GULF RESEARCH REPORTS Vol. 7, No. 4 December 1984 ISSN: 0072-9027 Published by the GULF COAST RESEARCH LABORATORY Ocean Springs, Mississippi Gulf Research Reports Volume 7 | Issue 4 January 1984 Effects of Space Shuttle Exhaust Plumes on Gills of Some Estuarine Fishes: A Light and Electron Microscopic Study William E. Hawkins Gulf Coast Research Laboratory^ William.Hawkins(^usm.edu Robin M. Overstreet Gulf Coast Research Laboratory^ robin.overstreet(^usm.edu Mark J. Provancha Kennedy Space Center, Florida DOI: 10.18785/grr.0704.01 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation HawkinS; W. E., R. M. Overstreet and M. J. Provancha. 1984. Effects of Space Shuttle Exhaust Plumes on Gills of Some Estuarine Fishes: A Light and Electron Microscopic Study. Gulf Research Reports 7 (4): 297-309. Retrieved from http://aquila.usm.edu/gcr/vol7/iss4/l This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 297-309, 1984 EFFECTS OF SPACE SHUTTLE EXHAUST PLUMES ON GILLS OF SOME ESTUARINE FISHES: A LIGHT AND ELECTRON MICROSCOPIC STUDY WILLIAM E. HAWKINS^ , ROBIN M. OVERSTREET^ AND MARK J PROVANCHA^ ^ Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564 ^ The Bionetics Corporation, Kennedy Space Center, Florida 32899 ABSTRACT The first few launches of the space shuttle resulted in fish kills in a lagoon near the launch site. To study this phenomenon further, sheepshead minnow (Cyprinodon variegatus), sailfin molly (Poecilia latipinna), and mosquitofish {Gambusia affinis) were exposed to the exhaust plume in buckets placed near the launch site. An open bucket provided a full exposure, a partly closed one provided an intermediate exposure, and a closed one was the control. Three h after launch, the pH of the water from the full exposure had decreased from about 7 to about 3, A1 and Fe levels had increased, and some fish had died. Gills of most fishes from full exposures and some from intermediate exposures were damaged. Gills, however, exhibited no aneurysms, mucus coagulation, or hemorrhaging. Some secondary lamellae swelled, some fused with adjacent lamellae, and others clubbed or retracted into the filament. Many lamellar pavement cells died and sloughed off. Mucous cells of intermediate exposure specimens bulged on the filament surface and pavement cells lost their microridges. Mineral deposits, probably aluminum oxide, occurred on gills of fishes from full exposures, Focally, pavement cells were eroded exposing the underlying structures. The sudden pH drop in the full exposures probably caused the gill damage. However, we could not determine the effect of previous exposure on the experimental fish, or whether gill damage was the lethal lesion. The possibility is indicated that some fish recover after exposure to the exhaust plume. INTRODUCTION Kills involving fewer than one hundred small fish oc- curred in a lagoon following each of the first three launches of the Space Transportation System (STS; space shuttle) from Kennedy Space Center, Florida, USA. The cause of the fishes’ deaths was not determined but was suspected to be gill damage resulting from a sudden drop in pH caused by the exhaust plume generated by the solid rocket boosters (Milligan and Hubbard 1983). Our preliminary histopatho- logical examinations of whole fishes that were exposed to the exhaust plume of STS-4 in June 1982 confirmed those observations. We, therefore, designed an experiment to study further this unique interface between technology and estuarine ecology where an extreme stress condition devel- ops and disappears rapidly. Our primary interest involved the effects of toxic agents or conditions on tissues, espe- cially gills, of fishes exposed to the exhaust plume. In the present study, we examined whole fishes exposed to the space shuttle exhaust plume by light microscopy and gills by light microscopy, transmission electron microscopy, and scanning electron microscopy. MATERIALS AND METHODS Species studied included the mosquitofish Gambusia affinis (Baird and Girard); sailfin molly Poecilia latipinna (Leseur); Gulf killifish Fundulus grandis Baird and Girard; and sheepshead minnow Cyprinodon variegatus LacepMe, Two experiments were conducted in which fish were exposed to the exhaust plume: one during the launch of STS4 in June 1982 and another during the launch of STS-5 in November 1982. To determine if previous expo- sure to the exhaust plume affected a fish’s subsequent ex- posure, the species named above were collected from two sites, Molly Pond and an unnamed lagoon. Molly Pond (tem- perature 25° C, sahnity 4 ppt), situated 6100 m and 260*^ west-southwest from the launch platform, was previously unaffected by shuttle launches. The lagoon (25°C, 14.5 ppt), a man-made body of water 400 m north from the platform, was the site of previous launch-related fish kills. For acclimatization, fish were transferred to two 75.7 liter aquaria with water temperature adjusted to 23— 24°C and sahnity to 10 ppt adjusted upward with Instant Ocean® and downward with deionized water. Artificial light hours occurred from 0800 to 1700 h daily. Fish were main- tained 12—19 days before the experiment on a diet of TetraMin® flakes once each morning. Stressed fish were removed. Fifteen and one-half h before the launch, fish were trans- ferred to plastic buckets containing 10 liters of deionized water adjusted to 10—12 ppt. Five buckets contained 12 fish, one contained 10 fish, and each bucket included speci- mens of all three species. One set of buckets contained fish from Molly Pond and the other from the lagoon. In each set, one bucket was protected from the exhaust plume by a plastic cover (control exposure), one was open to the plume (full exposure), and one was covered with cheese cloth to provide a partial exposure (intermediate exposure). The buckets were placed 10—15 meters north of the pad peri- meter fence, 3—4 meters west of the lagoon. This site is about 445 m north of the launch pad in a direct line with a concrete-lined flame trench that channels much of the ex- haust plume away from the platform. Manuscript received April 11, 1984; accepted August 24, 1984. 298 Hawkins et al. Control Closed Molly Pond Lagoon Intermediate Molly Pond Lagoon Open Molly Pond Lagoon pH Temp GO D.O. Salinity (ppt) AL (mg/1) Fe (mg/1) - - <0.2 0.33 7.2 7.2 24.0 22.5 5.8 6.2 10.0 9.5 <0.2 <0.2 0.22 ±0.01 0.2 ±0.0 4.7 4.8 22.0 22.0 6.2 5.6 10.5 10.5 0.4 ± 0.0 0.5 ±0.0 0.58 ±0.01 0.75 ±0.0 2.9 2.8 21.0 22.0 6.0 6.0 10.0 11.0 0.8 ±0.0 1.3 ±0.0 1.25 ±0.07 1.6 ±0.0 Access to the experimental site was gained within 1.5 h after launch. Temperature, pH, conductivity, dissolved oxy- gen, and salinity of water were measured from each bucket. Water samples for heavy metal analysis by atomic absorp- tion spectrophotometry were collected and placed on ice. Whole fish were fixed in 10% formalin. Specimens from which gills would be removed for ultrastructural examina- tion were placed on ice to be dissected and fixed 5 .5 h later. Gill arches, neither the first nor the last, were removed and fixed in ice-cold 3.0% phosphate-buffered glutaraldehyde for 3 h then placed in cold 0.1 M phosphate buffer and shipped on dry ice to Ocean Springs, Mississippi, for further processing and analysis which commenced 48 h later. For transmission electron microscopy, gill arches were cut into small pieces, postfixed in 1% osmium tetroxide for 2 h and dehydrated in ethanol. After treatment with pro- pylene oxide, the tissues were embedded in epoxy resin. For orientation and further light microscopical analysis, 1 -micron thick sections were cut on an LKB ultramicro- tome, mounted on glass slides, and stained with toluidine blue. Thin sections were cut on glass knives, collected on uncoated copper grids, stained with uranyl acetate and lead citrate, and examined in a Siemens 1 A electron microscope. RESULTS General Observations and Physical Parameters The exhaust plume from each of th.e first five STS launches affected an area near to and north of the launch pad. A strong acidic odor, probably HCl, lingered and aluminum oxide powder covered much of the vegetation and together with dust blown from the launch gave the sur- face of the lagoon a tannish tint. Dead fish were usually found in dense grasses at the southern end of the lagoon in 15-30 cm of water. . Text-figure 1 shows water chemistry data from the six experimental buckets. Temperature, dissolved oxygen and salinity changed little, if any, in the intermediate and lull exposures. Aluminum and iron content increased about 2 to 4 times There were no differences in the levels of other metals including Cd, Cr, Cu, Mn, Ni, Pb, and Zn The pH, initially 7.2 in water from both the Molly Pond and the lagoon decreased to 2.9 in the full exposure from Molly Pond and to 2.8 in the full exposure from the lagoon. Con- tinuous pH measurements from two succeeding launches were recorded. The pH of the lagoon was between 8 and 9 before the launch and dropped to about 1 within 2-3 rnin- utes following ignition (Text-figure 2). Within 60 minutes, the pH of the lagoon had recovered to about 7. In the MoUy Pond full exposure, 2 of 12 specimens died, whereas 9 of 10 died in the lagoon full exposure. Histopathological examination of paraffin-embedded whole fish revealed considerable damage involving gills but little if any, involving olfactory, nervous, integumentary digestive, and hemopoietic tissues. Studies of peripheral Text-figure 2. This graph represents continuous pH values taken during the launch of STS-7. The site was in the lagoon north of the launi* pad. Water depth was 12 centimeters and pH was momtore at approximately 6 centimeters. Exhaust Plume Effects on Fish Gills 299 blood were not conducted, but blood in tissues other than gill did not appear affected. Since the gill appeared to be the major target organ, it was chosen for more extensive study. Gill Morphology of Control Fish (Closed Bucket) Gills of all three species appeared typical for teleosts at the organ, tissue, cell, and organelle level as seen by light microscopy (LM) and transmission electron microscopy (TEM) (e.g., Laurent and Dunel 1980), and in surface mor- phology as seen by scanning electron microscopy (SEM) (e.g., Hossler et al. 1979a). Most observations were made by LM of paraffin and epoxy-embedded specimens and by SEM. Sectioning difficulties caused by mineral deposits which occurred in interlamellar spaces of fish from inter- mediate and full exposures made TEM observations diffi- cult to achieve. Observations could be made on broad areas of tissue but not on individual cells. Gills of Molly Pond and lagoon fishes from control ex- posures showed no damage that might have indicated pre- vious exposure to toxic conditions. Secondary lamellae were usually straight and interlamellar spaces free of de- posits (Plate 1, Figures 1, 2), A narrow lymphatic space separated the smooth pavement epithelial layer from the underlying intralamellar capillaries. Red blood cells were normal. Short, irregular projections arose from lamellar pavement cells of some specimens. Filaments of control gills contained undifferentiated cells, mucous cells, and chloride cells and often exhibited large, apparently inter- cellular, spaces. Mucous cells were especially numerous on the filament surface associated with the efferent artery whereas chloride cells were abundant near the filament sur- face associated with the afferent artery and in interlamellar regions (Plate 1 , Figure 3). Chloride cells stained lightly and had basally -situated nuclei. The identity of chloride cells was confirmed by TEM. Most chloride cells appeared to have deep apical pits opening to the filament surface. Gill lamellae of control specimens were thin, regular, overlapping plates with relatively smooth surfaces without pores or microridges (Plate 1, Figure 4). The filament sur- face, however, had numerous pores, the majority of which probably represent apical pits of chloride cells. Microridges were usually absent from the center of pavement cell sur- faces, but abundant near the peripheries (Plate 1 , Figure 5). Changes in Gills of Fishes from Intermediate Exposures Secondary lamellae showed no disruption or erosion, but some were angulated (Plate 2, Figure 6) and swollen. None of the fish died and no conspicuous differences in the types of pathological changes occurred among species. Some lamellae appeared thickened and retracted into the filament (Plate 2, Figure 7). Secretory granules of some mucous cells on interlamellar regions of filaments were denser than in others. Mucous cells moved to the surface and appeared to bulge outward (Plate 2, Figure 8). Interlamellar spaces of some fish had mineral deposits that ranged from granules less than 1.0 jum in diameter to aggregates more than 40.0 p.m in diameter. Pathological changes in gills, however, did not relate to the presence of granules. Numerous broad, shallow depressions and some deeper ones occurred near the interlamellar region (Plate 2, Figure 9). Mucous cell surfaces were usually smooth but sometimes had small granules (about 0.5 mm in diameter) attached (Plate 2, Figure 10). Such granules occurred often on pavement epithelial cells, especially microridged por- tions. Little change occurred in the microridge patterns of the pavement epithelial cells. Changes in Gills and Other Organs of Fish from Full Exposures Histopathological changes varied among specimens, arches, and filaments, often involved small portions of a few lamellae, and ranged from apparently mild to poten- tially lethal ones. Histopathological changes exhibited in some dead speci- mens that had not autolyzed appear relevant. In a few paraffin-embedded specimens that exhibited severe gill necrosis and had died following the exposure, blood spaces of the heart, particularly the atrium, were congested and the pericardial cavity filled with a transudate (Plate 3, Figure 11). Only one of four fish, a sailfin molly,from full exposures examined in epoxy-resin sections had not died following the exposure. In this fish, secondary lamellae shortened and epithelial cells lifted away from underlying tissues creating broad lymphatic spaces (Plate 3, Figure 12). Mineral de- posits occurred in many interlamellar spaces. Apices of mucous cells lay near the surface of the nonlamellar portion of the filament, and many mucous granules stained less densely with toluidine blue than did those from control or intermediate exposures (Plate 3, Figure 13). Changes in gills of fish that died in full exposures included fusion of adja- cent lamellae, clubbing of the ends of lamellae, hemostasis in afferent and efferent filament vessels and in lamellar capillaries, and erosion of cells of secondary lamellae (Plate 3, Figure 14). TEM confirmed that the eroded cells were pavement epithelial cells (Plate 3, Figure 15). Focal lesions involved primarily lamellae in the distal two-thirds of filaments (Plate 4, Figure 16). In some places, the surface epithelium eroded away exposing the under- lying filament vessels and lamellar capillaries (Plate 4, Figure 17). Mineral deposits occurred frequently. Neither micro ridges nor pores were often seen on filaments of these fish (Plate 4, Figure 18). Fish that died in full exposures exhibited many of the changes seen in fish that had not. This included erosion of epithelial layers. Lamellae in these fish frequently fused. Plate 4, Figure 19 shows a small area of lamellae exhibiting several degrees of fusion. In some places, fusion occurred between broad areas of epithelium and, in other places, among individual cells. Numerous bulges in the lamellae probably represent nuclei of pavement epithelial cells. 300 Hawkins et al. DISCUSSION Few field studies have been conducted to determine the ultrastructural effects of toxicants on fishes. Optimally, specimens for such studies are collected, fixed, and proc- essed rapidly. Hughes et al. (1978, 1979) developed morpho- metric techniques for determining subtle effects of pollu- tants on fish gills and emphasized the importance of con- sistent and appropriate fixation and processing protocols for specimens used for morphometry. In our study, logisti- cal problems including delayed access to the experimental site, a delay in fixation (although specimens were kept on ice), and a delay in processing caused by having to ship the tissues to a second laboratory were unavoidable. Such fac- tors could obviate morphometrical analyses but not qualita- tive ones, providing adequate control specimens are exam- ined. Even examination of dead specimens can give useful information. All experimental fish exposed to the exhaust plume had severely damaged gills. Damage consisted mainly of necrosis and sloughing of pavement cells of secondary lamellae. Other histological changes included swelling and clubbing of secondary lamellae, loss of microridges from the filament pavement cells, and mucus secretion. These changes were probably caused by sudden exposure to acid conditions as recorded in buckets exposed to the exhaust plume. Addi- tional measurements taken during the launches of STS-6 and STS -7 confirmed this pH decline in the lagoon near the experimental site. The ignition of the two solid rocket boosters and the simultaneous release of several thousand kiloliters of deluge water result in the formation of gases and particulates including carbon dioxide, aluminum oxide, water vapor, hydrogen chloride, and iron chloride. Hydro- gen chloride gas mixes with the ambient air and is readily scavenged by atomized water droplets and small drops which form from condensation as the exhaust plume cools. Most of the larger drops, possessing a pH of less than 0.5, are deposited near the pad (Keller and Anderson 1983). Our study indicates that exhaust plume components exert their primary histopathologic effects on gills of exposed fishes. This confirms an earlier preliminary study by Milligan and Hubbard (1983). Accurate diagnosis of gill effects must be based on exam- ination of large numbers of filaments because effects vary widely in different parts of a gill arch (Fromm 1980). SEM can help overcome some of these sampling problems and, when used in combination with LM and TEM, rather fine changes can be determined in specific cell types such as pavement epithelial cells, chloride cells and mucous cells. Some subcellular aspects of the histopathological re- sponse of gills to toxic conditions deserve comment. Fila- ment pavement cells of G. affinis, C. variegatus, and P. latipinna had microridges, but those on secondary lamellae did not. Similarly, Hossler et al. (1979a) reported that secondary lamellae of mullet Mugil cephalus Linnaeus lacked microridses. iio»-ever. were reported on secondary lamellae erf the caimh Hereropneutes fossilis (Bloch) by Rajbanshi (19"" L and the dogfish Scyliorhinus Canicula Linnaeus by Crespo il9S2f. The case of the rain- bow trout Richardson is not clear. Kendall and Dale (1979) reported no microridges on secondary lamellae, whereas Olson and Fromm (1973) and Hughes (1979) reported them to be present. More species under different exposure regimes and tecation procedures need to be examined by SEM to determine the nature and possibly the functions of these structures. In heat-stressed rainbow trout, the loss of microridges on gill surfaces was attributed to increased mucus production filling the depressions be- tween the microridges (Jacobs et al. 1981), Jagoe and Haines (1983) reported that microridges on gills of Sunapee trout Salvelinus alpinus oquassa dissappeared after exposure to pH 3 for 4 hours. They suggested that cellular swelling or membrane alterations were responsible. Cellular swelling generally occurs after acutely injured cells lose cell volume regulation (Trump and Ginn 1969). We consider the loss of microridges in fish exposed to space shuttle exhaust plume to be part of a spectrum of changes that probably eventu- ally leads to necrosis. LM, TEM, and SEM did not reveal an excess of mucus among microridges of the fish we examined. Fromm (1980) reviewed the effects of acid stress on freshwater fish and concluded that death may be caused by hypoxia brought on by alteration of gill membranes, coagu- lation of gill mucus, or a combination of the two. Gill mucus coagulation did not occur in the present study. How- ever, mucus was apparently discharged in exposed fish. Daye and Garside (1976) found that stress by pH caused hypertrophy and stimulated mucus secretion in gills of brook trout S. fontinalis. We did not see hypertrophy of mucous cells, but the heterogeneity of secretory granules in intermediate and full exposure groups suggested to us that those cells had been stimulated to release their stored mucus granules and had begun replacing them. Several hypotheses have been advanced to explain the role of mucus secretion as a protective response to acid stress. The benefit of mucus to the stressed fish might de- pend on the mucus being a barrier to ions and water, its being polyanionic and concentrating cations, or its specific binding of calcium, which is important for maintenance of permeability control (see review by McDonald 1983). Damage to secondary lamellae must be considered poten- tially serious because of the possible effects on respiration. Hu^es and Morgan (1973) reviewed the general histopath- ological responses of secondar>^ lamellae to pollutants. An initial response is thickening of the gill epitheHum due to swelling in acute exposures or to cell proliferation in long term exposures. Next, secondars- lamellae fuse, the pave- ment cell layer lifts, and pavement cells dissociate. Epithelial lifting might help protect the gill from a toxicant Exhaust Plume Effects on Fish Gills 301 by increasing the diffusion distance between the ambient water and the fish’s blood (Morgan and Tovell 1973) or by limiting water circulation between gill lamellae. In the pre- sent study, fusion of lamellae occurred not only between broad sheets of epithehum, but also processes of individual epithelial cells bridged the interlamellar space and joined adjacent lamellae. Using SEM, Engelhard! et al. (1981) re- ported fusion between broad areas of lamellae in rainbow trout exposed to crude oil emulsions whereas Jacobs et al. (1981) illustrated a focal type of fusion between secondary lamellae of heat-stressed rainbow trout. Possibly, the most severe gill injury that we saw in full exposures consisted of sloughing of epithelial cells of secondary lamellae, some- times exposing the underlying capillary network. A similar effect was noted by Daye and Garside (1976) in secondary lamellae of rainbow trout exposed to environments at and above pH 9.0 and below 5.6. Chloride cells, which are involved in monovalent ion regulation, occur in both euryhaline and stenohaline species of freshwater and marine fishes. These cells are located mainly in the interlamellar regions of filaments but in mar- ine and seawater-adapted species also along the surface of the filament related to the afferent filament artery (Laurent and Dunel 1980). Hossler et al. (1979b) showed with SEM that the numerous pores on filament surfaces of seawater- adapted M. cephalus represented apical pits of chloride cells. In freshwater-adapted specimens, pores were shallower, and cytoplasm of chloride cells extended above the level of the pavement epithelium. We confirmed the identity of chlor- ide cells by LM and TEM, With SEM, changes in the size, distribution or depths of filament pores after exposure could not be documented. Some filament pores, however, might represent evacuated mucous cells. Tissue damage does not necessarily indicate the cause of a fish’s death (Hughes and Morgan 1973). In heat-killed specimens of the banded killifish Fundulus diaphanus (Lesueur), Rombough and Garside (1977) considered the cause of death to be respiratory failure resulting from lesions in the medulla oblongata despite the presence of primary gill injury. For acutely lethal concentrations of some toxicants, however, death might not be accompanied by tissue damage. In gills of rainbow trout exposed for 2.5 h to lethal concentrations of ammonia. Smart (1976) reported neither increased mucus production nor hem- orrhage. He concluded that gill damage was not the cause of death in that situation. Whether fish surviving the acute exposure to the exhaust plume can recover is not known with certainty. The time course and mechanisms involved in repair of damaged tissues must be determined in controlled, laboratory experiments. Lloyd and Jordan (1964) found that rainbow trout that survived exposure to pH 3.8 for 24 h recovered when trans- ferred to clean water. Recovery from the exhaust plume, however, is indicated by several factors. First, fish kills that are caused by the exhaust plume occur abruptly, and fish do not continue to die afterwards. Second, examination of fishes from the lagoon area that had been the site of pre- vious kills revealed no latent pathologic changes that might have been related to previous exposures to the exhaust plume. However, lagoon fish might have been more suscep- tible to subsequent exhaust plume exposure since a much higher percentage of them died in full exposures than did fish from Molly Pond. ACKNOWLEDGMENTS We wish to thank Mr. Robert Allen, Mrs. Joan Durfee, and Mrs. Susan Fink for their technical assistance and Dr. Walter Wilborn and Mrs. Barbara Hyde of the EM Cen- ter, University of South Alabama, for assistance with the scanning electron microscopy. This study was funded in part by the U.S. Department of Commerce, NOAA, National Marine Fisheries Service, under PL 88-309 Project No. 2-393-R and by the National Aeronautics and Space Admin- istration, Biomedical Office, Kennedy Space Center, Florida. REFERENCES CITED Crespo, S. 1982. Surface morphology of dogii&h (Scyliorhinus canicula) gill epithelium, and surface morphological changes following treatment with zinc sulfate: a scanning electron microscope study. Biol. 67:159-166. Daye, P. G. & Garside, E. T. 1976. Histopathologic changes in superficial tissues of brook trout, Salvelinus fontinalis (Mitchill), exposed to acute and chronic levels of pH. Can. J. Zool. 545:2140-2155. Engelhardt, F. R., M. P. Wong & M. E. Duey. 1981. Hydromineral balance and gill morphology in rainbow trout Salmo gairdneri, acclimated to fresh and sea water, as affected by petroleum ex- posure. Tox. 1:175-186. Fromm, P. O. 1980. A review of some physiological and toxicologi- cal responses of freshwater fish to acid stress. Environ. Biol. Fish. 5:79-93. Hossler, F. E., J. R. Ruby & T. D. Mcllwain. 1979a. The gill arch of the mullet, Mugil cephalus. I. Surface ultrastructure. J. Exp. Zool. 208:379-398. . 1979b. The gill arch of the mullet, Mugil cephalus. II. Modification in surface ultrastructure and Na, K-ATPase content during adaptation to various salinities./. Exp. Zool. 208:399- 406. Hughes, G. M, 1979. Scanning electron microscopy of the respira- tory surfaces of trout gills./. Zool. (Lond.j. 187 :443-453. & M. Morgan. 1973. The structure offish gills in relation to their respiratory function. Biol. Rev. 48:419-475. , S. F. Perry & V. M. Brown. 1979. A morphometric study of effects of nickel, chromium and cadmium on the secondary lamellae of rainbow trout gills. Water Res. 13:665-679. , H. Tuurala & A. Soivo. 1978. Regional distribution of blood in the gills of rainbow trout in normoxia and hypoxia: a morphometric study with two fixatives. Ann. Zool. Fenn. 15: 226-234. 302 Hawkins et al. Jacobs D., E. F. Esmond, E. L. Melisky & C. H. Hocutt. 1981. Morphological changes in gill epithelia of heat-stressed rainbow trout, Salmo gairdneri: evidence in support of a ternperature- induced surface area change hypothesis. Can. J. Fish. Aquat. Sc . Jaeo! T. A. Haines. 1983. Alterations in gill epithelial mor- phology of yearling Sunapee trout exposed to acute acid stress. Trans. Am, Fish. Soc. 112:689-695. Keller V W & B. J. Anderson. 1983. Predication strategies for ex- ha^st 'cloud impacts: fallout of acidic droplets and inadvertent weather modification. Pp. 161-165 in A. Potter (ed.), Space shuttle environmental effects: the first five flights Report pre- pared by Lockheed Engineering and Management Services Com- pany, Inc. for NASA, Houston Texas. _ _ Kendall M. W. & J- E. Dale. 1979. Scanning and transmission elec- tron microscopic observations of rainbow trout (Salmo gairdneri) gill. X Fish. Res. Board Can. 36:1072-1079. Laurent, P. & S. Dunel. 1980. Morphology of gill epitheba in fish. Am. J. Physiol 238:1^1 -)S9. Lloyd R. & D. H. M. Jordan. 1964. Some factors affecting the re- sistance of rainbow trout (Salmo gairdneri) to acid waters. Int. Air Wat. Pollut. 8:393-403. McDonald, D. G. 1983. The effects of H+ upon the gills of fresh- water fish Can. J. Zool. 61:691-103. Milligan J E & G. B. Hubbard. 1983. STS-5 fish kill Kennedy S^Tce CeL. Florida. January 1983. USAF OEHL Report 83- 096EE003AFA. . , Morgan. M. & P. W. A. Tovell. 1973. The trout, Salmo gairdneri (Richardson). Z. Zellfo OlsorK* R & P. O. Fromm. 1973. A scanning electron niicroscope stid^f secondary lamellae and chloride cells of rainbow trout (Salmo gairdneri). Z. Zellforsch. 143:439 449. Raibanshi V 1977. The architecture of the gill surface of th 'iTneteropneustes fossilis (Bloch): SEM study. /. E.o/. Rombough'p^^i & E. T. Garside. 1977. Hypoxial death inferred from thermally induced injuries at upper lethal temperatures, m the banded kimfish, Fundulus diaphanus (LeSueur). Can. J. Zoo . Smll G7976^^^e effect of ammonia exposure on rainbow trout (5./.10 ..(rdn.W). / Fish ^-^8:47 -47 ^ Trump B. F. & F. L. Ginn. 1969. The pathogenesis of subcellular reaction to lethal mimy. Methods Achiev. Exp. Pathol 4:1- - PLATE 1 EXPLANATION OF FIGURES Cyprinodon vmegam from control exposure FBament (F); secondary lameUae (L). Paraffin section; hematoxylin and eosin stained, X 430. C. verigntur from control exposure. Chloride ceU (C);red blood ceUs (R). Epoxy restn section ; toluidine blue stained. X 4 30. C. «,negerur from control exposure. Note probably representing apical pit. Mucous cells (M). Epoxy resm blue stained. X 430. C. variegatus from control exposure. Secondary lameUae (L); filament (F). canning electron micrograph. X 370. pavement epithelial cells. Scanning election micrograph. X 3,66U. Exhaust Plume Effects on Fish Gills Plate i Hawkins et al. PLATE 2 EXPLANATION OF FIGURES Cyprinodon variegatm from intermediate exposure. Note angulation of secondary lamellae and that the lameUae are somewhat thicker than control lamellae m Figures 1-3. Epoxy resin section; toluidine blue stained. X 430. C variegatus from intermediate exposure. Note shortening, wrinkling, and swelling of secondary lamellae. Also, mucous cells (M) have different densities. Filament carti- lage (FC). Epoxy resin section; toluidine blue stained. X 430. C variegatus from intermediate exposure. Note mucous cells (arrowheads) on fila- ment surface bulge outward slightly. Epoxy resin section; toluidine blue stained. X430. C variegatus from intermediate exposure. Note depressions (*) in interlamellar re- gions of filament. Scanning electron micrograph. X 730. Enlargement of fUament surface shown in Figure 9. Note numerous bulging cells, probably mucous cells (M) and many pavement epithelial cells partially devoid of microridges (*). Chloride cell pore (P). X 1,830. 306 Hawkins et al. PLATE 3 EXPLANATION OF FIGURES 11. Poecilia latipinna that died from full exposure. Note blood congestion in atrium (A) of heart and transudate in pericardial space (PS). Paraffin section; hematoxylin and eosin stained. X 70. 12. P. latipinna from full exposure. Note retracted lamellae, wrinkling of pavement epi- thelial cells (arrowheads) and areas of epithelial lifting (*). Epoxy resin section; toluidine blue stained. X 430. 13. P. latipinna from full exposure. Note mucous cells (M) are lightly staining. Epoxy resin section; toluidine blue stained. X 430. 14. Cyprinodon variegatus that died from full exposure. Lamellae have fused so that normal architecture is disrupted. Epoxy resin section; toluidine blue stained. X 430. 15. C. variegatus that died from full exposure. Pavement epithelial cells (PC) are necrotic and separated from secondary lamella. Transmission electron micrograph. X 10,380. Exhaust Plume Effects on Fish Gills Plate 3 307 Hawkins et al. PLATE 4 EXPLANATION OF FIGURES 16. 17. 18. 19. PoeclUa taripmna from fuU exposure. Note areas of damaged seconds^ lamellae (arrow). GiU arch (A); mineral deposits (MD). Scanning electron micrograph. X 210. P. latipinm from full exposure. Loss of superficial epithelium reveals artery (FA) and lamellar capillaries (LC). Scanning electron micrograph. X 830. P. htipinm from full exposure. Note absence of microtidges from filament surface (F). Scanning electron micrograph. X 830. C. variegatus that died from full exposure. Note fusion between broad areas of lamellae^)*) and between nanow cellular bridges (arrows). Nuclei of pavement epi- thelial cells (arrowheads). Mineral deposits (MD). X 830. Exhaust Plume Effects on Fish Gills Plate 4 309 Gulf Research Reports Volume 7 | Issue 4 January 1984 Distribution and Ecology of the Synaphobranchidae of the Gulf of Mexico Douglas M. Martin National Oceanic and Atmospheric Administration DOI: 10.18785/grr.0704.02 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Martin; D. M. 1984. Distribution and Ecology of the Synaphobranchidae of the Gulf of Mexico. Gulf Research Reports 7 (4): 311-324. Retrieved from http;//aquila.usm.edu/gcr/vol7/iss4/2 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 311-324, 1984 DISTRIBUTION AND ECOLOGY OF THE SYNAPHOBRANCHIDAE OF THE GULF OF MEXICO DOUGLAS M. MARTIN National Oceanic and Atmospheric Administration, National Ocean Service, Office of Oceanography and Marine Services, Rockville, Maryland 20852 ABSTRACT Synaphobranchid eels of the Gulf of Mexico are an important part of the upper continental slope ichthyofauna, occurring most frequently between 500 and 1,500 m. Two of the four known genera {Histiobranchus and Diastobranchus) have not been reported from the Gulf. Synaphobranchidae tend to occur within a narrow range of temperatures compared to the North Atlantic synaphobranchid eels. However, distribution of these eels in the deeper parts of the Gulf appears to be correlated more to change in depth than to temperature, salinity, or dissolved oxygen. The distribution at the shallower limits of their depth range appear to be a result of synergistic effects of the dissolved oxygen demand and the change in temperature. The synaphobranchid eels’ apparent preferences for particular types of substrata are probably associated with the organisms preyed on rather than direct selection of bottom type by the eels. These eels are opportunistic feeders, feeding primarily on fish, squid, and crustaceans. Synaphobranchidae are frequently infested with parasites, but there do not appear to be any serious abnormal morphological results. INTRODUCTION Investigation of the deep-sea ichthyofauna has usually been conducted on a broad survey basis. Investigators have compiled lists and descriptions of families, genera, and species occurring throughout a particular area with a limited number of studies of the distributional and ecolog- ical aspects of individual groups of fishes. Springer and Bullis (1956) and Bullis and Thompson (1965) published a list of fishes collected in the Gulf of Mexico by the U.S. Fish and WildHfe Service research vessels which contained station locations, depths of capture, and for some stations, bottom type and temperature. Also, from these cruises Grey (1956, 1958, and 1959) published descriptions of the abyssal benthic fishes with short remarks about their general distribution and depths of capture. However, only a few investigations dealing with the distribution and ecology of particular families exist; most are lists (Mead 1952) or annotated checklists with some discussion of distribution and ecological factors included (Bright 1967). This investi- gation is particularly concerned with the eel group, about which ecological studies are practically nonexistent. Spe- cifically, the purposes of this study are to describe the distribution and ecology of the family Synaphobranchidae for the Gulf of Mexico. The paucity of information, until recently, on the distri- bution of synaphobranchid eels in the Gulf of Mexico and Caribbean Sea reflects the absence of intensive deep-sea exploration of this region. Synaphobranchid eels were first recorded in the Gulf of Mexico by Agassiz (1888) while working on the Blake collections. Adjacent to the Gulf, Parr (1932) working with collections from the PAWNEE expedition reported captures of Ilyophis and Synapho- branchus specimens from the Great Bahama Banks south- Manuscript received October 6, 1983; accepted April 10, 1984. east of the Straits of Florida. Castle (1960) described anew species of synaphobranchid eel, Synaphobranchus oregoni, from the Gulf and reported the occurrence of Synaphobranchus brevidorsalis, previously reported as Synaphobranchus kaupi by Grey (1956). In a doctoral dissertation on the deep-sea fish of the Gulf of Mexico, Bright (1967) noted the occurrence of several species of synaphobranchid eels with their distribution and some important ecological factors. Robins (1968) discussed some aspects of the distribution and general ecology of the family Synaphobranchidae in the Straits of Florida. METHODS Eel samples for this investigation were collected during cruises of the R/V ALAMINOS under the direction of Dr. Willis Pequegnat. Collections for this study were made with the benthic skimmer (Pequegnat, Bright, and James 1970), 2-m dredge, and the 20-m otter trawl. Table 1 is a summary of pertinent station information. Cruises of the R/V ALAMINOS are designated by a number and letter system. For example, in the series 71A1710 the first two digits refer to the year, the letter A is for ALAMINOS, the next two digits denote the number of the cruise, and the final two digits indicate the station number. On occasion, the station number will be followed by a letter which indicates more than one haul made at that station. Identification was accomplished by radiographing each specimen and counting vertebrae. Hydrographic data (temperature, salinity, and dissolved oxygen) and sediment samples were collected at most stations; however, in some instances it was necessary to supplement the existing data with data collected during physical and geological cruises in the same area, The hydro- graphic data were taken approximately 1 meter from the bottom which is within the range of occurrence of the Synaphob ranchidae . 311 312 Martin TABLE 1 Summary of station data. Indicates cruise, number of specimens, depth, equipment, location, and species taken at each station. Station Number of Species Depth (m) Equipment Latitude N Longitude W Species Cruise 68A7 July 25 - August 11 12B 3 900 Skimmer 29°14.0' 86°59.7' S. or ego m 13A 8 1060 Skimmer 29°03.0' 87°15.0' S. oregoni (4) 7. brunneus (4) 13D 1 1463 Skimmer 28°59.0' 87'’23.3' S. oregoni 15D 3 1097 Skimmer 29°10.3' 87°31.5' S. oregoni (1) 7 brunneus (2) 15H 11 914 Skimmer 29°10.5' 87°16.0' S. oregoni (10) 7 brunneus (1) 17B 1 900 Skimmer 29°09.5' 87°02.0' S. oregoni Cruise 68A13 November 12-21 1 6 878 Skimmer 25°38.0' 96°07.3' S. oregoni 3 1 714 2-m dredge 25°39.0' 96°11.0' S. oregoni 4 1 512 Skimmer 25^38.4' 96°18.3' S. oregoni 8 5 732 Skimmer 26°18.0' 96°08.0' S. oregoni 12A 4 1060-1317 Skimmer 25 '' 31 . 0 ' 95°51.0' S. oregoni 14 1 969 2-m dredge 25°39.5' 95°49.5' S. oregoni 15 1 659-860 Skimmer 27"34.5' 95°10.5' S. oregoni 16 1 714 2-m dredge 27°37.0' 95°08.0' S. oregoni 23 2 732 Skimmer 27°35.0' 95°23.0' S. oregoni 26 1 1371 -1435 Skimmer 27‘'00.3' 95°08.0' S. oregoni Cruise 69A11 August 5-27 4 8 1005 Skimmer 27°24.9' 94°44.5' S. oregoni 27 2 778 Skimmer 18‘'54.0' 94°58.8' S. oregoni I. brunneus 69 1 1371 Skimmer 20°07.5' 96°10,5' S. oregoni 75 1 1134 Skimmer 2l'’26.0' 96°48.5' S. oregoni 78 8 677-732 Skimmer 21°30.0' 96°55.0' S. oregoni 83 1 1236 Skimmer 21°35.0' 96°45.0' S. brevidorsalis 86 4 969-1097 Skimmer 21°41.0' 96°51.0' S. oregoni Cruise 69A13 October 4-16 44 19 752 20-m trawl 28‘'58.0' 88°28.0' S. oregoni Cruise 70A 10 July 4-30 9 8 1146 20-m trawl 18°57.0' 87°09.0' S. brevidorsalis 16 1 833-878 20-m trawl 16"ll.l' 84''48.0' S. affinis 29 1 1146 20-m trawl ll''31.8' 74°24.5' I. brunneus 40 4 622-659 20-m trawl 12°40.0' 72°00.0' S. oregoni 51 7 1097 20-m trawl 17°17.l' 79°50.6' S. brevidorsalis Cruise 71A7 July 13-25 9 8 906 20-m trawl 26'’32.0' 96''07.0' S. oregoni (7) 7 Brunneus (1) 10 6 936 20-m trawl 26°32.9' 96°06.4' S. oregoni 11 4 637 20-m trawl 26°32.3' 96^3.3' S. oregoni 43 61 1005-1847 20-m trawl 27°27.8' 92°46.0' S. oregoni 49 42 936 20-m trawl 27'’26.0' 92°42.0' S. oregoni (41) 7 brunneus (1) 57 10 1216-1234 20-m trawl 26^55.8' 92°57.9' S. oregoni Cruise 71A8 July 29-August 15 24 12 659-695 20-m trawl 23°56.8' 97°05.0' S. oregoni 29 34 936 20-m trawl 23°54.7' 96°59.9' S. oregoni 36 2 2151 20-m trawl 23°35.6' 96°25.5' S. brevidorsalis 47 35 936 20-m trawl 21°35.6' 96°54.6' S. oregoni 60 77 1097-1134 20-m trawl 19°00.3' 95°ll.l' S. oregoni Synaphobranchidae Distribution and Ecology 313 30“ 2 5“ 20 “ 95“ 90“ 85“ 80“ Figure 1. Distribution of the family Synaphobranchidae in the Gulf of Mexico. Data are derived from the collections of NMFS, UMML, and TAMU. The open circles show stations made by TAMU where no synaphobranchid eels were collected. Sediment samples were collected with piston and gravity corers. Sediment size analyses were performed on the upper surface of the piston core samples for percent sand, silt, and clay. The upper surfaces of gravity cores were analyzed for percent sand and the remaining core fractions were analyzed for percent silt and clay combined. DISTRIBUTION Synaphobranchidae occur within a narrow depth range primarily around the northern, western, and southeastern areas of the Gulf of Mexico, which was determined from the collections of the University of Miami Marine Laboratory (UMML), the National Marine Fisheries Service (NMFS), and Texas A&M University (TAMU) (Figure 1). The open circles indicate trawl stations and benthic skimmer stations made by the R/V ALAMINOS where no synaphobranchid eels occurred. Limited sampling of the Yucatan Peninsula prevents any inference concerning the absence of synapho- branchid eels from that area. For the purpose of this investi- gation, the Gulf of Mexico was considered to extend no further than 80° west longitude. Therefore, a number of occurrences of synaphobranchid eels reported by Robins (1968) from the Straits of Florida do not appear on the distributional maps. Between 1968 and 1971, 133 benthic stations were made by TAMU in the Gulf, 99 were taken with the benthic skimmer and 2-m dredge (modified skimmer). The remain- ing 34 stations were made with a 20-m otter trawl which was the most successful piece of sampling gear for taking demersal fishes. Of the skimmer stations, 25 contained 76 specimens of synaphobranchid eels. But from the 34 trawl stations, 1 1 contained 322 specimens representing approxi- mately 78% of the collection. The depth distribution of bottom stations made in the Gulf by TAMU, and the number of stations within a par- ticular depth interval which contained synaphobranchid eels are presented in Table 2. An estimate of the probability of taking a species of the family Synaphobranchidae within a given depth range is included, together with the 95% confidence limits. 314 Martin Depth distribution and total number of each species taken within a particular depth interval are shown in Table 3 and establish the depth range of each species. The depth ranges in the upper 1,500 m are considered closely repre- sentative of the actual distributions for these species. Below this depth, sampling is too sparse to make any conjectures as to the vertical limits of occurrence for the deeper dwell- ing members of the family. An examination of Tables 2 and 3 suggests that the synaphobranchid eels are primarily situated on the upper part of the continental slope TABLE 2 Depth distribution of bottom stations in the Gulf by TAMU (sample size) with number of stations containing synaphobranchid eels (occurrences), and the probability of occurrence of a species of the family in a particular depth interval with the associated confidence limit. Depth (m) Sample Size (n) Occurrence (r) Probability of Occurrence (P=5) Confidence Limits (95%) 100-600 40 1 .02 .00-.05 600-1100 40 1 .63 00 J oo 1100-1600 23 8 .35 .15-.54 1600 30 1 .03 .OO-.Ol CONFIDENCE LIMITS = p ± 1.96 V p(l-p) (R. V. Hogg and E. A.Tanis 1977). ^ TABLE 3 General depth distribution of synaphobranchid eels collected in the Gulf by UMML, NMFS, and TAMU. The values in each column represent the combined number of that species taken within the corresponding depth interval. Depth (m) S. oregoni S. brevidorsalis S. affinis I. brunneus 100-199 200-299 300-399 400-499 500-599 1 600-699 27 1 700-799 57 9 6 800-899 22 12 1 900-999 152 2 7 1000-1099 84 1 6 1100-1199 77 1 1200-1299 12 1300-1399 3 1 1400-1499 1500-1599 1600-1699 1700-1799 1800-1899 1900-1999 2000-2099 2100-2199 2200-2299 1 5 between 500 and 1,500 m. mth only one species occurring below 2,000 m. The family Synaphobranchidae contains four genera and eight species (Castle 1964), but only two genera and five species are recorded from the Gulf of Mexico. These are Synaphobmnchus oregoni Castle. S. brevidorsalis Gunther, S. affinis Gunther, 5. kaupi Johnson, andi7yop/ns bnmneus Gilbert. The two genera not represented are Histiobranchus and Diastobranchus. Synaphobranchus kaupi was not col- lected at any TAMU stations. The only occurrences recorded were taken by NMFS. Identification of these specimens was made in the field (Richard Roe, personal communication) and these could have been S. affinis, since the two species have a very similar scale pattern (Castle 1964). A histogram showing the frequency of distribution with depth for each species is presented in Figure 2 (a-d) and the horizontal distribution for each species is shown in Figure 3. Synaphobranchus oregoni Castle, 1960 Vertical Distribution The vertical range of S. oregoni, the most frequently occurring species collected by TAMU, is between 500 and 1,500 m (Figure 2a) placing this species in the upper conti- nental slope fauna. Most specimens were collected between orsahs 01 1 5 %71 0) ^ 4 ro // OF ro / tt 1 UJ CD n ' F7I / / DEPTH (m) Figure 2 a-d. Frequency distribution v,ith depth for S. oregoni (a), S. affinis (b), S. brevidorsalis (c). and I. bnmneus (d). Synaphobranchidae Distribution and Ecology 315 Figure 3. Horizontal distribution of S. oregoni, S. affinis, S. brevidorsalis, and/, brunneus. 900 and 1,000 m. The shallowest and deepest occurring specimens were recorded from the western Gulf at 512 m and 1 ,463 m, respectively. When comparing depths of maxi- mum occurrence of S. oregoni from the western Gulf (936 to 1,134 m) with those reported by Robins (1968) from the Straits of Florida (750 to 823 m), there is a significantly wider and deeper range of occurrence for this species in the western Gulf. There does not appear to be any significant change in the depth of maximum occur- rence in populations from north to south in the western Gulf based on the data from TAMU collections (Table 1). Horizontal Distribution Figure 3 shows the horizontal distribution of S. oregoni and indicates its occurrence throughout the Gulf. The absence of synaphobranchid eels off Yucatan was con- sidered previously. Robins (1968) reports a northern limit (Lat. 24°5l'N) for S. oregoni in the Straits of Florida. From the data avail- able for this investigation, the northern limit of S. oregoni for the Gulf proper is considered to be Lat. 29°18'N. However, there is an area farther north within the depth range of this species that has not been sampled by TAMU, but has been sampled extensively by the NMFS at Pasca- goula, Mississippi (unpublished cruise report). It appears that the absence of S. oregoni in this area is due to limiting environmental factors which will be discussed in the Ecology Section. The apparent southernmost occurrence for S. oregoni in the Gulf of Mexico is Lat. 18°54'N. However, this is possibly due to insufficient sampling and may not be related to physical conditions. Synaphobranchus affinis Gunther, 1877 Vertical Distribution Synaphobranchus affinis was not collected at any of the TAMU stations. Therefore, the following discussion is based primarily on Robins (1968) and a species list supplied by the NMFS at Pascagoula, Mississippi. A large number of the specimens reported by Robins are not included here since 316 Martin most were collected east of Long. 80°00^W, and, for the purpose of this study, are considered to be outside the Gulf of Mexico proper. The vertical range of S. affinis for the Gulf is between 600 and 1,000 m, with the largest number being collected from the 800 to 900 m depth interval (Figure 2b). From Robins’ (1968) data for the Gulf, the shallowest and deepest depths of occurrence for the species were reported at 671 m and 1,015 m, respectively. Horizontal Distribution The most significant aspects of the distribution of this species is its apparent absence from the western Gulf (Fig- ure 3). Robins (1968) reported that i". affinis occurred most frequently north of Lat. 25°00'N, the largest concentration being found in the Straits of Florida. The most northern and western stations where S. affinis have been taken are Lat. 29''17'N and Long. 87°09'W, respectively. Figure 1 indicates the extensive sampling carried out in the western Gulf. Such extensive sampling without capture makes it highly probable that Synaphobranchus affinis is limited to the eastern section of the Gulf of Mexico. Synaphobranchus brevidorsalis Gunther, 1887 Vertical Distribution Figure 2c shows the vertical range of S. brevidorsalis to be approximately 1,300 to 2,200 m. The largest number of specimens occurred within the 2,100 to 2,200 m depth interval. Shallowest occurrence was at 1,326 m and the deepest was 2,151 m. Absence of S. brevidorsalis captures between 1,326 and 2,151 m is peculiar, and is not due to the lack of sampling. Table 2 shows extensive sampling over that depth interval. It is possible that this shallow specimen was S. oregoni with a reduced vertebral count or a migrant S. brevidorsalis from the Caribbean. Horizontal Distribution This species of synaphobranchid eel, although wide- spread, has not been collected in abundance from the Gulf of Mexico. At the present, only six specimens have been reported, three taken by the NMFS from the northeastern section, and three collected from the southwestern section by TAMU. Figure 3 shows the locations where S. brevidorsalis have been collected. The small size of the population and wide horizontal distribution of this species is apparent when comparing the number of stations (3) containing S. brevi- dorsalis with the number of stations (33) containing other synaphobranchid eels. The occurrence of S. brevidorsalis in the Gulf of Mexico presents an interesting distributional problem. Heretofore, this species had been reported from the Gulf of Mexico and the Indian and Pacific Oceans (Bruun 1937 and Grey 1956). Robins (1968), working with a large collection of synapho- branchid eels did not report any S. brevidorsalis from the Straits of Florida. Two samples containing 15 specimens were taken in the Caribbean by TAMU in 1970. One station at 1 .097 m con- tained seven specimens and the other from 1,146 m had eight. More extensive sampling is needed off the northeast- ern coast of South America to further elucidate the distri- bution of Synaphobranchus brevidorsalis. Ilyophis brunneus Gilbert, 1891 Vertical Distribution Ilyophis brunneus was the second most frequently occurring synaphobranchid eel, although it was generally not collected in large numbers (the most taken in any trawl was four). Usually, I. brunneus was captured singly or in pairs; perhaps this is due to the eel’s burrowing habits. Figure 2d shows the vertical range of Ilyophis brunneus to be 700 to 1 ,200 m with the maximum number of speci- mens collected from 900 to 1,100 m. A second peak (700 to 800 m) in the frequency distribution histogram implies that /. brunneus possibly occurs in equal numbers through- out its vertical range. Robins (Figure 33, 1968) also shows a maximum occurrence within the 700 to 800 m depth inter- val for /. brunneus in the Straits of Florida; however, the data do not indicate a second area of maximum occurrence within the 900 to 1,100 m depth interval. This could indi- cate that there are factors affecting the vertical distribution of this species in the Straits of Florida which are not found at those depths in the Gulf proper. Horizontal Distribution Figure 3 shows that I. brunneus is distributed throughout the Gulf, being collected from every major geographic section. Ilyophis brunneus appears to occur more fre- quently in the eastern and northern sections. This is indi- cated by a comparison of the number of captures with the number of trawl stations within each major geographic section (Table 1). ECOLOGY Ecological investigations of deep-sea fishes for the Gulf are few and ecological studies for deep-sea eels are non- existent. One of the purposes of this study is to document the physical habitat and to some extent, the niche that the synaphobranchid eels occupy in the Gulf of Mexico. For the purpose of discussion, the ecology section is divided into two parts: (1) physical parameters where the tempera- ture, salinity, dissolved oxygen, and sediment data are reported for each species, and (2) biological parameters where feeding habits and parasites are discussed. Hydrographic data (Table 4) and sediment data (Table 5) were taken in the vicinity of, and on the same cruises as, the trawl stations where synaphobranchid eels were collec- ted. Close proximity of these hydrographic, sediment, and Synaphobranchidae Distribution and Ecology 317 TABLE 4 Hydrographic Data Station Lat. (N) Long. (W) Depth (m) T(C) S (ppt) 02 (ml/l) 71A7-25 27°54.6' 92°49.9' 209 13.95 35.783 2.608 71A7-21H 26°43.6' 96°25.5' 111 12.98 35.597 2.425 67A5-13C 29°30.0' 86°52.5' 350 10.75 35.305 2.835 71A7-36 if 36.5' 92°58.4' 460 8.84 35.076 2.536 71A8-69 19°39.3' 92°40.8' 536 7.69 34.988 2.658 71A8-45 21°25.5' 96°55.8' 547 7.56 34.928 2.631 71A8-5H 26°38.0' 96°15.0' 582 7.32 34.879 2.794 67A5-9B if 27.0' 86°51.l' 676 6.62 34.883 3.104 67A5-6F 28°47.3' 87°02.8' 750 5.73 34.885 3.511 66A5-5 11°52.S' 90°22.0' 785 5.77 34.895 3.450 65A3-1 27°30.0' 95°30.0' 813 5.52 34.899 3.870 67A5-7G 29°15.5' 86°59.0' 867 5.32 34.902 3.735 71A8-28 23°56.l' 97°01.3' 903 5.03 34.941 3.886 71A744 27°30.4' 92°49.3' 924 5.09 34.914 3.781 69A11-6 27°25.0' 94°45.6' 937 4.88 34.936 3.923 71A7-8H 26°31.2' 96°05.5' 957 5.02 34.876 3.861 71A8-62 19°01.0' 95°11.0' 1034 4.75 34.945 4.046 68A3-15B 26°28.8' 95°59.0' 1086 4.52 34.948 4.515 71A7-59 26°59.l' 92°58.5' 1193 4.38 _ 4.429 71A8-77 20°06.8' 92°20.4' 1316 4.28 34.964 4.638 71A8-5 3 21°37.l' 96°09,7' 1818 4.22 34.936 4.819 71A8-9 26°07.5' 92°42.0' 2043 4.20 34.987 4.813 71A8-35 23°39.0' 96°26.5' 2123 4.23 34.980 4.834 71A8-39 23°28.3' 95°30.3' 3006 _ 34.981 4.936 69A13-34 26°50.5' 86°40.0' 3074 4.32 34.780 5.024 66A5-3 25°25.0' 86°13.0' 3204 4.28 34.974 5.090 69A13-31 25°26.0' 86°09.0' 3221 4.33 34.876 4.990 68A7-4C 25°25.3' 86°05.3' 3246 4.32 35.143 5.388 71A8-15 25°05.8' 94°23.l' 3665 4.42 34.972 4.804 trawl stations presents an opportunity to compare the occurrence of some species of synaphobranchid eels with, essentially, direct observations of the environmental para- meters. The hydrographic data were collected during spring, summer, and fall cruises and show little variation seasonally at the depths occupied by synaphobranchids. To further show the uniform nature of the bottom temperature, salinity, and dissolved oxygen along the slope, data from Table 4 were plotted in Figure 4 (A-C) on a hydro- graphic transect (solid line) across the northern slope between 26° to 28° north latitude and 92° to 93° west longitude. The close fit of the data to the profiles of the transect indicate uniform conditions horizontally and are considered to be representative of the condition under which the eels generally occur. PHYSICAL PARAMETERS Temperature A discussion of temperature effect on animal distribu- tion and behavior was presented by Gunter (1957), where he considered the magnitude of change of the temperature to be of major importance. Table 4 shows that the tempera- ture decreased with increasing depth to about 2,000 m, where it reached a minimum of 4.20°C and then increased to 4.42°C due to adiabatic heating. Figure 4A is a transect of bottom temperatures (solid line) across the northern slope. It is clear from the slope of the temperature profile that the variability of the temperature range also decreased with increasing depth to approximately 1,300 m. The tem- perature varies by less than 0,10°C between 1,300 and 2,000 m. Synaphobranchus oregoni. There was a gradual decrease in the bottom temperatures with depth through the 500 to 1,500 m vertical range of S. oregoni. The temperature ranged from 7.70°C to 4.24°C over this depth interval (Fig- ure 4A), representing a temperature difference of 3.46°C. The largest number of specimens occurred within the 900 to 1 ,000 m range with a corresponding temperature range of 5.20°C to 4.75°C or a variation of 0.45°C. Syna- phobranchus oregoni tended to occur most frequently at depths where the temperature begins to vary the least. This is illustrated in Figure 2a, where the frequency of distri- bution is shown to be skewed toward the deeper depths with the least variable temperature. Table 2 also shows that the probability of capturing S. oregoni below 600 to 1,100 m was higher than above that depth interval. The equal number of attempts within each interval indicated 318 MARTIN TABLE 5 Sediment Data Station Lat. (N) Long. (W) Depth (m) Sand (%) Silt (%) Clay (%) SUt-Clay (%) 68A3-11C 26°18.5' 96°22.0' 91 89.4 10.6 99.1 71A842 21°21.7' 97°01.5' 179 0.9 73.2 67A5-11B 29°25.0' 86°20.0' 190 26,8 71.9 67A5-13D 29°30.0' 86°52.0' 379 28.1 97.3 71A8-68 19°39.3' 92°40.8' 528 2.7 98.0 71A8-44 70A8-8 21°25.3' 29°17.5' 96°55.8' 87°09.0' 565 686 2.0 2.7 14.5 82.8 97.3 97.0 68A3-12B 26°21.0' 96°08.5' 752 3.0 98.7 71A8-28 23°56.l' 97°01.3' 900 1,3 86,8 67A5-7B 29°08.0' 87°09.5' 918 13.2 97.3 68A3-14B 26°25.0' 96°03.8' 955 2.7 96.6 71A8-61 19°00.0' 95°11.0' 1057 3.4 98.4 68A3-15C 26°28.8' 95°59.0' 1104 1.6 90,7 71A7-60 70A8-11 26°57.4' 28°30.7' 92°58.5' 87°20.6' 1216 1335 9.3 2.9 16.7 80.4 97.1 95.7 71A8-76 70A8-34 20°06.4' 26°43.2' 92°19.2' 93°38.2' 1337 1348 4.3 6.9 14.5 78.6 93.1 91.6 67A5-5 70A8-12 70A8-9 70A8-33 70A8-32 if 21.2' 27°32.l' 29°00.8' 26°45.2' 26°39.0' 87°20.0' 85°23.l' 87°29.3' 94°10.6' 94°44.0' 1476 1646 1650 1716 1778 8.4 20.2 1.5 1.7 5.0 30.0 12.3 16.9 13.8 49.8 86.2 81.4 81.2 79.8 98.5 98.3 95.0 87.1 71A8-7 70A8-10 26°07.0' 28°43.2' 92°56.0' 87°45.5' 2113 2158 12.9 3.8 13.5 82.7 96.2 97.8 68A3-3D 25°09.0' 94°11.0' 3658 2.2 that the probabilities were not greatly biased by sample size, and since all trawls were fished about 30 minutes, approxi- mately the same amount of bottom was covered for each station. The maximum and minimum temperatures recorded within the range of distribution of S. oregoni in the Gulf of Mexico were 7.70°C and 4.24°C, respectively. As noted above, a minimum temperature of 4.20° C. occurred at approximately 2,000 m and beyond that depth the tem- perature increased to 4.42°C as a result of pressure. These data show only a 0.04°C change in temperature from 1,500 to 2,000 m, which indicates that either these eels were unable to adapt to the temperature differential for physio- logical reasons at 2,000 m depth (at wliich the ambient temperature beings to increase), or that some other limiting factors (such as sediment type or pressure) were involved in restricting 5. oregoni from inhabiting the lower continental slope or rise. Synapho bronchus affinis. The temperature ranged from 6.30°C to 4.70°C over the depth interval 600 to 1,000 m from which S. affinis was collected (Figure 4A). Synapho- branchus affinis was reported most frequently from 800 to 900 m where the temperature ranged from 5.90°C to 5.20°C. Temperature varied by 1.60°C over the 400 m depth span from which S. affinis was collected and by 0.70°C over the depth interval from which this species was most frequently reported. Synaphobranchus brevidorsalis. The temperature range over the depth inteiwal 1,300 to 2,200 m from which S. brevidorsalis was reported was 4.30 C to 4.12 C (Fig- ure 4A), a variation of 0.18°C. Although this species of synaphobranchid had a wide vertical distribution, it oc^curred at depths where temperature varied at most by 0.10 C and was most frequently collected at depths where the tempera- ture varied by less than 0.03°C. Ilyophis brunneus. The temperature range for / brunneus was 6.50°C to 4.50°C, based on the vertical range estabhshed in Figure 2d. Ilyophis brunneus was collected most frequently between 900 and 1,100 m, which had a temperature range of 5.20°C to 4.50 C (Figure 4A); and in almost equal numbers from the 700 to 800 m depth interval, which had a temperature range of6.50°C to5.90°C. Salinity There are few reports relating salinity to distribution of deep-sea fishes in the Gulf of Mexico. Although salinity is considered a rather stable factor in the deep waters of the Gulf, Ichiye and Sudo (1971) have shown that long-term secular variations of a few hundredths of a ppt over 5 -year periods do occur within the depth range of the Synapho- branchidae. Another interesting feature of the vertical distribution of salinity is the presence of high-salinity water (over 35.000 ppt) which flows westward along the southern Synaphobranchidae Distribution and Ecology 319 SALINITY (ppt) -34.5 35.0 35.5 36.0 36.5 V. I 1 1 ^ 1 DISSOLVED Oj (ml/i) » 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 “ 1 ^ ^ i 1 1 1 1 1 TEMPERATURE (C) ^ 3.0 4.0 5.0 6.0 7.0 8.0 9.0 iO.O 11.0 12.0 13.0 14.0 Figure 4 A-C. Transect of hydrographic data (solid line) from the northern continental slope of the Gulf of Mexico. continental slope and northward along the western slope (Ichiye and Sudo 1971). A salinity profile indicates a general trend of decreasing bottom salinity with increasing depth to about 900 m where the salinity begins to increase with depth (Table 4). When bottom salinities from other stations in the Gulf are plotted on the northern slope transect, a slightly variable structure of salinity (horizontally) is evident. Synaphobranchus oregoni. The salinity between 500 and 1,500 m decreases from 34.99 ppt at 536 m to 34.88 ppt at 957 m where the salinity then begins to increase to approxi- mately 34.90 ppt at 1,500 m (Table 4). The salinity is slightly more variable horizontally at 500 m (approximately 0.14 ppt) than it is at the deeper depths (approximately 0.04 ppt). Synaphobranchus oregoni was most frequently collected within 900 to 1 ,000 m where the saUnity range was typically 34.94 to 34.91 ppt and could be expected to vary by about 0.04 ppt horizontally. Synaphobranchus affinis. The salinity range for S. affinis is from 35.00 to 34.88 ppt (Figure 4C) based on the vertical range established in Figure 2b. Synaphobranchus affinis was most frequently collected from 800 to 900 m, which had a salinity range of 34.93 to 34.91 ppt with expected horizon- tal variations of up to 0.02 ppt. Synaphobranchus brevidorsalis. Salinity within the 1,300 to 2,200 m depth interval increases slightly from 34.96 to 34.98 ppt which indicates a salinity change of less than 0.02 ppt. Synaphobranchus brevidorsalis was reported most frequently from 2,100 to 2,200 m where salinities were typically 34.98 ppt and is shown (Table 4) to vary by less than 0.01 ppt from 2,000 to 3,000 m. Ilyophis brunneus. Within the 700 to 1,200 m depth interval from which /. brunneus was reported, the salinity (Table 4) decreases from 34.96 to 34.88 ppt at 957 m and then increases to 34.92 ppt at 1,200 m. Ilyophis brunneus was most frequently collected from 900 to 1 ,100 m and the salinity ranged from 34.92 to 34.91 ppt and varied horizon- tally by approximately 0.02 ppt (Figure 4C). Dissolved Oxygen The distribution of dissolved oxygen differs from that of the conservative properties of sea water (temperature, salin- ity, etc.), since oxygen concentration is affected by biologi- cal and chemical processes. Richards (1957) discussed at length the processes which affect the distribution of dis- solved oxygen in the oceans and various concepts on the origin of the oxygen minimum zone . The oxygen-minimum layer (2.50 ml /I) for the Gulf of Mexico has been described by Nowlin (1971) and occurs at approximately 300 m in the western Gulf, 600 m in the eastern Gulf, and 700 m near the Yucatan Straits. There is a secondary oxygen-minimum layer (3.50 ml /I) which occurs at approximately 250 m in the eastern Gulf and Yucatan Straits. Bruun (1957) stated that a correlation between concen- tration of dissolved oxygen and distribution of organisms may be expected, but it is not possible to demonstrate. There does not appear to be any conclusive evidence in the literature that dissolved oxygen concentration in the deep sea is low enough to have a direct effect on the distribution of deep-sea organisms by putting them under pysiological stress. Oxygen levels may in some cases be indicators of reduced concentrations of other nutrient elements which have a limiting effect on the occurrence of organisms, such as the concentration of phosphate and nitrate, which is inversely proportional to the oxygen concentration (Richards 1957). 320 MARTIN Figure 4B shows a profile of bottom oxygen concentra- tions for a transect of hydrographic stations from the northern slope of the Gulf of Mexico. The dissolved oxygen concentration increases rather rapidly with increasing depth from 500 to 1 ,200 m. Below 1 ,200 m, oxygen continues to increase but more slowly. Other important features of the oxygen profile which should be noted are the occurrence of the oxygen-minimum layer between 200 and 400 m and the variable nature of the oxygen concentration levels below 3,000 m. These two features, however, do not occur within the reported depth range of the Synaphobranchidae. Synaphobranchus oregoni. The dissolved oxygen concen- tration increased from 2.66 to 4.64 ml/1 (Figure 4B), a change of 1.98 ml /I within the 500 to 1,500 m depth inter- val. Most of the S. oregoni specimens were collected from 900 to 1,000 m where oxygen levels range from 3.89 to 4.05 ml/ 1, a 0.16 ml /I range. Based on the oxygen distribu- tion shown in Figure 4C and the oxygen range established for S. oregoni with this investigation, it was apparent that the dissolved oxygen concentration was not a major factor influencing the distribution of S. oregoni to deeper parts of the slope. Oxygen could, however, be an important factor limiting the distribution of S. oregoni into shaUower depths. A gradual increase in the depth of the oxygen-minimum layer from west to east coincides with the reported mini- mum depths of occurrence of S. oregoni. Robins (1968) reported an upper limit of 679 m for S, oregoni in the Straits of Florida, where the oxygen-minimum layer is around 600 m. Synaphobranchus affinis. The dissolved oxygen concen- tration increased from 2.79 to 4.32 ml/1 (Figure 4B) over the reported vertical range of 600 to 1,100 m for affinis as shown in Figure 2b. This represented a 1.53 ml/1 change in oxygen concentration over the depth of occurrence. Synaphobranchus affinis was reported most frequently from the 3.38 to 3.89 ml/1 oxygen range which indicated a 0.5 1 ml/1 change in oxygen within the 800 to 900 m depth interval. Dissolved oxygen may have a similar Umiting influence on the vertical distribution of S. affinis as that described for *5. oregoni Synaphobranchus brevidorsalis. The dissolved oxygen concentration increased slightly from 4.64 to 4.83 ml /I (Figure 4B) within the reported vertical range (1,300 to 2,200 m) of 5. brevidorsalis, which represented a 0.20 ml/1 range in oxygen concentration. The oxygen concentration changes by 0.20 ml /I over the 1,300 to 2,200 m depth interval reported for S. brevi- dorsalis and this eel was most frequently collected within the 2,100 to 2,200 m depth interval, where the dissolved oxygen concentration is shown to change very little both vertically and horizontally (Figure 4C). At 1,300 m the slope of the oxygen profile begins to change rather rapidly with decreasing depth. The oxygen concentration decreased by about 35% within approximately 200 m (1,300 to 1,100 m), which represents a substantial change to an animal whose environment is constantly at a low tempera- ture and a high oxygen content . Ilyophis brunneus. The dissolved oxygen concentration increased from 3.10 to 4.43 ml/1 (Figure 4B) over the 700 to 1 200 m depth interval from which was collected and ’represented a 1.33 ml/1 range. Ilyophis brunneus was most frequently collected within the 3.89 to 4.28 ml/1 oxygen range (900 to 1,100 m) which corresponds to a 0 . 39 ml / 1 change in oxygen . Ilyophis occurs in rather equal numbers throughout its vertical range, therefore, it has a rather wide dissolved oxy- gen range, comparable to that of 5". oregoni (1.98 ml/1). Dissolved oxygen may not influence the movement of 1. brunneus into deeper parts of the Gulf; however, it may play an important role in affecting the upper hmit of vertical distribution of Ilyophis. The burrowing habit of Ilyophis was reported by Robins (1968), and Richards (1957) found that the oxygen concentration of the water adjacent to the bottom was less than that of the water several meters above the bottom by approximately 0.27 ml/1. The dissolved oxygen of the water next to the bottom at 700 m is probably close to 2.83 ml/1, based on the 3.10 ml/1 observed several meters above the bottom. The basic relationship of temperature, metabolic rate, and oxygen requirements could possibly have an important effect on the distribution of/, brunneus. Sediment Substratum was considered by Thorson (1956) to be the primary factor which influenced the composition of manne level-bottom communities. The animal-sediment relation- ship was discussed by Sanders (1958); Wigley and McIntyre (1964); Sanders, Hessler, and Hampson (1965); and Day and Pe’arcy (1968). Of these studies, only Day and Pearcy dealt with benthic fishes, the others were concerned with invertebrate communities. For the invertebrates, a definite correlation between sediment type and distribution was observed. Benthic fishes on the other hand showed a corre- lation between sediment type and species association, how- ever, some of the species groups did not coincide exactly with a particular substratum. Table 5 shows the sediment composition with depth for a number of gravity and piston cores taken by TAMU. The continental shelf and slope transition zone (at 200 m) is composed primarily of coarse grained sediments. The slope (200 to 2,900 m) sediments in general are composed of clayey silts, althougli three stations had high percentages of sand (12.9, 13.2, and 20.2%) and indicate the presence of sediments from the Mississippi Cone. Synaphobranchus oregoni The sediment texture of the slope within the 500 to 1 ,500 m depth interval of 5. oregoni ranged from 13.2 to 1.3% sand, 16.7 to 14.5% silt, and 82.8 to 78.6% clay. The combined silt-clay fraction ranged from 98.7 to 86.8% (Table 5). The largest numbers of*S. oregoni were collected from areas where the sand fraction was Synaphobranchidae Distribution and Ecology 321 3.4 to 1.3% and the combined silt and clay fraction was 98.7 to 96.6%. Three stations (70A8-8, -11, and -34) within the 500 to 1,500 m depth interval were analyzed for the percent sand, silt, and clay. Stations 70A8-8 and 70A8-11 occurred in an area where numerous captures of S. oregoni were reported, and is considered to represent the typical sediment texture over which this species was most frequently found (Table 5). Station 34 occurred in an area where relatively few speci- mens of S. oregoni were taken, despite numerous attempts, and showed some slight differences in textural composition. These textural differences may seem insignificant. However, Sanders (1958) showed that small changes in particle size influenced the composition of invertebrate communities; therefore, the type of food available to S. oregoni. Synaphobranchus affinis. The substratum over which S. affinis was collected ranged from coarse-grained (13.2% sand and 86.8% silt-clay) sediment, such as that found on the northeastern slope at the westernmost and northernmost extensions of the distribution of S. affinis (Figure 3), to limestone and coral rock which is found along the eastern slope of the Gulf and northern part of the Straits of Florida. The preference by S. affinis for a hard substratum was pointed out by Robins (1968), and appears to be confirmed by the distribution established here for this species. It is apparently restricted to the eastern Gulf. Sediment data presented in Table 5 indicate that within the vertical range of S. affinis (Figure 2b) in the western section, sediment textures are primarily soft muds composed of 3.4 to 1.3% sand and 96.6 to 98.7% silt-clay. The absence of S. affinis from the western Gulf of Mexico could indicate an avoid- ance of soft sediment by this species. Synaphobranchus brevidorsalis. The sediment texture within the 1,300 to 1,400 m depth interval of S. brevidor- salis was 6.9 to 2.9% sand, 16.7 to 14.5% silt, 80.4 to 78.6% clay, and 97.1 to 93.1% silt-clay combined (Table 5). Gravity core station 71A876 was taken in the vicinity of trawl station 69A1183 (Table 1) where S. brevidorsalis was collected and had a 4.3% sand fraction and a 95.7% silt-clay fraction. Core station 70A810 was taken within the 2,100 to 2,200 m depth interval and was near trawl station 1303 where three specimens of S. brevidorsalis were collected by the NMFS R/V OREGON. The sediment composition was 3.8% sand, 13.5% silt, 82.7% clay (96.2% sUt-clay fraction combined). The data indicated that S. brevidorsalis occurred over soft mud bottoms. Sedi- ment of this composition is predominant on the lower part of the western and northern continental slopes of the Gulf (Lynch 1954). The absence of S. brevidorsalis from the northern Straits of Florida was considered to be partly due to the hard substratum found in that section of the Gulf. However, since calcareous muds are predominant in the southern part of the Straits of Florida, other limit- ing factors must be influencing the distribution of S. brevidorsalis in this area. Ilyophis brunneus. Ilyophis was collected over the 700 to 1,200 m depth interval which had a sediment composi- tion of 13.2 to 1.3% sand and 98.7 to 86.8% silt-clay (Table 5). Gravity core stations from this depth interval were not analyzed for the silt and clay fractions. Silt and clay are reported as a combined silty sand or clayey silt sub- strate, which was in agreement with the conditions reported by Robins (1968) for this species in the Straits of Florida. This preference of I. brunneus for a soft substratum is reflected in the eel’s external morphology which indicates an adaptation for burrowing (Robins 1968). BIOLOGIC.AL PARAMETERS Food Habits Little information has been published on the food of the Synaphobranchidae. Robins (1968) reported that synapho- branchid eels fed on fish and crustaceans. Information on food habits is reported here to determine if the synapho- branchid eels exliibit any food specialization. The generally accepted ideas on the availability of food in the deep sea are discussed in light of the data obtained from stomach content analyses of 153 specimens of synaphobranchid eels. Synaphobranchus oregoni. A total of 135 speciments of S. oregoni were examined and 53 (39%) were found to contain fish, squid, and crustaceans. Fish and fish parts represented 31% of the identifiable food items; squid and crustaceans each represented 17%. The remaining 35% of the stomach contents could not definitely be classified as belonging to any of the three groups. However, the major- ity of the food items that were not identifiable were pieces of muscle fiber which resembled fish flesh. Only two of the fish removed were in good enough condition for reliable identification. One was Canthidermis sufflaman of the family Balistidae (a surface fish) and the other was a young eel. Based on the condition of Canthidermis, it is highly probable that it was captured at the surface and swallowed in the trawl. It appeared from the size, shape, and texture of the fish particles, particularly the vertebrae and jaws removed from the stomach of S. oregoni, that no specific family of fish was predominant as a food item. The squid and crustacean parts tended to be in much better condition for identification than the fish parts. The squid were identified from several mantles and numerous beaks, and all belonged to the order Teuthoides and the suborder Oegopsida. The identifications of two families, Ommastrephidae and Onychoteuthidae are questionable. The crustaceans removed represented four orders and six families. Decapods were predominant, with sergestid and penaeid shrimp constituting the most numerous food items of the crustaceans. A large flatbacked lobsterette (Polycheles valida) was removed from one of the large specimens of S. oregoni. Synaphobranchus brevidorsalis. Of the 10 specimens examined, two (20%) contained food items. Fish eyes were 322 Martin removed from one eel and a large squid (Ommastrephes bartrami) was removed from the other. Ilyophis brunneus. Eight specimens of I. bmnneus were examined and two (25%) were found to contain food items. Only one had identifiable contents. It contained one adult isopod {Aega grarcililes) which had five young isopods in the brood pouch. Aega is a common ectoparasite that is free-living while gravid. Parasites Synaphobranchid eels are parasitized by nematodes, trematodes, cestodes, and copepods (Robins 1968). Of the 153 synaphobranchid eels examined for parasites, 131 (86%) were found to be infested. Cestodes occurred most fre- quently, with nematodes and trematodes appearing mod- erately. One eel had a parasitic copepod attached to the conjunctive membrane of the eye. Four new host records for digenetic trematodes and a new species, Helicometra robinsorum, were found in the synaphobranchid eels from the Gulf of Mexico (Overstreet and Martin 1974). Chandler (1954) reports that fish are commonly the intermediate hosts for larval cestodes. It appears probable that the adult cestodes infesting synaphobranchid eels were ingested while feeding on infested fish. This is based on the number of the adult cestodes removed from the abdominal cavity. The digenetic trematodes are reported to be host specific and usually occur in hosts which are within the same phyla. The intermediate hosts of Digenenea are generally con- sidered to be a moUusk (Manter 1954). Overstreet and Martin (1974) reported *5. oregoni to be moderately infested with trematodes and stomach content analysis indicated that fish and squid were common food items for S. oregoni. It is apparent that both fish and squid are probably impor- tant intermediate hosts for the trematodes that infest the synaphobranchid eels. CONCLUSIONS The synaphobranchid eels of the Gulf of Mexico are considered an important part of the upper continental slope ichthyofauna, with four species {Synaphobranchus oregoni, S. affinis, S. kaupi, and Ilyophis brunneus) occurring within the 500 to 1,500 m depth interval and only one species {S. brevidorsalis) occurring below 2,000 m. Synaphobranchus oregoni and Ilyophis brunneus were the most frequently captured synaphobranchid eels and occurred rather uniformly throughout the various geographic sections of the Gulf. Synaphobranchus brevidorsalis was less frequently collected and occurred only in the northern and western sections. S. affinis occurred only in the eastern section. Extensive trawling from the other sections of the Gulf seems to substantiate the distributional pattern shown in Figure 3. The absence of Histiobranchus and Diasto- branchus from the Gulf was reported and is considered valid since 29 trawl stations were taken below 1,800 m, within the reported depth range of both genera. Vinogradova (1959) considered macro-relief as an im- portant factor affecting the distribution of deep-sea benthic fauna. A thorough investigation of the geomorphology of the continental slopes of the Gulf of Mexico indicates that there are no major topographic features along the slopes with sufficient rehef to affect the horizontal distribution of the synaphobranchid eels (Bergantino 1971 and Wilhelm and Ewing 1972). Synaphobranchid eels of the Gulf of Mexico occurred over a rather narrow range of temperature (7.70 to 4.20 C) compared to that reported by Bruun (1937) for the Syna- phobranchidae of the North Atlantic (12.0 to 0.0°C). The largest number of synaphobranchid eels occurred within the 700 to 1,000 m depth interval which had a temperature range of 6.50 to 4.75°C and represented only a 1.75°C change in temperature over 300 m. A most interesting feature of the temperature regime is the 4.20°C minimum that occurs at approximately 2,000 m. When trying to assess the importance of the effect of temperature on the vertical distribution of the Synapho- branchidae, one has to speculate on the ability of the synaphobranchid eels to cross this few hundredths of a degree temperature gradient to a depth where the tem- perature begins to increase to a maximum of 4.42 C at approximately 3,700 m. From the data, one would expect S. oregoni to have little difficulty in adapting to a 0.04° C change in tempera- ture. It is therefore suggested that change in pressure is more effective in restricting the downward distribution of S. oregoni to the lower slope than temperature. Synapho- branchus oregoni would have to adapt to a 667 psi change in pressure to move from 1,500 m to 2,000 m which may be more significant than a 0.04°C change in temperature. Synaphobranchus affinis, on the other hand, would have to adjust to a 0.50°C change in temperature and a 1,335 psi change in pressure; therefore, it is felt that the combination of temperature and pressure are hmiting factors which restrict S. affinis from moving to the lower continental slope. Since /. brunneus occupies a position on the slope similar to that of S. affinis, temperature and pressure are considered to have comparable limiting effects on both species. Salinity within the depth range of the Synapho- branchidae decreases from 34.99 ppt at 500 m to 34,88 ppt at approximately 900 m, then increases to 34.95 ppt at 1,500 m. It was slightly more variable horizontally at 500 m than at the deeper depths. The salinity data from the Gulf tend to support the con- tention of Bruun (1957) that the small variations in sahnity do not appear to have any significant effect on the distribu- tion of Synaphobranchidae either horizontally or vertically. This was determined by comparing the number of syna- phobranchid eels collected at approximately the same Synaphobranchidae Distribution and Ecology 323 depth with the corresponding salinities from nearby hydro- graphic stations (Table 4). The dissolved oxygen concentration was shown to in- crease with depth throughout the depth range of the Syna- phobranchidae. The occurrence of the oxygen minimum layer in the eastern and western Gulf was noted and con sidered to be correlated with the distribution of synapho- b ran chid eels at the shallower limits of their depth range. This may be due to the basic relationship of increasing tem- perature with decreasing depth which causes an increase in metaboHc rate, resulting in an increased oxygen requirement at depths where oxygen approaches minimum values. The dissolved oxygen concentration was not considered to be a limiting factor on the distribution of synaphobranchid eels into the deeper depths of the Gulf of Mexico. Although synaphobranchid eels were associated with substrata from clayey silts to hard substratums such as lime- stone and coral rock, certain species were shown to occur over areas of a particular sediment texture. For instance, Synaphobranchus oregoni, S. brevidorsalis, and Ilyophis brunneus were collected over sediments which ranged from 13.2 to 1.3% sand, 16.7 to 14.5% silt, and 82.8 to 78.6% clay. Synaphobranchus af finis occurred over sediment tex- tures which ranged from coarse-grained sand to limestone. Synaphobranchid eels have been described as opportun- istic feeders or “croppers” (Dayton and Hessler 1972). Based on the size and condition of food items removed from their stomachs, it is assumed that the Synapho- branchidae forage on both live and dead organisms which consist primarily of fish, squid, and crustaceans. It was impossible to identify the fish to family but, based on the size and shape of the numerous fish parts removed, it was evident that several fish families were represented. Seven cmstacean families were represented. The squid ingested were confined to the suborder Oegopsida, where two families, Ommastrephidae and Onychoteuthidae, were ten- tatively identified. If one considers food niche specialization to exist only where a narrow range of food items are in- gested, the Synaphobranchidae do not exhibit food niche specialization. However, niche specialization probably oc- curs with the manner in which the synaphobranchid eels search out and ingest their food. The availability of food in the deep sea has been reported to be an important limiting resource (Bruun 1957 and Dayton and Hessler 1972). It seems significant that of the 153 synaphobranchid eels examined for stomach contents, 57 (38%) contained food items. Considering the general knowledge that deep-sea fish usually regurgitate stomach content when brought to the surface, this value probably represents a minimum estimate of the percentage of eels which had fed shortly before capture. On an individual station basis, 24 to 33% of the eels examined contained food. Synaphobranchid eels were heavily infested with ces- todes. Nematodes and trematodes occurred moderately. There was one parasitic copepod attached to the conjunc- tive membrane of the eye of S. oregoni. There were no apparent harmful morphological effects on the synaphobranchid eels infested with parasites. Hopkins (1957) reported that infested hosts usually com- pensate for loss of nourishment due to parasites by ingest- ing more food, and that under conditions of food scarcity the infested host might show harmful effects. This tends to indicate that food may not be quite as scarce in the deep sea as has been reported. ACKNOWLEDGMENTS The specimens for this investigation were collected by the Texas A&M University research vessel ALAMINOS dur- ing a research program on deep-sea benthic communities under the direction of Dr. Willis E. Pequegnat. I am indebted to the following persons: Dr. Arnold H. Bouma for the use of radiographic equipment; Dr. Douglas Lipka, Dr. Linda Pequegnat, and Dr. Robin M. Overstreet for the identification of squid, crustaceans, and parasites, respectively. REFERENCES CITED Agassiz, A. 1888. Three cruises of the United States Coast and Geodetic Survey steamer BLAKE from 1877 to 1880. Bull. Mus. Comp. Zool. 15:2136. Bergantino, R. N. 1971. Submarine regional geomorphology of the Gulf of Mexico, Geol Soc Am. Bull. 82(3): 741 -752. Bright, T. J. 1967. A survey of the deep-sea bottom fishes of the Gulf of Mexico below 350 meters. Ph.D. Dissertation, Texas A&M University, College Station. 218 pp. Bruun, A. F. 1937. Contributions to the life histories of the deep-sea eels: 'S>Yndiph 6 hi?Lnch\d 2 iQ.Dana-Rep.-Carhberg Found. No. 9: 131. - ■ 1957. Deep-Sea and Abyssal Depths. Geol. Soc. Am. Mem. 67.1: 159-184. Bullis, H. R., Jr., & J. R. Thompson. 1965. Collections by the ex- ploratory fishing vessels OREGON, SILVER BAY, COMBAT, and PELICAN made during 1956-1960. U.S. Fish Wildl. Serv. Spec. Sci. Rep. Fish. 510:1130. Castle, P. H. J. 1960. Two eels of the genus Synaphobranchus from the Gulf of Mexico. Fieldiana Zool. 39(35): 387-398. i964.Deep-Sea Eels: Family Synaphobranchidae. Galathea Report. 7:29-42. Chandler, A. C. 1954. Cestoda. U.S. Fish Wildl. Serv. Fish, Bull. 55(89):351-353. Day, D. S. and W. G. Pearcy, 1968. Species associations of benthic fishes on the continental shelf and slope off Oregon. J. Fish. Res. Board Can. 25(12):2665-2675. Dayton, P.K. and R. R. Hessler. 1972. Role of biological disturbance in maintaining diversity in the deep sea. Deep-Sea Res. 19:199-208. Grey, M. 1956. The distribution of fishes found below a depth of 2,000 meters. Fieldiana Zool. 36(2): 1337. 1958. Descriptions of abyssal benthic fishes from the Gulf of Mexico. Fieldiana Zool. 39(1 6): 149-1 83. 324 MARTIN 1959. Deep-sea fishes from the Gulf of Mexico with the description of a new species Squalogadus inmedius (Macruaroid- idae). Fieldiana Zool 39(29): 323-346. Gunter G. 1957 . Temperature. Geo/. So c. Am. Mem. 67.1:159-184. Hogg, R. V. and E. A. Tanis. 1977. Probability and Statistical In- ference. MacMillan Publishing Company, New York. 450 pp. Hopkins, S. H. 1957. Parasitism. Geol Soc. Am. Mem. 67.1 :41 3-428. Ichiye, T. and H. Sudo. 1971. Saline deep water in the Caribbean Sea and in the Gulf of Mexico. Texas A&M University Technical Report. Reference 7 1 1 6T : 1 27 . Lynch, S. A. 1954. Geology of the Gulf of Mexico. U.S. Fish Wildl. Serv. Fish. Bull 55{S9):61-S6. Manter, H. W. 1954. Trematoda of the Gulf of Mexico. U.S. Fish Wildl Serv. Fish. Bull 55(89):335-350. Mead, G. W. 1952. A list of the marine bony fishes known to occur in' the Gulf of Mexico. M.A. Thesis, Stanford University, Stan- ford, California. 180 pp. Nowlin, W. D. 1971. Water masses and general circulation of the Gulf of Mexico. Gcearto/. /«f. 6(2):28-33. Overstreet, R. M. and D. M. Martin. 1974. Some digenetic trema- todes from synaphobranchid eels. J. Parasitol. 60(1):80— 84. Parr, A. E. 1932. Deep-sea eels, exclusive of larval forms. Bull Bingham Oceanogr. Collect. 3(5 ) : 1 -4 1 . Pequegnat, W. E., T. J. Bright & B. M. James. 1970. The benthic skimmer, a new biological sampler for deep-sea studies. In. F. A. Chase, Jr. and W. E. Pequegnat (eds.), Texas A&M Univ. Oceanogr. Stud. 1. Contributions on the biology of the Gulf of Mexico. Gulf Publishing Co. Richards, F. A. 1957. Oxygen in the ocean. Geol Soc. Am. Mem. 67.1:185-238. Robins C H 1968. The comparative osteology and ecology ot tne synaphobranchid eels of the Florida Straits. Ph.D. Dissertation, University of Miami, Coral Gables, Florida. 1 92 pp. Sanders. H. L. 1958. Benthic studies in Buzzards Bay. 1. Animal- sediment relationships. Limnol Oceanogr. 3:245-258. Sanders H. L., R. R. Hessler & G. R. Hampson. 1965. An introduc- tion 'to the study of deep-sea benthic faunal assemblages along the Gay -Head Bermuda transect. Deep-Sea Res. 12:845-867. Springer S. & H. R. Bullis. 1956. Collections by the “Oregon” in the Gulf of Mexico. U.S. Fish Wildl Serv. Spec. Scl Rep. Fish. 196:1-134. _ Thorson, G. 1956. Marine level-bottom communities of recent seas, their temperature adaptation and their “balance” between pre- dators and food animals. Trans. N.Y. Acad. Scl Ser. 2. 18(3):693-700. . . Vinogradova, N. G. 1959. The zoogeographical distribution of the ocean. Deep-Sea Res. 5:205-208. Wigley, R. L. and A. D. McIntyre. 1964. Some quantitative com- parisons of offshore meiobenthos and macrobenthos south of Martha’s Vineyard, i/ww/. Gceflrtog/-. 9:485-493. Wilhelm, O. & M. Ewing. 1972. Geology and history of the Gull ol Mexico. Geol Soc. Am. Bull. 83(3). 575— 599. Gulf Research Reports Volume 7 | Issue 4 January 1984 Seedling Establishment of Spartina alterniflora and Sp ar Una p aims on Dredged Materials in Texas James W Webb Texas Agricultural Experiment Station J.D.Dodd Texas Agricultural Experiment Station B.H.Koerth Texas Agricultural Experiment Station AT. Weichert Texas Agricultural Experiment Station DOI: 10.18785/grr.0704.03 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Webb, J. W, J. Dodd, B. Koerth and A. Weichert. 1984. Seedling Establishment of Spartina alterniflora and Spartina patens on Dredged Materials in Texas. Gulf Research Reports 7 (4): 325-329. Retrieved from http://aquila.usm.edu/gcr/vol7/iss4/3 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 325-329, 1984 SEEDLING ESTABLISHMENT OF SPARTINA ALTERNIFLORA AND SPARTINA PATENS ON DREDGED MATERIAL IN TEXAS JAMES W. WEBB/ J. D. DODD, B. H. KOERTH, AND A. T. WEICHERT Texas Agricultural Experiment Station, College Station, Texas 77843 ABSTRACT Effects of fertilizer, elevation, and tidal inundation on seedling establishment of Spartina alterniflora and Spartina patens were tested at a wave-protected sandy dredged material site, Galveston Bay, Texas. No seedlings that grew from sown seeds became established at elevations below 36 cm (msl) while the greatest number established in the upper tier. Seedlings of S. alterniflora were more numerous than S. patens in the upper and middle tiers. Naturally occurring seedlings of S. alterniflora, which apparently germinated from seeds produced on transplants in adjacent plots, established at aU elevations of the site during winter. The average time of tidal inundation at a particular elevation was less during winter than spring. Thus, establishment of plants by seed at low intertidal elevations appears feasible only during low seasonal winter tides and with S. alterniflora. Fertilizers did not enhance growth, and high concentrations of fertilizer caused stress to some S. alterniflora seedlings. INTRODUCTION Means of disposal of dredged material in U. S. coastal environments is a major environmental problem. One bene- ficial use of dredged material is the establishment of salt marshes. Successful establishment of salt marsh depends on proper location of the dredged material and planting of the material with Spartina alterniflora and Spartina patens or other intertidal plants (Lewis 1982). When site conditions are suitable, sowing of seed has been shown to be the most economical method of plant establishment on dredged material (Woodhouse 1979). However, establishment has generally been with transplants since they are more tolerant of waves and currents than seeds and young seedlings (Lewis 1982). Planting trials were carried out on dredged material to establish a new marsh in Texas (Webb et al. 1978). Seeds of S. alterniflora and S. patens were used: (1) to test the feasi- bility of using seeds for marsh establishment; (2) to deter- mine how elevation in relationship to tidal inundation af- fects seed germination and seedling survival; and (3) to test the effects of various fertilizer treatments on seed germina- tion and seedling growth. The occurrence of seedlings of naturally invading plants also was monitored in permanent quadrats in plots established at the site in 1976 (Webb et al. 1978). Comparisons of the number of naturally occurring seedlings to the number of seedlings that established from sown seeds showed that better establishment occurred dur- ing the seasonally lower tides of winter than spring. Ferti- lizer treatments did not enhance establishment. DESCRIPTION OF STUDY AREA A 7.3-ha (18-ac) study site with a northeasterly exposure to Galveston Bay was, established in 1976 on dredged ^Present address: Marine Biology Department, Texas A&M at Galveston. Manuscript received December 12, 1983; accepted April 2, 1984. material deposited in 1974. Physical and chemical character- istics of the sediment prior to planting were reported by Dodd et al. (1978) and after planting by Lindau and Hossner (1981). Sediments were approximately 98% sand with low amounts of organic material. Because of a fetch length of over 15 miles, a sandbag dike was constructed to minimize wave action on the plantings (Figure 1). The site was sloped to a 0.7 % grade. The lowest elevation at the site was -4.9 cm (-0.16 ft), in reference to mean sea level (msl), while the upper elevation was +1 m (msl). The mean low water (mlw) for Galveston Bay is actually 0.23 m (0.75ft) above msl while mean high water (mhw) is +0.55 m (1.79 ft) (Lankford and Rehkemper 1969). The mean an- nual water level is 0.3 m (msl). MATERIALS AND METHODS During 1976 at Bolivar Peninsula, Texas, 270 plots (6 X 1 0 m in size) were established in randomized complete block design with three elevational tiers (Webb et al. 1978). Plots were sprigged in 1976 and others were sown with seed in 1977. Plots received one of five fertilizer treatments. The five fertilizer treatments were mixtures of ammonium sul- fate, triple super phosphate, and potassium sulfate. Treat- ments were: FO-no fertilizer; FI -122 kg N/ha, 122 kg P 2 05 /ha, and 122 kg K 2 0/ha; F2-double the amounts of FI ; F3-split application of FI ; F4— split application of F2. In preparation for spring seeding, S. alterniflora and S. patens seeds from local marshes were collected and threshed during fall 1976. S. patens seeds were stored dry at ambient room temperature while S. alterniflora seeds were stored in an 8% salt solution (S. F. Broome, North Carolina State, pers. comm.) refrigerated at 6°C (Mooring et al. 1971). The percentage of glumes with a caryopsis was determined by physical examination of glumes. Samples of glumes with a caryopsis were placed into petri dishes in the dark at alter- nating thermoperiods (Mooring et al. 1971) to determine percent viability of filled glumes. 325 326 Webb et al. DESIGN FOR 30 PLOTS IN Figure 1. Design of Bolivar Peninsula site showing plot design and 6 cm contour intervals across the site. Establishment of seedlings from hand sown seeds occurred only above 36.6 cm elevation (shaded area). Ninety unplanted plots, 45 plots sprigged with S. alterni- flora, and 45 plots sprigged with S. patens in 1976 were monitored for plant invasion utilizing three permanent 3-m^ quadrats in each plot. The data from 24 February 1977 were compared to plots seeded in 1977. During 21-23 March 1977 at low tides, 5. alterniflora at 100 viable seeds per m^ , and S. patens at 125 viable seeds per m^ were hand spread in 90 plots along with phosphate and potassium fertilizers. Plots were then disced with a tractor to cover seeds with soil to a depth of 2.5 cm, which is ideal planting depth (Tanner 1979, unpublished data). Nitrogen as ammonium sulfate was broadcast on the soil surface on 26—28 April 1977 rather than at time of seeding to lessen chances of damage by nitrogen salts. To avoid dis- turbance of seedlings, nitrogen fertilizer was not disced into the soil. Thus, there was a possibility of loss during tidal exchange and by volatilization. F3 and F4 plots (split rates) were refertilized 26 July by broadcast application. Nine permanent 0.1-m^ quadrats were established in each seeded plot (three in each 1/3 of each plot). Seedlings were counted on 14 April, 27 April, 2 June, 27 June, and 14 October 1977 and converted to number per m^ . In addition to measuring density on 27 June and 11-14 Octo- ber 1977, the following measurements were taken; height of extended leaves; visual estimates of foliage cover; growth characteristics, such as presence of flowers and amount of seed production; and plant stress as exhibited by chlorosis, stunted growth, or wilted leaves. Root and shoot biomass also was randomly sampled in each plot (outside of perma- nent quadrats) with a 25 -cm deep circular coring device with a 0.1-m^ surface area. Biomass was reported as dry weight after oven drying at 83°C to a constant weight. Height of tides was automatically punched on ticker tape at 15 -minute intervals by a tide gauge established at the site. The raw data was converted by computer programs to histo- grams showing the percent inundation at 0.1 -ft contour intervals for selected time periods, winter and spring. Bench marks, which were established at the site by the Galveston District, Corps of Engineers, allowed the establishment of the tidal datum (1.42 ft below msl) for the tide gauge and furnished the basis for site elevations, which were taken at one corner of each of the 270 plots (Webb et al. 1978). RESULTS Natural Seed Germination The number of seedlings on 24 February 1977 in plots which were monitored for plant invasion indicated that winter germination of S. alterniflora seeds had occurred. In the low tier the number of naturally occurring S. alterniflora seedlings was much greater in S. alterniflora sprigged plots (3.87/m^) than inS. patens sprigged plots (0.28/m^) or un- planted plots (0.1 8/m^). Significant differences (P<0.0001) among tiers in the number of naturally occurring seedlings also occurred in S. alterniflora sprigged plots (3.87, 2.50, and 0.44/m^ in lower, middle, and upper tiers, respec- tively). No significant differences in the number of seed- lings were detected between fertilizer treatments. During the evaluation period scheduled for May 1977, wind elevated tides prevented counts of seedlings in plots at low elevations. However, 0.43 seedlings/m^ , which was the same number as February, were counted in 43 S. alterniflora sprigged plots in the upper tier. In the middle tier 0.50 seed- lings/m^ were counted in 19 of the 5. alterniflora plots as Establishment of Spartina Seedlings 327 compared to 2.50 in February. These data indicated that survival and growth of seedlings occurred after germination. Seedhngs could not be distinguished from shoots growing from sprigged plants at the June 1977 evaluation. In early December 1977, many seedlings with two to three leaves and less than 5 cm tall were observed at the Bolivar site. Most seedlings were at the elevation of mean high water (mhw), but many were in soil depressions at lower elevations. Seeds probably were produced at the site since there were at least 92 kg of S. alterniflora seeds pro- duced at the site by 14 October 1977 (Webb et al. 1978). Seedlings also were observed in late January 1979 in natural marshes of the area. Additional evidence of winter germina- tion has been presented by Tanner (1979), who reported 14.6 S. alterniflora seedlings/m^ in a marsh several miles from our site. However, Tanner reported that the number of seedlings declined 50% between 27 February and 24 April. Rhizome production caused the number of shoots to in- crease after 24 April. Seedlings also were located only above 36 cm (msl) elevation and in a wave protected area. Spring Seed Sowing Experiments The number of seedlings of S. alterniflora was greater than that of S. patens in the upper and middle tiers (Table 1). The greatest number of seedlings occurred in the upper tier while no survival for either species was recorded in the lower tier. Examination of contour maps (Figure 1) of the study area showed that no seedlings were observed below an elevation of 36.6 cm (msl). An 84% decline in the num- ber of S. alterniflora seedlings in the middle tier occurred between 14 April and 27 April, indicating that most seed- lings failed to establish after germination. An increase in the number of S. patens seedlings in the upper tier from April to June indicated that germination of S. patens occurred several weeks later than S. alterniflora. Fertilizers apparently did not enhance survival or growth since stem density and height of plants were not significantly TABLE 1 Number of seedling shoots per in dredged material plots seeded 21-23 March 1977 at 100 viable seeds per m^. Evaluation Date Species^ Tier^ 14 April 27 April 2 June 27 June Spartina Lower 0.0 0.0 3 0.0 alterniflora Middle 5.5 0.9 - 4.2 Upper 23.8 19,4 21.1 53.4 Spartina Lower 0.0 0.0 - 0.0 patens Middle 0.1 0.1 - 1.6 Upper 1.2 1.5 6.1 33.2 ^Differences between species significant at P, 22 July 1981,89 m, coarse sand; Id, 26°16'45"N, 83^47'45"W, 30 April 1981, 90 m, fine sand; Id, 26°16'00"N, 84°15'00"W, 25 July 1981, 180 m, medium sand; 299 (1 ovig), 25°15'00"N, 84'^ 15'00''W, 2 August 1981, 180 m, medium sand. Description of male - Male very similar to female, differ- ing in following aspects; smaller than female with branchial tubercles fewer in number; accessory spinules of lateral spines of carapace well developed, but not as numerous as in female; carapace as long as broad; abdominal segments 4—7 fused with medial and lateral elevations evident on somites 1—3; gonopod as illustrated (figure 1). Chelipeds of female heavy, spinose; merus stout, inflated with few anterior spinules at midlength and posterior at base; palm inflated with few large spines, fingers narrow with large spines on dorsal surface of fixed finger; movable finger with spines on outer face with small tubercles proxi- mally on dactyl. 351 352 GOEKE AND Heard Figure 1. Clythrocerus stimpsoni. A. Female, legs removed; B. Male, cheliped outer face; C. Male, gonopod one. Remarks — Clythrocerus stimpsoni was described by Rathbun (1937) from a single specimen collected off the west coast of Florida in 1872 by W. Stimpson. This report is the first subsequent record of this taxon and has made the description of the male possible with notes on variation and ecology. The material on which this study is based agrees closely with the original description of Rathbun (1937 : 121) with the exception of the following minor points: (1) Rathbun describes and figures a medial rostral tooth on the type specimen. Our specimens possess 2 rostral teeth, closely approximated medially; (2) our material has only branchial regions with numerous large tubercles, whereas Rathbun reports “surface finely granulate, a few larger tu- bercles in advance” (1937:121); (3) the large teeth of the lateral margins with large, well-defined spines, not “minute spinules”; (4) pterygostomial ridge of largest specimens armed with 12 to 15 spinules; and (5) a large superior lateral tooth. The variance exhibited in these characters is relatively minor and within the range for natural variation when con- sidering the size differences and sexual maturity of available material. No ecological data was presented with the description. The range for this species may now be expanded to cover the entire west coast of Florida, from south of Mobile Bay to northwest of the Dry Tortugas in 67 to 180 m of water. Collection data indicate substrata of coarse sand to silty, very fine sand composed primarily of carbonates. Clythrocerus granulatus (Rathbun, 1898) (Figure 2) Cyclodorippe granulata Rathbun, 1898:293, pi. 9, fig. 1. Clythrocerus granulatus: Rathbun, 1937:119, text-fig. 31, pi. 33, figs. 5-8; Williams, McCloskey and Gray, 1968: 45, fig. 3. Diagnosis - Single dorsolateral tooth at widest part of carapace; carapace and appendages densely granulate, mar- gins of carapace spinuliferous in posterior 1/2; interorbital region with teeth; rostral and orbital region depressed with remainder of carapace little inflated; pterygostomial region with deep furrow. Carapace slightly broader than long. Material examined — 1 9 (ovig), 28° 49 59 N, 85°37'02"W, November 1977, 175 m, clayey, sandy silt; 1 9 (ovig), 27°57'00"N, 84°47'59''W, September 1977, 189 m, silty, very fine sand; 1 9 (ovig), 26°45^00"N, 84°15'00"W, 17 July 1981, 170 m, medium sand; 2 dS, 2 juveniles, 25°45'00"N, 83°59'00"W, 27 July 1981, 170 m, medium sand. Remarks - Our records constitute the first reported oc- currence of C. granulatus from the Gulf of Mexico. erus granulatus is a distinctive Httle crab ranging from North Carolina, Florida and the type-locality of Trinidad Clythrocerus in the Eastern Gulf of Mexico 353 Figure 2. Clythrocerus granulatus. A. Female, legs removed; B. Male, cheliped outer face; C. Male, gonopod one. to Venezuela, in waters as deep as 567 m. In the Gulf of Mexico this species has been collected along the west coast of Florida as shallow as 29 m. Material from the eastern Gulf agrees well with descriptions of Rathbun (1937). Our speci- mens were collected on substrata of clayey, sandy silt and medium coarse sand of carbonate origin. Clythrocerus perpusillus Rathbun, 1901 Figure 3 Clythrocerus perpusillus Rathbun, 1901:90, fig. 14; Rathbun, 1937:111, text-fig. 28, pi. 33, figs. 3 and 4; Williams, McCloskey and Gray, 1968:44. Diagnosis — Carapace flat, very finely granulate, slightly broader than long; a single tooth at widest part of carapace on margin, margins sometimes pubescent; a slight indenta- tion in margin of carapace in front of lateral teeth. Material examined - 3 dd, 10 $?, 28°38'00"N, 97°20'00"W, 90 m, 27 May 1979, coarse sand; 1 d. 27°37.2'00"N, 83‘'53.5'00"W, 50 m, 9 August 1977, coarse sand; 1 d, 26°24'56.8''N, 84°15'00"W, 168 m, 9 August 1977, silty fine sand; 1 d, 28°49'59.l"N, 85°37'01 .9''W, 175 m, August 1977, clayey, sandy silt; 1 d, 29°42'59.9"N, 85° 15'28.6'^W, 67 m, February 1977, coarse sand; 1 d, 27°56'29.5"N, 83°52'59.5"W, 43 m, February 1977, coarse sand. Remarks — This material represents the first reported oc- currence of C. perpusillus in the Gulf of Mexico where it was the most commonly occurring species of Clythrocerus collected in our study . Specimens were examined from south Florida to the DeSoto Canyon in the northeastern Gulf In the western Atlantic this species has been reported from the type-locahty of Puerto Rico, Barbados, and North Carolina; in depths of 27-175 m. Our material occurred in depths of 43 to 175 m on substrata composed of clayey silt to coarse sand. All specimens from the Gulf of Mexico fit the descrip- tion of Rathbun (1937) except for lack of lateral marginal pubescence on our specimens. 354 GoEKE AND Heard Figure 3. Clythrocerus perpusillus. A. Female, legs removed; B. Male, cheliped outer face; C. Male, gonopod one. Clythrocerus nitidus (A. Milne-Edwards, 1880) Figure 4 Cyclodorippe nitida A. Milne-Edwards, 1880:24. Clythrocerus nitidus: A. Milne-Edwards and Bouvier, 1902:90, pi. 18; Rathbun, 1937:109, text-figs. 26, 27, pi. 33, figs. 1, 2;Wass, 1955: 170; Powers, 1978:26. Diagnosis - Carapace slightly oval from side to side, cara- pace smooth, single supramarginal lateral tooth, no rostral teeth, branchial sutures distinct. Material examined — USNM 66843, 16 dd, 18 99 (11 ovig), 16 June 1893, off Sand Key, Florida, 219 m. Remarks - No specimens of Clythrocerus nitidus were collected during this study although previous records include South Carolina, the type-locahties of the Florida Keys and Grenada and northwest Florida in depths of 12—479 m. Wass (1955:170) reported this species as “known or ex- pected to occur” from an area southwest of Cape San Bias. That report was based on Rathbun’s (1937) examination of an ALBATROSS specimen collected 7 February 1885 (USNM 19878). No sediment data was given for that speci- men but others are reported from rocky bottoms, coral, sand, and soft coral ooze. Material figured for this report was collected from the southeast Atlantic coast of Florida. Discussion - Rathbun (1937:109) reported seven mem- bers of the genus Clythrocerus from the east and west coasts of middle America. This genus is a group of compara- tively small crabs (often <5 mm) which may be confused with the closely related genus Cyclodorippe A. Milne- Edwards, 1880. This latter genus is represented by two nomi- nal species in the western Atlantic and is separated from Clythrocerus by elongate antennules and antennae with a narrow peduncle. The broad range of variation in selected morphological features (i.e. gonopods, carapace spination) within the genus Clythrocerus may reflect a polyphyletic origin of the group. The establishment of new generic or subgeneric levels must accompany a review of the group as a whole and is beyond the scope of this contribution. Clythrocerus in the Eastern Gulf of Mexico 355 Figure 4. Clythrocerus nitidus. A. Female, legs removed; B. Female, cheliped outer face; C. Male, gonopod one. PRELIMINARY KEY TO THE GENUS CLYTHROCERUS IN THE WESTERN ATLANTIC 1 . Lateral margins of carapace unarmed except for single tooth at widest part 2 Lateral margins of carapace with tooth at widest part above margins and with spinules or additional teeth 3 2. Carapace smooth, shiny, convex from side to side ; pseudorostrum not developed forward; interocular teeth acute. . . . Clythrocerus nitidus Carapace finely granulate, flat; pseudorostrum developed beyond frontal teeth; interocular teeth blunt Clythrocerus perpusillus 3. Surface of carapace densely covered by coarse granules, single large lateral tooth with most accessory spinules in posterior half of margins of carapace Clythrocerus granulatus Surface of carapace finely granulate, 3 lateral teeth with accessory spinules on the 2 marginals Clythrocerus stimpsoni REFERENCES CITED Milne-Edwards, A. 1880. Ltudes preliminaires sur les Crustaces, lere partie. In: Reports on the Results of Dredging under the Super- vision of Alexander Agassiz, in the Gulf of Mexico, and in the Caribbean Sea, 1877, ‘78, ‘79, by the U.S. Coast Survey Steamer “Blake.” Bull. Mus. Comp. ZooL Harv. Coll. 8(1): 1-68. & E, L. Bouvier. 1902. Les Dromiaces et Oxystomes. In: Reports on the Results of Dredging under the Supervision of Alexander Agassiz, in the Gulf of Mexico, and in the Caribbean Sea, 1877, ‘78, ‘79, by the U.S. Coast Survey Steamer “Blake.” Mem. Mus. Comp. ZooL 27:1-127. Powers, L. W. 1978. A Catalog and Bibliography to the crabs (Brachyura) of the Gulf of Mexico. Contrib. Mar. Sci. Supple- ment to Vol. 20. 1 p. Rathbun, M. J. 1898. The Brachyura of the biological expedition to the Florida Keys and the Bahamas in 1893. Bull. Lab. Nat. Hist. State Univ. Iowa. 4(3):250-294. 1901. The Brachyura and Macrura of Puerto Rico. Ru//. U.S. Fish Comm. 20(2):1-127. . 1937. The oxystomatous and allied crabs of America. U.S. Nat. Mus. Bull. 166:1-278. Wass, M. L. 1955. The decapod crustaceans of Alligator Harbor and adjacent inshore areas of northwestern Florida. Q. J. Fla. Acad. Sci. 18:129-176. Williams, A. B., L. R. McCloskey & I. E. Gray. 1968. New records of brachyuran decapod crustaceans from the continental shelf off North Carolina, U.S.A. Crustaceana. 15(l);41-66. Gulf Research Reports Volume 7 | Issue 4 January 1984 Growth and Production of the Dwarf Surf Chm Mulinia lateralis (Say 1822) in a Georgia Estuary Randal L. Walker Skidaway Institute of Oceanography Kenneth R. Tenore Skidaway Institute of Oceanography DOI: 10.18785/grr.0704.07 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Walker, R. L. and K. R. Tenore. 1984. Growth and Production of the Dwarf Surf Clam Mulinia lateralis (Say 1822) in a Georgia Estuary. Gulf Research Reports 7 (4): 357-363. Retrieved from http://aquila.usm.edu/gcr/vol7/iss4/7 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, VoL 7, No. 4, 357-363, 1984 GROWTH AND PRODUCTION OF THE DWARF SURF CLAM MVLINIA LATERALIS (SAY 1822) IN A GEORGIA ESTUARY RANDAL L. WALKER AND KENNETH R. TENORE Skidaway Institute of Oceanography, Savannah, Georgia 31416-0687 ABSTRACT The bivalve Mulinia lateralis is a dominant member of estuarine benthos, but its presence and abundance in Georgia estuarine waters is sporadic over time. Recruitment and production was monitored from 1977 through 1981 at three inner and one outer more saline ( > 18 ppt) areas of Wassaw Sound. Until the winter of Mulinia lateralis was absent or at very low densities. Significant settlement occurred in January 1981 when densities in the outer sound reached as high as 63,000 individuals • m“2 . The clam was more abundant in sandy mud (x = 10,161 • m"^ ) than mud ( x= 277 • m-2 ) or sand ( x= 263 • m-2 ). Cohort production varied from 0.3 g dry wt • m“2 • 4 months”^ in the inner sound to 325 g dry wt • m“^ • 7 months"^ in the outer Sound, with the mean biomass ranging from 0.6 to 513 g dry wt • m“2, respectively. When present, Mulinia lateralis contributes significantly to benthic production available to com- mercially valuable fish and crabs. That this food resource is annually and seasonally episodic could contribute to year-to- year fluctuations in production of species preying on benthos. INTRODUCTION The dwarf surf clam Mulinia lateralis (Say 1822) (Bi- valvia;Mactridae) is a typical dominant member of estuarine benthos whose density characteristically fluctuates widely. Populations of this clam may dominate the benthos one year or part of a year, only to be absent the following year(s). Fluctuations in the abundance of benthos of Wassaw Sound, in Georgia (Fig. l),may be in part caused by salinity depres- sions in winter/spring when many benthic species spawn (Walker et al. 1980, Walker and Tenore 1984). For example, M. lateralis and the northern hard c\ 2 an Mercenaria mercen- aria (Linne) did not settle significantly between 1977 and 1980, when low winter salinities resulted from heavy rain- fall in upstate Georgia. Because of a drought in 1981, salin- ities were not depressed in winter/spring and a significant set of juveniles ofM. mercenaria andM lateralis occurred. The contribution ofM. lateralis to benthic production is especially important because this species, when present, is an important source of food for many commercially valu- able fish and crabs (Brever 1957, Tagatz 1969, Virnstein 1977). Little information exists on the production of op- portunistic species such asM. lateralis. We describe here the production of a single cohort age-class of M. lateralis follow- ing the 1981 set of this bivalve after several years of recruit- ment failure. Information was gained on the contribution of the clam to benthic production during a period of high clam density. STUDY SITE Wassaw Sound (Fig. 1) is a coastal estuarine embayment located in the Georgia Bight (Howard and Frey 1980). Semi- diurnal tides average 2.4 m, with spring tides ranging ap- proximately 3.4 m (Hubbard et al. 1979). Water tempera- tures (Dorjes 1972) and salinities at the mouth of the Sound (Howard and Frey 1980) range from 8°C and 20 ppt in the Manuscript received April 23, 1984; accepted May 14,1984. winter to 30°C and 30 ppt in the summer. Sediments range from silt -clay to fine sand with interbedded sand and mud the most prevalent (Howard and Frey 1975). MATERIALS AND METHODS Four stations (Fig. 1) were sampled monthly from Janu- ary to December 1981 by taking six 0.05 -m^ van Veen grabs at each station. Samples were sieved through a 0.297 -mm mesh and preserved in 10% formalin in sea water. Samples were returned to the laboratory, sorted under a dissecting scope and specimens ofM. lateralis were counted and measured for shell length (longest possible measurement, i.e., anterior-posterior distance). Station 1 was located in the Skidaway River approxi- mately 1 mile south of the Skidaway Institute of Ocean- ography where the clams occurred in a muddy substrate in approximately 1.5 m of water at mean low water. Station 2 was located in the Wilmington River at the U.S. 80 draw- bridge at Thunderbolt, Ga., where the clams occurred in a muddy substrate in approximately 0.5 m of water at mean low water. Station 3 was located at the junction of Skid- away and Wilmington rivers, where the clams occurred in a sandy mud substrate in approximately 2 m of water at mean low water. Station 4 was located in the Wilmington River near the junction of Wilmington and Cabbage islands, where the clams occurred in approximately 0.2 m of water at mean low water. The shell-length to dry-weight (DW) relationship was determined for M. lateralis (n = 100). After clams were measured to the nearest mm, the flesh was removed and dried to constant dry weight at 80°C for 48 h. Secondary production was calculated using the instan- taneous growth model of Waters and Crawford (1973): P = GB where P = production in grams • m , G = instantaneous 357 358 Walker and Tenore Figure 1. The distribution and relative abundance otMulinia lateralis in Wassaw Sound, Georgia. Letters below the density symbols refer to substrate type: sh = shell, cs = coarse sand, s = sand, s/m = sandy mud, and m = mud. growth for the time interval, and B = mean standing crop between given time intervals (B= [B^ + B^+i ] /2). Instantan- eous growth rate (G) is calculated as ln(W^/Wo) where o and t represent the beginning and end of each time interval. Annual production is equal to the summation of the indivi- dual intervals’ production estimates. Individual weights for the table were obtained by taking the mean of the clam lengths per month per station and applying that value to the shell-length to dry-weight regression equation. Growth was determined by plotting the mean weight of the clams against time. Mean weights were determined using monthly mean shell lengths and converting to biomass. RESULTS Clams were absent or at low densities (< 10 • m"^) from 1977 to winter 1981 . In January 1981 newly set clams were found throughout the Sound. Clams set intertidally to a depth of 7 m, with heaviest settings in the outer Sound (up to 63,000 • m"^). Inshore of Skidaway and Wilmington islands, densities were < 2000 • m"^ . Densities also varied with sediment type (Fig. 1). Clams had average densities of 10,161 ± 19,475 (SD) • m“^ in sandy mud, 277 ±522 (SD)*m~^ in mud, 263 ± 468 (SD) • m"^ in sand, and were absent in coarse sand and shelly bottoms. In areas where the substrate changed from sand to mud, clams were more dense in the sand-to-mud interphase. Densities increased at the four stations from January to February and then declined. Some specimens ofM lateralis in Wassaw Sound were mature and ripe in April but there was no new recruitment. None were found at Sta 1, 2, and 3 after April. Clams persisted at Sta 4 until August (Fig. 2). Densities varied greatly from a low of 525 • m ^ at Sta 2 to Growth and Production of the Dwarf Surf Clam 359 SURVIVORSHIP CURVES OF MULINIA LATERALIS • • Station 1 y = 2.17 + 0.04X-0.0003658 x2 0.990 • * Station 2 y = 2.48 + 0.02X-0.0003145X^ r^=0.980 ■ ■ Stations y = 1.07 +0.05X-0.0004635X^ r 0.930 • • Station 4 y = 3.82 + 0.03X -0.0001 883X^ r^= 0.840 Days [*day 1 is 1 January 1981] Figure 2. Survivorship curves for Mulinia lateralis at Stations 1 through 4. Day one is 1 January 1981. a high of 63,168 • at Sta 4 in February. From January to March, individuals declined from 63,168 to 17,346 • m"^ at Sta 4; similar declines occurred at the other stations from February to April. Histograms show changes in clam size with time and because there was only a single set, cohort production at the four stations could be estimated (Fig. 3). The regression equation of shell length (SL) in cm to mean dry weight (DW) in grams is: g DW = 0.01095 (SL cm)2*^^® , r^ = 0.94 and compares well to other bivalves (Winberg 1971). Changes in biomass with time were examined by the equation: w = at^ where w = mean dry weight and t = time in days from settle- ment at each of the stations. The estimate of initial settle- ment was the beginning of January. By using monthly data points, the prediction was made by varying the day of settle- ment until the highest correlation coefficient was obtained. The best fit (r^ = 0.99) was obtained when 1 or 2 January was used as the day of initial settlement. Exponential growth rates were highest at Sta 3 and low- est at Sta 4 (Fig. 4). Slow individual growth rates at Sta 4 probably resulted from the high clam densities at that sta- tion. Cohort production, standing crop, and cohort turnover ratios varied from a high production value of 325 g DW • m~^ • 7 mo"^ with a high standing crop of 513.44 g DW • m~^ at Sta 4 to a low production value of 0.29 g DW • m'"^ • 4 mo“^ and low standing crop of 0.60 gDW • m“^ at Sta 2. Mulinia lateralis population: STATION 4 0 § 1 n 26 January 1981 55=55, 965±26,560(SD) x=0.29±0.08(SD) cm 24 February 1981 55 =63,168 ±32, 529(SD) m' 55 = 0.50+0.12(30) cm u O' O' V- ' 25 March 1981 55 =17,346±8589{SD) m' 55 = 0. 67±0. 09(30) cm 6 May 1981 55 = 17, 7 124±4956(SD) m"^ 55 = 0.80 + 0.09(30) cm • ^ o -2 O) QC O- N- - ,\o ^ 1 'P nP .0 vO o vP 23 May 1981 30 June 1981 Q' O' O' N- vp kO ,0 .0 .p .p 22 July 1981 'f' cF <1/’ 4^ O' O- O- S- N+ N- ,p ,p ,0 ,p ,p .p 24 August 198 Shell Length (cm) Figure 3. Monthly histograms for Station 4 showing changes in number • m ^ , average size, and the formation of only one cohort. Days 360 Walker and Tenore Growth Curves for Mulinia lateralis Station #1 Station #2 Station #3 = 41.3X-395 r2 = .9998 = 33.14X-692 r2= .9620 = 32.60X-513 r2= .9642 = 45.59X'472 r2= .9935 Figure 4. Growth rates (oi Mulinia lateralis at Stations 1 through 4. Cohort production was estimated at 7.3 g DW • m ^ • mo"^ with a standing crop of 9.19 g DW * m ^ and 4.12 4mo"^ with a standing crop of 8.05 g DW TABLE 1 Cohort production by instantaneous growth method, cohort turnover ratio, mean density of clams for duration of population, and the duration of the population for Stations 1 through 4. Cohort production is m grams dry weight m per duration of the population. Cohort* Production Cohort* P/B Mean* Monthly Density (± SD) Duration of Population 2.38 1437±304 January to March 1.93 1481252.6 January to April 2.05 4621517 January to April 4.44 24,770124,540 January to July DW*m" ^ at Sta 1 and 3 , respectively. Cohort turnover rates (P/B) ranged from a low of 1.93 for Sta 2 to a high of 4.40 for Sta 4 with Sta 1 and 3 having ratios of 2.38 and 2.05, res- pectively. The differences in estimates were attributed to differences in densities in clams. The higher the densities, the higher the production, standing crop, and turnover ratio (Table 1). DISCUSSION Salinity is a major regulator of benthic populations (Wells 1961) and year-to-year excessive salinity depression in wintex/spring appears to regulate the annual recruitment of M lateralis in Wassaw Sound. Low salinity (< 20 ppt) oc- curred during the winters from 1977 to 1980, during the period of normal reproduction which could affect gamete and larval development and survival. Larval development of M. lateralis is most successful (> 70%) from 22.5 to 30 ppt but can occur as low as 15 ppt (Calabrese 1969). Larva Station 1 7 .29 Station 2 0.29 Station 3 4.12 Station 4 325.28 ^ Leased on less than one yeafI2 3 mo fol Sta 1, 4 mo for Sta 2 and 3, and 7 mo for Sta 4. survival and growth is optimum at 20 to 27.5 ppt. The distribution of animals within estuarine systems is generally related to sahnity (Wells 1961 , Menzel 1964, Wass 1965). Other environmental factors associated with salinity reductions, however, could be responsible for the lack of successful annual recruitment of M lateralis in Georgia. For instance, with heavy freshwater runoff, a major shift m water mass could affect larval transport and settlement as well as changes in primary production. Furthermore heay runoff could increase the amount of suspended sediments as well as alter bottom sediments. Davis (1960) showed that growth and survival of clam (Mercenaria mercenaria) eggs and larvae was correlated to the type and concentration of various suspended material. Instability of the bottom sur- face can result in clogged filtering structures of suspension feeders, burying newly settled larvae or discouraging settling of suspension feeding bivalves (Rhoads and Young 1970). Total cohort production was 100 times greater at Sta 4, located in the more saline region of the outer Sound, than at Sta 1 and 3 in the inner Sound. Further, Sta 1 and 3 were 24 and 14 times, respectively, more productive than Sta 2 located in the area of lowest salinity. This resulted from clam density and duration of the various populations. Clams at Sta 4 were dense and survived for 7 mo, while those at Sta 2 had a low density and survived 4 mo. Populations of M. lateralis were quickly decimated fol- lowing a heavy set in January 1981. Mortality probably re- sulted from predation by blue crabs Callinectes sapidus Rathbun. An abundance at all stations of shell fragments characteristic of crab predation (MacKenzie 1977) suggested heavy predation by the blue crab, a major predator of adults of M. lateralis (Virnstein 1977 ). Mortality of M. lateralis also resulted from the moon snail Po/mte duplicatus (Say) as determined by type of bore hole (Carriker 1951), ^‘^counted for a small percentage of the monthly losses at Sta 4. Mean clam mortalities caused by snails were: 0, 504, 231 and 1008 clams • m'^ in February, March, April, and May, Growth and Production of the Dwarf Surf Clam 361 TABLE 2 Annual production and P/B ratios of species of bivalves (production in g Ash Free Dry Weight m“2 unless otherwise stated). Bivalve age is in years. Species Production g AFDW m"2 yr-i P/B (yrs.) Max. Age Locality Reference Geukensia* demissus (Dillwyn) 3.34 7 0.28 Georgia, U.S.A. Keunzler 1961 Tagelus divisus (Spengler) 21.0 gDW 1.78 2 Biscayne Bay, FL Fraser 1967 Tellina martinicensis (Orbigny) 0.23 g DW 2.40 2 Biscayne Bay, FL Penzias 1969 Chione cancellata (Linne) 8.90 g DW 0.42 7 Biscayne Bay, FL Moore & Lopez 1969 Dosinia elegans (Conrad) 0.13 g DW 1.25 2 Biscayne Bay, FL Moore & Lopez 1970 Anodontia alba (Link) 14.09 g DW 1.43 7 Biscayne Bay, FL Moore & Lopez 1972 My a arenaria (Linne ) 11.60 gDW 2.54 3 Petpeswich Inlet, Can. Burke & Mann 1974 My a arenaria (Linne) 2.66 0.5 8 Lynher Estuary, U.K. Warwick & Price 1975 Scrobicularia plana (da Costa) 0.48 0.20 9 Lynher Estuary, U.K. Warwick & Price 1975 Macoma balthica (Linne) 0.31 0.90 6 Lynher Estuary, U.K. Warwick & Price 1975 Macoma balthica (Linne) 1.93 gDW 1.53 3 Petpeswich Inlet, Can. Burke & Mann 1974 Macoma balthica (Linne) 3.40 1.93 8.10 Grevelingen Estuary, Netherlands Wolff&deWolf 1977 Macoma balthica (Linne) 0.94 1.00 8.10 Grevelingen Estuary, Netherlands Wolff & de Wolf 1977 Ensis siliqua (Linne) 1.37 0.27 10 Carmarthen Bay, South Wales Warwick et al. 1978 Cerastoderma edule (Linne) 0.21 0.20 7 Lynher Estuary, U.K. Warwick & Price 1975 Cerastoderma edule (Linne) 29.25 1.59 5 Southampton Waters, U.K. Hibbert 1976 Cerastoderma edule (Linne) 71.36 1.10 5 Southampton Waters, U.K. Hibbert 1976 Cerastoderma edule (Linne) 46.44 2.61 5 Southampton Waters, U.K. Hibbert 1976 Cerastoderma** edule (Linne) 10.21 0.69 3.5 Grevelingen Estuary, Netherlands Wolff &deWolf 1977 Cerastoderma** edule (Linne) 119.82 2.59 3.5 Grevelingen Estuary, Netherlands Wolff&deWolf 1977 Cerastoderma** edule (Linne) 51.76 1.13 3.5 Grevelingen Estuary, Netherlands Wolff&deWolf 1977 Venerupis aurea (Gmelin) 0.70 1.11 5 Southampton Waters, U.K. Hibbert 1976 Venerupis aurea (Gmelin) 1.25 1.10 5 Southampton Waters, U.K. Hibbert 1976 Venerupis decussata (Linne) 0.21 0.52 7 Southampton Waters, U.K. Hibbert 1976 Venerupis decussata (Linne) 0.60 0.28 7 Southampton Waters, U.K. Hibbert 1976 Donax vittatus (da Costa) 0.72 2.10 2.5 Carmarthen Bay, South Wales Warwick et al. 1978 Venus striatula (da Costa) 0.62 0.41 10 Carmarthen Bay, South Wales Warwick et al. 1978 Tellina fabula (Gmelin) 0.29 0.90 6 Carmarthen Bay, South Wales Warwick et al. 1978 Tellina deltoid es 2.35 1.42 4 Westernport Bay, Australia Robertson 1979 Abra alba (Wood) 1.45 2.0 1.2 Concarneau Bay, France Glemarec and Menesquen 1980 Crassostrea virginica (Gmelin) 4132 Kcal 2.01 2 South Carolina, U.S.A. Dame 1976 Mytilus edulis (Linne) 3.68 1.00 7 Southampton Waters, U.K. Hibbert 1976 Mytilus edulis (Linne) 4.82 1.00 7 Southampton Waters, U.K. Hibbert 1976 Mytilus edulis (Linne) 29.43 KJy-l 7 7 Lynher Estuary, U.K. Bayne & Worrall 1980 Mytilus edulis (Linne) 14.40 KJ y-i 7 7 Cattewater Estuary, U.K. Bayne & Worrall 1980 Mytilus edulis (Linne') 790.0 7 1 Nyckelbyviken Bay, Sweden Loo & Rosenburg 1983 Mytilus edulis (Linne) 648.0 7 1 Nyckelbyviken Bay, Sweden Loo & Rosenburg 1983 Mytilus edulis (Linne) 476.0 7 1 Nyckelbyviken Bay, Sweden Loo & Rosenburg 1983 Mulinia lateralis (Say) 7.29 DW 2.38 0.25 Georgia, U.S.A. This study Mulinia lateralis (Say) 0.29 DW 1.93 0.33 Georgia, U.S.A. This study Mulinia lateralis (Say) 4.12 DW 2.05 0.33 Georgia, U.S.A. This study Mulinia lateralis (Say) 325.28 DW 4.44 0.58 Georgia, U.S.A. This study Mercenaria mercenaria (Linne) 62.82 3.02 1 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 23.71 1.85 1 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 133.60 3.38 1 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 0.51 0.25 9 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 6.15 0.18 34 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 18.53 0.17 30 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 0.24 0.25 9 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 6.57 0.19 34 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 6.49 0.22 30 Georgia, U.S.A. Walker 1984 Mercenaria mercenaria (Linne) 3.99 0.52 8 Southampton Waters, U.K. Hibbert 1976 Mercenaria mercenaria (Linne) 14.00 0.28 8 Southampton Waters, U.K. Hibbert 1976 Mercenaria mercenaria (Linne) 6.19 0.17 9 Southampton Waters, U.K. Hibbert 1976 * Given 2 .^ Modiolus demissus in Keunzler (1961). ** Given as Cardium edule in Wolff and. deWolf (1977). 362 Walker and Tenore TABLE 3 Some literature values for annual production (values in g Ash Free Dry Weight) of marine communities. Production Locality g AFDW • m • yr -1 Source Long Island Sound, U.S.A. 8.0 to 64.5 Sanders 1956 Lynher Estuary, U.K. 13.3 Warwick & Price 1975 Southampton Waters, U.K. 220.0 Hibbert 1976 Grevelingen Estuary, Netherlands 0.1 to 219.9 Wolff&deWolf 1977 Carmarthen Bay, South Wales 25.8 Warwick et al. 1978 respectively. These values represented 0, 1.1, 1, and 16% of total mortality. The spot Leiostornus xanthurus LacepMe is also a major predator ofM lateralis (Virnstein 1977); those caught in June had been feeding primarily on M. lateralis (personal observations). Production estimates of M. lateralis ranged from 0.3 g DW • m"^ *4 mo'^ to 325 gDW • mf^ • 7mo“^ and are com- parable to production data for other bivalves (Table 2) and benthic communities (Table 3). Cohort turnover ratios were considerably higher in Wassaw Sound, however, than those cited for other bivalves because the population studied was comprised only of young individuals. Turnover ratios de- creased with increase in age of organisms (Nichols 1975, Warwick 1980, Walker 1984). The short-term production rate i e the rate for the 3 to 7 mo that M. lateralis was present, was higher than reported for other bivalves. Thus, at least for a short period of time,Af. lateralis effectively exploits available food resources and in turn can be a signifi- cant source of food for predators; however, year-to-year variations in production that resulted from recruitment fail- ure that were caused by low winter salinities also caused a significant instability in the availability of this clam to pre- dators. ACKNOWLEDGMENTS The authors wish to thank Drs. E. Chin and D. Menzel for reviewing the manuscript. Special thanks are given to Ms. A. Boyette and S. McIntosh for the graphics and to L. Land for typing the manuscript. The work was supported by the Georgia Sea Grant Program under grant number USDL-RF /8 3 1 0-2 1 -RR 1 00- 1 02 . REFERENCES CITED Bayne, B. L. & C. M. 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The distribution and produc- tion of the hard clam, Mercenaria mercenaria, in Wassaw Sound, Georgia. Estuaries 7:19-27. Warwick, R. M. 1980. Population dynamics and secondary produc- tion. Pages 1—24 in: Tenore, K. R. and B. C. CouU {eds.), Marine Benthic Dynamics. Univ. South Carolina Press, Columbia. , C. L. George and J. R. Davies. 1978. Annual macro- fauna production in a Venus community. Estuarine Coastal Mar. Sci. 7:215-241. & R. Price. 1975. Macrofauna production in an estuarine mud-flat. J. Mar. Biol. Assoc. U.K. 55:1-18. Wass, M. L. 1965. Checklist of the marine invertebrates of Virginia. Va. Inst. Mar. Sci. Spec. Sci. Rep. 24:55. Waters, T. F. & G. W. Crawford. 1973. Annual production of a stream mayfly population: a comparison of methods. Limnol. Oceanogr. 18(2):286-296. Wells, H. W. 1961. The fauna of oyster beds with special references to the salinity factor. Ecol. Monogr. 31:239—266. Winberg, G. G. (ed.). 1971. Methods for the Estimation of Produc- tion of Aquatic Animals. Academic Press, London. 175 pp. Wolff, W. J. & L. deWolf. 1977. Biomass and production of zoo- benthos in the Grevelingen estuary, The Netherlands. Estuarine Coastal Mar. Sci. 5:1-24. Gulf Research Reports Volume 7 | Issue 4 January 1984 Ultrastructure of Rodlet Cells: Response to Cadmium Damage in the Kidney of the Spot Leiostomus xanthurus Lacepede William E. Hawkins Gulf Coast Research Laboratory, William.Hawkins(^usm.edu DOI; 10.18785/grr.0704.08 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation HawkinS; W. E. 1984. Ultrastructure of Rodlet Cells: Response to Cadmium Damage in the Kidney of the Spot Leiostomus xanthurus Lacepede. Gulf Research Reports 7 (4): 365-372. Retrieved from http://aquila.usm.edu/gcr/vol7/iss4/ 8 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 365-372, 1984 ULTRASTRUCTURE OF RODLET CELLS: RESPONSE TO CADMIUM DAMAGE IN THE KIDNEY OF THE SPOT LEIOSTOMUS XANTHURUS LACEPEDE WILLIAM E. HAWKINS Microscopy Section, Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564 ABSTRACT Rodlet cell ultrastructure was studied in normal and cadmium-damaged kidney tissues of the spot Leiosto- mus xanthurus, an estuarine teleost. Rodlet cells in control fish occurred in all parts of the nephron except the renal cor- puscle, were oblong to pear-shaped (about 5x10 pm), and contained up to 30 rodlet bodies, a basally situated nucleus, poorly developed mitochondria, and a filamentous cortex. Desmosomes and tight junctions joined rodlet cells to kidney epithelial cells. After cadmium exposure, rodlet cells showed a range of responses from secretory stimulation to necrosis. Rodlet bodies, which were membrane-bound, club-shaped granules, were secreted by a merocrine process, apparently aided by contraction of the filamentous cortex. New rodlet bodies were assembled in the Golgi apparatus. Mitochondria hyper- trophied and developed well-defined cristae. The ultrastructural organization of the rodlet cells in this study and their responses to stimuli suggest that these are tissue or host cells rather than parasites as proposed by some authors. Further studies, however, are needed to confirm the nature of these cells. INTRODUCTION Rodlet cells occur frequently in fish tissues and have long been the subject of controversy over whether they are protozoan parasites (Thelohan 1892) or tissue cells (Plehn 1906). Most ultrastructural studies agree that the principal cytologic features of these cells are rodlet bodies, a fila- mentous cortex that lies beneath the plasma membrane, and a basally situated nucleus. However, there is little agree- ment on the nature of the rodlet cell and reports on ultra- structural details vary. Some consider the cells to be para- sites because of their widespread distribution in tissues or because of the resemblance of some rodlet cell organelles to those of apicomplexan protozoans (Bannister 1966, Iwai 1968, Mourier 1970, Flood et al. 1975, Mayberry et al. 1979). Others consider rodlet cells to be unicellular glands in which the rodlet bodies are secretory granules formed in the Golgi apparatus from material synthesized in the rough endoplasmic reticulum (RER) (Leino 1974, Desser and Lester 1975, Morrison and Odense 1978,Mattey et al. 1979). In most studies, rodlet cells have been examined in nor- mal tissues. Few studies have involved rodlet cells in patho- logical or toxicological situations. In a study on the effect of cadmium on the kidney of the spot Leiostomus xanthurus, an estuarine teleost (Hawkins et al. 1980), we found that parts of the renal tubule had abundant rodlet cells. Since cadmium caused severe damage to renal tubular epithelial cells, we thought it worthwhile to examine the ultrastructural changes in rodlet cells in cadmium-damaged renal tubules. MATERIALS AND METHODS Twenty-six spot, 10-15 cm in total length, were col- lected by trawl, seine, and hook and line from the Missis- sippi Sound. Specimens were taken to the laboratory and Manuscript received April 1 3, 1984; accepted September 21, 1984. either processed immediately or maintained in glass aquaria containing filtered and circulating artificial sea water with a salinity of 15—25 ppt. Fish were killed by pithing. Kidneys were fixed in situ in either 3.0% glutaraldehyde in 0.1 M phosphate buffer or in Karnovsky’s fixative (Karnovsky 1965) in 0.1 M cacodylate buffer. For transmission electron microscopy (TEM), tissues were minced, rinsed in the appro- priate buffer and postfixed in 1.0% osmium tetroxide. Some tissues were en bloc stained with aqueous uranyl ace- tate. Tissues were dehydrated in ethanol and embedded in epoxy resin. Thin sections were stained with lead citrate and examined with a Phillips 301 or Siemens Elmiskop lA electron microscope. For orientation, semithin sections (1—2 pm thickness) were cut, mounted on glass slides, and stained with toluidine blue. For scanning electron microscopy (SEM), whole kidneys were dissected as described above and allowed to fix for 2 h to several days and then cut with a razor blade into sec- tions about 2 mm thick. The sections were postfixed for 1 h in buffered 1.0% osmium tetroxide, dehydrated in ethanol and critical point dried using CO 2 . Tissues were sputter-coated with gold and examined with an ETEC Autoscan. Procedures for exposing fish to cadmium have been des- cribed (Hawkins et al. 1980). Briefly, spot were exposed in static aquaria to levels of cadmium chloride from 1 to 100 ppm for 48 h. Tissues were processed for electron micro- scopy as described above. RESULTS Rodlet cells in control kidney Rodlet cells occurred in the epithelium of the neck seg- ment, proximal tubule, collecting tubule, and ureteric duct. In control kidneys, rodlet cells were not found in renal cor- puscles, blood vessels, or hemopoietic tissues. SEM of 365 366 Hawkins Figure 1. Scanning electron micrograph of a rodlet ceU (RC) between epithelial cells (EC) of the ureteric duct. Note ridges and furrows on surface of rodlet cell. Duct lumen (L); microvilli (Mv). X 13,200 Figure 2. Transmission electron micrograph of rodlet cells (RC) in proximal tubule. X 3,200 Rodlet Cells after Cadmium Damage 367 ureteric duct epithelium showed that the rodlet cells were oblong to pear-shaped and wedged between the epithelial cells (Figure 1). The rodlet cell surface formed circum- ferential ridges and furrows. The apex of the rodlet cell often bordered on the lumen and occasionally issued micro- villus-like processes into the duct lumen. The space that separated the rodlet cell from surrounding epithelial cells was not present in TEM samples or in SEM samples that were prepared by freeze-cracking (unpublished observa- tions). In some proximal tubules, rodlet cells (about 5X10 jum) were almost as abundant as tubule epithelial cells (Figure 2). The structure and organization of most rodlet cell organ- elles conformed with those of other species. Some impor- tant features are described for comparison with cadmium- exposed cells but are not illustrated. The rodlet cell apex faced the tubule lumen. The basally situated nucleus (3—4 /rm in diameter) contained dense, marginated chromatin. As many as 30 club-shaped mem- brane-bound rodlet bodies, each with an electron-dense core, extended from near the nucleus to the cell apex. Golgi complexes were rarely seen. Elongate, sinuous, poorly dif- ferentiated mitochondria (about 0.15 to 0.30 iim in dia- meter) occurred near the apex. A filamentous cortex (about 0.5 fj.m thick) which lay beneath the plasmalemma, except at the apex, contained thick filaments (20 nm in diameter) oriented around the long axis of the cell and thin filaments (6—8 nm in diameter) that were not regularly oriented. Microtubules (about 10 nm in diameter) ran along the inner aspect of the cortex from the apical to the basal region. Dense plaques situated 15-20 nm from the plasmalemma lined the cell at regular intervals. Rodlet cells and tubular epithelial cells were connected by desmosomes and tight junctions. Some rodlet cells appeared open to the tubule lumen (Figure 3). Membrane-bound rodlet bodies were seen in the tubule lumen near such cells. The nuclei of these rodlet cells resembled those of normal resting cells. Usually, the tubule lumens that contained rodlet cell debris were compressed and also contained debris from the tubular epithelium. Cadmium-exposed kidney Exposure to cadmium levels greater than 10 ppm for 48 h damaged proximal tubular epithelium (Hawkins et al. 1980). Concurrently, changes took place in rodlet cells. Rodlet cells were not disrupted or damaged as severely as the tubular epithelial cells. Detached rodlet cells, however, lay among epithelial cells, in tubule lumens, and in Bowman’s space of the renal corpuscle (Figure 4). Some rodlet cells were joined by desmosomes (Figure 5). In many cells, the filamentous cortex was thickened and the dense plaques were nearly continuous. Vesicles often occurred within the filamentous cortex or between it and the plasmalemma. Some rodlet cells appeared to expel their rodlet bodies by a merocrine process whereby the membrane surrounding a rodlet body became continuous with the plasmalemma (Figure 6). Other organelles of these secreting cells were similar to those of resting cells. Rodlet cells appeared to reform rodlet bodies in the Golgi apparatus (Figure 7). The dense core of forming rodlet bodies was smaller than in mature rodlet bodies. The origin of the dense core was not determined. RER was abundant in the supranuclear cytoplasm, especially near developing rodlet bodies. The mitochondria of these cells were rounder, larger, and cristae better developed than in control rodlet cells (Figure 8). Nucleoh, usually absent in control rodlet cells, were sometimes present in these cells. In some rodlet cells, the area between the filamentous cortex and the cytoplasm was not distinct and the cortex lacked subplasmalemmal dense plaques. These cells often contained dense spherical structures 0.5 to 1.0 ijim in dia- meter (Figures 4, 9, 10). Rodlet bodies were similar to those in control rodlet cells. Mitochondria were often swollen and vacuolated. Membrane-bound inclusions of homogenous material, membranes, and vesicles frequently occurred in these cells. Centrioles were often present in the apical cytoplasm (Figure 10). Nuclei contained one or more dense spherical inclusions that were as large as 2.0 pm in diameter. Otherwise, the nucleus was electron lucent with a flocculent nucleoplasm (Figure 9). Many rodlet cells appeared to be in late stages of necro- sis. The plasmalemma was often disrupted, especially at the apex. Nuclei were pyknotic and sometimes in the process of being expelled (Figure 11). The fibrillar cortex was intact although dense plaques were lacking. Also lacking were the microtubules that ran in the junction between the cytoplas- mic core and the fibrillar cortex. Mitochondria were round with prominent cristae and a few dense deposits. Occasion- ally, degenerating rodlet cells were phagocytosed by mono- cytic macrophages (Figure 12). DISCUSSION The origin and functions of rodlet cell mitochondria and rodlet bodies are disputed by the tissue-cell (Leino 1974, Desser and Lester 1975, Morrison and Odense 1978, Mattey et al. 1979) and parasite (Bannister 1966, Mourier 1970, Mayberry et al. 1979) proponents. Distinct, ovoid mito- chondria with prominent cristae occur in immature, devel- oping rodlet cells (Leino 1974, Desser and Lester 1975) whereas mitochondria in mature rodlet cells are tubular with indistinct cristae (Bannister 1966, Wilson and Wester- man 1967, Mourier 1970, Leino 1974, Desser and Lester 1975, Morrison and Odense 1978, Barber et al. 1979). Mayberry et al. (1979) described structures reported to be mitochondria in mature rodlet cells as micronemes. Micro- nemes are osmiophilic, cord-like organelles of apicomplexan parasites (Chobotar and Scholtyseck 1982). Rodlet cells in control spot kidney had tubular mitochondria with indis- tinct cristae similar to the mitochondria in mature rodlet cells of other species. After exposure to nephrotoxic 368 Hawkins Figure 3. Membrane-bound rodlet bodies (arrowheads) in lumen of proximal tubule. Note apex of rodlet cell appears to open into lumen Also note other debris in lumen. X 4,100 . . Figure 4. Detached rodlet cell in Bowman’s space following cadmium exposure. Note dense nuclear and cytoplasmic bodies in rodlet cell Visceral glomerular epithelium (VE). X 6,400 Rodlet Cells after Cadmium Damage 369 Figure 5. Desmosome (arrowhead) between two rodlet cells. Note disrupted and damaged mitochondria (M) of renal tubule epithelium. Cadmium-exposed. X 8»400 Figure 6. Rodlet body apparently being secreted without disruption of plasma membrane. Note that at the arrowhead, the plasma membrane becomes continuous with membranes of the rodlet body vacuole. Cadmium-exposed. X 17,300 Figure 7. Immature rodlet body (arrowhead) associated with Golgi-like membranes and vesicles. Cadmium-exposed. X 27,600 Figure 8. Rodlet cell mitochondria (M) following cadmium damage. X 30,800 370 Hawkins Figure 9. Rodlet cell following cadmium damage showing swollen filamentous cortex (F) and dense bodies in nucleus (N) and cytoplasm. X 12,800 Figure 10. Centriole (arrowhead) in rodlet cell following cadmium exposure. X 15,000 Figure 11. Necrotic rodlet cells following cadmium exposure. Note pyknotic nuclei (N). X 4,000 Figure 12. Rodlet cell (RC) phagocytosed by monocyte (Mo) following cadmium exposure. X 6,600 Rodlet Cells after Cadmium Damage 371 cadmium levels, however, the tubular mitochondria became ovoid with prominent cristae. Thus, these structures were clearly identifiable as mitochondria. Cytochemical studies of nucleic acids in rodlet bodies disagree. Leino (1982) identified carbohydrates and protein in the granular matrix of the rodlet body and determined that the rodlet core contained protein but no carbohydrate or nucleic acids. Based on RNAase digestion studies, Barber et al. (1979) suggested that rodlet body cores contained RNA. Bielek and Viehberger (1983), supporting the para- sitic nature of rodlet cells, identified DNA in rodlet cores by fluorescence staining and DNAase digestion studies. Several studies showed that rodlet bodies are synthesized in Golgi apparatus of immature cells (Leino 1974, Desser and Lester 1975, Barber et al. 1979, Mattey et al. 1979). In spot exposed to cadmium, rodlet cells apparently were stim- ulated to secrete their rodlet bodies which were replaced by the Golgi apparatus. The release of rodlet bodies occurred by a merocrine process without disruption of the plas- malemma and was accompanied by contraction of the fila- mentous cortex. Leino (1974) suggested that rodlet cell secretion was holocrine and that the secretion involved con- traction of the filamentous cortex, disruption of the apical plasmalemma, and expulsion of the rodlet cell contents. Mayberry et al. (1979) who referred to rodlet bodies as rhoptries, coccidian organelles that appear to aid in the penetration of the host cell by the coccidium (Chobotar and Scholtyseck 1982), observed rodlet cell organelles and whole rodlet cells in the lumens of epithelial tissues and suggested that this resulted from handling or processing damage whereas intact rodlet cells were parasites that had left the host tissues. Mattey et al. (1979) also maintained that the appearance of holocrine secretion by rodlet cells was the result of handling or fixation damage. In the spot, holocrine secretion by rodlet cells also appears to be arti- factual because tubule lumens that contained rodlet cell debris often contained epithelial cell debris as well. How- ever, it is possible, as Leino (1974) suggested, that slough- ing of most or all of the rodlet cell contents is the final stage of the cycle of this cell. If the normal secretion of the rodlet cell is merocrine, then the function of the filament- ous cortex is not clear. Perhaps contraction of the filament- ous cortex is necessary to aid in expelling the large rodlet body with its apparently rigid core. Rodlet cell junctional complexes vary among species. Desmosomes occur between rodlet cells and epithelial cells in several species of freshwater fishes (Leino 1974, Mattey et al. 1979) and tight junctions between rodlet cells and epithelial cells in the operculum and gill raker of the white sucker Catostomus commersoni Lacep^de (Desser and Lester 1975). Mourier (1970), who considered rodlet cells to be parasites, reported desmosomes between rodlet cells but not between rodlet cells and tubule epithelial cells in the kidney of the stickleback Gasterosteus aculeatus L. Rodlet cells in cadmium-damaged spot kidney were occa- sionally joined by desmosomes although such junctions in normal kidney were not observed. The significance of this is not clear. Intercellular junctions were not reported between immature or developing rodlet cells or between such cells and epithelial cells by Leino (1974) or Desser and Lester (1975). The ability of rodlet cells to form desmosomes and tight junctions is not shared with any apicomplexan parasite. The present study confirms neither the parasitic nor the tissue-cell nature of the rodlet cell. Confirmation must await studies characterizing rodlet cell DNA and immunological properties and comparing these with known fish cells. It is likely that preparations rich in rodlet cells such as the spot proximal tubule could be exploited for these studies. Never- theless, the ultrastructural organization of rodlet cells in control and cadmium-damaged renal tubules of the spot suggests to us that these are tissue cells rather than apicom- plexan parasites. ACKNOWLEDGMENTS The author wishes to thank Mrs. Debby Jennings and Mr. Robert Allen for their technical assistance, Drs. Robin Overstreet and Harold Howse for critically reading the manuscript, and Walter Wilborn of the University of South Alabama for use of his SEM facilities. REFERENCES CITED Bannister, L. H. 1966. Is Rhabdospora thelohani (Laguesse) a sporozoan parasite or a tissue cell of lower vertebrates? Parasitol- ogy 56:633-638. Barber, D. L., J. E. M. Westermann & D. N. Jensen. 1979. New ob- servations on the rodlet cell {Rhabdospora thelohani) in the white sucker Catostomus commersoni (Lacepede): LM and EM studies. J. Fish Biol 14:277-284. Bielek, E. & G. Viehberger. 1983. New aspects on the “rodlet cell” in teleosts. /. Submicrosc. Cytol. 15:681-694. Chobotar, B. & E. Scholtyseck. 1982. Ultrastructure. Pages 101- 166 in: Long, P. L. (ed.), The Biology of the Coccidia. Univer- sity Park Press, Baltimore, Maryland. Desser, S. S. & R. Lester. 1975. An ultrastructural study of the enigmatic “rodlet cells” in the white sucker, Catostomus commersoni (Lacepede) (Pisces: Catostomidae). Can. J. Zool. 53:1483-1494. Flood, M. T., R. F, Nigrelli & J. F. Gennaro. 1975. Some aspects of the ultra structure of the “Stabchendrusenzellen,” a peculiar cell associated with the endothelium of the bulbus arteriosus and with other fish tissues. J. Fish Biol. 7:129-138. Hawkins, W. E., L. G. Tate & T. G. Sarphie. 1980. Acute effects of cadmium on the spot Leiostomus xanthurus (Teleostei): Tissue distribution and renal ultrastructure. J. Toxicol. Environ. Health 6:283-295. Iwai, T. 1968. Notes on the pear-shaped cell (rodlet cell) in the epi- thelium of the digestive tract of fishes. Bull. Jpn. Soc. Sci. Fish. 34:133-137 (In Japanese). 372 Hawkins Karnovsky, M. J. 1965. A formaldehyde-glutaraldehyde fixative of high osmolarity for use in electron microscopy. J. Cell Biol 27A;127-138. Leino, R. L. 1974. Ultrastructure of immature, developing, and secretory rodlet cells in fish. Cell Tissue Res. 155:367 — 381. Leino, R, L. 1982. Rodlet cells in the gill and intestine of Catosto- mus commersoni and Perea flavescens: A comparison of their light and electron microscopic cytochemistry with that of mucous and granular cells. Can. J. Zool. 60:2768 2782. Mattey, D. L., M. Morgan & D. E. Wright. 1979. Distribution and development of rodlet cells in the gills and pseudobranch of the bass, Dicentrachus labrax (L). J. Fish Biol 15:363—370. Mayberry, L. F., A. A. Marchiondo, J.E. Ubelaker & D. Kazic. 1979. Rhabdospora thelohani Laguesse, 1895 (Apicomplexa): New host and geographic records with taxonomic considerations. J. Protozool 26:168—178. Morrison, C. M. & P. H. Odense. 1978. Distribution and morphology of the rodlet cell in fish. J. Fish. Res. Board Can. 35 : 101 -1 1 6. Mourier, J. -P. 1970. Structure fine de Rhabdospora thelohani Henneguy, protiste parasite de Gasterosteus aculeatus L.Z. Para- sitenkd. 34:198-206. Plehn, M. 1906. Ueber eigentumliche drusenzellen im gefasssystem und in anderen organen bei fischen. Anat. Anz. 28:192—203. Thelohan, P. 1892. Sur des sporozoaires indetermine's, parasites des poissons. /. (Paris) 38:163 171. Wilson, J. A. F. & R. A. Westerman. 1967. The fine structure of the olfactory mucosa and nerve in the teleost Carassius carassius L. Z. ZellforscK Mikrosk. Anat. 83:196—206. Gulf Research Reports Volume 7 | Issue 4 January 1984 The Epiphytic Diatom Flora of Two Sargassum Species Robert S. Maples McNeese State University DOI; 10.18785/grr.0704.09 Follow this and additional works at; http://aquila.usm.edu/gcr & Part of the Marine Biology Commons Recommended Citation Maples; R. S. 1984. The Epiphytic Diatom Flora of Two Sargassum Species. Gulf Research Reports 7 (4): 373-375. Retrieved from http;//aquila.usm.edu/gcr/vol7/iss4/9 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community For more information, please contactJoshua.Cromwell@usm.edu. Gulf Research Reports, Vol. 7, No. 4, 373-375, 1984 SHORT COMMUNICATIONS THE EPIPHYTIC DIATOM FLORA OF TWO SARGASSUM SPECIES ROBERT S. MAPLES Department of Biological and Environmental Sciences, McNeese State University, Lake Charles, Louisiana 70609 ABSTRACT The epiphytic diatom flora on the brown algae Sargassum natans (L.) J. Meyer and 5. fluitans B0rgesen were investigated and compared. A total of 50 taxa representing 21 genera were identified. The most abundant taxa were Amphora exigua Greg., A. coffeiformis (Ag.) Kiitz., Synedra fasciculata (Ag.) Ktitz., Cocconeis pseudodiruptoides Foged, and Navicula ramosissima (Ag.) Cleve. Comparisons of the dominant species and diversity statistics characterizing the two samples indicated the two brown algal species supported nearly identical epiphytic diatom floras. INTRODUCTION Most of the recent studies of Gulf Coast benthic diatoms have involved sediment-associated floras and pertinent ex- amples include Wood (1963), Sullivan (1978), Cook and Whipple (1982), and Stowe (1982). Although epiphytic diatoms on seagrasses in the Gulf of Mexico have been stud- ied (Montgomery 1978, Sullivan 1979), there has been only one investigation of diatoms epiphytic on attached seaweeds from the Gulf Coast (Medlin 1983). The studies of Grunow (1867) (Honduras), Hentschel (1921) (Sargasso Sea), and Carpenter (1970) (western Sargasso Sea) are the only reports of diatoms epiphytic on Sargassum species. The purpose of this report is to describe and compare the epiphytic diatom floras on Sargassum natans (L.) J. Meyer and S. fluitans B0rgesen. Sargassum natans and S. fluitans are the two most com- mon species of Sargassum found in the Gulf of Mexico, and both species range throughout the Gulf, in particular coastal areas where drifting plants wash ashore. Unlike most species of Sargassum, S. fluitans and S. natans are obligate drifters with S. natans often comprising 95% of the mass of floating communities (Conger et al. 1972). MATERIALS AND METHODS Samples of S. natans and S. fluitans were collected with a hand net from a single station in the Gulf of Mexico (lon- gitude 29'^31'N and latitude 93°3l'W) approximately 22 km southwest of Calcasieu Pass, Louisiana, on 25 June 1982. Composite samples of each host (including 2 cm of stipe, 4—5 pneumatocysts, and 2 or 3 blades) were boiled in HNO3 with K2Cr2 07 to oxidize all organic matter. A por- tion of each sample was mounted in Hyrax for identifica- tion and counting with an Olympus BHTU microscope. A sample from each host plant consisted of exactly 500 valves from five counts of 100 valves where each count was made Manuscript received April 13, 1984; accepted June 11, 1984 from a separate slide prepared from the composite sample. After each sample had been analyzed taxonomically , the two floras were compared using Slander’s (1970) Similarity Index (SIMI) and the Shannon-Weiner Information Index (Pielou 1975). RESULTS AND DISCUSSION A total of 50 taxa representing 21 genera were identified in the two samples. Forty-three taxa were collected from S. fluitans and 39 from S. natans. The identity and relative abundance of each diatom taxon is listed in Table 1. The dominant genera, in terms of taxa encountered, were Mastogloia (8), Navicula (1), Amphora (4), md Nitzschia (4). The five most abundant taxa of the pooled sample, in order of decreasing abundance, were as follows: Amphora exigua, A. coffeiformis, Synedra fasciculata, Cocconeis pseudodiruptoides, 2 ind Navicula ramosissima. The first four taxa were also the four most abundant diatoms on baths'. natans and S. fluitans. These five accounted for 65% of the 1,000 valves counted. Additional scans of the slides re- vealed several taxa not included in the counts. These taxa were: Achnanthes hauckinana Grun., Cymbella pusilla Grun., Eunotogramma laeve Grun., Navicula comoides (Ag.) Perag., Nitzschia frustulum (Kiitz.) Grun., A. micro- cephala Grun., and A. palea (Kiitz.) Grun. Of the 50 taxa identified, 6 taxa are new records for the north-central Gulf: Amphora bigibba, Cocconeis pseudo- diruptoides, Licmophora remulus, Mastogloia ovalis, M. pusilla var. subcapitata, and Synedra provincialis var. tor- tuosa. All of the taxa except C. pseudodiruptoides and M. pusilla var. subcapitata have been previously reported from the greater Gulf of Mexico (Conger et al. 1972; Sulli- van 1981, Maples 1983a and 1983b). Cocconeis pseudo- diruptoides was described by Foged (1975) as a littoral species along the Tanzania Coast. The chief difference be- tween this species and C diruptoides Hust. is the presence of a dilated central area which reaches the margin of both 373 I 374 Maples TABLE 1 Relative abundance (expressed as number of valves in a sample of 500) of epiphytic diatom taxa on Sargassum fluitans and S. natam from the coastal marine waters of southwestern Louisiana. Collected on 25 June 1982. SN = both samples pooled as one. Sargassum Diatom taxon fluitans natans Sn Achnanthes biasolettiana (Kiltz.) Grun. 15 10 25 A. brevipes var. intermedia (Kiitz.) Cl. 1 - 1 Amphora angusta var. ventricosa Greg. 4 6 10 A. bigib ba Grun. 4 - 4 A. coffeiformis (Ag.) Kiitz. 114 84 198 A. exigua Greg. 103 98 210 Bacillaria paxillifer (Miill.) Hendey 4 1 5 Cocconeis pseudodiruptoides Foged 36 60 96 C. scutellum Ehr. 8 10 18 Coscinodiscus radiatus Ehr. 1 1 2 Cyclotella atomus Hust. 20 4 24 C. striata (Kutz.) Grun. 4 6 10 C. meneghiniana Kiitz. 1 - 1 Diploneis weissflogi (A.S.) Cl. 2 - 2 Fragilaria construens var. venter (Ehr.) Grun. 2 1 3 Grammatophora oceanica Ehr. 1 1 2 Licomphora abbreviate Ag. 8 16 24 L. cf. debilis (Kutz.) Grun. 4 4 8 L. remulus Grun. 2 2 4 Mastogloia acutiuscula Grun. 1 2 3 M. binotata (Grun.) Cl. 4 3 7 M. crucicula (Grun.) Cl. 8 6 14 M. erythraea Grun. - 10 10 M. exigua Lewis - 18 18 M. ovalis A.S. 2 - 2 M. pusilla Grun. 4 32 36 M. pusilla var. subcapitata Hust. 6 4 10 Navicula ramosissima (Ag.) Cl. 36 14 50 N. amphipleuroides Hust. 4 - 4 N. abunda Hust. 8 8 16 N. incomposita var. minor Hagelstein N. tripunctata — 3 3 var. schizonemoides (V.H.) Patr. 1 2 3 Navicula sp. #1 2 2 4 Navicula sp. #2 1 2 3 Nitzchia bicapitata Cleve 1 1 2 N. dissipate (Kiitz.) Grun. 4 - 4 N. fasciculate (Grun.) Grun. - 2 2 N. gandersheimiensis Krasske 6 1 7 Pleurosigma normanii Ralf, 4 - 4 P. salinarum (Grun.) Grun. Psammodiscus nitidus (Greg.) 1 “ Round & Mann 3 - 3 Rhopalodia gibberula (Ehr.) Miill. 4 2 6 R. operculata var. producta Grun. - 1 1 Synedra fasciculate (Ag.) Kutz. 48 58 106 S. provincialis var. tortuosa Grun. 4 6 10 Striatella unipunctata (Lyngb.) Ag. 10 10 20 Thalassionema nitzschioides (Grun.) V.H. - 1 1 Thalassiosira eccentrica (Ehr.) Cl. 1 - 1 T. leptopus (Grun.) Hasle & Fryxell - 1 1 Trachysphenia acuminata Perag. 2 1 3 h' 2.796 2.755 — S 43 39 50 the raphe and rapheless valves in the former. It is interesting to note that the illustrations of C dirupta Greg, reported on Sargassum by Carpenter (1970) are identical to C pseudo- diruptoides. Apparently this record pf C. pseudodiruptoides is new for the United States, which is interesting since it constituted nearly 10% of the epiphytic diatom flora in the pooled Sargassum samples. A comparison of the epiphytic diatom flora on the two Sargassum species revealed few differences. The species diversities (H' log 2 ) for each of the Sargassum samples were almost identical (Table 1). A comparison of the structural similarity (SIMI) of the two samples revealed a value of 0.931. SIMI has the limits of 0 and 1; the larger the SIMI value, the greater the similarity between two samples. A total of 32 taxa were recorded as common to both Sargassum species (Table 1). Of the 18 taxa found only on one of the Sargassum species, all but 2 of these taxa (Mastogloia erythraea and M. exigua) were represented by 4 valves or less. This data, along with very similar values of H' and S for the two samples (Table 1) and a high SIMI value, indicates the two brown algal species supported nearly identical epiphytic diatom floras. A comparison was made of the results from this study with others on the epiphytic diatom flora of Sargassum. Grunow (1867) recorded 91 species from the coastal waters of Honduras and only 7 of these were encountered in the present study. None of the species found to be common to both studies was abundant in the present study. Since Hentschel (1921) recorded only one taxon {Cocconeis sp.), no meaningful comparison can be made. Carpenter (1970) identified only 10 taxa to species from samples collected in the western Sargasso Sea, only 5 are common to the present study. Although Carpenter (1970) collected the same species of Sargassum as examined in the present study, the domi- nant taxa were quite different. Mastogloia binotata was the dominant taxon in 6 of his 7 samples, but constituted less than 1 percent of the total valves in the pooled samples of the present study. It is interesting to compare the low num- ber of epiphytic diatom taxa (10) reported by Carpenter (1970) on open-ocean Sargassum as opposed to the much higher numbers found on cQdiStdd Sargassum , 91 by Grunow (1867) and 50 in the present study. The differences between these studies may be related to unknown physiochemical differences among the habitats and the small number of samples investigated. ACKNOWLEDGMENTS This study was supported by a faculty grant awarded by McNeese State University to defray publication costs. Short Communications 375 REFERENCES CITED Carpenter, E, J. 1970. Diatoms attached to floating Sargassum in the western Sargasso Phycologia 9:269-274. Conger, P. S., G. A. Fryxell & S. Z. El-Sayed. 1972. Diatom species reported from the Gulf of Mexico. Pages 18-23 in: V. C. Bush- ness (ed.), Serial Atlas of the Marine Environment. American Geographical Society, Folio 22. Cook, L. L. & S. A. Whipple. 1982. The distribution of edaphic dia- toms along environmental gradients of a Louisiana salt marsh. J.Phycol. 18:64-71. Foged, N. 1975. Some littoral diatoms from the coast of Tanzania. BiblPhycol. 6:1-127. Grunow, A. 1867. Diatomeen auf Sargassum von Honduras, gesam- melt von Lindig. Hedwegia 6:1-8, 17-37. Hentschel, E. 1921. Uber den Bewuchs auf den Treibenden Tagen der Sargassosee. Mitteil. Zool. Staatsinst. Mus. Hamburg. 38: 1-26. Maples, R. S. 1983a. Community structure of diatoms epiphytic on pneumatophores of the black mangrove, Avicennia germinans, in a Louisiana salt marsh. Gulf Res. Kept. 7(3):255-259. 1983b. A preliminary checklist of marine planktonic dia- toms of southwestern Louisiana. /Vo c. La. Acad. Set 46:34-40. Medlin, L. K. 1983. Community Analysis of Epiphytic Diatom Com- munities Attached to Selected Species of Macroalgal Host Plants Along- the Texas Gulf Coast. Ph.D. dissertation. Texas A&M University, College Station. 150 pp. Montgomery, R. T. 1978. Environmental and Ecological Studies of the Diatom Communities Associated with the Coral Reefs of the Florida Keys. Ph.D. Dissertation. Florida State University, Talla- hassee. 320 pp. Pielou, E. C. 1975. Ecological Diversity. Wiley-Interscience, New York. 165 pp. Stander, J. M. 1970. Diversity and Similarity of Benthic Fauna off Oregon. M.S. Thesis. Oregon State University, Corvalis. 72 pp. Stowe, W. C. 1982. Diatoms epiphytic on the emergent grass Spar- tina alterniflora in a Louisiana salt marsh. Trans. Am. Microsc. Soc. 101:162-173. Sullivan, M. J. 1978. Diatom community structure; taxonomic and statistical analysis of a Mississippi salt marsh. J. Phycol. 14: 468-475. 1979. Epiphytic diatoms of three seagrass species in Mis- sissippi Sound. Bull. Mar. Set 29:459-464. 1981. A preliminary checklist of marine benthic diatoms of Mississippi. Gulf Res. Rept. 7(1): 13-1 8. Wood, E. J. F. 1963. A study of the diatom flora of fresh sediments of the south Texas bays and adjacent waters. Publ. Inst. Mar. Sci. Univ. Tex. 9:237-310. Gulf Research Reports Volume 7 | Issue 4 January 1984 Sexual Dimorphism in Species of Raninoides (Brachyura: Raninidae) and the Status of Raninidoides schmitti Sawaya^ 1944 GaryD. Go eke Gulj Coast Research Laboratory DOI; 10.18785/grr.0704.10 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Goeke, G. D. 1984. Sexual Dimorphism in Species of Raninoides (Brachyura: Raninidae) and the Status of Raninidoides schmitti Sawaya, 1944. Gulf Research Reports 7 (4): 377-380. Retrieved from http://aquila.usm.edu/gcr/vol7/iss4/10 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 377-380, 1984 SEXUAL DIMORPHISM IN SPECIES OF RANINOIDES (BRACHYURA: RANINIDAE) AND THE STATUS OF RANINOIDES SCHMITTI SAWAYA, 1944 GARY D. GOEKE Fisheries Section, Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564 ABSTRACT The frog crab Raninoides schmitti was described from Sao Paulo, Brazil, as closely related to 7?. loevis. De- tailed comparison shows i?. schmitti to be a junior synonym of R. loevis. Absence of information detailing sexual dimor- phism of species in the genus Raninoides contributed to the designation of a dimorphic male as a discrete taxon. Examples of sexual dimorphism within the genus Raninoides are described. INTRODUCTION Thirty-five extant species of frog crabs are currently assigned to the family Raninidae which is composed of ten Recent genera. This group appears to be most numerous in the western Pacific where approximately 22 species have been recorded. Nine species in four genera are represented in the western Atlantic. Members of the genus Raninoides H. Milne-Edwards, 1837, are the subject of this report. Reports of sexual dimorphism within frog crabs have been largely confined to that exhibited in the type species, Ranina ranina (Linnaeus, 1758). It is well documented (Barnard 1950, Fielding and Haley 1976) that the dimor- phism affects the anterolateral spines of the carapace in that taxon. However, until this report other species were not known to show strong sexual dimorphism. Within the genus Raninoides, sexual dimorphism is exhibited by the form of the cheliped and in some species the anterior spines of the carapace and the male gonopod. Material examined -Raninoides benedicti: 1 d, 47.5 mm, 27 Aug. 1976, Isla Chepillo, Bay of Panama, coll. Gordon Hendler. Raninoides loevis: (Florida Department of Natural Resources, Marine Research Laboratory), FSBC I 2649, 9 Mar. 1966, 2 males (35.2-38.1); FSBC I 2648, 3 Mar. 1966, 1 male (39.2); FSBC I 2737, 11 Apr. 1966, 1 male (37.2); FSBC I 19940, 18 June 1966, 1 male (42.3); FSBC I 19963, 25 Oct. 1967, 1 male (42.2); EJ 66-444, 20 Nov. 1966, 1 male (39.1); FSBC I 19955, 14 Mar. 1967, 1 male (36.8); FSBC I 19967, 14 Nov. 1967, 1 male (36.7); EJ 67-113, 12 Apr. 1967, 1 male (39.8); FSBC I 19936, 19 Jan. 1966, 1 male (38.7); FSBC I 19961, 7 Aug. 1967, 4 males (38.0-41.6); FSBC I 19945, 6 Nov. 1966, 1 male (36.7); FSBC I 19948, 6 Jan. 1967, 1 male {A2.0). Ranin- oides louisianenis: USL 836 (University of Southwestern Louisiana), 30 Oct. 1975, 1 male (61.2); TAMU 2-0961 (Texas A&M University), 19 Nov. 1968, 1 male (27.2); TAMU 2-1264, 28 Jan. 1971, 2 males (52.6-53.6); TAMU 2-1272, 23 June 1972, 2 males (59.1-61.2); TAMU 2-1269, 5 Feb. 1972, 1 male (49.5); USA 100401 (University of Manuscript received December 19, 1983; accepted September 21, 1984. South Alabama), 28 Aug. 1976, 3 males (49.8—52.3); GCRL 1125 (Gulf Coast Research Laboratory), 2 Apr. 1980, 1 male (57.3). Raninoides schmitti: Museu Nacional do Brasil, Nov. 1955, 1 male (45.0). Remarks - Adult dimorphic males of R. louisianensis Rathbun, 1937, R. loevis (Latreille, 1825), and the Pacific species R. benedicti were examined. In R. louisianensis, adult males with a carapace length of over 50 mm often ex- hibit dimorphism in the shape of the above mentioned fea- tures. The chelae and frontal spines are perhaps the most evident of the dimorphic characters (Figure 1 A and lB).The movable finger of the claw in females and young males is very nearly equal in length to the fixed finger. In dimorphic males, however, the movable finger greatly exceeds the length of the fixed finger, sometimes by up to twice the length. The terminal portion of the finger becomes strongly curved, and the small spine at the base of the finger de- creases in size. The propodus also increases in size, although the ventral spines of the palm do not. This gives the impres- sion of a decrease in size of the spines of the palm. The second obvious dimorphic character in some species is the development of a sharply curved hepatic spine on the cara- pace. This feature is not as obvious at the early stages as is the increased finger length; however, a formidably curved spine is the eventual result. A third dimorphic character evident in the males of R. louisianensis is the development of the three spines which surround the apex of the first male gonopod. Among larger dimorphic males, these acces- sory spines become elongated and slightly curved. Raninoides loevis and R. benedicti exhibit dimorphism in the shape of the chela only. No males examined showed evidence of dimorphism in the shape of the frontal spines of the carapace or the apical spines of the gonopods. The single dimorphic male ofR. benedicti examined closely parallels the situation found in R. loevis, its Atlantic cognate. Raninoides benedicti closely agrees in the shape of the first gonopod with published accounts (Knight 1968) and no evidence of curvature was found in the frontal spines of the carapace. Rathbun (1937) recognized seven nominal species of the frog crab gemxs> Raninoides H. Milne-Edwards, 1837, from 377 378 Goeke Figure 1. (A) Cheliped and (B) frontal carapace region of R. louisianensis; (C) cheliped and (D) frontal carapace region of R. loevis (E) cheliped and (F) frontal carapace region of R. benedicti. Short Communications 379 Figure 2. Raninoides schmitti (topotype). (A) Frontal carapace region, (B) pleopod 2, (C) pleopod 1 (detail), (D) cheliped, (E) ultimate seg- ments of pereopods 2, (F) 3, (G) 4, and (H) 5. American waters. A single species, R. schmitti Sawaya, 1944, has been described off Brazil since Rathbun’s report. Three species assigned to this genus were recently removed or designated synonyms. Raninoides fossor H. Milne- Edwards and Bouvier, 1923, is considered by Manning (1975) to be a junior synonym of Notosceles chimmonis Bourne, 1922, and not a member of the western Atlantic fauna. Raninoides nitidus A, Milne-Edwards, 1880, was shown to be a senior synonym for Lyreidus bairdii Smith, 1881, and was removed to Lyreidus de Haan, 1841, by Goeke (1980). Characters of diagnostic value used to separate the closely related genera Notosceles Bourne, 1922, and Raninoides are listed by Goeke (1981) and the eastern Pacific species Raninoides ecuadorensis Rathbun, 1935, was transferred to Notosceles. Raninoides schmitti Sawaya, 1944, was described from a single male from the beach of Sao Sebastio, Sao Paulo, Brazil. Sawaya (1944:141) states “i?. schmitti is distinct from R. loevis principally by the size of the dactylus in rela- tion to the immobile finger of the cheliped and the not curved lateral spines.” Additional specific characters for R. schmitti are listed as the two spine-like processes of the sternum between the bases of pereopods 1 and 2, and the “process” opposite the distal spine of the merus of the cheliped. A pronounced asymmetry in the size of the chelipeds is evident from the figures of the holotype and Sawaya noted this as either a specific character or attri- buted this to regeneration. The size of the unique holotype was also given as 49 mm, “the biggest hitherto noted in the genus.” The only additional record for R. schmitti is based on a large male (carapace length of 45 mm) from Sao Paulo by Gomes Correa (1970). That specimen (Figure 2) was col- lected by Sawaya in November, 1955, from Praia do Se- gredo, Sao Sebastiao, Sao Paulo, and was examined by me. As was detailed previously, sexual dimorphism in the ge- nus Raninoides affects the length of the dactylus of the che- lipeds. In the taxa examined by this author, the dactylus of pereopod 1 is disproportionately lengthened and in some in- stances, the dactyl approaches twice the length of the fixed fmger. This increase in length of the finger is not a specific character as it has been noted in congeneric species. Other features of the dactylus and propodus are affected as well. The small size of the right chela of the holotype is probably due to regeneration as all known raninids are horn oisoche lie. The second character detailed by Sawaya (1944) is the pair of spine-like processes between the bases of pereopods 1 and 2. This feature has been noted by previous workers on other species of Raninoides and has been used as evi- dence for the separation of Raninoides from Notosceles (Bourne 1922; Ser&ne and Umali 1972; Goeke 1981). This feature is evident in seven species of Raninoides that have been examined by me and is of generic value and 380 Goeke not a species specific character. The “not curved lateral spines” listed by Sawaya (1944) is not a specific feature of value in separating R. schmitti from R. loevis. Considerable variation in the form of the lateral spines of R. loevis has been observed in material from the eastern Gulf of Mexico (Goeke, unpublished data). Gomes Correa (1970) illustrated distinctly curved lateral spines in the specimen identified by Sawaya as R. schmitti from the type-locality. These spines are now broken and I am not able to observe the degree of curvature. A “process” of unspecified form is mentioned by Sawaya as opposite the distal spine of the merus of pereo- pod 1 . No process other than a slight swelling at the carpal- meral articulation is indicated or could be located on the specimen examined by this author. This swelling is a normal condition within the group . A final important consideration is the form of the gono- pod of the male. This important taxonomic character is unique for each of the described species within Raninoides with the exception of R. schmitti This feature was not dis- cussed by Sawaya. The illustration of Gomes Correa (1970, Figure 35) closely resembles the previously published illus- trations of R. loevis by Guinot-Dumortier (1960) and Knight (1968). The gonopod of the specimen examined (Figure 2C) agrees very well with those of R. loevis from the eastern Gulf of Mexico. Because of the examination of other specimens with small regenerative claws {R. benedicti from Panama) and the description of the form of sexual dimorphism found in crabs of the genus Raninoides, I con- sider Raninoides schmitti Sawaya, 1944, to be a junior syn- onym of Raninoides loevis (Latreille, 1825). Four species of Raninoides are recognized by the author from American waters; 3 western Atlantic and 1 eastern Pacific. Eight species are now assigned to this genus, with the possibility that an additional species, Raninoides har- nardi Sakai, 1974, will be transferred XoNotosceles. REFERENCES CITED Barnard, K. H. 1950. Descriptive catalogue of South African Decapod Crustacea. Ann. S. Afr. Mus. 38:1-837. Bourne, G.C. 1922. The Raninidae: A study of Carcinology. J. Linn. Soc. Land, Zool. 35:25-78. Fielding, A. & S. R. Haley. 1976. Sex ratio, size at reproductive maturity, and reproduction of the Hawaiian Kona crab, Ranina ranina (Linnaeus) (Brachyura, Gymnopleura, Raninidae). Pac. Set 30:131-145. Gomes Correa, M. M. G. 1970. Crustaceos Braquiros brasiluros da Familia Raninidae. BoL MuseuNac., new series No. 276:1-21. Goeke, G. D. 1980. Range extensions of six western Atlantic frog crabs (Gymnopleura; Raninidae) with notes on the taxonomic status of Lyreidus bairdti. Proc. Biol. Soc. Wash. 93(1):145-152. Goeke, G. D. 1981. Symethinae, new subfamily, and Symethis garthi, new species, and the transfer of Raninoides ecuadorensis to Notosceles (Brachyura: Raninidae), Proc. Biol. Soc. Wash. 93(4);971-981. Guinot-Dumortier, D. 1960. Sur une collection de Crustac^ (Deca- poda, Reptantia)de Guyane Francaise, I. Brachyura (Oxyrhyncha exclus.) (suite). Bull. Mus. Natl. Hist. Nat., Paris. Series 2, 31(6): 423-434 for 1959. Knight, M. D. 1968. The larval development of Raninoides benedicti Rathbun (Brachyura, Raninidae), with notes on the Pacific re- cords of Raninoides laevis (Latreille). Crustaceana, Supplement II; 145-169. Manning, R. B. 1975. The identity of Raninoides fossor A. Milne- Edwards and Bouvier, 1923 (Decapoda). Crustaceana 29:297- 298. Rathbun, M. J. 1937. The oxystomatous and allied crabs of America. U.S. Natl Mus. Bull 166:1-276. Sawaya, M. P. 1944. Raninoides schmitti, sp. n. (Crustacea-Brach- yura). Bol Fac. Filos. Cienc. Let. Univ. Sao. Paulo Ser. Zool 43(8):137-145. Serdne, R. & A. F. Umali. 1972. The family Raninidae and other new and rare species of Brachyuran decapods from the Philip- pines and adjacent regions. Philipp. J. Sci. 99(1— 2):21— 105. Gulf Research Reports Volume 7 | Issue 4 January 1984 A Record ofBermudriluspeniatus (Oligochaeta: Tubificidae) from the Gulf of Mexico Christer Erseus University ofGoteborg DOI; 10.18785/grr.0704.11 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Erseus, C. 1984. A Record ofBermudriluspeniatus (Oligochaeta: Tubificidae) from the Gulf of Mexico. Gulf Research Reports 7 (4): 381-381. Retrieved from http://aquila.usm.edu/gcr/vol7/iss4/l 1 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 381, 1984 A RECORD 0¥ BERMUDRILUS PENIATUS (OLIGOCHAETA: TUBIFICIDAE) FROM THE GULF OF MEXICO CHRISTER ERSfeUS Swedish Museum of Natural History , Department of Zoology, University of Goteborg, Goteborg, Sweden ABSTRACT The marine tubificid Bermudrilus peniatus Erseus, 1979 (subfamily Phallodrilinae) is reported from off the west coast of central Florida, at about 75 m depth. The species was previously known only from coral reefs at Bermuda. Bermudrilus peniatus is known only from medium to coarse sand in a depth of 10 to 15 meters in coral reefs at Bermuda (Erseus 1979). Recently when examining a collec- tion of offshore oligochaetes from the eastern part of the Gulf of Mexico, I found a single specimen that extends con- siderably the known distribution of the species. Conse- quently, it is reported here. The specimen originated from a Bureau of Land Manage- ment baseline study by personnel at Dauphin Island Sea Lab, Alabama. It was mounted whole in Canada balsam be- fore examination and is deposited in the National Museum of Natural History (USNM), Smithsonian Institution, Wash- ington, D.C. Bermudrilus peniatus Erseus, 1979 Bermudrilus peniatus Erseus, 1979, pp, 425-426, fig. 4. Type material — USNM 56314—56316, five specimens, all from the type locality. Type locality — Southeast of Charles’ Island, Bermuda, 15 m, medium to coarse sand. Additional specimens in original material (author’s col- lection) - Eight specimens; seven from the type locality and one from east side of Castle Roads, Bermuda, 10 m, coarse sand with gravel and pebbles. New material examined - USNM 97379, one specimen from about 155 km west of Sarasota, west coast of Florida, USA, about 75 m, sediment unknown (collected 23 August 1977). Remarks - The individual is 4.1 mm long and has 39 segments. It fits the original description except for some minor differences. There are 6 penial setae, 16—22 pm long, per bundle located ventrally in segment XI (Fig. 1). The funnel-shaped, cuticularized penes (Fig. 1) are 24-30 pm long with a base 10—11 jum wide and a midsection about 5 pm wide. As in the original material, the prostate glands are large and located anteriorly, with no posterior prostate glands present. ACKNOWLEDGMENTS I am indebted to Dr. M. Susan Ivester, for placing the material at my disposal. I 25 pm I Figure 1. Bermudrilus peniatus Erseus from off west coast of Florida showing ectal part of atrium (a), penis (p) and penial setae (ps). Manuscript received June 15, 1984; accepted July 30, 1984. REFERENCES CITED Erseus, C. 1979. Bermudrilus peniatus n.g., n.sp. (Oligochaeta, Northeast Atlantic. Traws. Aw. Mictosc. 5oc. 98:418-427. Tubificidae) and two new species of Adelodrilus from the 381 I Gulf Research Reports Volume 7 | Issue 4 January 1984 Comments on Density Inversions in Marine Shallow Waters and Beyond Gordon Gunter Gulf Coast Research Laboratory Forrest V Durand Bureau of Outdoor Recreation, Atlanta DOI: 10.18785/grr.0704.12 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Gunter^ G. and F. V. Durand. 1984. Comments on Density Inversions in Marine Shallow Waters and Beyond. Gulf Research Reports 7 (4): 383-384. Retrieved from http;//aquila.usm.edu/gcr/vol7/iss4/12 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 383-384, 1984 COMMENTS ON DENSITY INVERSIONS IN MARINE SHALLOW WATERS AND BEYOND GORDON GUNTER, DIRECTOR EMERITUS AND FORREST V. DURAND^ , RETIRED Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564, and Bureau of Outdoor Recreation, Atlanta, Georgia It has been shown within the past 70 years that salinity and thus density inversions are often detectible in shallow bays and estuaries. This terminology means that surface salinities are sometimes higher than those at lower depths. The first such discoveries in this country were made by Sumner, Louderback, Schmitt and Johnston (1914) in San Francisco Bay. They used Negretti-Zambra reversing ther- mometers for temperature and silver nitrate titration for salinity determination. These were by then considered to be classical methods and had been worked out in northern Europe, mostly in Scandinavia. They were introduced to the United States Gulf Coast and the authors in 1931 by Frank W. Weymouth, of Stanford University, who headed the Shrimp Investigations of the U.S. Bureau of Fisheries from 1930, which were later taken over by Milton J. Lindner. Forrest V. Durand, as a cooperative agent of the Loui- siana Department of Conservation, carried on the hydro- graphic work in Louisiana, mostly in Barataria Bay and ad- jacent offshore waters. The first author, as biologist for the Bureau, was a close observer, but of not much hydrographic assistance. Durand was under J. Nelson Gowanloch. After Durand left Louisiana the data were unfortunately mis- placed. Thirty -one years after Sumner et al. (1914), Gunter (1945) reported 5.5 percent inversions in 109 readings taken during a biological study of Copano and Aransas bays in Texas in the years 1941 and 1942. Albert Collier, first marine biologist of the Texas Game, Fish, and Oyster Commission, had conducted a hydrographic survey in the same area in 1936 and 1937. During these years he took 385 salinity readings in Copano Bay and 874 in Aransas Bay at 47 station locations. He found 20.9 per- cent salinity inversions, 101 in Copano Bay and 144 in Aransas Bay, the higher salinity bay next to the sea. There were 197 top and bottom equalities of salinity in Copano Bay and 85 in Aransas Bay. Copano is about 7 feet deep as compared to 11 feet for Aransas, the outer bay. In Copano Bay there were 14 readings of only 0.1 per mil dif ference in inversions, that is with the surface 0.1 parts per thousand higher in salinity. In Aransas Bay there were 17 such readings. ^Present address: 105 Pine Street Drive, Jackson, IN 38301. Manuscript received June 22, 1984; accepted June 25, 1984. The data used here were taken from Tables 5 and 6, pages 186—192 (Collier and Hedgpeth 1950). Collier’s data had been transported around to various places between 1936 and 1949 and moved hurriedly three times in front of hurri- canes. Finally they aroused the interest of Joel W. Hedgpeth who resurrected them and completed the writing of the Collier, Hedgpeth paper with the addition of the Laguna Madre data which Hedgpeth had collated and in part gath- ered himself. In the meantime various parts of Collier’s data were lost or displaced but we have held to Tables 5 and 6 as stated above. These comprised 1,169 salinity readings. Strangely enough, ColUer and Hedgpeth did not mention salinity inversions, which they so carefully recorded in their data, nor did they refer to similar data collected by Sumner et al. (1914) or the previously published reference of Gunter (1945) in their own region. However, their work has been referred to as the seminal paper in shallow-water hydro- graphy on the United States Gulf coast and the authors had many subjects to address. In Copano Bay the inversions ranged from 0.1 parts to 2.9 parts per thousand difference. There were only two of the larger size with many more at lower ranges. In Aransas Bay there were much wider variations, 2 up to 12 per mil, which could be doubted except for other high readings at nearby stations. These high readings at the surface in Aransas Bay may have been due to overriding of Gulf water or current aberrations in turbulent waters. In any case it is not thought to be worthwhile to try to analyze these data further in view of the impossibility of determining what caused the high figure inversions. In Aransas Bay there were 399 more salinity samplings than in Copano Bay. In Copano Bay 101 density inversions were found among 385 readings. In Aransas Bay there were 144 inversions at 785 stations. Thus in the lower bay there was a decrease in density inversions per number of stations. This is apparently a real difference with a confidence limit of p = 0.95 . Aransas Bay is about 4 feet deeper than Copano and this may be an important fact but we cannot be sure that wind velocity and some other factor made a difference nearer the sea. In any case, if this inversion trend were to continue on into saltier water of the open sea, density in- versions at the surface would decrease in number. These matters need to be studied with sensitive instruments near the surface of the ocean. However, we cannot expect that any effect of physical factors will change merely because 383 I 384 Gunter and Durand they are farther offshore. Thus it is to be assumed that winds and atmospheric conditions will affect the waters of the open sea in the same manner as they do in the bays. Thus it is expected that density inversions in surface waters will be found offshore, although the depth to which they extend is unknown. This should be a field for inquiry in the future because the situation remains very much as it was when Sverdrup stated, “. . . , but nothing is known as to the annual variation of salinity at subsurface depths, ...” (Sverdrup, Johnson and Fleming 1946, p. 146). In the past when salinity and temperature data were collected only at finite depths, oceanographers increased vertical spacing by wide intervals at sea when depth permitted, with some skipping of intervening phenomena. Jacobs (1942) has given information on the evaporation rates in the Gulf of Mexico, the presumed basic cause of density inversions. In the open ocean, turbulence would not play such a strong part as we have implied above in the bays, channels, and confined waters. Density inversions have been noted many times in Missis- sippi waters but the tables showing inversions are rather scarce and the matter is nowhere clearly discussed. Charles Eleuterius (1973) in a processed report says of salinity on page 106, “During periods of high evaporation, the measurements in the surface layer of water were higher than those immediately beneath; however, the temperature differential substantiated the stability of this structure.” This is not the clearest possible language but it does men- tion the essential conditions for density inversions. They occur first at the surface due to evaporation, then sink to their own level of specific gravity, where essentially they dis- appear. The lighter, displaced water then rises to the surface where it is subjected to evaporation. Thus the process is cyclical and continuous at all water surfaces, varying with temperatures of the water and air, the water salinity, the percentage of water vapor in the air and the wind speed. It causes an exchange of various surface layers of water and deeper layers, varying with the numerous conditions listed above. It has not been studied thoroughly and carefully any- where. In the above discussion we have spoken of saHnity inver- sions although the temperature readings at the same stations have substantiated the reality of density inversions based on both factors, salinity and temperature. It seems to be of some importance to consider that the sinking of high-salinity water to its equilibrium level, and a compensating rise of water from a greater depth, is some- what analogous to a breathing process at the surface of the sea modified by various climatic and atmospheric condi- tions, and results in modified exchange of water and atmos- pheric components. This process is continually carried on or “powered” so to speak by evaporation at the sea surface. REFERENCES CITED Collier, Albert & Joel W. Hedgpeth. 1950. An introduction to the hydrography of tidal waters of Texas. Publ. Inst. Mar. Sci. Univ. Tex. 1(2):121-194. Eleuterius, Charles K. (1973). Biloxi Bay Hydrography Final Re- port. NASA Contract NAS9- 12965. 112 pp., (unpublished report), Gunter, Gordon. 1945. Studies on marine fishes of Texas. Publ. Inst. Mar. Sci. Univ. Tex. 1(1):1-190. Jacobs, W. C. 1942. On the energy exchange between sea and atmos- phere, 7. Mar. Res. 5:31 —66. Sumner, Francis B., George D. Louderback, Waldo L. Schmitt & Edward C. Johnston. 1914. A report upon the physical condi- tions in San Francisco Bay, based upon the operations of the United States Fisheries Steamer “Albatross” during the years 1912 and 1913. Univ. Calif. Publ. Zool. 14(1):1-198. Sverdrup, H. U., M, W. Johnson & R. H. Fleming. 1942. The Oceans, their Physics, Chemistry, and General Biology. Prentice Hall, Inc., New York. Gulf Research Reports Volume 7 | Issue 4 January 1984 A Preliminary Checklist of Epiphytic and Benthic Marine Diatoms of Louisiana Robert S. Maples McNeese State University DOI: 10.18785/grr.0704.13 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Maples, R. S. 1984. A Preliminary Checklist of Epiphytic and Benthic Marine Diatoms of Louisiana. Gulf Research Reports 7 (4): 385-388. Retrieved from http;//aquila.usm.edu/gcr/vol7/iss4/13 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 385-388, 1984 A PRELIMINARY CHECKLIST OF EPIPHYTIC AND BENTHIC MARINE DIATOMS OF LOUISIANA ROBERT S. MAPLES Department of Biological and Environmental Sciences, McNeese State University, Lake Charles, Louisiana 70609 ABSTRACT A checklist of diatoms collected from the various habitats in coastal salt marshes, estuaries, and nearshore Gulf waters of Louisiana has been compiled for the first time. The checklist includes 193 taxa (species and their varieties) in 38 genera. The largest number of taxa are species oi Navicula SiXid Nitzschia with 46 and 36, respectively. Future studies of the varied habitats along the Louisiana coast should result in many new additions to this preliminary checklist. INTRODUCTION The algal flora of coastal Louisiana has been variously studied since the first reports of Featherman (1871, 1872). Kapraun (1974) surveyed the marine benthic green, red, and brown algae found on jetty structures bordering Loui- siana’s marine passes. Vaucheria species were recorded by Pecora (1977, 1980) from coastal salt marsh habitats. Maples (1982) described an edaphic bluegreen algal commu- nity associated with a coastal salt panne in southwestern Louisiana. Checklists of marine planktonic diatoms in the nearshore waters of Louisiana are found in papers by Feathemian (1871, 1872), Simmons and Thomas (1962), Bamforth (1974), Housley (1976), Fucik and El-Sayed (1979), and Maples (1983a). Studies of marine benthic diatoms have been largely centered in the Mississippi delta region of Louisiana. Cook and Whipple (1982) described the spatial and temporal distribution of edaphic diatom communities along a complex gradient from brackish to saline marshland. Stowe (1982) investigated the distribution of epiphytic diatoms on the culms of Spartina alterniflora Loisel. Maples (1983b) reported on the taxonomy, diver- sity, and similarity of benthic diatom assemblages on the pneumatophores of the black mangrove Avicennia ger- minans (L.) L., in a Louisiana salt marsh. Kalinsky (1983) compiled a checklist of non-marine algae from Louisiana. Many species found in Louisiana by this author were not included in Kalinsky’s (1983) checklist. An up-to-date list of diatoms in Louisiana’s coastal environ- ments was thought to be needed. In light of the reports of Wood (1963) and Medlin (1983) for Texas, and Sullivan (1981) for Mississippi, the present checklist contributes to our knowledge of the geographic distribution of marine diatoms. Three different papers were used in the preparation of this checklist (Cook and Whipple 1982, Stowe 1982, Maples 1983b) as well as unpublished observations by this author. The present checklist is biased toward the epiphytic diatom flora of coastal salt marshes, but edaphic (sediment- associated) diatom taxa are included. A number of taxa are primarily freshwater forms, but these may be occasionally observed in brackish water habitats. The flora reported herein is of an edaphic or epiphytic nature, and represents marsh, estuarine, and nearshore habitats. CHECKLIST FORMAT For the purpose of this checklist, diatoms were con- sidered to constitute the single class Bacillariophyceae. Genera are arranged alphabetically, and species with their varieties are arranged alphabetically within each genus fol- lowing the format of Hendey’s (1974) checklist for British marine diatoms. Species and their varieties collected only from the pelagic alga Sargassum are marked with an asterisk. BACILLARIOPHYCEAE ACHNANTHES^ory, 1822 biasolettiana (Ag.) Grun. brevipes var. intermedia (Kiitz.) Cl. curvirostrum Brun. exigua Grun. hauckiana Grun. lanceolata var. dubia Grun. lemmermanni Hust. submarina Hust. subsessilis Kiitz. Manuscript received May 3, 1984; accepted June 11,1984 temperei M. Perag. AMPHIPRORA Ehrenburg, 1843 alata Kiitz. paludosa W. Sm. AMPHORA Ehrenburg, 1831 angusta Greg, var. angusta var. oblongella Grun. bigibba Grun. caroliniana Giffen coeffeiformis (Ag.) Kiitz. exigua Greg. 385 386 Maples granulata Greg. laevis var. perminuta Grun. libyca Ehr. pediculus (Kiitz.) Grun. proteus Greg. sabyii Salah tenerrima Hust. tenuissima Hust. ventricosa Greg. ANOMOENEIS ?fitzex, 1871 sphaeophora (Kutz.) Pfitzer BACILLARIA Gmelin, 1778 paxillifer (Mull.) Hendey BERKELEYA Greville, 1827 rutilans (Trent.) Grun. CALONEIS Cleve, 1894 westii (W. Sms.) Hendey CAMPYLOSIRA Grunow, 1882 alexandrica Salah CAPARTOGRAMMA Kufferath, 1956 crucicula (Grun.) Ross COCCONEIS Ehrenburg, 1838 fluviatilis Wallace placentula Ehr. var. placentula var. euglypta (Ehr.) Grun. pseudodiruptoides Foged* scutellum Ehr. var. scutellum var. parva Grun. CYCLOTELLA Ktitzing, 1833 atomus Hust. caspia Grun. comta (Ehr.) Kiitz. meneghiniana Kiitz. striata (Kiitz.) Grun. stylorum Brightwell CYLINDROTHECA Rabenhorst, 1859 gracilis (Breb.) Grun. CYMATOSIRA Grunow, 1862 belgica Grun. CYMBELLA Agardh, 1830 pusilla Grun. DENTICULA Kiitzing, 1844 sub tills Grun. DIPLONEIS Ehrenburg, 1840 didyma (Ehr.) Ehr. interrupta (Kiitz.) Cl. var. interrupta var. caffra Giffen pseudovalis Hust. smithii (Breb.) Cl. weissflogi (A .S .) C 1 . EUNOTOGRAMMA Weisse, 1854 laevis Grun. (laeve) FRA GIL ARIA Ly ngbye , 1 8 1 9 brevistriata Grun. construens (Ehr.) Grun. var. construens var. venter (Ehr.) Grun. GOMPHONEMA Agardh, 1824 gracile Ehr. littorale Hendey parvulum Kiitz. GRAMMATOPHORA Ehrenberg, 1840 oceanica Ehr.* GYROSIGMA Hassall, 1845 balticum (Ehr.) Rabh. beaufortianum Hust. fascicola (Ehr.) Cl. hummi Hust. obliquum Boyer peisonis (Grun.) Cl. LICMOPHORA Agardh, 1827 abbreviata Ag. cf. debilis (Kiitz.) Grun. remulus Grun.* MASTOGLOIA Thwaites, 1856 acutiuscula Grun.* binotata (Grun.) Cl. crucicula (Grun.) C 1 . dubia Kiitz. erythraea Grun.* exigua Lewis jurgensii Ag. ovalis A.S.* pumila (Grun.) Cl . pusilla (Grun.) C 1 . var. pusilla var. subcapitata Hust.* MELOSIRA Agardh, 1824 nummuloides Ag. NAVICULA Bory, 1822 abunda Hust. accornoda Hust. aequorea Hust. ammophila Grun. amphipleuroides Hust. capitata var. hungarica (Grun.) Ross circumtexta Meister contenta Grun. creuzburgensis Krasske crucicula (W.Sm.) Donk. cryptocephala Kiitz. cryptolyra Brockman diserta Hust. elegans W.Sm. flanatica Grun. gregaria Donk. hudsonis Grun. hyalinula DeToni Short Communications 387 incomposita Hagelstein var. incomposita var. minor Hagelstein lanceolata (Ag.) Ktitz. marina Ralfs menisculus Schum. mutica (Hilse) Grun. var. mutica var. stigma Patr. nolens Simonsen obsoleta Hust. pavillardi Hust. peregrina (Ehr.) Kiitz, phyllepta Kiitz. platyventris Meister comoides (Ag.) Perag. pseudocrassirostris Hust. pupula var, rectangularis (Greg.) Grun. salinarum Grun. salinicola Hust. schroeteri Meister spicula (Hickie) C 1 . subforcipata Hust. taraxa Hohn & Hellerm. tenera Hust. teneroides Hust. tripunctata (Miill.) Bory var. tripunctata var. schizonemoides (V.H.) Patr. yarrenis Grun. zoster eti Grun, NITZSCHIA Hassalk 1845 amphibia Grun. angu laris W. Sm. apiculata (Greg.) Grun. bicapitata Cl.* bilobata var. ambigua Mang, brittonia Hagelstein closterium W. Sm. communis var. hyalina Lund debits (Arnott) Grun. dissipita (Kiitz.) Grun. epithemioides Grun. fasciculata (Grun.) Grun. filiformis (W. Sm.) Schutt frustulum (Kiitz.) Grun. ydLi.frustulum var. perminuta Grun. gandersheimiensis Krasske grana Hohn & Hellerm. granulata Grun. hungarica Grun. lanceolata W. Sm. lorenziana var. subtilis Grun. minutala Grun. microcephala Grun. obtusia W. Sm. var. obtusia var. nana Grun. palea (Kiitz.) W. Sm. panduriformis Greg, var. panduriformis var. continua Greg. perversa Grun. romana Grun. romanoides Mang. scalaris (Ehr.) W. Sm. sigma (Kiitz.) W. Sm. tryblionella Hantz. vitrea Norman var. vitrea var. salinarum Grun. OPEPHORA Petit, 1888 parva (Grun.) Krasske PARALIA Heiberg, 1863 sulcata (Ehr.) Cl . PLEUROSIGMA W. Smith, 1852. angulatum (Quek.) W. Sm. normanii Ralfs salinarum (Grun.) Grun. PSAMMODISCUS Round & Mann, 1980 nitidus (Greg.) Round & Mann RHOPALODIA O. Miiller, 1895 gibberula (Ehr.) Miill. musculus Ya.r . producta Grun. STAURONEIS Ehrenberg, 1984 amphioxyis Greg, var. amphioxyis var. obtusa Hendey legeri Hust. STRIATELLA Agardh, 1832 unipunctata (Lyngb.) Ag.* SURIRELLA Turpin, 1828 angusta Kiitz. atomus Hust. ovalis Brdb. SYNEDRA Ehrenberg, 1830 affinis Kiitz. fasciculata (Ag.) Kiitz. V 2 ii . fasciculata var. intermedia M. Sullivan demerarae Grun. provincialis var. tortuosa Grun.* tabulata vm. parva (Kiitz.) Hust. THALASSIOSIRA Cleve, 1873 eccentrica (Ehr.) Cl. leptopus (Grun.) Hasle & Fryxell TRACHYSPHENIA Petit, 1877 acuminata Perag.* TROPIDONEISQXqwq, 1891 lepidoptera (Greg.) Cl. vitrea (W. Sm.) Cl. 388 Maples GENERAL SUMMARY A total of 193 taxa (species and their varieties) represent- ing 38 genera comprise the present checklist. Genera with the largest number of taxa are Navicula Sind Nitzschia v^ith 46 and 36, respectively. The next most abundant taxa were species of Amphora (15), Mastogloia (11), and Achnanthes (10). Also well represented are Cocconeis, Cydotella, Diploneis, Gyrosigma, and Synedra with six taxa each. Eleven taxa were collected only from Sargassum in the near- shore waters of southwestern Louisiana. The present checklist provides important distributional information of an ecologically important group of organ- isms. Future studies of the varied habitats along the Louisi- ana coast should result in many new additions to this pre- liminary checklist. REFERENCES CITED Bamforth, S. S. 1974, Coastal plankton off Grand Isle, Louisiana. Proc. La. Acad. Sci. 36:64-69. Cook, L. L. & S. A. Whipple. 1982. The distribution of edaphic dia- toms along environmental gradients of a Louisiana salt marsh./. Phycol. 18:64-71. Featherman, A. 1871. Second annual report of botanical survey of southwest and northwest Louisiana, made during the year 1870. Pages 63 — 131 in: Annual Report of Prof. D. F. Boyd, Superin- tendent, Louisiana State University, for year 1871, to the Gov- ernor of State of Louisiana. New Orleans, Louisiana. 1872. Third annual report of botanical survey of south- west and northwest Louisiana, made during the year of 1870. Pages 101—161 in: Annual Report of Prof. D. F.Boyd, Superin- tendent, Louisiana State University, for year 1871, to the Gov- ernor of State of Louisiana. New Orleans, Louisiana. Fucik, K. W. and S. Z. El-Sayed. 1979. Effect of oil production and drilling operations on the ecology of phytoplankton in the OEI study area. Pages 325 — 353 in: C. H. Ward, M. E. Bender and D. J. Reish (eds.). The Offshore Ecology Investigation, Vol. 65, Effects of Oil Drilling and Production in a Coastal Environment. Rice University, Houston, Texas. Hendey, N. I. 1974. A revised checklist of British marine diatoms. /. Mar. Biol. Assoc. U. K. 54:277 — 300. Housley, H. L. 1976. Distribution, Periodicity, and Identification of the Phytoplankton in the Bay of St. Louis, Mississippi and the Northeastern Gulf of Mexico. Ph.D. Dissertation, University of Southern Mississippi, Hattiesburg. 206 pp. Kalinsky, R. G. 1983. Notes on Louisiana algae. 11. A checklist of the non-marine algal flora of Louisiana. Proc. La. Acad. Sci. 46: 62-96. Kapraun, D. F. 1974. Seasonal periodicity and spatial distribution of benthic marine algae in Louisiana. Contrib. Mar. Sci. 18: 138-167. Maples, R. S. 1982. Bluegreen algae of a coastal salt panne and surrounding angiosperm zones in a Louisiana salt marsh. North- east Gulf Sci. 5:39-43. . 1983a. A preliminary checklist of marine planktonic diatoms of southwestern Louisiana. Proc. La. Acad. Sci. 46: 34-40. . 1983b. Community structure of diatoms epiphytic on pneumatophores of the black rmugiov c,, Avicennia germmans, in a Louisiana salt marsh. Gulf Res. Kept. 7(3):255-259. Medlin, L. K. 1983. Community Analysis of Epiphytic Diatom Com- munities Attached to Selected Species of Macroalgal Host Plants Along the Texas Gulf Coast. Ph.D. Dissertation. Texas A&M University, College Station. 150 pp. Pecora, R. A. 1977. Brackish water species of Vaucheria (Xantho- phyceae, Vaucheriales) from Louisiana and Texas. Gulf Res. Rept. 6(1): 25-29. , 1980. Observations on the genus Vaucheria (Xantho- phyceae, Vaucheriales) from the Gulf of Mexico. Gulf Res. Rept. 6(4):387-391. Simmons, E. G. and W. H. Thomas. 1962. Phytoplankton of the east- ern Mississippi delta. Contrib. Mar. Sci. 8:269—288. Stowe, W. C. 1982. Diatoms epiphytic on the emergent grass, Spartina alterniflora, in a Louisiana salt marsh. Trans. Am. Microsc. Soc. 101:162-173. Sullivan, M. J. 1981. A preliminary checklist of marine benthic dia- toms of Mississippi. Gulf Res. Rept. 7(1): 13— 18. Wood, E. J. F. 1963. A study of the diatom flora of fresh sediments of the South Texas bays and adjacent waters. Publ. Inst. Mar. Sci. Univ. Tex. 9:237-310. Gulf Research Reports Volume 7 | Issue 4 January 1984 A Range Extension for Manajwnfcia aestuarina (Bourne^ 1883) (Polychaeta: Sabellidae) to the Gulf Coast of the United States with a Review of Previous Habitat Information T. Dale Bishop University of Georgia DOI; 10.18785/grr.0704.14 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Bishop, T. 1984. A Range Extension for Manayunkia aestuarina (Bourne, 1883) (Polychaeta: Sahellidae) to the Gulf Coast of the United States with a Review of Previous Habitat Information. Gulf Research Reports 7 (4): 389-392. Retrieved from http://aquila.usm.edu/gcr/vol7/iss4/14 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 389-392, 1984 A RANGE EXTENSION ¥OK MAN AYUNKIA AESTU ARINA (BOURNE, 1883) (POLYCHAETA: SABELLIDAE) TO THE GULF COAST OF THE UNITED STATES WITH A REVIEW OF PREVIOUS HABITAT INFORMATION T. DALE BISHOP Institute of Ecology, University of Georgia, Athens, Georgia 30602 ABSTRACT The sabeiiid polychaete Manayunkia aestuarina (Bourne, 1883) is reported for the first time from the Gulf coast of the United States and from a Juncus roemerianus marsh. Individuals were collected from a brackish J. roemerianus marsh in St. Louis Bay, Mississippi, (30°22'N, 89°15'W) during the period of June 1979 to May 1980. Adults with eggs were first noted in early January and increased in number through May. Brooded young were observed from late January through May. Habitat comparisons are made between this and other North American and European populations. The pre- sent population is associated with lower salinities, more sandy sediments, and much less frequent tidal inundation than the others. A brief taxonomic discussion is presented. INTRODUCTION Two species of the sabeiiid polychaete genus Mana- yunkia (subfamily Fabricinae) have been reported from the North American continent. Manayunkia speciosa Leidy, 1858, has been collected from all coasts of the United States, the Great Lakes region, and from unnamed lakes in northern Alaska (for a review of existing records see Brehm 1978). A second species, Manayunkia aestuarina (Bourne, 1883), has been infrequently collected in North America. This species was initially reported on the Atlantic coast by Teal (1962) from Sapelo Island, Georgia, S’pai'fmiz a/ferw- flora marshes where it was the most abundant polychaete. Light (1969), apparently being unfamiliar with Teaks (1962) work, mistakenly claimed that his collection of M. aestu- arina from mudflats near Vancouver, British Columbia, was the first North American record for the species. Light (1969) suggested that M, aestuarina could probably be con- sidered a circumarctic and circumboreal estuarine inhab- itant but that a lack of intensive sampling or improper technique had resulted in the true extent of its range remaining unknown. Since the time of Light’s (1969) prediction, the occurrence of M, aestuarina has been redocumented for the southeastern coast of the United States (Bell and Coull 1978) and for the Pacific coast (Eckman 1979). Bell and Coull (1978) iounA M. aestuarina in the North Inlet estuary, Georgetown, South Carolina, and Bell (1982) subsequently reported on the population biology ofM aestuarina from that area (see also Bell 1979, 1980, 1983). Kneib and Stiven (1982) reported effects of predator size on a population of M. aestuarina (and other infauna) at Tar Landing marsh in the vicinity of Beaufort, North Carolina. Eckman (1979, 1983) studied the small- scale distribution and recruitment patterns of M. aestuarina and other benthos in Skagitt Bay, Washington. The present paper is the first Gulf coast record of a population of Manuscript received March 27, 1984; accepted October 8, 1984. M. aestuarina and is the first time the species has been found associated with a Juncus roemerianus marsh. It is logical to expect that with the current increase of interest in meiofaunal assemblages on all coasts, the presence of M. aestuarina will be reported from more localities. Indeed, Heard (1982) suggests but does not confirm the presence of additional populations of M. aestuarina in other Gulf estuaries. TAXONOMIC REVIEW Manayunkia aestuarina is a typical representative of the sabeiiid subfamily Fabricinae Rioja, 1917, which is charac- terized by minute forms that show a high degree of adapt- ability to a wide range of intertidal and salinity conditions (Hartman 1951). This species was first described by Bourne (1883) who erected the new genus Haplobranchus for it. McIntosh (1923) alluding to earlier work by Leidy (1858) on Mana- yunkia speciosa cited numerous similarities between the two species and subsequently placed Haplobranchus aestu- arinus Bourne, 1883, in the genn% Manayunkia. Light, in his 1969 report of Manayunkia aestuarina from British Columbia, lists two synonyms {M. polaris Zenke- witsch, 1935, and Haplobranchus balticus Karling, 1934) for this species, at least one of which seems very doubtful. In her work on the Pacific Fabricinae, Hartman (1951) states that M. polaris is near M. aestuarina but does not ex- plicitly state that the two should be equated. In discussing H. balticus however, Hartman (1951) points out that due to differences in number of body segments and setal arrangements this species is not referrable to any named genus in the subfamily. It would seem that because of her extensive work with the group Hartman’s view should be given acceptance and H. balticus should not be used as a synonym of M. aestuarina. That however is simply this author’s opinion and any final resolution of the matter will be left to the more qualified professional taxonomists. 389 I 390 Bishop TABLE 1 Minimum densities of Manayunkia aestuarina and associated environmental data from St Louis Bay, Mississippi Collection Date Temperature UO Salinity (ppt) Sediment M. aestuarina No./m^ Air Water Soil Water Soil pH % Organics 06-29-79 40.0 30.0 24.5 2.0 5.0 4.5 13.22 3 07-30-79 26.5 31.5 25.5 1.0 1.0 4.5 8.10 47 08-23-79 30.0 29.0 25.0 6.0 3.0 5.5 14.96 6 09-23-79 24.0 23.0 23.0 3.0 6.0 6.0 9.51 9 10-29-79 21.0 19.0 14.5 6.0 11.0 5.5 9.02 0 11-30-79 13.0 10.0 8.5 2.0 10.0 6.5 10.47 9 01-04-80 11.0 11.0 9.0 6.0 9.0 6.5 9.48 70 01-26-80 16.0 15.0 13.0 0.0 4.0 6.5 10.63 32 02-23-80 16.0 16.0 15.5 6.0 5.0 6.5 9.07 32 03-22-80 21.5 17.0 13.5 0.0 5.0 6.5 9.90 58 04-26-80 31,0 28.0 23.0 0.0 4.0 6.5 10.85 105 05-23-80 33.0 29.0 24.5 1.0 3.0 6.5 15.30 64 Specimens of Manayunkia aestuarina collected from the Mississippi population and deposited with the United States National Museum of Natural History (USNM No. 097391) agree with the detailed descriptions given for the species (Bourne 1883, McIntosh 1923, Fauvel 1927, Light 1969) except for the possibility of a few additional rows of teeth located above the main fang of the thoracic uncini (Fitzhugh personal communication). To avoid repetition, the reader is referred to Bourne (1883) (and the other pa- pers cited) for characteristics and drawings of M. aestuarina. COLLECTION DATA Specimens of Manayunkia aestuarina were collected incidentally during a study of the Mollusca associated with a Juncus roemerianus marsh (Bishop 1981), The study was conducted on a small marsh island (30°22'N, 89°15'W) on the western side of St. Louis Bay, Mississippi, during the period June 1979 to May 1980. The marsh was adjacent to tidally influenced Catfish Bayou and the nearby Jourdan River. Considerable information on the study area and past work there is reviewed by Hackney and de la Cruz (1982). Sampling techniques of the study (Bishop 1981) were designed to quantify macrofaunal organisms and not those species in the meiofaunal size range such as Manayunkia aestuarina. Therefore, the numbers of organisms collected should be viewed as minimum estimates only and are pre- sented in Table 1 along with environmental data from each sample date. Bell (1980, 1982) used first setiger width as a measure of size class (i.e. body length) ofM aestuarina. In the present study, small individuals (first setiger width <0.14 mm) and large M. aestuarina (first setiger width >0.15 mm) were present in approximately equal numbers in all seasons. Adults with eggs (Berrill 1977) were first noted in the early January sample. The percentage of adults with eggs was greatest in April and May (17% and 27%, respectively). Brooded young were observed from late Jan- uary through May. DISCUSSION Although no quantitative comparisons can be drawn between this population and those of other studies, differ- ences in reported habitat types do emerge. A summary of habitat similarities and differences taken from the literature is presented in Table 2. Entries for European populations represent summaries compiled from a number of sources while East coast (U.S.) information is mainly from the work of Bell (see Table 2 for publication dates). In Europe, most reports of Manayunkia aestuarina give its habitat as unvegetated mudflats from the high intertidal to well within the subtidal zone. It may be present in brack- ish and low salinity areas, but according to Shutz (1965) it does not occur naturally in areas that lack a marine influ- ence. It is unclear if “does not occur naturally” means total absence or presence only after introduction to such an area. The habitat for M. aestuarina as reported by Light (1969) and Eckman (1979, 1983) for Pacific coast populations is the same as for European ones. Both Bell (1982) and the present study indicate that Af. aestuarina may also be found in vegetated zones of the high intertidal, and Teal (1962) collected many specimens from streamside and levee areas vegetated with Spartina alterniflora. The habitat distinctions of vegetated streamside-levee and high intertidal marsh versus unvegetated, intertidal mudflats may represent a lack of collecting in reciprocal areas on these coasts, differences in sampling techniques (e.g. sieve mesh size, lack of staining, etc.), oversight of such a small species or possibly misidenti- fication, and not true habitat differences. Further collec- tions will be required to detennine the true range of the spatial distribution ofM. aestuarina. The Mississippi population was found to be associated with consistently lower salinities than those reported for other areas (Table 2) and was frequently exposed to bay salinities < 3.0 ppt (Table 1). Although Manayunkia aestu- arina is known to exist in areas where brackish to oligohaline conditions persist for short periods of time, such as during Short Communications 391 TABLE 2 Habitat comparisons for Manayunkia aestuarina from European and North American coastal regions. Geographic Region Estimated Density (m"^) Habitat Description Salinity Regime Sediment Composition EUROPE Kendall (1979) From 1.0 X lO"^ Mid to high 33ppt (Kendall 1979). Mud or muddy with Muus (1967) to intertidal un- Brackish to low sal- mean grain size of Shiitz (1965) vegetated mud inity but always with 8 /im. Thin layer Light (1969) 1.0 X 10® flats to 20 m marine access. of sand in Kendall Zenkewitsch (1957) subtidal. 5-50 ppt (Light 1969). (1979). NORTH AMERICA Pacific Coast Light (1969) “Many” Exposed flats. 5.0 ppt when collected. Mud. Eckman (1979) 5.0 X 10® Flats 2 m above Thin mud veneer MLLW. over sand. East Coast Teal (1962) 3.0 X lO"^ S. alt erni flora 20-30 ppt. Undetermined . Bell and levee marsh. Coull (1978) Bell (1979) 1.0 X 10® High intertidal “High-salinity 60—80% silt-clay. Bell (1980) S. alterni flora estuary.” 5-10% sand. Bell (1982) marshes. Gulf Coast Present Report Undetermined J. roemerianus 0-6.0 ppt Bay. 36.5% sand, 17.5% mid-high marsh. 1.0-11.0 ppt Soil. silt, 46% clay. spring runoff (Light 1969), the effects of long term expo- sure to lowered salinities are unknown. Soil salinities in the Juncus roemerianus marsh were higher than bay salinities on nine sample dates (Table 1) and could have provided a refuge closer to the more marine salinities reported for M. aestuarina (Table 2). The Juncus roemerianus marsh studied is flooded only 12 percent of the time (Hackney and de la Cruz 1978) com- pared to approximately 25 percent of the time (3-4 hr per tidal cycle) for the South Carolina marsh (Bell 1982) and presumably for other coastal areas experiencing semidiurnal tidal regimes. Since Manayunkia aestuarina is a deposit and suspension feeder (Fauchald and Jumars 1979), potential feeding time would be reduced on the irregularly flooded J. roemerianus marsh. The effects of such a stress on the abundance, reproductive activity, and general physiological condition of the Mississippi population are unknown and intriguing. Most reports of Manayunkia aestuarina populations are from areas with muddy sediments (but see Eckman 1979, 1983). The soil in the Juncus roemerianus marsh was more sandy compared to other studies providing data on sedi- ment composition. Kendall (1979) suggests that M. aestu- arina is capable of incorporating sand grains in tube con- struction. Bell (1982) gives the only data on seasonal recruitment of juveniles for a U.S. population of Manayunkia aestuarina. She states that the South Carolina population, unlike Euro- pean counterparts, exhibits discontinuous recruitment. Also, Bell (1982) states that recruitment of juveniles did not take place in the winter in South Carolina. From observations of brooded juveniles and adults with eggs, recruitment and reproduction in the Mississippi population was also discon- tinuous but did take place in the winter months. However, adults with eggs were more common in April and May. Early onset of reproduction in the Mississippi population may reflect latitudinal differences between it and the South Carolina population. Increases of soil, air, and water tem- peratures (Table 1) coincided with the first evidence of juveniles in the Juncus roemerianus marsh. Reproductive activity may be triggered in this population by a seasonal warming trend. This type of pattern was also observed (especially in the late spring and summer increases) in the South Carolina population (Bell 1982). Manayunkia aestuarina is a numerically and perhaps functionally important component of the annelids from this irregularly flooded, low salinity, Juncus roemerianus marsh (Bishop 1983). Its ability to survive oligohaline con- ditions and infrequent inundation is potentially important because such marshes are generally faunally depauperate. The differences noted between the St. Louis Bay, Missis- sippi, population and those found in other coastal areas of the United States and Europe pose many unanswered ques- tions about the physiological tolerances and exact habitat requirements for the North American populations of M. aestuarina and emphasize the fact that we know very little of the basic biology of many non-commercial marsh and estuarine invertebrates. 392 Bishop ACKNOWLEDGMENTS Funds for this research were provided by the Mississippi Marine Resources Council (Grant No. GR-ST-79-005), the Department of Biology, and the Graduate Student Organi- zation of the University of Southwestern Louisiana. I thank Dr. Courtney T. Hackney, Dr. Mark W. LaSalle, Shirley Bishop, and reviewers for comments on the manuscript. I express my appreciation to Dr. Kristian Fauchald and Kirk Fitzhugh at the National Museum for confirmation of the identification of my specimens. REFERENCES CITED Bell, S. S. 1979. Short- and long-term variation in a high marsh meio- fauna community . Estuarine Coastal Mar. Set. 9:331-350. 1980. Meiofauna-macrofauna interactions in a high salt marsh habitat. Ecol Monogr. 50:487-505. 1982. On the population biology and meiofaunal charac- teristics of Manayunkia aestuarina (Polychaeta: Sabellidae: Fabricinae) from a South Carolina salt marsh. Estuarine Coastal Mar. Sci. 14:215-221. 1983. An experimental study of the relationships between below-ground structure and meiofaunal taxa. Mar. Biol. 76(1): 33-39. & B. C. CouU. 1978. The meiobenthic polychaete yunkia aestuarina in South Carolina salt marshes. Am. Zool 18:643. Berrill, N. J. 1977. Dwarfism in a sabellid polychaete, a study of an interstitial species. 5 wl/. (Woods Hole). 153:113—120. Bishop, T. D. 1981. The seasonal abundance of the molluscan fauna of a Juncus roemerianus and a Spartina cynosuroides brackish tidal marsh in Mississippi. M.S. thesis. University of Southwest- ern Louisiana, Lafayette. 79 pp. 1983. Analysis of the structure of polychaete communi- ties from two intertidal marshes. Assoc. Southeast. Biol. Bull. 30(2):46. Bourne, A. G. 1883. On Haplobranchus, a new genus of capito- branchiate annelids. Q. J. Microsc. Sci. 23:168—176. Brehm, W. T. 1978. First Gulf of Mexico record of Manayunkia speciosa (Polychaeta: SsLbQlMd-e). Northeast Gulf Sci. 2:73-75. Eckman, J. E. 1979. Small-scale patterns and processes in a soft sub- strate interstitial community. J. Mar. Res. 37 :437-457. 1983. Hydrodynamic processes affecting benthic recruit- ment. Oceanogr. 28(2):241-257. Fauchald, K. & P. A. Jumars. 1979. The diet of worms: a study of polychaete feeding guilds. Oceanogr. Mar. Biol. Annu. Rev. 7: 193-284. Fauvel, P. 1927. Polychetes sedentaires. Addenda aux errantes archiannelides, myzostomaires. Faune Fr. 16:1 -494. Fitzhugh, K. 1984. Personal communication. Pre-Doctoral Fellow at the United States National Museum (Dept, of Invert. Zool.). Hackney, C. T. & A. A. de la Cruz. 1978. Changes in interstitial water salinity of a Mississippi tidal marsh. Estuaries. 1(3):185-188. 1982. The structure and function of brackish marshes in the north central Gulf of Mexico: a ten year case study. Pages 89-107 in: B. Gopal, R. E. Turner, R. G. Wetzel, and D. F. 'ATiigham (eds.), Wetlands: Ecology and Management (Proceed- ings of the First International Wetlands Conference, New Dehli, India). International Scientific Publications, Jaipur, India. Hartman, 0. P. 1951. Fabricinae (Feather-duster polychaetous annelids) in the Pacific. Pac. Sci. 5 (4): 379 -391 . Heard, R. W. 1982. Guide to Common Tidal Marsh Invertebrates of the Northeastern Gulf of Mexico. Mississippi-Alabama Sea Grant Consortium, MA-SGP-79-004. 82 pp. Kendall, M. A. 1979. The stability of the deposit feeding commu- nity of a mudflat in the River Tees. Estuarine Coastal Mar. Sci. 8:15-22. Kneib, R. T. & A. E. Stiven. 1982. Benthic invertebrate responses to size and density manipulations of the common mummichog, Fundulus heteroclitus, in an intertidal salt marsh. Ecology. 63(5):1518-1532. Leidy, J. 1858. Manayunkia speciosa. Page 90 in: Proc. Acad. Nat. Sci. Phila. Light, W. J. 1969. Extension of range for Manayunkia aestuarina (Polychaeta: Sabellidae) to British Columbia./. Fish. Res. Board Can. 26:3088-3091. McIntosh, W. C. 1923. A monograph of the British marine annelids. Polychaeta-Hermellidae to Serpulidae. The Ray Society -London. 4:305-307. Muus, B. J. 1967. The fauna of Danish estuaries and lagoons. Distri- bution and ecology of dominating species in the shallow reaches of the mesohaline zone. Meddelelser Danmarks Fiskeri og Havun- dersogelser. 5:1-316. Shiitz, L. 1965. Uber Verbreitung, Okologie und Biologic des Brack- wasser-polychaeten Manayunkia aestuarina (Bourne), inbeson- dere an ded Kusten Schleswig-Holsteins. Faunistiche Mitt. Norddent. 2:225—234. Teal, J. M. 1962. Energy flow in the salt marsh ecosystem of Geor- gia. E’eo/ogy. 43(4):614-624. Zenkewitsch, L. A. 1957. Caspian and Aral Seas. In: J. R. Hedge- peth (ed.), Treatise on Marine Ecology and Paleoecology . Vol- ume I. Geol. Soc. Am. Mem. 67. Gulf Research Reports Volume 7 | Issue 4 January 1984 Amphipods of the Family Ampeliscidae (Gammaridea). IV Infraspecific Variation in Ampelisca agassizi GaryD. Go eke Gulf Coast Research Laboratory Richard W Heard Gulf Coast Research Laboratory, richard.heard^usm.edu DOI; 10.18785/grr.0704.15 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Goeke, G. D. and R. W. Heard. 1984. Amphipods of the Family Ampeliscidae (Gammaridea). IV. Infraspecific Variation in Ampelisca agassizi. Gulf Research Reports 7 (4): 393-395. Retrieved from http://aquila.usm.edu/gcr/vol7/iss4/15 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 7, No. 4, 393-395, 1984 AMPHIPODS OF THE FAMILY AMPELISCIDAE (GAMMARIDEA). IV. INFRASPECIFIC VARIATION IN AMPELISCA AGASSIZI GARY D. GOEKE AND RICHARD W. HEARD, JR. Fisheries and Parasitology Sections, Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564 ABSTRACT Considerable variation noted in Ampelisca agassizi is herein described. The variations in the shape of the basis of pereopod 7 and the carina of urosomite 1 are most obvious. No relationship was found with the atypical specimens and their age, associated sediment or location. One of the most abundant and geographically widespread species of the family AmpeHscidae in the western Atlantic and eastern Pacific Ocean is Ampelisca agassizi (Judd 1896). In the western Atlantic this species is recorded from south- ern Nova Scotia to the Caribbean Sea in depths to 450 m (Barnard 1954b, Mills 1967, Bousfield 1973). Population densities of 15,000/m^ have been reported by Dickinson et al. (1980) in the Middle Atlantic Bight region. In the east- ern Pacific Ocean, representatives of this species have been collected from Queen Charlotte Islands, British Columbia, to Ecuador in depths to 300 m (Dickinson 1982). Ampelisca agassizi was described from the waters off of the state of Rhode Island in the United States, from pelagic males gathered in a plankton tow and it was originally placed within the genus Byblis, Since that work, this species has been described under the names Ampelisca compressa Holmes, 1908, from females in the Atlantic and A. vera Barnard, 1954, in the Pacific. Mills (1967:645) first desig- nated A. vera a junior synonym of A. agassizi and noted that “Pacific Coast specimens agree in remarkable detail with those from the Atlantic Coast as J. L. Barnard [1960] has stated and as I have been able to confirm.” Recent examin- ations of representatives of these disjunct populations by Dickinson (1982:6) led that author to write he has “been unable to find a morphological basis for separating the pop- ulations on either side of the Isthmus of Panama.” Many Ampelisca Kroyer, 1842, species have been re- ported with transpanamic distributions. A detailed compari- son of some of these nominal species has shown the Atlantic and Pacific populations to represent distinct tzxdi. Ampelisca bicarinata Goeke and Heard, 1983, has been separated from the Pacific A. cristoides Barnard, 1954, (Barnard 1954a), and A. parapacifica Goeke and Heard, 1984, has been shown to be discrete and is separated from A. pacifica Holmes, 1908. Atlantic populations of additional “transpanamic” species are yet to be elevated to the species rank (Goeke and Heard, unpublished data). Variation within the genus Ampelisca has been considered a problem by workers in the past. Reid (1951:197) stated Manuscript received May 10, 1984; accepted July 9, 1984. “there appears to be a great range of real minor variations which is very strange considering the great constancy of characteristics in many species in other genera.” However, Barnard (1960:6) states that he has “identified nearly 10,000 specimens of the 23 species in southern California and is impressed with the ease with which they may be dis- tinguished.” He further notes that part of the confusion of workers in the past centered around gerontic males and females. The extreme sexual dimorphism of pelagic males may be disconcerting if not recognized. We agree with Barnard (1960) and note that the western Atlantic taxa are well defined. Much of the confusion arises from suites of closely related species, some of them common but as yet undescribed. The shape of the seventh leg and the dorsal carina of urosomite 1 are of paramount importance in the systematics of this genus, and minor variation is often attributable to the stage of development of the specimens (e.g.,A. excavata. Gray and Barnard, 1970). Infraspecific differences noted in A. agassizi are not attributable to either developmental stage or location. It is not unusual to examine a group of speci- mens from a single collection and observe broad variation. For the purpose of this study, material is illustrated from the western, northwestern and southeastern Gulf of Mexico and from off the Atlantic coast of South Carolina. Pereopod 7 is normally diagnosed for A. agassizi as being broad distally. Specimens are often found where the basis is distally rounded (Figure IK) and not the transversely rounded form figured by Mills (1967: Figure 3J) and Bousfield (1973: Figure 38). This atypical form of leg 7 often makes it difficult to identify the specimen with the use of currently available artificial taxonomic keys. Material which displayed this leg shape came from both the Gulf of Mexico and the East Coast. No relationship was noted with leg shape and developmental stage of the specimens or with sediment. The variation of the carina of urosomite 1 is not as criti- cal as that noted for the seventh leg because it is often con- sidered a secondary character. The dorsal elevation of the carina varies considerably in height and prominence. The degree of variation in the carina of urosomite 1 is well illus- trated by a compilation of figures attributed to Ampelisca 393 394 Goeke and Heard Figure 1. Ampelisca agassizi; A. from Dickinson (1982): British Colombia; B. from Barnard (1954a): California; C. from Barnard (1954a): California; D. from Barnard (1954b): Caribbean; E. from Barnard (1954b): Caribbean; F. from Mobile Bay specimen; G. from Mobile Bay specimen; H. from Louisiana specimen with atypical leg; I. from Louisiana specimen with atypical leg; J. from Bousfield (1973): New England; K. from Barnard (1954a): California; L. from Louisiana specimen;M. from Louisiana specimen with atypical leg. Short Communications 395 agassizi from the Pacific and Atlantic (Figure lA-J). These have been gathered from various sources and represent a very broad geographic range. None of the Atlantic material ex- amined by these authors has any indication of a second ele- vation on the fused urosomite 2—3 as shown by Dickinson (1982 .'Figure 1) for material from British Colombia. No relationship with the stage of development, sediment or leg shape and form of carina was indicated. The atypical specimens examined by us were also checked for variation in other important taxonomic characters. No significant variation was noted in antennal features, structure of mouthparts or pereopods 1—6. REFERENCES CITED Barnard, J. L. 1954a. Amphipoda of the family Ampeliscidae collected in the eastern Pacific Ocean by the VELERO III and YELERO lY . Allan Hancock Pac. Exped. 18:1. 1954b. Amphipoda of the family Ampeliscidae collected by the VELERO III in the Caribbean Sea. Allan Hancock Atl. Exped. Report No. 7. 1960. New bathyal and sublittoral ampeliscid amphipods from California, with an illustrated key to Ampelisca. Pac. Nat. 1:1-48. Bousfield, E. L. 1973. Shallow -water gammaridean Amphipoda of New England. Cornell Univ. Press. 312 pp. Dickinson, J. J., R. L. Wigley, R. D. Brodeur & S. Brown-Leger. 1980. Distribution of gammaridean Amphipoda (Crustacea) in the Middle Atlantic Bight region. U.S. Dep. Commer. NOAA Tech. Rep. NMFS SSRF-741, 46 pp. 1982. Family Ampeliscidae, Gznm Ampelisca. Pages 1- 41 in: Studies on amphipod crustaceans of the northeastern Pacific region I, Natl. Mus. Nat. Sci. (Ottawa) Publ. Biol. Oceanogr. No. 10. National Museums of Canada. Goeke, G. D. & R. W. Heard, Jr. 1983. Amphipods of the family Ampeliscidae (Gammaridea). I. Ampelisca bicarinata, a new spe- cies of amphipod from the Gulf of Mexico. Gulf Res. Rept. 7(3): 217-233. Goeke, G. D. & R. W. Heard, Jr. 1984. Amphipods of the family Ampeliscidae (Gammaridea). III. Ampelisca parapacifica, a new species of amphipod from the western North Atlantic with the designation of a substitute name for A. eschrichtii pacifica Gurjanova, 1955. Gulf Res. Rept. 7(4):331 -337. Gray, W. S. & J. L. Barnard. 1970. South African Ampelisca excavata K. H. Barnard (Amphipoda, Gammaridea), a redescrip- tion with notes on the domicile. Crustaceana 19(l):67-83. Holmes, S. J. 1908. The Amphipoda collected by the U.S. Bureau of Fisheries steamer “Albatross” off the west coast of North Amer- ica, in 1903 and 1904, with descriptions of a new family and several new genera and species. Proc. U.S. Natl. Mus. 35: 489-543. Judd, S. D. 1896. Description of three species of sand fleas (Amphi- pods) collected at Newport, Rhode Island. Ptoc. U.S. Natl. Mus. 18:593-603. Mills, E. L. 1967. A re-examination of some species of Ampelisca (Crustacea: Amphipoda) from the east coast of North America. Can. J. Zool. 45:635-652. Reid, D. M. 1951. Report on the Amphipoda (Gammaridea and Caprellidea) of the coast of tropical West Africa. Atl. Rep. 2: 189-291,