Bivalve contribution to shallow sandy bottom food web off mar del plata (Argentina): inference from stomach contents and stable isotope analysis.ABSTRACT Two infaunal species, the purple clam Amiantis purpurata and the razor clam razor clam Any of several species of marine clams (family Solenidae) common in intertidal sands and muds, particularly of temperate seas. Razor clams have narrow and elongated shells (shaped like straight razors) up to 8 in. (20 cm) long. Solen tehuelchus, are common species in the 15-20 m sandy bottom sediments between southern Brazil and central Argentina. Both species are food sources for the coastal food web, but the extent of their contribution to this food web is still unknown. Based on stomach content analysis and [[delta].sup.15]N and [[delta].sup.15]C stable isotope stable isotope n. An isotope of an element that shows no tendency to undergo radioactive breakdown. signatures we explored the position of these clams in the food web. Stomach content shows that the ray Sympterigia bonapartei and the white croaker croaker, member of the abundant and varied family Sciaenidae, carnivorous, spiny-finned fishes including the weakfishes, the drums, and the whitings. The croaker has a compressed, elongated body similar to that of the bass. Micropogoniasfurnieri prey on entire A. purpurata and S. tehuelchus. The stable isotopic analysis confirms this result. The elephant fish (Zool.) a chimæroid fish (Callorhynchus antarcticus), with a proboscis-like projection of the snout. See also: Elephant Callorynchus callorynchus and the Brazilian codling cod·ling 1 also cod·lin n. 1. A greenish elongated English apple used for cooking. 2. A small unripe apple. Urophycis brasiliensis also show values of C and N consistent with those expected from species that are preying on A. purpurata. Based on the prediction from the isotopic analysis the clam A. purpurata is a food source for the shrimps Artemesia longinaris, Pleoticus muelleri, the anemone anemone (ənĕm`ənē) or windflower, any of the perennial herbs, wild or cultivated, of the genus Anemone of the family Ranunculaceae (buttercup family). Antholoba achates and the gastropod gastropod, member of the class Gastropoda, the largest and most successful class of mollusks (phylum Mollusca), containing over 35,000 living species and 15,000 fossil forms. Buccinanops monilifer. The gastropods Adelomelon brasiliana, Olivancillaria deshayesiana, Olivancillaria urceus and Zidona dufresnei also show evidence of consuming A. purpurata but with contribution from other species with heavier C content. According to complementary results the razor clam Solen tehuelchus may be this other species. The stable isotopic analysis shows that both clam species are at the base of the consumers in the food web. A. pupurata showed lighter C mark than S. tehuelchus, but the N isotopic mark showed higher value but still being within the same trophic level. KEY WORDS: food web, bivalves, fish, crustaceans, gastropods, SW Atlantic INTRODUCTION Two infaunal bivalves, the purple clam Amiantis purpurata (Lamarck, 1818) and the razor clam Solen tehuelchus (D'Orbigny 1843), are common species in the coastal ([less than or equal to]20-m depth) sandy bottom of the SW Atlantic. The purple clam is distributed from Espirito Santo, Brazil (20[degrees]S) to the Golfo San Matias, Argentina (42[degrees]S) (Carcelles 1944, de Castellanos 1967, Scarabino 1977) occurring in high-density patches (maximum abundance: 632 clams [m.sup.-2]) at depths ranging from 10-18 m dominated by 1- or 2-year-classes (Morsan 2003). The razor clam S. tehuelchus ([less than or equal to]61-mm length) shows similar distribution, from Rio de Janeiro Rio de Janeiro, city, Brazil Rio de Janeiro (rē`ō də zhänā`rō, Port. rē`  thĭ zhənĕē`r , Brazil (22[degrees]54'S) to Bahfa Blanca, Argentina
(38[degrees]44'S) (Rios 1994, Capitoli 1997). However, the
abundance of this species is not truly reflected in the literature,
probably because of their deep burrowing habits. There is evidence that
both species are important food sources for a number of species in
shallow coastal areas but the extent of their contribution to the food
web is still unknown.
Several predators have been described for these species based on gut content analysis (Olivier et al. 1968, Radonic 1997). For example, siphon siphon (sī`fən, –fŏn), tube through which a liquid is lifted over an elevation by the pressure of the atmosphere and is then emptied at a lower level. tips of A. purpurata are the main food item of the electric ray Discopyge tschudii, Heckel 1846 (Arrighetti et al. 2005), which is the regionally most abundant torpediniform species. Also, entire clams are preyed by the fish Pogonias cromis (Linnaeus, 1766) (Garcia & Gianuca 1997). However, gut content analysis is limited and may be biased toward larger species that can hold the bivalves for longer time (see Sutela & Huusko 2000, Hyslop 1980) and toward food items recently consumed; moreover, this method cannot provide information on the rate of ingestion ingestion /in·ges·tion/ (-chun) the taking of food, drugs, etc., into the body by mouth. in·ges·tion n. 1. The act of taking food and drink into the body by the mouth. 2. and regarding long-term assimilation (Creach et al. 1997). As an alternative, measurement of stable isotope ratios has become widely used to define relationships between consumers and their food sources (Peterson & Fry 1987, Michener & Schell 1994, Cabana & Rasmussen 1994), and they have been applied to study foraging, migration and other life history phenomena (Hesslein et al. 1991, Alisauskas & Hobson 1993, Walker et al. 1999, Best & Schell 1996, Hansson et al. 1997, Kline et al. 1998, Griffin & Valiela 2001, McGinnis & Emslie 2001). Stable isotopes are relatively consistently fractionated by biological and physical processes as they pass through food webs becoming heavier by 3%0 to 4%0 for N and by 1%o to 2%0 for C with each trophic trophic /tro·phic/ (tro´fik) (trof´ik) pertaining to nutrition. troph·ic adj. Of, relating to, or characterized by nutrition. transfer (Peterson & Fry 1987, Cabana & Rasmussen 1994). This fractionation fractionation /frac·tion·a·tion/ (frak?shun-a´shun) 1. in radiology, division of the total dose of radiation into small doses administered at intervals. 2. from potential food sources to tissues in consumers has been used to identify trophic relationships. Trophic relationships between motile mo·tile adj. 1. Moving or having the power to move spontaneously. 2. Of or relating to mental imagery that arises primarily from sensations of bodily movement and position rather than from visual or auditory sensations. consumers like fishes and their food sources may depend on size of consumers and foraging patterns. Larger animals are able to feed higher in the food web and often acquire heavier isotopic signatures in their tissues (France et al. 1998, Harvey et al. 2002). Therefore, combining isotope analysis with gut contents can provide a better understanding of trophic pathways, given that some items could be ingested in·gest tr.v. in·gest·ed, in·gest·ing, in·gests 1. To take into the body by the mouth for digestion or absorption. See Synonyms at eat. 2. but not assimilated. Also, isotope analysis can provide information on those organisms in which it is not possible to evaluate gut content. In this study, we used stomach content analysis whenever possible and [[delta].sup.15]N and [[delta].sup.13]C stable isotope signatures to define the position of the purple clam Amiantis purpurata and the razor clam Solen tehuelchus in the food web of the shallow northern Argentinean costal ecosystem. MATERIAL AND METHODS Sampling and Study Areas The study was performed at the coastal area of northern Argentina (38[degrees]20'S) between April 2002 and December 2002. This area is dominated by sandy and sandy-silty bottoms (Cortelezzi in Olivier et al. 1968). The community studied is typical of a temperate marine environment where few taxa taxa: see taxon. are dominant over a large number of occasional species. The low diversity of the infaunal assemblages has been described (Olivier et al. 1968, Scelzo et al. 2002). Samples of the two bivalves and of the most representative and abundant organisms coexisting with them were obtained from the study area with bottom trawls using a 2-cm cup net from water depth of 10-18 m. The species sampled were the fishes Urophycis brasiliensis (Kaup 1858), Cynoscion striatus (Cuvier 1829), Sympterygia bonapartei (Muller & Henle 1841), Micropogonias furnieri (Desmarest 1823) and Callorynchus callorynchus (Meuschen 1778); the gastropods Buccinanops monilifer (Kiener 1834) Adelomelon brasiliana (Lamark 1811), Olivancillaria deshayesiana (Duclos 1857), Olivancillaria urceus (Roding 1798), and Zidona dufresnei (Donovan 1823); the anemone Antholoba achates (Drayton 1984) and the shrimps Artemesia longinaris (Bate bate 1 tr.v. bat·ed, bat·ing, bates 1. To lessen the force or intensity of; moderate: "To his dying day he bated his breath a little when he told the story" 1888) and Pleoticus muelleri (Bate 1888). Stomach Content Analysis The stomach of 15 Urophycis brasiliensis, 35 Cynoscion striatus, 11 Sympterygia bonapartei and 42 Micropogonias furnieri were injected aboard with 10% formaline to stop the digestive process. In the laboratory, the total length of each fish was measured to the nearest mm. To analyze the stomach contents, the digestive tract digestive tract n. See alimentary canal. Digestive tract The organs that perform digestion, or changing of food into a form that can be absorbed by the body. anterior to the intestine was removed and preserved in 10% formaline. Stomach contents were observed under a dissecting dis·sect tr.v. dis·sect·ed, dis·sect·ing, dis·sects 1. To cut apart or separate (tissue), especially for anatomical study. 2. microscope. Additional information was made on the gastro-vascular cavity of Antholoba achates and its associated snail Adelomelon brasiliana. This information was complemented by reported information from the same area (i.e., Olivier et al. 1968, Radonic 1997). Stable Isotopes Analysis Samples of white dorsal muscle of all fish species were removed and frozen for stable isotopic analysis. Samples were also obtained from the epibenthic fauna (5 pools of 5 individuals each) for the same analysis. All these samples were dried at 60[degrees]C, tissues were ground using a mortar and pestle A mortar and pestle is a tool used to crush, grind, and mix substances. The pestle is a heavy stick whose end is used for pounding and grinding, and the mortar is a bowl. The substance is ground between the pestle and the mortar. , and all samples were sent to the University of California-Davis Stable Isotope Facility to determine [[delta].sup.13]C and [[delta].sup.15]N signatures by mass spectrometry mass spectrometry or mass spectroscopy Analytic technique by which chemical substances are identified by sorting gaseous ions by mass using electric and magnetic fields. . RESULTS AND DISCUSSION Stable isotope analysis shows three trophic levels based on expected N fractionation (3.4 [per thousand]). The two bivalves Solen tehuelchus and Amiantis purpurata are at the base of the food web, with [[delta].sup.15]N values between 10.9 [per thousand] and 12.3 [per thousand]. S. tehuelchus has [[delta].sup.3]C values more depleted de·plete tr.v. de·plet·ed, de·plet·ing, de·pletes To decrease the fullness of; use up or empty out. [Latin d than A. purpurata but similar N isotope ratios. The fishes Callorynchus callorynchus and Cynoscion striatus and the squid Loligo gahi (d'Orbigny 1835) are in the upper trophic level with [[delta].sup.13]N values between 16.7 [per thousand] and 17.5 [per thousand]. In our study system, stomach content analysis can only be reliable with fishes and anemones. Based on information previously reported and our sampling (Table 1), the ray Sympterigia bonapartei prey on siphons of Amiantis purpurata and S. bonapartei. A similar result was previously found for other ray species, the electric ray Discopyge tschudii (Arrighetti et al. 2005). S. bonapartei showed C and N isotopic values expected from a clam diet, but N isotope ratios showed high variability and could be the result of a mixed diet of both clam species and some contribution of Artemesia longinaris (see Fig. 1, Table 1). [FIGURE 1 OMITTED] Stomach contents showed that the white croaker Micropogonias furnieri prey on entire individuals of A. purpurata and Solen tehuelchus (Table 1). This fish species showed different isotopic values between juveniles (<30 cm in length) and big individuals (Fig. 1), suggesting a shift in diet during their life cycle. Juveniles have values more depleted in C suggesting a food source other than clams, probably crustaceans or polychaetes (Olivier et al. 1968, Radonic 1997 and stomach content results). Adults, however, showed values that suggest an influence of clams. This shift in diet between sizes for this species was found for other sites (Olivier et al. 1968). The Brazilian codling Urophycis brasiliensis, and the stripped weakfish weakfish: see croaker. weakfish or sea trout Any of several species (genus Cynoscion) in the drum family (Sciaenidae), carnivorous bottom-dwelling fishes along warm and tropical seashores. Cynoscion striatus (Olivier et al. 1968, Radonic 1997 and our results; Table 1), did not show clams in their stomachs. Carbon isotope ratios of the stripped weakfish C. striatus showed no evidence of preying on these clams (Fig. 1). The elephant fish Callorynchus callorynchus and the Brazilian codling U. brasiliensis show values of C consistent with those expected from species that are preying on the purple clam A. purpurata, but higher N signatures. This could be the result of a mix diet of items in more than one trophic level for example; in this case they could be feeding on shrimps (as seen by stomach contents) and having some contribution of clams. For invertebrates it is much more difficult, or just impossible, to recognize items in the stomach content by microscopical analysis. Based on the prediction from the isotopic analysis the clam Amiantis purpurata is a food source for the shrimps Artemesia longinaris and Pleoticus muelleri, and the gastropod Buccinanops monilifer. However, the gastropods Adelomelon brasiliana, Olivancillaria deshayesiana, Olivancillaria urceus and Zidona dufresnei also show evidence of consuming the purple clam but with contribution from the razor clam Solen tehuelchus (Fig. 1). One of the few invertebrate invertebrate (ĭn'vûr`təbrət, –brāt'), any animal lacking a backbone. The invertebrates include the tunicates and lancelets of phylum Chordata, as well as all animal phyla other than Chordata. species where items in the stomach content can be recognized is the anemone Antholoba achates (see Acuna et al. 2003). Our results show that 60% of the weight was Amiantis purpurata, whereas the other species contributed with much lower values (Solen tehuelchus 5%, Encope emarginata 11.5%, Artemesia longinaris 11.5%, Olivancelaria uretai, O. Urceus and Buccinanops moniliferum 10%, the hermit crab Pagurus excilis 0.6%, Leucipa patagonica 0.4% and polychaetes 1.1%). Isotope C and N also showed values expected for a diet mainly on A. purpurata. Interestingly, this anemone lives epibiotic on the gastropod Adelomelon brasiliana (see Acuna et al. 2003). Adelomelon brasiliana is a common inhabitant INHABITANT. One who has his domicil in a place is an inhabitant of that place; one who has an actual fixed residence in a place. 2. A mere intention to remove to a place will not make a man an inhabitant of such place, although as a sign of such intention he of the studied area, which preys on Amiantis purpurata and Solen tehuelchus of all sizes (Cledon 2005). These snails are long-lived and can reach over 200 mm in length (Cledon et al. 2005), which means a high predatory pressure for the bivalves, because no size is out of predation predation Form of food getting in which one animal, the predator, eats an animal of another species, the prey, immediately after killing it or, in some cases, while it is still alive. Most predators are generalists; they eat a variety of prey species. risk and their burrowing in the sediment is not always effective, the snails can also do that (Cledon 2005). The anemone and the snail are at the same trophic level (i.e., same n values) but C isotope ratios suggest that their food sources are somewhat different (i.e., the C mark differ). Whereas the anemone showed [[delta].sup.13]C values expected of a predator feeding on A. purpurata and no on S. tehuelchus, the gastropod A. brasiliana showed [[delta].sup.13]C values suggesting a diet that incorporates both bivalves at similar proportion. The sea anemone and the snail, although highly associated, do not show evidence of large diet overlap. This fact could be related to the burrowing activity of A. brasiliana, whereas A. achates would remain in contact with the upper sediment levels (Arrighetti et al. 2004). In conclusion, the purple clam Amiantis purpurata and the razor clam Solen tehuelchus are species clearly located at the bottom of the food web. These two species contribute to the diet of some gastropods and sea anemones and to some economically important fish. ACKNOWLEDGMENTS This project was supported by UBACyT X-316, Agencia Nacional de Promocion Cientifica y Tecnologica PICT 10975 and PICT 14419, CONICET CONICET Consejo Nacional de Investigaciones Científicas Y Técnicas (National Council for Science and Technology, Argentina) PIP 02193, Fundacion Antorchas 13672/ 1-5 (to P. E. Penchaszadeh) and Fundacion Antorchas 13900-13, CONICET PIP 0686, Agencia Nacional de Promocion Cientifica y Tecnologica PICT 1-13527 (to O. O. Iribarne). LITERATURE CITED Acuna, F. H., A. C. Excoffon & M. A. Scelzo. 2003. Mutualism Mutualism An interaction between two species that benefits both. 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Sharp and biting, as the cold. 2. Bitingly sarcastic. nip  ping·ly adv.Adj. of the bivalve bivalve, aquatic mollusk of the class Pelecypoda ("hatchet-foot") or Bivalvia, with a laterally compressed body and a shell consisting of two valves, or movable pieces, hinged by an elastic ligament. Amiantis purpurata by the electric ray Discopyge tschudii (Heckel 1846) in Mar del Plata, Argentina. J. Mar. Biol. Ass. U.K. 85:1151-1154. Best, P. B. & D. M. Schell. 1996. Stable isotopes in southern right whale The Southern Right Whale (Eubalaena australis) is a baleen whale, one of three species formerly called classified as the Right Whale belonging to the genus Eubalaena. (Eubalaena australis) baleen baleen: see whale. as indicators of seasonal movements, feeding and growth. Mar. Biol. 124:483-494. Cabana, G. & J. B. Rasmussen. 1994. Modeling food chain structure and contaminant contaminant /con·tam·i·nant/ (kon-tam´in-int) something that causes contamination. contaminant something that causes contamination. bioaccumulation bi·o·ac·cu·mu·la·tion n. The increase in the concentration of a substance, especially a contaminant, in an organism or in the food chain over time. using stable nitrogen isotopes. Nature 372:255-257. Capitoli, R. R. 1997. Continental Shelf Benthos benthos: see marine biology. . In: U. Seeliger, C. Odebrecht & J. P. Castello, editors. Subtropical sub·trop·i·cal adj. Of, relating to, or being the geographic areas adjacent to the Tropics. subtropical Adjective of the region lying between the tropics and temperate lands convergence environments: the coast and sea in the southwestern Atlantic. Springer-Verlag, Berlin. pp. 117-120. Carcelles, A. 1944. Catalogo de moluscos marinos de Puerto Quequen (R. Argentina). Revista del Museo La Plata, Nueva Serie. Seccion Zoologia. 3:233-309. Cledon, M. 2005. Reproductive biology and ecology of Adelomelon brasiliana off Mar del Plata, Argentina. Berichte far Polar und Meeresforschung. Bremerhaven, Germany. 100 pp. Cledon, M., T. Brey, P. E. Penchaszadeh & W. Arntz. 2005. Individual growth and somatic somatic /so·mat·ic/ (so-mat´ik) 1. pertaining to or characteristic of the soma or body. 2. pertaining to the body wall in contrast to the viscera. so·mat·ic adj. production in Adelomenlon brosiliana (Gastropoda; Volutidae) off Argentina. Mar. Biol. 147:447-452. Creach, V., M. T. Schricke, G. Bertru & A. Mariotti. 1997. Stable isotopes and gut analyses to determine feeding relationships in saltmarsh macroconsumers. Estuar. Coast. Shelf Sci 44:599-611. de Castellanos, Z. A. 1967. Catalogo de moluscos marinos bonaerenses. Anales de la Comision de Investigaciones Cientificas 8:1-365. France, R., M. Chandler & R. Peters. 1998. Mapping trophic continuity of benthic ben·thos n. 1. The collection of organisms living on or in sea or lake bottoms. 2. The bottom of a sea or lake. [Greek. food webs: body size-d15 N relationships. Mar. Ecol. Prog. Ser. 174:301-306. Garcia, V. M. T. & N. M. Gianuca. 1997. Relationships and function of coastal and marine environments. In: U. Seeliger, C. Odebrecht & J. P. Castello, editors. Subtropical convergence environments: the coast and sea in the southwestern Atlantic. Berlin: Springer-Verlag. 308 pp. Griffin, M. P. A. & I. Vatiela. 2 001. [[delta].sup.15]N isotope studies of life history and trophic position of Fundulus heteroclitus and Menidia menidia. Mar. Ecol. Prog. Ser. 214:299-305. Hansson, S., J. E. Hobbie, R. Elmgren, U. Larsson, B. Fry & S. Johansson. 1997. The stable nitrogen isotope ratio as a marker of food-web interactions and fish migration. Ecology 78:2249-2257. Harvey, C. J., P. C. Hanson, T. E. Essington, P. B. Brown & J. Kitchell. 2002. Using bioenergetics bioenergetics, n 1. system in which natural healing is enhanced by creating harmony between the patient's body and the natural environment. 2. models to predict stable isotope ratios in fishes. Can. J. Fish. Aquat. Sci. 59:115-124. Hesslein, R. H., M. J. Capek D. E. Fox & K. A. Hallard. 1991. Stable isotopes of sulfur, carbon, and nitrogen, as indicators of trophic level and fish migration in the lower Mackenzie River Basin, Canada. Can. J. Fish. Aquat. Sci. 48:2258-2265. Hyslop, E. J. 1980. Stomach contents analysis--a review of methods and their application. J. Fish Biol. 17:411-429. Kline, T. C., Jr., W. J. Wilson & J. J. Goering. 1998. Natural isotope indicators of fish migration at Prudhoe Bay, Alaska
Prudhoe Bay (IPA: [ˈpɹu doʊ]) is a census-designated place (CDP) located in North Slope Borough in the U.S. state of Alaska. . Can. J. Fish. Aquat. Sci. 55:1494-1502. Michener, R. H. & M. Schell. 1994. Stable isotope ratios as tracers Tracers Refers to investment trusts which are populated by corporate bonds. In October 2001, Morgan Stanley's Tradable Custodial Receipts (Tracers) was launched. Tracers contain a number of coporate bonds and credit default swaps which are selected for liquidity and diversity. in marine aquatic food webs. In: K. Lajtha & R. H. Michener, editors. Stable isotopes in ecology and environmental science. Blackwell Scientific, pp. 138-158. McGinnis, T. W. & S. D. Emslie. 2001. The foraging ecology of royal and sandwich terns in North Carolina North Carolina, state in the SE United States. It is bordered by the Atlantic Ocean (E), South Carolina and Georgia (S), Tennessee (W), and Virginia (N). Facts and Figures Area, 52,586 sq mi (136,198 sq km). Pop. , USA. Waterbirds 3:361-370. Morsan, E. M. 2003. Spatial analysis and abundance estimation of the southernmost population of the purple clam, Amiantis purpurata in Patagonia, Argentina. J. Mar. Biol. Ass. U.K. 83:1073-1082. Olivier, S. R., M. R. Torti & R. Bastida. 1968. Ecosistema de las aguas litorales. Servicio de Hidrografia Naval. H. 1025. 46 pp. Peterson, B. J. & B. Fry. 1987. Stable isotopes in ecosystem studies. Ann. Rev. Ecol. Syst. 18:293-320. Radonic. M. 1997. Diversidad, abundancia y aspectos troficos de la fauna icticola acompanante de la captura del camaron y langostino, frente a las costas de Mar del Plata. Tesis de grado, Universidad Nacional de Mar del Plata. 53 pp. Rios, E. 1994. Seashells of Brazil. Rio Grande: FURG FURG Finite Unitary Reflection Group . 492 pp. Scarabino, V., 1977. Moluscos del Golfo San Matias (Prov. Rio Negro, Argentina). Inventario y claves Claves(pronounces Clar-vays) is a percussion instrument (idiophone), consisting of a pair of short (about 20-30 cm), thick dowels. Traditionally they were made of wood, but nowadays they are also made of fibreglass or plastics due to the longer durability of these materials. para su identificacion. Comunicaciones de la Sociedad Malacologica del Uruguay IV (31-32). pp. 177-297. Scelzo, M. A., J. Martinez Arca & N. M. Lucero. 2002. Diversidad, densidad y biomasa de la macrofauna componente de los rondos de pesca "camaron-langostino", frente a Mar del Plata, Argentina (1998-1999). Rev. Invest. Desarr. Pesq. 15:43-65. Sutela, T. & A. Huusko. 2000. Varying resistance of zooplankton zooplankton: see marine biology. zooplankton Small floating or weakly swimming animals that drift with water currents and, with phytoplankton, make up the planktonic food supply on which almost all oceanic organisms ultimately depend (see prey to digestion: implications for quantifying larval larval 1. pertaining to larvae. 2. larvate. larval migrans see cutaneous and visceral larva migrans. fish diets. Trans. Am. Fish. Soc. 129:545-551. Walker, J. L., C. W. Potter & S. A. Macko. 1999. The diets of modern and historic bottlenose dolphin populations reflected through stable isotopes. Mar. Mamm. Sci. 15:335-350. PABLO E. PENCHASZADEH, (1,2) FLORENCIA ARRIGHETTI, (1,2) * MAXIMILIANO CLEDON, (1,2) JUAN PABLO LIVORE, (1) FLORENCIA BOTTO (2,3) AND OSCAR (Open System for CommunicAtion in Realtime) AOL's internal project name for AOL Instant Messenger (AIM). The core functions of OSCAR, known as the Basic OSCAR Services (BOS), include Login/Logoff, Locate (find out about other AIM users), Instant Message O. IRIBARNE (2,3) (1) Facultad de Ciencias Exactas y Naturales, UBA UBA Universidad de Buenos Aires (Argentina) UBA Umweltbundesamt (German: Federal Environment Agency) UBA Ubiquitin-Associated UBA Urstadt Biddle Properties Inc UBA Urstadt Biddle Properties Inc. & Museo Argentino de Ciencias Naturales, Av Angel Gallardo 470 (1405), Buenos Aires, Argentina; (2) CONICET; (3) Laboratorio de Ecologia. Departamento de Biologia. Facultad de Ciencias Exactas y Naturales, UNMDP UNMDP Universidad Nacional de Mar Del Plata (Argentina) . CC 573 Correo Central 7600 Mar del Plata, Argentina. * Corresponding author. E-mail flora@bg.fcen.uba.ar
TABLE 1.
Biomass of the prey items identified in the stomach content analysis
(%)
C. striatus
Olivier Radonic
Prey items et al. 1968 1997 Ours
Crustacea
Artemesia longinaris 5 17.5
Pleoticus muelleri 0.6 0.5
Other 93 77 69.2
Polychaete 1.2 1 2.7
Ostheichthyes 2 2
Mollusca
Bivalve
Amiantis pupurata
Solen tehuelchus
Other
Gastropoda
Buccinanops monilifer
Cephalopoda
Loligo gahi
Cnidaria 3
Chaetognata 17
Others 8.1
U. brasiliensis S. bonapartei
Olivier Olivier
Prey items et al. 1968 Ours et al. 1968 Ours
Crustacea
Artemesia longinaris 46.7 6 21.6 7
Pleoticus muelleri 5.1 1 4.2 10
Other 43.8 75 62 71
Polychaete 5.4
Ostheichthyes 4.4 18 6.8
Mollusca
Bivalve
Amiantis pupurata 4
Solen tehuelchus 3
Other
Gastropoda
Buccinanops monilifer
Cephalopoda
Loligo gahi
Cnidaria
Chaetognata
Others
M. Furnieri
Olivier Radonic
Prey items et al. 1968 1997 Ours
Crustacea
Artemesia longinaris 22.4
Pleoticus muelleri
Other 57.2 45 37.3
Polychaete 6.1 13
Ostheichthyes 6.1 1
Mollusca
Bivalve
Amiantis pupurata 34.7
Solen tehuelchus 28
Other 6.1
Gastropoda
Buccinanops monilifer 2
Cephalopoda
Loligo gahi 41
Cnidaria
Chaetognata
Others
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