes of Vertebrates. Interscience Publ., New York. 1261 pp. 1963. Systema Helminthum. Vol. V. Acanthocephala. Interscience Publ., New York. 423 pp. 1971. Synopsis of Digenetic Trematodes of Vertebrates. Keigaku Publ. Co., Tokyo. 1074 pp. Accepted 29 January 1982 Life History of a Coastal Plain Population of the Mottled Sculpin, Coitus bairdi (Osteichthyes: Cottidae), in Delaware Fred C. Rohde Charles T. Main, Inc., Prudential Center, Boston, Massachusetts 02199 AND Rudolf G. Arndt Faculty of Natural Sciences and Mathematics, Stockton State College, Pomona, New Jersey 08240 ABSTRACT. — Aspects of the biology of a Coastal Plain population of Cottus bairdi in a lowland forest stream in Delaware were examined during 1973-81. Cottus bairdi occurs primarily over a gravel substrate; naturally-occurring rocks are absent. Individuals are shorter-lived and attain sexual maturity at a smaller size than in other studied popula- tions. Two age groups, and a presumed third, were found. Only 33% of age group 0 survives to spawn in age group I. Spawning occurs in February and March at a water temperature of 6.5° to 12.5° C, and mean ovum diameter is 2.15 mm. There is a strong relationship between ova number and standard length (Y = -157.11 + 6.80 SL). Fecundity is lower than that reported for most populations of C. bairdi. Most eggs are deposited in single-spawn clusters, with a mean egg number of 134.2 per cluster. Condition factor indicates that males are generally more robust than females. Most growth in length occurs in age group 0, males are longer than females, and there is a highly significant difference in sex ratio of mature specimens taken. Dominant food is trichopteran and dipteran larvae, and plecopte- ran nymphs; crustaceans, ephemeropteran nymphs, and coleopteran larvae are of minor importance. There is seasonal variation in food items. Diet differs only slightly as a function of sculpin size. INTRODUCTION The mottled sculpin, Cottus bairdi, is widely distributed in the United States and Canada (Lee 1980) and there are numerous studies of aspects of its life history (Gage 1878; Smith 1922; Hann 1927; Koster 1936, 1937; Bailey 1952; Daiber 1956; Ludwig and Norden 1969; Patten 1971; Nagel 1980). There are, however, only four known Atlantic Coastal Plain populations, all located in the Nanticoke River system, Chesa- peake Bay drainage. We studied one of these, in Butler Mill Branch and Brimleyana No. 7:69-94. July 1 98 1 . 69 70 Fred C. Rohde and Rudolf G. Arndt its tributaries, near Seaford, Sussex County, Delaware, during 1973-75 and 1978-81 and report here on habitat, reproduction, age and growth, food habits, and abundance. Franz and Lee (1976) reported on a popu- lation in Caroline County on the Eastern Shore of Maryland, 4.0 km north of Federalsburg and 15.2 km northwest of Butler Mill Branch, and briefly considered habitat, food habits, and size. In spring 1981 we discovered a third population, in upper Sullivan Branch and the lower parts of its tributaries, Wolfpit and Raccoon branches, 6.4 km north of Federalsburg, Caroline County, Maryland, and a fourth in Skinners Run, at a point just upstream of Route 307 and 4.0 km southwest of Federalsburg, Dorchester County, Maryland. All data herein refer to the Butler Mill Branch population, unless otherwise specified. MATERIALS AND METHODS Specimens of C. bairdi (N = 1009) were collected with a 3.0 m X 1.2 m, 3.2 mm mesh nylon flat seine. All habitats were sampled. Collections were made on 28 October and 4 November 1973; 20 January, 17 Febru- ary, 17 March, 20 July, 8 September and 30 November 1974; 2 and 23 March 1975; 7 September and 26 November 1978; 16 March and 25 July 1979; 9, 15, 22 and 30 March, 13 April, 4 and 20 May, 8 and 28 June, 12 and 25 July, and 9 August 1980; and 22 and 27 February, 7, 14, 22, 26 and 29 March, 5, 11, 18 and 25 April, and 19 May 1981, between 1050 and 2000 hours. Fish were preserved in 10% formalin and stored in 40% isopropyl alcohol until examined. For conservation pur- poses, the last specimens taken in each collection, regardless of sex, size, and reproductive condition, were usually released. Through 1979, only relatively small samples were taken, because of the presumed small size of the population. Sampling was intensified in 1980 and 1981 to pin- point spawning time, locate eggs, and collect larvae. In 1981, fish were primarily observed in the field, and most of those collected were released alive. An additional 41 adult C. bairdi were taken by seine in spring 1981 at the new Caroline County locality, 6 adults at the Dorchester County locality, and 1 adult at the locality given by Franz and Lee (1976); these were preserved. Air and water temperature, pH (Hach Kit), and dissolved oxygen (Yellow Springs meter) were recorded at time of capture. To help char- acterize the habitat in areas particularly frequented by C. bairdi, semi- quantitative substrate samples of about 8 liters were taken from Butler Mill Branch and about 1.2 liters from an upper tributary. The samples were dried and sieved, and the percentage by weight of several gravel/ sand particle size categories determined. Coitus Life History in Delaware 71 Gonadal development was determined by calculating the gonoso- matic ratio (gonad weight as a percentage of total weight) of 235 females and 121 males taken during 1973-80. This sample included only sculpins that could be sexed and with gonads of 0.001 g or heavier (young-of-the-year from September, October, and November collec- tions, and all adults). Gonads were weighed to the nearest 0.001 g. Fecundity of 67 pre-spawning females collected in January (20) and February (3) 1973, March (10) 1979, and March (34) 1980 was deter- mined. Ten ova from each of 57 mature females were measured to the nearest 0.1 mm using an ocular micrometer, and the ova growth rate determined. Deviation from a 1:1 ratio of ova number between right and left ovary in 22 fish was tested with chi-square, as was deviation from a 1:1 sex ratio. Standard length (SL) and total length (TL) were measured to the nearest mm and total body weight to the nearest 0.01 g. Eggs were collected where adults were most common. Pieces of concrete block, bricks, and water-logged wood suitable as egg attach- ment sites were provided on 9 March 1980 and 22 February 1981. Color was recorded on live eggs; other data are from preserved eggs. Attempts to collect larvae with a fine-mesh dip net and a 0.5 mm plankton net were made in the same area. Age was determined by the length-frequency method. Although otoliths have been used to determine age in sculpins (Koster 1936: Lud- wig and Norden 1969; Patten 1971; Petrosky and Waters 1975), our results using otoliths from both fresh and preserved C. bairdi were inconclusive. The relationship between growth in weight and in length for specimens that could be sexed was determined by fitting a regression line on the logarithms of mean weights and SL for 3 mm intervals. Fitness was determined with the coefficient of condition (K) using the formula K - W X 1Q5, where W is weight (g) and L is SL (mm). L3 Based on examination of 539 stomachs, we determined the number of food items in five fish SL groups (< 20 mm, 20-29 mm, 30-39 mm, 40-49 mm, > 49 mm), and the percent occurrence of food by month. Voucher specimens from all localities were deposited in the Academy of Natural Sciences of Philadelphia (ANSP 145647, 145648, and others), and specimens from the Butler Mill Branch locality were also deposited at Iowa State University (ISU 1995, 1996), and the Uni- versity of Florida (UF 30136, 30137). STUDY AREA The Butler Mill Branch system lies between 8 km northwest and 4 km southwest of Seaford, Sussex County, Delaware. It consists of Horse 72 Fred C. Rohde and Rudolf G. Arndt Pen, Green Briar, and Butler Mill branches, and several unnamed tribu- taries. Its maximum length is 10.5 km (9.0 km straight-line) and its area 23.8 km2. The creeks are bordered by mature lowland forest of red maple, Acer rubrum; American holly, Ilex opaca; green ash, Fraxinus pennsylvanica; tulip tree, Liriodendron tulipifera; sweetgum, Liquidamber styraciflua; black tupelo, Nyssa sylvatica; and sweetbay, Magnolia virgin- iana; some upper parts, however, pass through agricultural fields. In the upper system the dominant creek substrate is mud and mud- sand, and typical stream width and depth in spring are 1 m or less, and some 20 cm, respectively. Gravel patches appear downstream and become more common lower in the system. Greatest stream width is 7 m, at a point below an impoundment (Craigs Pond) on lower Butler Mill Branch. The uppermost waterways sometimes dry completely, and areas just downstream of these form pools. Current and flow in the lower system are strong all year. Storms often cause local creekside flooding. Aquatic vegetation, consisting of several vascular species and filamentous green algae, is local and often luxuriant. Rocks, usually prominent in C. bairdi habitat, are absent. Coitus bairdi is found only in areas of permanent and pronounced flow (Fig. 1). In its upstream distribution, C. bairdi is found only over gravel patches, where concomitantly there is a stronger current. Creek width here is often only 1 m, with depths to 5 cm. Patches are typically about 1 m long and 0.3 m wide, comprised of fine gravel and sand, and located several dozen meters apart. Cottus bairdi occurs but sparingly on these patches. Gravel patches and C. bairdi are both progressively more common farther downstream in Horse Pen, Green Briar, and Butler Mill branches. Cottus bairdi is not found below or just above Craigs Pond, although prior to impoundment it likely did occur in both areas. All preserved specimens and related data, unless otherwise specified, were collected in a sampling area located in the downstream part of the study area (Fig. 1), over and near two large and easily accessible gravel riffles (of 4.6 m X 6.5 m and 4.6 m X 28.0 m). The strongly meandering stream here is 4 to 5 m wide, with a substrate of alternating gravel riffles, mud-bottom pools, and sand. The riffles are several cm deep, the pools to 1.2 m, and sand occurs at intermediate depths. The banks are steep and frequently undercut, with masses of exposed fine tree roots. The south bank abuts lawns behind homes, and the north side is mostly forested. Concrete block riprap has been placed along the developed shore to prevent erosion. Dominant aquatic vegetation is pondweed, Potamo- geton sp.; water starwort, Callitriche palustris; water purslane, Ludwigia palustris\ bur reed, Sparganium sp.; and unidentified filamentous green algae. Vegetation occurs primarily in cleared, sunlit areas near the homes and highway. Cottus bairdi is abundant throughout. The water, usually Cottus Life History in Delaware 73 i N 0 .5 1.0 Kl LOMETERS ...... indicates distri- bution of Cottus bairdi in Butler Mill Branch and tributaries • •• — indicates sampling SEAFORD -no 7T\ SAMPLING Fig. 1. The Butler Mill Branch system near Seaford, Sussex County, Delaware, showing Cottus bairdi distribution and sampling area. clear, is turbid after rain. Temperature in the sampling area ranged from 5.5° C (February) to 20.0° C (July), pH from 5.7 to 7.0 (typically 6.5), and dissolved oxygen concentrations from 9.1 to 12.8 ppm. Stream flow data were taken in the sampling area on 22 dates between 30 June 1955 and 16 April 1969 by the U.S. D.I. Geological Survey, Water Resources Division (Robert H. Simmons, pers. comm.) at low-flow conditions (after periods of no rain for four or five days). Aver- age stream cross-section area was 0.76 m2 (range 0.20-2.17), mean flow 0.16 m3/sec (0.04-0.46), and mean water velocity 0.21 m/ sec (0.10-0.29). The lowest values were from summer, the highest from spring and late fall. Fifteen fishes were taken with C. bairdi (number of times in paren- theses) in a total of 26 collections made in the sampling area during 1973-80: Lampetra aepyptera (20), Anguilla rostrata (18), Umbra pyg- maea (11), Esox americanus (1), Esox niger (6), Notemigonus crysoleucas (4), Erimyzon oblongus (17), Ictalurus natalis (2), Ictalurus nebulosus (1), 74 Fred C. Rohde and Rudolf G. Arndt Aphredoderus sayanus (10), Acantharchus pomotis (1), Enneacanthus gloriosus (3), Lepomis gibbosus (5), Lepomis macrochirus (6), and Etheostoma olmstedi (26). Cottus bairdi habitat in Caroline and Dorchester counties, Mary- land, including physicochemical characteristics, is as described for Butler Mill Branch. Maryland fish species-associates include some of those listed previously, plus Etheostoma fusiforme and Percaflavescens. RESULTS AND DISCUSSION Reproduction Spawning occurs in February and March. Two females taken 17 March 1974 each contained only two ova, indicating the end of spawning. On 2 March 1975, 1 of 3 1 females was spent and, although other females contained ova, there were fewer than in 1974, 1979, and 1980 pre- spawning samples, indicating spawning was under way. Spawning was completed by 23 March; all ovaries were empty except for some ova being resorbed. Spawning in 1979 was later, and females collected on 16 March still possessed a full ova complement. In 1980 females spawned primarily between 9 and 22 March: on 9 March none had spawned, on 15 March 2 of 22 were spent, by 22 March all but 1 were spent, and on 30 March all taken were spent. Examination of specimens in the field in 1981 yielded the following ratios of females heavy with eggs to spent females: 22 February, 13:1; 27 February, 10:2; and 7 March, 7:3. On subsequent dates all taken had completed spawning. February and March spawning is generally earlier than that reported for C. bairdi. Other reports based on direct (deposited eggs) or indirect (mature ova or specimens in breeding condition) evidence are: Nagel (1980), Tennessee, early April; Ludwig and Norden (1969), Wisconsin, 1 April to 3 May; Ricker (1934), Ontario, middle of May; Bailey (1952), Montana, most of June; Gage (1878), New York, April; Koster (1936), New York, April to June; Smith (1922), Michigan, April and May; Rob- ins (1954), Appalachian region, late March to early May. Pflieger (1975) found presumed C. bairdi eggs in Ozark streams from early November to late February. William L. Pflieger (pers. comm.) has confirmed records of eyed eggs from 2 February 1971 and of males guarding egg masses with embryos far enough advanced to show movement on 23 and 29 February 1971, which indicates spawning occurred at least as early as January. This early spawning, however, may not be attributable to C. bairdi, as most Ozark populations are considered to represent an undescribed species. Ovary weight as a measure of gonad development during 1973-75 was low in October and November 1973, increased rapidly in January, and peaked in February 1974 (Fig. 2, Table 1). The gonosomatic ratio Cottus Life History in Delaware 75 SONDJ FMAMJ JASONDJ FMAMJ JA 1973 1974 1975 197B 1979 1980 MON THS Fig. 2. Relationship between gonad weight and body weight in male and female Cottus bairdi from Butler Mill Branch, Sussex County, Delaware, October 1973- March 1975 (solid lines) and September 1978-August 1980 (broken lines). dropped markedly in March 1974, at spawning, was low through summer, and increased again in November. The maximum value was reached early in March 1975, and was followed rapidly in mid-March by another sharp post-spawning decrease. The gonosomatic ratio pattern for males was similar to that for females, but monthly differences were not as pronounced (Fig. 2, Table 1). Maximum development in 1974 was in January, followed by a summer decline and a fall increase, and values 76 Fred C. Rohde and Rudolf G. Arndt Table 1. Average combined monthly gonosomatic ratios (expressed as %) for Cottus bairdi from Butler Mill Branch, Sussex County, Delaware, 1973- 1980. Number of specimens in parentheses. 1973-75 1978-80 Month Male Female Male Female January 1.52 (4) 7.57 (20) February 1.40 (2) 19.51 (3) March 1.05(15) 20.73 (33) 0.85 (35) 16.51 (71) May 0.09 (3) 0.65(14) June 0.09 (5) 0.74(17) July 0.21 (5) 0.57(14) 0.16 (6) 0.56(13) August 0.20 (1) 0.53 (1) September 0.53 (3) 0.71 (14) 0.16(14) 0.49 (5) October 1.21 (7) 1.46 (4) November 1.26(17) 2.18(25) 1.94 (4) 2.68 (1) remained high from November through March. Both sexes in 1978-80 showed patterns similar to those of 1973-75. The March 1979 value for females, however, was markedly higher than that of other years, and reflects a later spawning in 1979. Fecundity, a general term that refers to number of ova produced, is restricted in this study to the number of mature ova present in the ovaries from January to mid-March. Mean ova number per female (N = 67) is 93.7 (range 37-156), and mean female SL is 36.9 mm. The regression equation for the relationship between SL and ova number (Y) is: Y = -157.1 1 + 6.80 SL (Fig. 3). The correlation coefficient, r = 0.90, indicates a strong positive relationship between ova number and SL (P< 0.001). Fecundity of the Butler Mill Branch sculpins is low when compared with data for other species of Cottus and for other populations of C. bairdi in Williams (1968), Ludwig and Norden (1969), Patten (1971), Foltz (1976), and Nagel (1980). Exceptions are the diminutive C. pyg- maeus, with a range of 30 to 43 ova (Williams 1968), and C. bairdi from northeastern Tennessee with means of 55.5 to 67.7 ova (Nagel 1980). The low fecundity observed in our specimens and in C. pygmaeus is correlated with their small size, while in the Tennessee population it appears to be correlated with a greater ova size. Females taken in 1978-80 were more fecund (Y = -209.87 + 8.13 SL) than in 1973-75 (Y = -142.24 + 6.46 SL). This difference is significant (0.05 level, testing the slope), and may be a function of size. However, although females in 1978-80 were larger (x SL = 38.2 mm) than in 1973-75 (xSL= 34.5 mm), the difference of the means is not significant. Nagel (1980) noted a similar difference in fecundity Cottus Life History in Delaware 77 160- 140 120- « 100 LU CO s D Z 80- < > O 601- 40- 20- 10 20 30 40 STANDARD LENGTH (mm) 50 Fig. 3. Relationship between number of mature ova and standard length of Cottus bairdi from Butler Mill Branch, Sussex County, Delaware. between two sampling periods, in which there also was no significant difference in size of adults. Hann (1927) generalized that fecundity in C. bairdi is approximately proportional to the cube of the female's length. This is in agreement with relationship, Log F = -2.738 + 2.962 Log SL, observed by Ludwig and Norden (1969) in Wisconsin. Their fecundity-length relationship is higher than that observed by us for all Butler Mill Branch females examined: LogF= -2.129 + 2.608 Log SL. The regression equation for the relationship of ova number (Y) to 78 Fred C. Rohde and Rudolf G. Arndt body weight (W) is: Y = 49.19 + 31.43 W. The correlation coefficient of 0.77 is significant (P< 0.001), and indicates a positive relationship between ova number and gravid female weight. Mature ova (large and orange) were not observed in 235 females until January. In 1974, mean diameter of ova from 14 preserved females increased from 1.18 mm in January to 2.07 mm just prior to spawning in March. The largest ovum measured 2.4 mm (early March). Values in 1975 (N - 23 females) fell within these ranges. In March 1980 (N = 20 females) the range was 1.8 to 2.5 mm (x = 2.15 mm). There was no difference in mean ovum diameter between ovaries (N = 22 females). Ludwig and Norden (1969) gave ova diameters of 1.50 to 2.06 mm (x = 1.88 mm) in Wisconsin, and Hann (1927) of 2 to 2.5 mm in Michigan. Nagel (1980) observed a larger average ovum size (3.32 mm) in Tennessee C. bairdi and suggested that it correlated with the smaller number of ova produced. The relationship between diameter of mature ova and SL is signifi- cant (r = 0.55; P<0.01). This is in agreement with Hoar (1957) who stated that mature ova size depends both on size of parent and on nutri- tion during the pre-spawning period. In seven females, the right ovary was usually longer (x = 9.5 mm) and narrower (x - 4.2 mm) than the left (x = 8.7 and 5.0 mm, respectively). The right contained a mean of 41.2 ova, the left 39.9. There is no signifi- cant chi-square difference from the expected 1:1 ratio (P>0.05). A total of 2 egg clusters was found in 1980, and 37 in 1981. The larger number was due to additional egg attachment sites provided in February 1981, and to more extensive searching. In 1980, the first cluster was found on 15 March and the second on 22 March (deposited in the interim). In 198 1 , the first seven clusters were found on 27 February, five others on 7 March, and another six on 14 March. Additional clusters found on subsequent dates resulted (at least primarily) from searching in areas not examined earlier, rather than from later egg deposition. All clusters were found in and near two gravel riffles in the sampling area (Fig. 1), and to about 30 m upstream. All were in areas of fast current, usually near the stream center, and over gravel or gravel-sand substrate. Water depth by the eggs (on several dates in early 1980 and 1981) ranged from 3 to 50 cm (x = 20.0 cm, N = 40 measurements). With one exception, every cluster was attached to the underside of a submerged object. The exception was in a hollow on the upper surface of a submerged log. One cluster was under a beer can and another under a bottle, and three others were under waterlogged wood: a branch, a piece of board, and a piece of cut log. Favored egg-attachment sites were pieces of concrete block and bricks, and 23 (58.9%) of the clusters were found on such objects. Ten clusters (25.6%) were on ironstone and silicified Cottus Life History in Delaware 79 sandstone (both usually flat and concave beneath). Both occur naturally in this part of the Delmarva Peninsula, but the large local concentration was probably dumped there for old construction. Only two clusters (5.1%) were found on naturally-occurring material (log and branch). The general absence of rock or other suitable spawning sites in Delmarva Peninsula streams may limit C. bairdi distribution. Four substrate samples from these two gravel riffles yielded particles that ranged in size from greater than 2.5 cm to smaller than 0.05 cm; about half the particles (by weight) were in the size category 0.8 to 2.5 cm (Table 2). By contrast, about half the particles (by weight) in three samples from three gravel patches in Horse Pen Branch were 0.05 cm or smaller (Table 2). The largest pieces of gravel collected in the sampling area riffles measured (maximum length and width, cm) 7.5 X 3.9, 6.1 X 3.5, and 5.9 X 4.2, while the largest from Horse Pen Branch were 2.2 X 1 .7, 2.3 X 1 .4, and 2.0 X 1 .4. Cottus bairdi was much more common over the riffles of larger gravel, perhaps because under natural conditions these facilitate spawning. We consider 32 of the 39 clusters to represent the spawn of 1 female, 3 the spawn of 2 females, and 4 the spawn of 3 females. Ludwig and Norden (1969) noted a mean of 3.3 spawns per cluster. Koster (1936) observed up to six clusters in a nest, but noted that most nests contained from one to four egg masses. Clusters resulting from multiple spawnings can be identified by their larger size, varied egg mass colors, and irregular configuration. There were four instances of two single spawns found under one piece of substrate (each cluster was counted as the spawn of one female), and several cases of single- and multiple-spawn clusters on substrate with multiple-spawn clusters. Thus, the result of a total of 50 spawnings was found, deposited on a total of 31 pieces of substrate. Color of live eggs was usually pink-orange, but the range in color of clusters was from orange to yellow to tan, and one cluster was almost white. About half of the clusters contained one to several white eggs, presumed to be unfertilized. Most clusters were approximately circular in outline, with eggs arranged in irregular rows, usually to four or five layers deep. They adhered strongly to the substrate and to each other. Egg cluster mean length, width, and height, respectively, and the range of each (in mm), for the total sample sizes given previously were: single spawn, 24.8 (16-37), 20.6 (13-29), 8.1 (6-12); two spawns, 40.0 (28-45), 24.3 (22-26), 8.6 (7-10); and three spawns, 48.2 (40-56), 30.0 (28-32), 1 1.7 (8-19). Egg number in 1 1 single-spawn clusters ranged from 64 to 201, with an egg diameter range (measured to nearest 0.1 mm) of 2.2 to 3.5 mm, and a mean egg diameter per cluster range of 2.32 to 3.09 mm; egg number for one triple-spawn cluster was 623, with a range in egg diameter 80 Fred C. Rohde and Rudolf G. Arndt 00 Ej O oo !_ ON £ > ^ c T3 3 C O cd U vs 1 X 0J > 03 =3 00 CZ3 .X en O 00 cd cu c« c Tt On sO p ' Os rn <* Tt u c/a cj 00 C oo c cd c cd u cd a: S 0* 00 c Cu _ £ ^ c 1) cu i cd Tt -C Z i— O w CJ Cu) oq £ C/3 3 OQ o PC CJ ^ C en cd ll Cottus Life History in Delaware 81 of 2.5 to 3.4 mm, and a mean egg diameter of 2.87 mm (Table 3). Range in egg number was higher than that determined by examination of ova in females, as was the mean of 134.2 eggs (measured only for single-spawn clusters) versus 93.7 ova per female. These differences are not readily explained. Butler Mill Branch sculpin eggs are smaller in diameter than those found by Nagel (1980) in Tennessee (x - 3.73 mm). There was no relationship between egg diameter and date collected, or between egg diameter and cluster size. Eggs preserved on the following dates were in the indicated stages of development: 27 February 1981, morula or earlier; 14 March 1981, morula and blastoderm; 15 March 1980, morula or earlier; 22 March 1981, morula or earlier ( 1 cluster), and with large, well-developed, curled embryos with large, black-pigmented eyes (3); 26 March 1981, with less well-developed young than the latter 22 March eggs, with large, gray eyes (1), and with well-developed young (1); and 29 March 1981, with well- developed young. Eggs in many clusters in the field on 22 March 1981 contained well-developed, active young. The number of eggs and clusters found with such advanced embryos increased on subsequent dates. Eggs hatching in the field were first noted on 29 March 1981, when several empty egg shells were found in each of four clusters. Embryos in the remaining eggs were advanced and active. One cluster missing on this date may have totally hatched (rather than being destroyed by predators or high water). By 5 April 1981, all eggs in nine clusters had hatched, by Table 3. Data on Cottus bairdi egg clusters collected in 1980 and 1981 at Butler Mill Branch, Sussex County, Delaware. Date collected and preserved N spawns/ N eggs/ cluster cluster Range egg diameter (mm) x egg diameter (mm) N eggs measured 27 February 1981 170 2.6 - 3.4 2.86 20 27 February 1981 201 2.5 - 2.9 2.66 20 14 March 1981 117 2.2 - 2.5 2.32 20 15 March 1980 133 2.2 - 2.5 2.33 30 22 March 1980 64 2.3 - 2.4 2.35 20 22 March 1981 119 2.6 - 2.9 2.77 20 22 March 1981 170 2.8 - 3.1 2.94 20 22 March 1981 126 2.7 - 3.1 2.85 20 22 March 1981 ; 5 623 2.5 - 3.4 2.87 50 26 March 1981 126 2.3 - 2.7 2.51 20 26 March 1981 181 2.7 - 3.5 3.09 20 29 March 1981 70 2.4 - 2.7 2.56 20 82 Fred C. Rohde and Rudolf G. Arndt 1 1 April almost all clusters had totally hatched, and by 18 April all had hatched. Relatively detailed data on hatching are available for two single- spawn clusters. On 7 March 1981, a pair of C. bairdi and eight eggs were found under a brick and we assumed the fish were spawning. No eggs were found here on 27 February. On 14 March, what we assumed to be the remainder (and much larger portion) of that cluster was found nearby on the brick. (Lifting of the brick on 7 March presumably interrupted spawning and caused its resumption at another point.) On 22 March, eggs of the group of eight contained well-developed embryos. On 26 March, well-developed young were still visible, with earlier-stage young in the larger portion. On 29 March, the eight eggs were missing and we presume they hatched. The incubation period was thus some 22 days. The remainder had not hatched by 5 April. The brick with eggs and guarding male were then placed in a plastic gallon jar with netting at each end to allow passage of a current of water, and replaced in the stream. On 1 1 April, most eggs and hatchlings had decayed, but three eggs were near hatching. The development period of these eggs was thus about 35 days. About half the eggs of another cluster found on 7 March 1981 (not present on 27 February) was hatched by 5 April, and the remainder contained well-developed embryos. On 1 1 April only 10 eggs remained, and on 18 April there was none. Time to hatching was some 29 to 42 days. As in the field, eggs of a cluster also hatch over a period of days in the laboratory. A field-collected cluster maintained at approximately field water temperatures (10° to 12° C) hatched as follows: 7-8 April, 4; late 8 April, 59; 9 April, 14; evening of 9 April to mid-afternoon on 12 April, several; by mid-afternoon on 13 April, 4. Three eggs from another cluster hatched on 8 April 1981. A male guards each cluster, and a male guarding a multiple-spawn cluster was presumably successful in spawning with up to three females. Koster (1936) stated that a successful male spawns with one or more females, and Scott and Crossman (1973) noted that it is usual for more than one female to deposit eggs in a male's nest. The same male stays with a given cluster until the last eggs hatch. He is usually hidden under the egg-deposition site, but sometimes lies with the head or body exposed. Rarely a guarding male was found with a second male, and once two males were hidden with a female heavy with eggs. These latter occurren- ces, however, may have been sampling artifacts. Early in the 1981 reproductive season, from 22 February through 7 March, each male examined was in dark reproductive coloration. The dorsum and sides were olive-drab to blackish, the head and fins blackish, and the first dorsal fin edged with dull yellow and orange. The posterior Cottus Life History in Delaware 83 venter was smoky-gray with fine black stippling, and the breast and abdomen dull whitish. The normally prominent black saddles were indis- tinct. On 14 March, seven of eight males were so colored, while one had the more typical tan background color with prominent chocolate-brown saddles. On each subsequent date, through 29 March 1981, some males had the dark coloration described above, but the number of such males then found per date never exceeded those with the brown body. Even some males guarding eggs on and after 14 March 1981 were brown. Water temperature during the spawning period ranged from 7.5° to 12.5° C in March 1975, and from 6.5° to 11.0° C in March 1980. Temperatures from other years were within these ranges. Koster (1937) reported spawning in upper New York State at 10° C, Bailey (1952) in Montana at 7.8° to 12.8° C, Ludwig and Norden (1969) in Wisconsin at 8.9° to 13.9° C, and Nagel (1980) in Tennessee at 12° C and 14° C. Water temperature fluctuates considerably during egg development. Tempera- tures (°C) at Butler Mill Branch in 1981, from the date before the first eggs were found (22 February) through the date after the last were found (18 April), were: 10.0, 9.0, 7.5, 8.0, 7.0, 11.0, 11.5, 13.5, 12.0, and 16.0. Eggs in 1980 (two dates) were found at 8.0° C and 6.5° C. The difference between number of males (69) and females (156) collected during the reproductive season was highly significant (chi- square, P<0.001, expected ratio 1:1). The observed values may be a sampling artifact. However, as a male is known to spawn with more than one female, it is also possible that the observed values reflect a real difference. Ludwig and Norden (1969) noted a reduction in number of males at commencement of the spawning season, and suggested it resulted from competition for nesting sites and some segregation of sexes. Koster (1936) found no significant difference in the proportion of males to females. Age and Growth The Butler Mill Branch sculpins are more short-lived than reported for any other Cottus species. This may be related to early onset of sexual maturity. Further, only few Butler Mill Branch C. bairdi that reach age group I survive to spawn twice. Length-frequency distributions based on the total sample through 1980 indicate the existence of three age groups: O, I, and a presumed II (Figs. 4,5). In 1974, group I fish were present from January to September, but none was collected in November. Of later samples, some group I fish were still present in November 1978. A few may have survived the winter, as indicated by the large specimens Q> 50 mm SL) collected in March and July 1979, which would then have been in age group II. Fish corresponding to this age group were also present in the 1980 samples. Of the 403 sculpins collected in 1980, 262 (65.0%) were 84 Fred C. Rohde and Rudolf G. Arndt 10 20 15- 10- 5- UJ 10 CO i 5 20 15 10 5- T ikOa.. 20 * 30 40 STANDARD LENGTH (mm) 2,23 MAR. 1975 N 65 30 NOV. 1974 N 122 8 SEPT. 1974 N 101 20 JULY 1974 N 94 17 MAR. 1974 N 5 17 FEB. 1974 N 5 20JAN. 1974 N 26 28 OCT., 4 NOV. 1973 N 17 Fig. 4. Length frequencies of Cottus bairdi from Butler Mill Branch, Sussex County, Delaware, October 1973-March 1975. Solid bars = males; open bars - females; hatched bars = unsexed young. Coitus Life History in Delaware 85 15- 10- 10- i 5- d EL. tHbi-- cLAm. .. 30 40 50 STANDARD LENGTH (mm) 9 AUG. 1980 N 55 25 JULY 1980 N 68 12 JULY 1980 N 77 28 JUNE 1980 N 61 8 JUNE 1980 N 35 4,20 MAY 1980 N 17 9,15,22,30 MAR. 1980 N 90 25 JULY 1979 N 67 16 MAR. 1979 N 17 26 NOV. 1978 N 6 7 SEPT. 1978 N 46 Fig. 5. County females: Length frequencies of Cottus bairdi from Butler Mill Branch, Sussex Delaware, September 1978-August 1980. Solid bars = males; open bars = hatched bars = unsexed young. 86 Fred C. Rohde and Rudolf G. Arndt in age group O at time of capture, 133 (33.0%) in group I, and 8 (2.0%) in presumed group II. Although the data are limited, and assuming that each age group was collected proportional to its actual number in the population, 33.0% of group 0 survived to spawn as group I fish, and 2.0% to spawn a second time. Survival rates have not been calculated for other populations of any species of Cottus. Three just-hatched young (measured to nearest 0.1 mm) from one cluster averaged 6.56 mm SL, and 24 from a second cluster averaged 6.05 mm. Hann (1927) observed a mean size at hatching of 6.4 mm SL. Newly hatched young in other studies ranged from 5.6 mm SL to 9.8 mm TL (see Nagel 1980). The body of a newly hatched young is slightly opaque, with no evidence of the dark saddles, and with a prominent yolk sac. Five siblings of 98 hours of the second cluster averaged 6.54 mm SL. The yolk sac of these is greatly reduced and only slightly protrudes from the body, and melanophores form weakly-defined saddles. Five siblings of 195 hours averaged 6.96 mm SL. Their yolk sac appears fully resorbed, melanophores are conspicuous on the body, and the saddles are better defined. Three additional siblings of 288 hours averaged 6.63 mm SL. Two young-of-year taken on 19 May 1981 were 10 mm SL and 12 mm SL, and resembled the adult in morphology and coloration. No young were taken until 8 June in 1980 (Table 4, Fig. 5), at which time they averaged 13.5 mm SL (range 1 1-16 mm), an assumed post-hatching increase of 7.5 mm. Subsequent samples taken approximately biweekly revealed a decrease in growth rate, from a 4.9 mm increase over 20 days to 28 June, to but a 2.4 mm increase in the 15 days to 9 August. Most growth occurred in the first calendar year of life. Young taken in July 1974 ranged from 16 to 26 mm SL (x= 21.1 mm). From hatching at 6 mm in early to mid-April, growth in the 1974 year class was rapid: to 21.1 mm in July, 24.2 mm in September, and 30.0 mm in November Table 4. Monthly mean standard lengths, by sex, for 1978, 1979, and 1980 year classes of Cottus bairdi from Butler Mill Branch, Sussex County, Delaware. Number of specimens in parentheses. 1978 Year Class 1979 Year Class 1980 Year Class Date Unsexed Male Female Unsexed Male Female Unsexed 37.8(10) 44.0 (8) 23.1 (56) 59 (1) 59.5 (2) 7 Sept. 1978 30.9(19) - 16 Mar. 1979 - 49.9 (7) 25 Jul. 1979 - 43.3 (3) 9, 15,22,30, Mar. 1980 - 59.4 (4) 4, 20 May 1980 - - 8 Jun. 1980 - 61 (1) 28 Jun. 1980 - - 12 Jul. 1980 - - 25 Jul. 1980 - - 9 Aug. 1980 - - 45.0 (24) 38.2(62) - 47.3 (3) 41.4(13) - 47.0 (3) 42.8 (8) 13.5(23) 45 (1) 41.3 (7) 18.4(51) 47.0 (4) 41.5 (4) 22.2 (69) 50 (1) 43 (1) 24.5 (66) 51 (1) 45 (1) 26.9(53) Cottus Life History in Delaware 87 Table 5. Monthly mean standard lengths, by sex, for 1973 and 1974 year classes of Cottus bairdi from Butler Mill Branch, Sussex County, Delaware. Number of specimens in parentheses. Date 1973 Year Class 1974 Year Class Male Female Unsexed Male Female 28 Oct., 4 Nov. 1973 32.5 (6) 27.7(10) 20 Jan. 1974 36.6 (5) 33.8(21) 17 Feb. 1974 41.5(2) 38.7 (3) 17 Mar. 1974 41.0(3) 38.0 (2) 20 Jul. 1974 46.7 (3) 41.5 (8) 21.1 (83) - - 8 Sep. 1974 43.5 (6) 40.5(13) 24.2 (82) - - 30 Nov. 1974 - 41 (1) 30.0(121) - - 2 Mar. 1975 - - - 30.7(18) 29.8 (37) 23 Mar. 1975 - - - 35.0 (3) 30.4 (7) (Table 5). By next March these fish, now in age group I, were mature and had spawned. Males (N = 21) now averaged 31.3 mm SL and females (N = 44) 29.9 mm. Growth in the 1973 year class was at first similar, with a combined October-November sample mean length of 29.5 mm SL. However, growth did not decrease pronouncedly or cease in winter as noted in the 1974 year class and as reported for a population by Bailey (1952). Rather, sculpins of the 1973 year class apparently continued to grow from November to March. For combined February-March 1974 samples, both sexes (5 males, 5 females) averaged some 10 mm longer than those taken in early March 1975. The reason for this difference is not known; it may be an artifact of small sample size. Nagel (1980) also noted such between- year variation in growth rate. The 1979 year class (age group I) exhibited little growth, if any, from June through August (Table 4). A few fish presumed of the 1978 year class (age group II) were also present in the 1980 samples. These were 10 to 15 mm longer than those collected the previous spring, interpreted as growth continuing during the second year of life. Cottus bairdi in Montana exhibited a growth rate comparable to Butler Mill Branch specimens during age group 0, but none matured until in age group II and when usually longer than 74 mm TL (Bailey 1952). Ludwig and Norden (1969) observed growth similar to Sussex County Cottus in age groups 0 to II, but reported earliest maturity in Wisconsin sculpins in age group II (x SL = 54.5 mm, range 37-70). Nagel (1980) noted reproduction in Tennessee at the end of the second year of life, at 88 Fred C. Rohde and Rudolf G. Arndt 50-81 mm TL. Hann (1927) stated that sexual maturity in Michigan is attained by two years of age, at 45-70 mm SL. Koster (1936) found that first spawning in a stream-dwelling population near Ithaca, New York, occurred at the end of the second year of life (age group II), while some specimens of a lake-dwelling population from nearby Cayuga Lake apparently matured at the end of the first year of life (age group I). This early maturity may result from a genetic or an environmental difference between these populations. Butler Mill Branch sculpins reached sexual maturity at a smaller size than any other population of C. bairdi (x SL = 37.4 mm, range 22-64, N = 225). Mean length of 33 Butler Mill Branch adults taken in 1981 was 44.7 mm SL (range 35-65 mm). Adults from the new localities in Caroline and Dorchester counties, Maryland, were of similar size (x SL = 38.7 mm, range 29-62, N = 48), and Franz and Lee (1976) noted small size in the other Caroline County population. Mature males in the March and May 1978-80 samples were larger (x SL = 47.6 mm, range 37-64, N = 38) than mature females (x SL = 38.9 mm, range 32-59, N = 86), a highly significant difference (P<0.001). However, there was no significant difference at the 0.05 level in the January, February, and March 1973-75 samples (mature males, x SL = 33.7 mm, range 25-47, N = 31; mature females, x SL = 31.7 mm, range 22-40, N = 70). The reason for the size difference of 1978-80 is not appar- ent. Such sexual dimorphism was also observed by Hann (1927), Bailey (1952), Ludwig and Norden (1969), and Nagel (1980), but not in New York sculpins by Koster (1937). Regressions for the weight-length relationship derived for males and females from both sampling periods are: (1973-75) males, Log W = - 10.8985 + 3.0585 Log L, r = 0.99; females, Log W = -10.3999 + 2.8814 Log L, r = 0.99; (1978-80) males, Log W = -1 1.8313 + 3.3681 Log L, r = 0.99; and females, Log W = -1 1.0505 + 3.1412 Log L, r= 0.99. Analysis of covariance reveals significant differences (P<0.05) in slope between sexes and between years. A slope greater than 3.00, indicating that relative weight increased faster than length (Ricker 1971), is noted in three of four regressions. Only females in 1973-75 showed a slightly faster increase in length when compared to weight. There is a strong, and expected, positive correlation between SL and TL: SL= 1.21 + 0.76 TL, r= 0.93. Condition factor (K) for both sexes is lowest during the coldwater months preceding spawning (Table 6). Highest K values were recorded during the warmwater period subsequent to spawning. With the excep- tions of October and November, males were more robust than females. Cottus Life History in Delaware 89 Table 6. Combined monthly averages of coefficient of condition (K) for male and female Cottus bairdi from Butler Mill Branch, Sussex County, Delaware, 1973-1980. Male N = 145, female N = 278. Month Male Gonads Gonads in situ excised 2.06 2.06 2.10 2.08 2.88 2.84 3.07 3.07 2.88 2.88 2.53 2.70 3.33 3.33 2.36 2.26 2.19 2.17 2.34 2.32 Female Gonads Gonads in situ excised Jan. Feb. Mar. May Jun. Jul. Aug. Sep. Oct. Nov. 2.06 1.93 2.44 1.96 2.58 2.12 2.63 2.62 2.67 2.65 2.27 2.26 2.68 2.66 2.14 2.06 2.20 2.17 2.39 2.34 Food Habits Based on stomach contents of 539 fish ( 1 2-64 mm SL), food is prim- arily larval trichopterans (in 55.7% of stomachs) and dipterans (42.3%), and plecopteran nymphs (19.7%); less important are crustaceans (9.2%), ephemeropteran nymphs (8.0%), and coleopteran larvae (2.4%) (Table 7). Nineteen taxa were identified. One hundred and twenty-eight (23.7%) stomachs were empty. Franz and Lee (1976) found 5 taxa in 10 speci- mens. Ricker (1934), Koster (1936, 1937), Dineen (1951), Bailey (1952), and Daiber (1956) also found that the primary food was benthic insect larvae. Seasonal variation in diet is evident (Table 7). Trichopterans, mainly Hydropsychidae, were eaten in all months except February, and were dominant in March, July, August, and September. Dipterans, primarily Chironomidae, were the most common food in January, June, October, and November. Plecopterans were common from January through May. Prey taxa differed only slightly by fish size group (Table 8). Chiro- nomids were relatively more important to sculpins smaller than 19 mm SL than to longer fish. Larger specimens (>49 mm SL) ate fewer chiro- nomids but more larger simulids. A 43 mm SL sculpin contained one 25 mm SL Etheostoma olmstedi, and a 53 mm SL specimen had eaten an egg of Lampetra aepyptera. 90 Fred C. Rohde and Rudolf G. Arndt C/3 o c 1 X) o ^ © oo o — as 5 o o d H > 00 d CM m ^d r-' rn q q »ri d o u u u 03 o "Q a> C3 S3 £ S. e ^ s 4> 03 >» 'C j** "O o3 T3 a, «-• emero] eptage eptoph nident o3 O O o D- o 03 o O > j= >» j= = £ o D- U D ^OC J D o < N O X Ou D < (/i £ uu O H Cottus Life History in Delaware 91 © — — — o • — SO so — 6 « «fr r- NO O x> S 3 92 Fred C. Rohde and Rudolf G. Arndt Table 8. Mean number of food items, by length groups, in stomachs of Cottus bairdi from Butler Mill Branch, Sussex County, Delaware, 1973-1980. Food Cottus SL (mm) <20 20-29 30-39 40-49 >49 .01 .04 .01 .01 .15 .04 .16 .01 .01 .36 .53 .03 .04 .13 .15 .06 .04 .10 .06 .02 .02 .02 .02 .01 Nematoda Oligochaeta Crustacea Amphipoda .22 .15 .04 .16 .08 Isopoda Insecta Plecoptera Perlodidae Chloroperlidae Unidentified Ephemeroptera Heptageniidae .06 .04 .06 Leptophlebiidae Unidentified Odonata Anisoptera .01 Zygoptera .01 Trichoptera Hydropsychidae 1.17 Phryganeidae Unidentified Coleoptera Elmidae Gyrinidae Unidentified Diptera Chironomidae 7.89 Simuliidae Tipulidae Unidentified .01 Osteichthyes Lampetra aepyptera .08 Etheostoma olmstedi .0 1 Number of stomachs with countable food items 18 122 152 68 13 Abundance Throughout most of this study we assumed that the Butler Mill Branch sculpin population was small. Work in early 1980, however, revealed the species to be more widely distributed here than previously .89 .94 1.16 1.23 .01 .09 .19 .04 .01 .06 .01 .01 .01 1.61 2.51 .28 .23 .10 .05 .03 .19 .46 Cottus Life History in Delaware 93 known, and in March both frequency of sampling and sample size were increased. Surprisingly, no effect of increased collecting on the popula- tion was noted. Although on each collection date the sampling area was almost cleared of specimens, and no additional sculpin could be found, on each subsequent visit the area again was productive. Thus, it appears that many fish escaped capture, or that there was extensive and rapid movement into the sampling area from nearby. Probably both were important. Certainly larval C. bairdi are secretive, which probably explains our failure to catch them at Butler Mill Branch. Hatchlings in the laboratory are benthic to at least 288 hours. When disturbed they are strong swimmers, but then settle rapidly and remain quietly in gravel. This larva-gravel association may explain why C. bairdi is restricted to areas of gravel. Further, lower Butler Mill Branch, including all of the sampling area, was poisoned with rotenone in May 1976 by Delaware Division of Fish and Wildlife personnel to foster game fish in Craigs Pond (Roy W. Miller, pers. comm.). Sampling for sculpins in 1978 revealed no effect of the rotenoning. We conclude that the population of C. bairdi here is healthy, and the adjacent Maryland populations also appear to be strong. ACKNOWLEDGMENTS.— We thank the following individuals for their help. Johnson C.S. Wang, Nancy J. Bieber, Ruth A. Hermansen, Judith K. Heyman, Michael J. Hozik, Joan A. Pienta, and several Stock- ton State College students assisted in collecting. J. C.S. Wang also exam- ined sculpin eggs, and Michael J. Hozik provided information on geol- ogy. Robert H. Simmons, U.S. D.I. Geological Survey, Water Resources Division, Dover, Delaware, provided stream flow data. Roy W. Miller, Supervisor of Finfisheries, Delaware Division of Fish and Game, Dover, supplied information on rotenoning in Butler Mill Branch. William L. Pflieger, Missouri Department of Conservation, Columbia, provided information on the Ozark populations of C. bairdi. Robbin N. Rogers searched samples for fish eggs and larvae. Bruce W. Menzel and Steve W. Ross made numerous helpful comments during manuscript preparation. Nancy J. Bieber and Deborah K. Wozniak typed drafts of the manus- cript. John E. Cooper and an anonymous reviewer provided helpful comments during manuscript review. LITERATURE CITED Bailey, Jack E. 1952. Life history and ecology of the sculpin Cottus bairdi punctulatus in southwestern Montana. Copeia 1952(4):243-255. Daiber, Franklin C. 1956. A comparative analysis of the winter feeding habits of two benthic stream fishes. Copeia 1956 (3): 141-151. Dineen, Clarence F. 1951. A comparative study of the food habits of Cottus bairdi and associated species of Salmonidae. Am. Midi. Nat. 46(3): 640-645. 94 Fred C. Rohde and Rudolf G. Arndt Foltz, Jeffrey W. 1976. Fecundity of the slimy sculpin, Cottus cognatus, in Lake Michigan. Copeia 1976(^:802-804. Franz, Richard, and D.S. Lee. 1976. A relict population of the mottled sculpin, Cottus bairdi, from the Maryland Coastal Plain. Chesapeake Sci. /7(4):301-302. Gage, Simon H. 1878. Notes on the Cayuga Lake star gazer. Cornell Rev. 6(2):91-94. Hann, Harry W. 1927. The life history of the germ cells of Cottus bairdi Girard. J. Morphol. Physiol. 43(2):427-497. Hoar, W.S. 1957. The gonads and reproduction, pp. 287-317 in M.E. Brown (ed.). The Physiology of Fishes, Vol. I. Academic Press, Inc., New York. 465 pp. Koster, William J. 1936. The life-history and ecology of the sculpins (Cottidae) of central New York. Unpubl. Ph.D. dissert., Cornell Univ., Ithaca. 87 pp. 4- Appendix and figures. . 1937. The food of sculpins (Cottidae) in central New York. Trans. Am. Fish. Soc. (56:374-382. Lee, David S. 1980. Cottus bairdi Girard. Mottled sculpin. p. 805 in D.S. Lee et al. Atlas of North American Freshwater Fishes. N.C. State Mus. Nat. Hist., Raleigh, x + 867 pp. Ludwig, Gerald M., and C.R. Norden. 1969. Age, growth and reproduction of the northern mottled sculpin (Cottus b. bairdi) in Mt. Vernon Creek, Wis- consin. Milw. Public Mus. Occas. Pap. Nat. Hist. 2:1-67. Nagel, Jerry W. 1980. Life history of the mottled sculpin, Cottus bairdi, in north- eastern Tennessee (Osteichthyes: Cottidae). Brimleyana 4:1 15-121. Patten, Benjamin G. 1971. Spawning and fecundity of seven species of north- west American Cottus. Am. Midi. Nat. #5(2):493-506. Petrosky, Charles E., and T.F. Waters. 1975. Annual production by the slimy sculpin population in a small Minnesota trout stream. Trans. Am. Fish. Soc. 104(2):237-244. Pflieger, William L. 1975. The Fishes of Missouri. Mo. Dep. Conserv., Jefferson City. 343 pp. Ricker, William E. 1934. An ecological classification of certain Ontario streams. Univ. Toronto Stud. Biol. Ser. No. 37. 1 14 pp. . 1971. Methods for assessment of fish production in fresh waters. 2nd ed. IBP Handbook No. 3. Blackwell Sci. Publ., Oxford. 348 pp. Robins, C. Richard. 1954. A taxonomic revision of the Cottus bairdi and Cottus carolinae species groups in eastern North America (Pisces, Cotti- dae). Unpubl. Ph.D. dissert., Cornell Univ., Ithaca. 248 pp. Scott, W.B., and E.J. Crossman. 1973. Freshwater Fishes of Canada. Fish. Res. Board Can. Bull. 184. 966 pp. Smith, Bertram G. 1922. Notes on the nesting habits of Cottus. Pap. Mich. Acad. Sci. Arts Lett. 2:222-224. Williams, James D. 1968. A new species of sculpin, Cottus pygmaeus, from a spring in the Alabama River Basin. Copeia 1968(2):334-342. Accepted 28 December 1981 Distribution and Ecology of the Seepage Salamander Desmognathus aeneus Brown and Bishop (Amphibia: Plethodontidae), in Tennessee R. L. Jones ' Graduate Program in Ecology, University of Tennessee, Knoxville, Tennessee 37916 ABSTRACT. — The seepage salamander, Desmognathus aeneus, is found at elevations from 280 to 1000 m in the Unicoi Mountains of Polk and Monroe counties, southeastern Tennessee. It inhabits leaf litter along small streams and seepage areas. Oviposition probabh occurs in late April and early May, and hatching from mid-June through mid-July. Clutch sizes range from 8 to 15 (x - 12.2) eggs. The major prey items for Tennessee D. aeneus appear to be mites ana collembolans. INTRODUCTION Two dwarf species of salamanders in the genus Desmognathus occur in Tennessee. The pygmy salamander, Desmognathus wrighti King, is found primarily at higher elevations along the main ridge of the Unaka Mountains (Great Smokies, Bald Mountains, and Roan Moun- tain) on the Tennessee-North Carolina border. The seepage salamander, Desmognathus aeneus Brown and Bishop, has been reported from one locality in the extreme southeastern corner of the state (Harrison 1967). I here present additional information on the distribution, status, and ecology of D. aeneus in Tennessee. Most of my data were obtained during a 1976 study of habitat use among plethodontid salamanders in the Unicoi Mountains (Jones 1977). Supplemental information was obtained during later collecting trips and from specimens in the Verte- brate Zoology Collection, University of Tennessee, Knoxville. RESULTS Distribution Harrison (1967) reported D. aeneus from Turtletown, Polk County. Additional localities are shown in Figure 1. The species seems to occur in isolated populations throughout the Unicoi Mountains in both Polk and Monroe counties. All localities are within the Blue Ridge Physiographic Province and range from 280 to 1000 m elevation. Harri- 1 Present address: Mississippi Museum of Nature Science, Jackson, MS 39202 Brimleyana No. 7:95-100. July 1981. 95 96 R. L. Jones Georg i a Fig. 1. Distribution of D. aeneus in Tennessee. Solid symbols represent localities from which specimens were examined, open symbol represents a literature record, dashed line represents approximate western boundary of Blue Ridge Physiographic Province. son (1967) felt that the Little Tennessee River acted as a barrier to the dispersal of this species. My efforts to locate populations in the area immediately north of this river in Tennessee have been unsuccessful. Habitat Desmognathus aeneus has been characterized as an inhabitant of seepages and of the leaf litter near small streams in wooded areas (Fol- kerts 1968). I found that the mean distance from nearest open water was 7.8 m (range 0.3-30.1 m) for 55 D. aeneus from the Citico Creek watershed, Monroe County, during summer 1976. Sixty percent of these were found within 5 m of streams and seepage areas (Table 1). How- ever, specimens also can be found a considerable distance into the sur- Desmognathus aeneus in Tennessee 97 Table 1. Values of 3 habitat variables for 55 D. aeneus in the Citico Creek watershed, Monroe Co., Tennessee. Values in parentheses represent percentages of salamanders found in each habitat category. Cover type Substrate type Distance from water (meters) Leaf litter 22(40.0) Leaf-soil interface 22(40.0) 0-5 33(60.0) Moss 16(29.1) Rock-soil interface 2( 3.6) 6-10 10(18.2) Log 11(20.0) Leaf litter 6(10.9) 11-20 8(14.5) Rock 6(10.9) Log Soil Rock 9(16.4) 10(18.2) 6(10.9) >20 4( 7.3) rounding woodland, since almost 22 percent occurred farther than 10 m from open water. Hairston (1973) also found D. aeneus in relatively terrestrial situations in the Nantahala Mountains of North Carolina. Both mosses and small logs were frequently used as cover objects, but I found most salamanders beneath leaf litter at the leaf-soil interface (Table 1). Canopy cover at the point of capture for the 55 specimens ranged from 60 to 90 percent (x = 78.4%). In the Citico Creek watershed, the species seems to especially favor areas with heavy growths of Rho- dodendron maxium. The habitat requirements for D. aeneus in this area are most similar to those of Eurycea bislineata (unpubl. data), although D. aeneus also shares its habitat to some extent with Desmognathus ochrophaeus Cope, D. fuscus (Rafinesque), D. monticola Dunn, and Plethodon glutinosus (Green). Diet Donovan and Folkerts (1972) reported that the stomach contents of D. aeneus from Alabama and Georgia consisted primarily of arthro- pods. Insects (collembolan and dipteran larvae) and arachnids (primar- ily mites) were the two most frequently ingested prey types. I also found arthropods to be the most common prey items in the stomachs of 47 D. aeneus from the Citico Creek watershed, Monroe County (Table 2). This group comprised slightly over 95 percent of the prey items ingested and was found in almost 96 percent of the stomachs. The most fre- quently ingested arthropods were mites, representing about 58 percent of the total prey items and found in almost 79 percent of the stomachs. Insects, primarily collembolans, were found in almost 62 percent of the stomachs but made up only 30 percent of all prey items ingested. The composition of prey found in the stomachs suggests that D. aeneus does 98 R. L. Jones Table 2. Stomach contents of 47 D. aeneus from the Citico Creek watershed, Monroe Co., Tennessee. Category N prey % freq. N stomachs % freq. Nematoda 2 0.8 2 4.2 Mollusca 10 4.1 8 17.0 Arthropoda 233 95.1 45 95.7 Crustacea (Isopoda) 1 0.4 1 2.1 Insecta 71 30.0 29 61.7 Collembola 40 16.3 17 36.2 Diptera 7 2.9 6 12.8 Coleoptera 5 2.0 5 10.6 Hymemoptera 4 1.6 4 8.5 Lepidoptera 2 0.8 2 4.2 Hemiptera 2 0.8 2 4.2 Insect larvae 11 4.5 9 19.1 Chilopoda 1 0.4 1 2.1 Diplopoda 3 1.2 2 4.2 Arachnida 154 62.9 38 80.8 Araneae 3 1.2 3 6.4 Pseudoscorpionida 8 3.3 6 12.8 Acarina 143 58.4 37 78.7 Unidentified arthropods 3 1.2 3 6.4 most of its foraging within the leaf litter rather than at the surface. This idea is further supported by approximately 72 hours of monitoring noc- turnal activity of salamanders during both wet and dry nights in the Citico Creek watershed in 1976; no D. aeneus were observed active on the surface in either seepage areas of leaf litter along small streams, although they were known to be abundant in the immediate area. I have found the species crossing roads during rainstorms, but it appears to rarely leave the protection of surface cover in its habitat, an observation first noted by Folkerts (1968) for D. aeneus in Alabama. Reproduction Folkerts (1968) found evidence for both spring and fall periods of oviposition in Alabama D. aeneus. He suggested that the species may deposit eggs at any time of year except mid-winter. Harrison (1967) reported egg deposition from late April to early May, but suggested that considerable variation probably occurred in the time of oviposition Desmognathus aeneus in Tennessee 99 from year to year. Folkerts (1968) found that clutch size varied from 5 to 17 (x = 8.8) and that hatching in the laboratory occurred in 43 to 54 days. Harrison (1967) observed hatching from late May to early August, and reported that hatching in the laboratory occurred in 34 to 45 days. He found that clutch size varied from 6 to 18 (x = 10.7). Eleven D. aeneus clutches have been found in the Citico Creek watershed. The earliest date for a clutch containing uncleaved eggs was 10 May. Clutches that were ready to hatch or hatching were observed on 23 June and 26 June, respectively. This indicates that, in Tennessee, oviposition probably occurs from late April through early May and hatching from mid-June through mid-July. I found no fall clutches. Clutch size ranged from 8 to 15 (x = 12.2). Most of the 11 clutches were beneath moss at ground level near streams or seepage areas. However, a female attend- ing a clutch was found beneath a small log, 1.6 m from a small stream; a second female and clutch were beneath moss on a rotting tree stump, 28 cm above ground level and 7.2 m from a stream. DISCUSSION The range of D. aeneus in Tennessee is apparently restricted to the Unicoi Mountains of Polk and Monroe counties. Tennessee populations are probably continuous with those in western North Carolina and northern Georgia, since D. aeneus has been collected in counties border- ing Tennessee in both states (Martof, et al. 1980; Harrison 1967). Within the Unicoi Mountains, D. aeneus is an apparently wides- pread but relatively uncommon species. Its range in Tennessee lies primarily within the Cherokee National Forest, which should provide some measure of protection since much of this area remains relatively undisturbed. However, populations of D. aeneus are sensitive to drying conditions caused by clear cutting (Folkerts 1968), a common method of timber harvest in the Cherokee National Forest. Disruption by wild boar, Sus scrofa, of seepage area habitats is also a relatively common phenomenon within the range of D. aeneus in Tennessee. The apparent susceptibility of its populations to habitat destruction, coupled with its restricted distribution in the state, indicate that D. aeneus should be monitored for any sudden population changes in order to insure its con- tinued survival in Tennessee. ACKNOWLEDGMENTS.— A. C. Echternacht, University of Ten- nessee, and W. H. Redmond, Jr., Tennessee Valley Authority, provided many useful comments on earlier versions of this manuscript. Two anon- ymous reviewers also provided comments. 100 R. L. Jones LITERATURE CITED Donovan, Lois A., and G. W. Folkerts. 1972. Foods of the seepage salamander Desmognathus aeneus Brown and Bishop. Herpetologica 2#(l):35-37. Folkerts, George W. 1968. The genus Desmognathus Baird (Amphibia: Ple- thodontidae) in Alabama. Unpubl. Ph.D. dissert., Auburn Univ., Auburn. 129 pp. Hairston, Nelson G. 1973. Ecology, selection and systematics. Breviora 414:1-21. Harrison, Julian R. 1967. Observations on the life history, ecology and distri- bution of Desmognathus aeneus aeneus Brown and Bishop. Am. Midi. Nat. 77(2):356-370. Jones, R. L. 1977. Resource partitioning among six species of the salamander family Plethodontidae. Unpubl. MS thesis, Univ. Tennessee, Knoxville. 59 pp. Martof, Bernard S., W. M. Palmer, J. R. Bailey and J. R. Harrison III. 1980. Amphibians and Reptiles of the Carolinas and Virginia. Univ. North Caro- lina Press, Chapel Hill. 264 pp. Accepted 11 January 1982 Dental and Cranial Anomalies in the River Otter (Carnivora: Mustelidae) Thomas D. Beaver, George A. Feldhamer and Joseph A. Chapman Appalachian Environmental Laboratory, Gunter Hall, Frostburg State College Campus, Frostburg, Maryland 21532 ABSTRACT.— Dental or cranial anomalies were noted in 65 (32.2%) of 202 skulls of river otters, Lutra canadensis, collected from the Ches- apeake Bay region of Maryland and Virginia from 1974 to 1979. The most frequent anomaly was alveolar thinning. Anomalies probably did not adversely affect individuals or the population structure. INTRODUCTION The dentition and cranial structure of many mammalian species have been well studied because of their importance in systematics and taxonomy. Also, the condition of teeth affects nutritional status, which in turn directly affects behavior, reproduction and longevity (Robinson 1979). As a result, anomalies have been described for several orders and numerous mammalian species (Choate 1968; Colyer 1936; Hershkovitz 1970; LaVelle and Moore 1972; Manville 1963; Pavlinov 1975; Sheppe 1964; Shultz 1923). However, relatively few studies have dealt with the Mustelidae (Hall 1940; Heran 1970; Parmalee and Bogan 1977). Here we describe dental and cranial anomalies noted in skulls of river otters, Lutra canadensis, from the Chesapeake Bay region of Maryland and Virginia and assess their probable impact upon individuals and the population. MATERIALS AND METHODS A total of 202 skulls was collected from trappers in Dorchester County, Maryland, during the trapping seasons of 1974 through 1979. The material was considered a random sample representative of the river otter population as no skull was obtained specifically because it had an anomaly. All skulls were individually numbered and are housed in the museum collection of the Appalachian Environmental Labora- tory (AEL). Each skull was examined for the following: 1) plagio- cephaly — asymmetrical cranial growth due to premature closure of one frontal-parietal suture; 2) bregmatic bones — extra bones derived from accessory ossification in any of the fontanelles; 3) heterotopic bones — small accessory bones; 4) caries — decay of dental tissue; 5) alveolar thinning — exposure of the buccal tooth roots; 6) supernumerary teeth — those in excess of the normal dental pattern; 7) congenital agenesis Brimleyana No. 7:101-109. July 1981. 101 102 Thomas D. Beaver, George A. Feldhamer, Joseph A. Chapman — reduced dental complement due to teeth that failed to develop; and 8) irregular placement — teeth in positions other than the normal pat- tern. Skulls were X-rayed to provide confirmation of suspected agenesis or supernumeration. RESULTS AND DISCUSSION A total of 137 skulls (67.8%) exhibited no cranial abnormalities or deviation from the normal dental pattern of 3/3, 1/1,4/3, 1/2 = 36 in L. canadensis. Anomalies were found in 65 skulls (32.2%). This is similar to the results of Colyer (1936) who noted "marked irregularities" in 75 of 161 (46.6%) skulls of Lutra sp. — a greater percentage of occurrence of anomalies than in any other genus of Mustelidae he examined. Cranial anomalies. — Cranial anomalies occurred in only 2 (1.0%) of the skulls examined. Plagiocephaly was found in an adult female over 3 years of age, and there was a small hole in the frontal bone (Fig. 1). Mowbray et al. (1979) indicated that 1 1% of the 296 river otter carcasses that they examined from this study area showed evidence of gunshot wounds, although few animals (1.7%) were judged to have died from such wounds. Dougherty and Hall (1955) and van Soest et al. (1972) noted that characteristics similar to those seen in Figure 1 may result from metastrongylid nematode (Skrjabingylus sp.) involvement. Thus, the plagiocephaly may have resulted from an extrinsic agent, either a nonlethal gunshot wound or a parasite, rather than genetic factors. Heterotopic bones occurred on the premaxilla of an adult male over 3 years of age (Fig. 2); there were no indications of previous injury. Whether this condition was genetic in origin or resulted from previous trauma could not be determined. No instances were found of bregmatic bones. Dental anomalies. — Dental anomalies were much more prevalent than cranial anomalies. With the exception of caries, an example of each dental anomaly was represented in the sample. The lack of caries in wild animals is consistent with previous studies. Hall (1940) found caries in only 8 of 3,761 specimens (0.2%) of North American carniv- ores, and all cases occurred within the Ursidae. Colyer (1936) reported only 4 cases of caries in 7,635 specimens (0.05%) of North American carnivores. The reason for lack of caries in the river otter, as well as most other carnivores, is unknown, although it may be associated with absence of carbohydrates in the diet. Irregular tooth placement was noted in two individuals: a juvenile female had teeth that were abnormally far apart (Fig. 3), and in an adult female they were exceedingly close together (Fig. 4). Alveolar thinning (Fig. 5) was the most common anomaly, occurr ing in 47 skulls (23.3%). Of these, 39 (82.9%) involved the last upper River Otter Skull Anomalies 103 Fig. 1. Plagiocephaly in adult female river otter (AEL-302); also note small hole in frontal bone. Fig. 2. Heterotopic bones in adult male river otter (AEL-303). 104 Thomas D. Beaver, George A. Feldhamer, Joseph A. Chapman molar, and 7 others involved both upper and lower premolars in which thinning was associated with the posterior premolar in the tooth row. Smith et al. (1977) also found alveolar thinning associated "almost exclusively" with the last upper molars in three species of platyrrhine monkeys. They attributed the condition to internal pressures associated with mastication. Such thinning may predispose underlaying tissues to periodontal disease, and both local and systemic factors have been implicated in this process (Clark et al. 1970). Congenital agenesis occurred in 8 (3.9%) of the skulls. Three addi- tional skulls appeared to possess this condition, however X-ray roent- genograms revealed a non-erupted tooth. Agenesis was bilateral in two individuals; one case involved the second lower premolars and the other the second upper premolars (Fig. 6). The other six cases, all unilateral, involved two different locations in the maxillary tooth row: five instances occurred at the first premolar and one at the second premolar. Agenesis can result from delayed tooth formation and eruption, or a genetically induced reduction associated with phylogenetic shortening of the tooth row (LaVelle and Moore 1972). Delayed eruption was noted in three instances; however, this was not the case for the nine individuals in which no unerupted tooth or alveolus was present. In all cases congenital agenesis involved the premolars. Hall (1940:1 18) stated, "when a premolar is missing the place most often is at the anterior end of the premolar series." This was the situation in only 5 of 9 individuals (55.6%) in our sample; the remainder involved the second premolar. Supernumerary teeth were found in 8 (3.9%) of our specimens. Seven cases occurred near the first upper premolar; one was posterior to the last upper molar. X-rays revealed distinct alveoli for three of the supernumerary premolars and the molar. In the other four cases, two teeth appeared to protrude from the same alveolus, although this was difficult to verify. Previous explanations for supernumerary dentition include: 1) splitting of a permanent or milk tooth bud; 2) failure to shed deciduous teeth; 3) atavism; and 4) "arising of tooth as a new crea- ture (genetic conditioning possible)" (Pavlinov 1975:516). We regard the latter as the least probable. Splitting of the tooth bud is a reasonable explanation in the four examples of two teeth, virtually identical in size, protruding from the same alveolus (Fig. 7). To attribute supernumerary upper premolars in the river otter to atavism is unreasonable. The resulting five premolars exceeds the primi- tive number of four — already present in the normal upper premolar complement of the genus. The supernumerary premolars with distinct alveoli, therefore, are more likely due to failure of the deciduous teeth to shed. However, atavism is a likely explanation regarding the super- numerary molar. Because teeth tend to be lost at the end of a row (Hall River Otter Skull Anomalies 105 Fig. 3. Irregular spacing of dentition in immature female river otter (AEL-304). Fig. 4. Irregular tooth placement resulting in rotation from the toothrow (AEL-305). 106 Thomas D. Beaver, George A. Feldhamer, Joseph A. Chapman 'if Fig. 5. Extreme alveolar thinning associated with upper molars (AEL-306). •> I'. V Fig. 6. Bilateral congenital agenesis of second upper premolars (AEL-307). River Otter Skull Anomalies 107 i ■ Fig. 7. Two teeth protruding from same alveolus. Apparent difference in length due to one tooth partially forced from alveolus (AEL-308). Fig. 8. Supernumerary molar assumed to be atavistic (AEL-309). 108 Thomas D. Beaver, George A. Feldhamer, Joseph A. Chapman 1940), placement of the extra molar at the posterior end of the series (Fig. 8) would be expected if the condition were an atavistic trait. Based solely on the age of certain anomalous skulls, dental and cranial anomalies in the river otter did not appear to be detrimental to the overall condition or survival of individuals. As noted, anomalous animals more than three years of age were found. The carcasses were not available to assess body fat or other indices of physical condition, however, so this conclusion must remain conjectural. We suspect, though, that in contrast to the possible detrimental effects of anomalies on individual mantled howler monkeys, Alouatta palliata, and subse- quent effects postulated for dominance relationships and population dynamics (Smith et al. 1977), anomalies probably are of little impor- tance in the population dynamics of the river otter. ACKNOWLEDGMENTS.— We thank Dr. William Newman, Pam Askins and Denise Andrews, Radiology Department, Sacred Heart Hospital, Cumberland, Maryland, for providing X-rays of the study material. Dr. J. Edward Gates, Appalachian Environmental Labora- tory, critically reviewed the manuscript, and an anonymous reviewer provided helpful comments. This is Contribution No. 1284-AEL, Appala- chian Environmental Laboratory, Center for Environmental andEstuar- ine Studies, University of Maryland. Specimens were collected as part of a study funded by Maryland Federal Aid in Wildlife Restoration W-49-R. LITERATURE CITED Choate, Jerry R. 1968. Dental abnormalities in the short-tailed shrew, Blarina brevicauda. J. Mammal. 49{2):25 1-258. Clark, James W., E. Cheraskin and W. M. Ringsdorf, Jr. 1970. Diet and the periodontal patient. Charles C. Thomas, Springfield, IL. 370 pp. Colyer, F. 1936. Variations and diseases of the teeth of animals. John Bale, Sons and Danielsson, Ltd., London. 750 pp. Dougherty, Ellsworth C, and E. R. Hall. 1955. Biological relationships between American weasel (genus Mustela) and nematodes of the genus Skrjabingy- lus Petrov 1927 (Nematoda: Metastrongylidae), the causative organism of certain lesions in weasel skulls. Rev. Iber. Parasitol., Tomo Extraordinario: 531-576. Hall, E. Raymond. 1940. Supernumerary and missing teeth in wild mammals of the orders Insectivora and Carnivora, with some notes on disease. J. Dent. Res. 79:103-143. Heran, Ivan. 1970. Anomalies in the position of lower teeth in the fisher, Martes pennanti Erxl. (Mammalia; Mustelidae). Can. J. Zool. 48:1465. Hershkovitz, Phillip. 1970. Dental and periodontal diseases and abnormalities in wild-caught marmosets (Primates — Callithricidae). Am. J. Phys. Anthropol. 52:377-394. River Otter Skull Anomalies 109 LaVelle, C. L. B., and W. J. Moore. 1972. The incidence of agenesis and poly- genesis in the Primate dentition. Am. J. Phys. Anthropol. 55:671-680. Manville, Richard H. 1963. Dental anomalies in North American lynx. Z. Saeugeterkd. 28(3): 166-169. Mowbray, Elmer E., D. Pursley and J. A. Chapman. 1979. The status, popula- tion characteristics and harvest of the river otter in Maryland. Md. Wildl. Admin. Publ. Wildl. Ecol. No. 2:1-16. Pavlinov, I. Y. 1975. Tooth anomalies in some Canidae. Acta Theriol. 20(33): 507-519 Parmalee, Paul W., and A. E. Bogan. 1977. An unusual dental anomaly in a mink. J. Tenn. Acad. Sci. 52(3): 1 15-1 16. Robinson, P. T. 1979. A literature review of dental pathology and aging by dental means in nondomestic animals — Parts I and II. J. Zoo Anim. Med. 70:57-65,81-91. Sheppe, Walter. 1964. Supernumerary teeth in the deer mouse, Peromyscus. Z. Saeugeterkd. 29( l):33-36. Shultz, Adolph H. 1923. Bregmatic fontanelle bones in mammals. J. Mammal. 4(2):65-77. Smith, James D., H. H. Genoways and J. K. Jones, Jr. 1977. Cranial and dental anomalies in three species of Platyrrhine monkeys from Nicaragua. Folia Primatol. 25:1-42 van Soest, R. W. M., J. van der Land and P. G. H. van Bree. 1972. Skrjabingy- lus nasicola (Nematoda) in skulls of Mustela erminea and Mustela nivalis (Mammalia) from the Netherlands. Beaufortia 20:85-97 Accepted 30 November 1981 Life History and Ecology of Chauliodes rastricornis Rambur and C. pectinicornis (Linnaeus) (Megaloptera: Corydalidae) in Greenbottom Swamp, Cabell County, West Virginia Pamela S. Dolin and Donald C. Tarter Department of Biological Sciences, Marshall University, Huntington, West Virginia 25701 ABSTRACT. — Life history and ecology of two congeneric fishflies, Chauliodes rastricornis Rambur and C. pectinicornis (Linnaeus), were investigated from March 1978 to September 1980 at Greenbottom Swamp, Cabell County, West Virginia. Frequency histograms of head width indicate both species are univoltine. Larval C. rastricornis showed greatest growth (66%) between June and October, while C pectinicornis had two growth periods, from July to October (106%) and April to June (17%). Larvae of both species ingested organic detritus, copepods, and algae during the winter months, and ostracods, rotifers, cladocerans, and immature insects during the warmer seasons. Chauliodes rastricornis pupated from April to May and emerged at dusk from May to June; peak emergence was on May 9. Chauliodes pectinicornis pupated in June and emerged at night during July. The chi-square test showed a significant difference (0.05 level) from the 1:1 sex ratio in adults of C. rastricornis. Total counted eggs ranged from 922 to 1612 (x = 1 166) and 967 to 1500 (x = 1250) eggs per female in C. rastricornis and C pectinicornis, respectively. INTRODUCTION Several authors, including Moody (1877), Brimley (1908), Cuyler (1956, 1958), Hazard (1960), Baker and Neunzig (1968), Watkins et al. (1975), Tarter and Watkins (1974), Tarter et al. (1976) and Tarter et al. (1977), have reported ecological and taxonomical studies of members of the genus Chauliodes. Chauliodes rastricornis Rambur is known from 24 eastern states and Ontario, Manitoba, and Nova Scotia (Davis 1903; Hazard 1960; Parfin 1952; Tarter et al. 1976), and Chauliodes pectinicornis (Linnaeus) from 26 eastern states and Quebec (Davis 1903; Hazard 1960; Tarter et al. 1976). These species are often sympatric. Chauliodes larvae inhabit a variety of lentic waters including marshes, swamps, swamp channels, ponds, small lakes, woodland pools, and sinkholes (Cuyler 1956). The objective of this investigation was to compare the life history and ecol- ogy of C. rastricornis and C. pectinicornis in Greenbottom Swamp, Cabell County, West Virginia. MATERIALS AND METHODS Greenbottom Swamp is located in the Union district of northwest Cabell County, West Virginia (Krebs and Teets 1913). The swamp is Brimleyana No. 7:111-120. July 1981. Ill 112 Pamela S. Dolin and Donald C. Tarter approximately 8050 m east of Homestead, West Virginia, on State Road n2. The study area is located 550 m from the Ohio River's south edge. The swamp proper is 1450 m long and has a contiguous marsh on the north end that continues another 1200 m, forming about 14 ha of swamp forest. The mean water depth varies from 0.5 m during dry peri- ods to 1.5 m during high waters. Elevation is 168 m above sea level. In the permanently inundated areas, the only tree species is black willow, Salix nigra Marsh. Button-bush saplings, Cephalanthus occidentalis L., have the greatest density of any woody plant seedling in the swamp. The study began in March 1978 and ended in September 1980 (Dolin 1980). Larval collections of both species were made on a monthly basis, by searching under moss, duckweed, and loose bark of small stems and decaying logs. Monthly water chemistry was assessed with a Hach chemical kit, Model AL-36B. The measurements taken included: hydrogen ion con- centration (pH) determined colorimetrically; dissolved oxygen and car- bon dioxide (mg/ 1); and total hardness and alkalinity (mg/ 1 of CaCO^). Water temperature ranges were measured with a Taylor maximum- minimum thermometer secured 0.3 m below the surface. Head width was measured to obtain growth records. Total width was taken at the widest section of the head capsule, usually at the eyes. Using a compound microscope and a caliper, the measurements were taken to the nearest 0.1 mm. Monthly differences in head widths of 246 C. rastricornis and 1 12 C pectinicornis larvae were determined to show the mean, range, standard deviation, and two standard errors of the mean in a Hubbs and Perlmutter (1942) population range diagram. Per- cent growth was calculated monthly by comparing the mean head width values. Size classes were assessed by frequency histograms arranged in 0.5 mm head width categories. Generally, foreguts were examined from five larvae of each species per month. After the head was removed with microdissecting scissors, the abdomen was cut and the foregut extracted. The gut was then slit ventrally and the contents placed on a clean slide for identification. The number of foreguts containing the various taxa was recorded, and the mean and percent frequency of occurrence were calculated. Chauliodes pupae were obtained by digging into the grooves of logs that had started to desiccate due to receding spring waters. For both species, a few larvae in the last instars were reared to the pupal and adult stages. Rearing was accomplished by leaving the larvae in place and quickly transporting the log section to aerated pint jars containing water from the swamp. Larvae were placed one to a jar to help insure pupation by reducing competition for foodstuffs, to prevent cannibal- ism, and to determine when the individuals pupated. Pupae were placed Corydalid Life Histories 113 in a rearing cage, and the range and mean pupation dates were recorded. Adults were collected at night by means of a black light trap. For C. rastricornis, the trap was set out between 9 and 10 PM twice a week during the emergency period to obtain a quantitative number of emer- gents per hour. Various times wee sampled in hopes of finding the peak period of emergence for C. pectinicornis. The range and peak emergence times were registered. To determine fecundity, the thorax and head of each adult fishfly was removed with microdissecting scissors. The abdomen was then cut ventrally and the ovaries with the eggs teased out. All eggs were counted and the length (mm) of the female's body was recorded. The mean and range were computed for each species. RESULTS AND DISCUSSION Swamp environment . — The pH ranged from 6.0 in February to 7.3 in November; x = 6.8. Dissolved oxygen values ranged from 2.0 to 11 mg/ 1 in August and March, respectively; x = 6.0 mg/ 1. In July, a car- bon dioxide value of 85 mg/ 1 was recorded versus 15 mg/ 1 in the win- ter and spring. Carbonate alkalinity values ranged from 51.3 mg/ 1 in December and January to 102.6 mg/ 1 in July and August; x = 73.4 mg/ 1. Total hardness ranged from 68.4 to 171.0 mg/ 1 in June and May, respectively; x = 99 mg/ 1. Larval development .— Frequency histograms of head width indi- cated that the life cycles of both species are univoltine (Figs. 1, 2). In C. rastricornis, hatching probably begins in early June, but due to small size and concealment larvae were not collected until the end of June (Fig. 1). April was the last month larvae were found before they pupated. Hatching of C. pectinicornis occurred in July, making this month unique in that two different size classes of larvae as well as pupae were found (Fig. 2). Apparently, two cohorts were present. Population range diagrams of larval head capsule widths show the monthly growth of both fishflies (Figs. 3, 4). Chauliodes rastricornis showed the greatest growth (66%) between June and October, while C. pectinicornis had two growth periods, from July to October (106%) and April to June (17%). Growth of both was retarded when the monthly water temperatures averaged below 15°C (November through March). The second growth period of C. pectinicornis corresponds with the absence of C. rastricornis larvae from the swamp (Fig. 5). In North Carolina, Cuyler (1956) found prepupal C. rastricornis and larval C. pectinicornis from March 28 to April 17. He collected C. pectinicornis larvae on land in April even though no adults were found until the second week in May. This leaves five weeks for the fishfly 114 Pamela S. Dolin and Donald C. Tarter A d 40% -i 30% 207,, 10% 0% 50% -. 40% - 30% 20% H 10% 0% A Head Width (mm) Fig. 1. Head-width frequencies at monthly intervals of Chauliodes rastricornis larvae from Greenbottom Swamp, Cabell County, West Virginia. Number in parentheses after month is sample size. larvae to pupate in the drier environment before emerging as adults. Larval food habits. — The following taxa were found in the fore- guts of Chauliodes larvae (Dolin 1980): ostracods, cladocerans, copep- ods, amphipods, odonates, rotifers, dipterans, and the alga Tribonema. Detritus and unidentifiable materials were also found. Based on a yearly mean, organic detritus ranked first (96%) in fre- quency of occurrence in C. rastricornis, and ostracods (26%) were second. Chironomids were found with a frequency of 16 percent. Based on a yearly mean, organic detritus ranked first (82%) in frequency of occurrence in C. pectinicornis, and ostracods (14.5%) and cladocerans (14.5%) ranked second. Copepods were found only in winter in both fishflies. The unidenti- Corydalid Life Histories 115 40% 30% 20% 10% 0% Aug. (10) =-"J , 50% g 40% = 30% f 20% - 0% 20% 10% 0% Sept. (101 60% -i Nov. (10) 50% - Ak Head Width (mm) Fig. 2. Head-width frequencies at monthly intervals of Chauliodes pectinicornis larvae from Greenbottom Swamp, Cabell County, West Virginia. Number in parentheses after month is sample size. fied materials, amphipods, and chironomids occurred sporadically throughout the year in both species. Empty foreguts were found 20 per- cent of the time in C. rastricornis and 30 percent in C. pectinicornis. These insects apparently indiscriminately ingested whatever food source was available during the season, with detritus being the only constant category in their diet. Under laboratory conditions, Weed (1889) and Lintner (1892) fed fishfly larvae the backswimmer Notonecta undulata, dipteran larvae, and spiders. Davis (1903) reported the larvae as carnivores that ate smaller members of their own species, larvae of Sialis, caddisflies, dipte- rans, and other accessible soft-bodied insects. 116 Pamela S. Dolin and Donald C. Tarter Head Width (mm) Water Temp. (C) Fig. 3. Monthly variations in larval head widths of Chauliodes rastricornis from Greenbottom Swamp, Cabell County, West Virginia. Horizontal lines = means; vertical lines = ranges; open rectangles = standard deviation; closed rectangles = two standard errors of the mean; numbers above vertical lines = sample size; and solid line = mean water temperatures. Pupal stage. — Pupae have been collected under bark and in decay- ing logs and stumps by various authors: Walsh (1863), Weed (1889), Needham and Betten (1901), and Brimley (1908). Parfin (1952) and Davis (1903) reported Chauliodes pupating under rocks, and Davis also observed them in rotten wood and earthen cells. Cuyler (1956) reported finding C. rastricornis in pine and oak stumps as far as 25 feet from water and observed eight C. pectinicornis pupae under the bark of one large log on the swamp bank. In May, eight C. rastricornis pupae were found deep in rotten logs that were drying because of receding waters. Pupae of C. pectinicornis were found under bark of drying logs, and in earthen cells under logs left on the bank of the swamp after water had receded. Seven C. rastricornis and eight C. pectinicornis were reared from larvae to adults. Chauliodes rastricornis larvae transformed to pupae from April 23 to May 1, with the pupal stage lasting a range of 6 to 18 Corydalid Life Histories 117 days; x = 12. Chauliodes pectinicornis larvae transformed to pupae between June 26 and July 28, with the pupal stage lasting from 8 to 17 days; x = 10. Adult stage. — Seventy-seven C. rastricornis adults were collected from 9 May 1979 to 2 June 1980. The peak emergence was on 9 May, with 28 adults trapped in the night light per hour. Only five C. pectini- cornis males were collected between 14 and 30 July by light-trapping, even though trapping between 9 PM and 3 AM occurred from May to the end of August. This could be due to the low occurrence of C. pecti- nicornis in the swamp. Davis (1903) reported collecting adult Chauliodes between 14 and 16 June, noting they lived only a few days in captivity and would not eat. Smith (1922) reported collecting adult Chauliodes in June, and Chaplain and Kirk (1926) trapped C pectinicornis from 11 July to 6 August in a fermented syrup of molasses and water. Tarter et al. (1977) recorded C pectinicornis emerging from 28 February in Louisiana to 1 1 November in Maryland, with the West Virginia emergence from 22 May to 9 September. Chauliodes rastricornis emerged from 10 January to 28 Head Width (mm) 1 July Water Temp. (C) Fig. 4. Monthly variations in larval head widths of Chauliodes pectinicornis from Greenbottom Swamp, Cabell County, West Virginia. Legend symbols are the same as in Figure 3. 118 Pamela S. Dolin and Donald C. Tarter ^^H Pupae Larval Head Width (mm) 5 - Larval 4 - 3 - 2 _ 1 - Width (mm) Adults . Pupae January I I O November Fig. 5. Summary graph of life cycles of Chauliodes rastricornis (bottom), and C. pectinicornis (top), from Greenbottom Swamp, Cabell County, West Virginia. Larval head width means are plotted against months of the year. Straight lines = emergence periods of pupae and adults. December in Florida, and specimens of C. rastricornis in West Virginia were only found on 2 June (Tarter et al. 1977). The C. rastricornis pupae reared in our laboratory transformed into adults between 29 April and 13 May, and the C. pectinicornis emerged between 10 July and 27 August. This separation of emergence times helps keep these two species from interbreeding. No mating, ovip- ositing, eating, or drinking was observed. Brimley (1908) reported rearing larval Chauliodes caught on 4 April 1906 to adults, which first emerged 21 April and continued trans- forming until 20 May 1906. Parfin (1952) recorded rearing C. rastricor- nis, which first emerged on 5 June and lived approximately six days on honey and water. The sex ratio of 77 C. rastricornis captured by the light traps was 5 males: 1 female, and a chi-square test indicated a significant difference (0.05 level). Since all five C. pectinicornis trapped were males, a chi- square value was not calculated. Adult C. rastricornis, reared from pupae, showed a fecundity range of 922 to 1612 eggs (x = 1 166) per female, but light-trapped females of the same species contained between 8 and 637 eggs (x = 388). Chauliodes Corydalid Life Histories 119 pectinicornis adults light-trapped by other collectors contained either all or none of their eggs, indicating only one oviposition. The fecundity ranged from 967 to 1500 eggs (x = 1250). No egg masses were found in the field. Adult C. rastricornis laid their eggs a short distance away from the water (Needham and Betten 1901). The grayish eggs were layed in V- shape rows attached to flat surfaces. A pair of C. pectinicornis was observed and photographed while copulating on a fern. After the male left, the female, who had already laid most of her eggs, continued ovip- ositing using the outline of the pattern she had already begun. Around 900 eggs were laid, all of which hatched 17 days later. Davis (1903) reported 30 to 40 egg masses, of 1000 to 2000 eggs each, on the under- side of a wooden boat-landing in June and July. Other masses were as high as 10 to 15 feet above water on stones and leaves. Hatching was reported to occur five to six days later. On 16 June, Smith (1922) observed C. pectinicornis depositing 1000 to 2000 eggs in winding paral- lel rows one layer deep. The eggs hatched eight days later in a 45-minute period at night. A complete description of the egg masses and eggs of C. pectinicornis was given by Baker and Neunzig (1968). ACKNOWLEDGMENTS.— Special thanks are extended to Miss Vickie Crager for typing the manuscript. Also, we express our appreciation to the following persons for help in the field work: Kerry Bledsoe, Bill Cremeans, Steve Lawton, Tom Rone, Mary Beth Roush, and Jan Taylor. LITERATURE CITED Baker, J. R., and H. H. Neunzig. 1968. The egg masses, eggs, and first instar larvae of eastern North America Corydalidae. Ann. Entomol. Soc. Am. 6/(5): 118 1-1 187. Brimley, C. S. 1908. Notes on some Neuropteroids from Raleigh, N.C. Entomol. News 79:133-134. Chaplain, A. B., and H. B. Kirk. 1926. Bait pan insects. Entomol. News 57(9):288-291. Cuyler, R. D. 1956. Taxonomy and ecology of the larvae of sialoid Megaloptera of east-central North Carolina, with a key to and descriptions of the larvae of genera known to occur in the U. S. Unpubl. MS Thesis. N. C. State Coll., Raleigh. 150 pp. 1958 The larvae of Chauliodes Latreille (Megaloptera: Corydalidae). Ann. Entomol. Soc. Am. 57:582-586. Davis, K. C. 1903. Sialididae of North and South America. In Aquatic Insects in New York State. N.Y. State Mus. Bull. 65:442-487. Dolin, Pamela S. 1980. The life history and ecology of Chauliodes rastricornis Rambur and C. pectinicornis (Linnaeus) (Megaloptera: Corydalidae) in Greenbottom Swamp, Cabell County, West Virginia. Unpubl. MS Thesis. Marshall Univ., Huntington. 58 pp. 120 Pamela S. Dolin and Donald C. Tarter Hazard, Edwin I. 1960. A revision of the genera Chauliodes and Nigronia (Megaloptera: Corydalidae). Ann. Entomol. Soc. Am. 57:582-586. Hubbs, Carl L., and A. Perlmutter. 1942. Biometric comparison of several samples, with particular reference to racial investigations. Am. Nat. 76:582-592. Krebs, C. E., and D. D. Teets. 1913. West Virginia Geological Survey County Reports, Cabell, Wayne and Lincoln Counties. Wheeling News Litho Co., Wheeling. 483 pp. Lintner, J. A. 1892. Chauliodes pec Unicornis, rastricornis, and serricornis. N.Y. State Entomol. 8th Annu. Rep.: 155-1 59. Moody, Henry L. 1877. Habits and transformations of Chauliodes pectinicor- nis. Psyche 2:52-53. Needham, J. C, and C. Betten. 1901. Aquatic Insects in the Adirondacks. N.Y. State Mus. Bull. 47:383-612. Parfin, Sophy L. 1952. The Megaloptera and Neuroptera of Minnesota. Am. Midi. Nat. 47(2):42 1-434. Smith, J. B. 1922. Hatching in three species of Neuroptera. Ann. Entomol. Soc. Am. 75:169-176. Tarter, Donald C, and W. D. Watkins. 1974. Distribution of the fishfly genera Chauliodes Latreille and Nigronia Banks in West Virginia. Proc. W. Va. Acad. Soc. 46(2): 146-150. , , M. Little and J. T. Goodwin. 1976. New state records of fishflies (Megaloptera: Corydalidae). Entomol. News