Hydromedusae (Cnidaria: Hydrozoa) from the temperate southwestern Atlantic Ocean: a review

Hydromedusae are one of the best-represented planktonic groups in waters of the South Atlantic Ocean in terms of species richness. Nevertheless, medusae of the region are inadequately known because earlier studies have been limited and restricted to few areas. During the last two decades, almost 2000 samples from 54 research cruises have been collected, mostly within the continental shelf of Argentina and Uruguay (33 - 55° S). These samples provide an opportunity to significantly augment knowledge of the richness of the medusa fauna in the southwest Atlantic. Forty species of hydromedusae (six of them new records for the area), including 15 of Anthomedusae, 14 of Leptomedusae, three of Limnomedusae, four of Narcomedusae, and four of Trachymedusae, were identified. Our results indicate that previous lists overestimated species richness of hydromedusae in the area. When misidentifications, updated species synonymies, and doubtful records are taken into account, 71 valid species are recognized here from the study area. Based upon this corrected inventory list, the data suggest that the number of species of hydromedusae decreases markedly with increasing latitude, corresponding with that observed in other planktonic groups of invertebrates.Fil: Genzano, Gabriel Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mianzan, Hermes Walter. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Bouillon, Jean. Université Libre de Bruxelles; Bélgic

Primer registro de la medusa urticante invasora Gonionemus vertens en el hemisferio sur (Mar del Plata, Argentina)

En este trabajo registra el primer hallazgo de la hidromedusa Gonionemus vertens Agassiz, 1862 en el hemisferio sur. Alrededor de 30 medusas recientemente liberadas fueron encontradas en un acuario en septiembre de 2008. Este acuario contenía muestras bentónicas colectadas en la franja rocosa intermareal y submareal de Mar del Plata, cerca de uno de los puertos más importantes de Argentina. Las medusas fueron alimentadas con Artemia salina hasta su maduración gonadal. Se discute la posible vía de introducción de esta especie.In this paper we report the first finding of the hydromedusa Gonionemus vertens Agassiz, 1862 in the southern hemisphere. About thirty newly released medusae were found within an aquarium on September 2008. The aquarium contained benthic samples collected in intertidal and subtidal rocky fringe off Mar del Plata, near a commercially important harbor in Argentina. Medusae were feed with Artemia salina until sexual maturation. Possible way of species introduction is discussed.Fil: Rodriguez, Carolina Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pujol, M. G.. Provincia de Buenos Aires. Municipalidad de General Pueyrredon. Secretaría de Cultura. Museo Municipal de Ciencias Naturales Lorenzo Scaglia; ArgentinaFil: Mianzan, Hermes Walter. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Genzano, Gabriel Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentin

Amphipod-supported food web: Themisto gaudichaudii, a key food resource for fishes in the southern Patagonian Shelf

The trophic role of the hyperiid amphipod Themisto gaudichaudii in the southern Patagonian shelf food web was assessed from the analysis of stomach contents of the local fish assemblage. A total of 461 trawl samples were collected during seven seasonal cruises. A total of 17 out of 38 fish species were found to ingest T. gaudichaudii. This amphipod was a main prey item in five of these species, showing high values of alimentary index: Seriolella porosa (99.9%), Macruronus magellanicus (68.8%), Micromesistius australis (59.1%), Patagonotothen ramsayi (48.6%), and Merluccius hubbsi (10.9%). The contribution of T. gaudichaudii, in weight, to their summer diet was 60%, on average. This contribution was minimal in winter and maximal in summer. Fisheries studies have indicated that these five species, mainly M. magellanicus, account for almost 85% of the fish biomass in the area. Although the remaining 15% did not feed heavily on T. gaudichaudii, they are known to prey on the main hyperiid predators. Our study shows that T. gaudichaudii contributes greatly, both directly and indirectly, to supporting the fish community. We thus proposed that T. gaudichaudii plays a key role as a "wasp-waist" species in the sub-Antarctic region, similar to that of krill in Antarctic waters, channeling the energy flow and enabling a short and efficient food chain.Fil: Padovani, Luciano Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Viñas, Maria Delia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Sánchez, Felisa. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Mianzan, Hermes Walter. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentin

Reproductive biology of Lychnorhiza lucerna (Cnidaria: Scyphozoa: Rhizostomeae): Individual traits related to sexual reproduction

We studied individual traits related with sexual reproduction of Lychnorhiza lucerna and review how sexual maturation has been studied for scyphomedusae, focusing on the particular case of non-brooding species. L. lucerna is a gonochoric species and sexual dimorphism was found in the colour of the gonads. There were no brooding structures or any other distinguishable feature that enable macroscopic determination of sex. Gametogenesis in L. lucerna resembled the descriptions available for other rhizostomes and semaeostomes. Both processes are asynchronous since gametes at all stages of development occurred simultaneously. Oocytes arose from the gastrodermis and maintained contact with it via trophocytes throughout vitellogenesis. Spermatogenesis occurred within the spermatic follicles arising from nested primary spermatogonia in the mesoglea. Population features of sexual reproduction are defined by characterizing and quantifying individuals at different stages of sexual maturity. Regarding sexual maturation in Scyphozoa, sexually mature medusae can be detected by i) the presence of fully-developed gametes in the gonads indicating near future spawning, or ii) by the presence of spent spermatic follicles as evidence of ongoing or recent spawning events. Whereas the former allows getting a more detailed study of sexual reproduction patterns of any species, the later constitutes an option for non-brooders equivalent to the search of fertilized eggs or planulae for brooder species, as exemplified in this work.Fil: Schiariti, Agustin. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Christiansen, Enesto. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Morandini, Andre Carrara. Universidade de Sao Paulo; BrasilFil: da Silveira, Fabio Lang. Universidade de Sao Paulo; BrasilFil: Giberto, Diego Agustin. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mianzan, Hermes Walter. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

The taxonomic position of the pelagic 'staurozoan' Tessera gemmaria as a ceriantharian larva

Based on 16 specimens from the Southwestern Atlantic coast (Argentina and Brazil) we reinterpret the taxonomic position of Tessera gemmaria Goy, 1979, a stauromedusa considered as incertae sedis for a long time. Using external morphology histological preparations and molecular data (16S and COI) we conclude that T. gemmaria is an early stage of a cerinula,the long-lived planktonic larval stage of the Ceriantharia (Anthozoa).Tessera gemmaria Goy, 1979, a stauromedusa considered as incertae sedis for a long time. Using external morphology histological preparations and molecular data (16S and COI) we conclude that T. gemmaria is an early stage of a cerinula,the long-lived planktonic larval stage of the Ceriantharia (Anthozoa).Fil: Rodriguez, Carolina Soledad. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Marques, Antonio C.. Universidade de Sao Paulo; BrasilFil: Stampar, Sérgio N.. Universidade de Sao Paulo; BrasilFil: Morandini, André C.. Universidade de Sao Paulo; BrasilFil: Christiansen, Ernesto. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Genzano, Gabriel Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mianzan, Hermes Walter. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin

Pesca y consumo de medusas en Iberoamérica

Debido a su capacidad urticante, las medusas suelen causar cierto rechazo en la población. En Latinoamérica se las conoce por aguas vivas, aguamalas o malaguas. En China y Japón, en cambio, son muy valoradas. Se las considera una delicia gastronómica digna de las ocasiones más especiales; en las celebraciones del año nuevo chino, bodas o cualquier otra fiesta con banquete, raramente falta una buena ensalada o sopa de medusas.Fil: Schiariti, Agustin. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Mianzan, Hermes Walter. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Fuentes, Verónica. Consejo Superior de Investigaciones Científicas. Instituto de Ciencias del Mar; Españ

Hyperoche medusarum (KRØYER, 1838) (Amphipoda, Hyperiidae) and Mnemiopsis mccradyi (Mayer, 1910) (Ctenophora): a new host and first record of this association for the Southwestern Atlantic

The association of gelatinous zooplankton (ctenophores, medusae, siphono- phores, and salps) with hyperiid amphipods, has reached a total of 85 species of amphipods up to 1980 (Harbison et al., 1977; Laval, 1980). Some of these amphipods begin their life cycle as obligate parasites, being found afterwards as free-swimming adults in the plankton (Von Westernhagen, 1976; Hoogenbaum & Hennen, 1985; Dittrich, 1992). Others use the host as a substrate, as food for their brood, and protection against enemies during their whole life. The amphipod Hyperoche medusarum (Krøyer, 1838), has been found as a parasite on six species of cnidarian medusae and ve ctenophores (Laval, 1980; Cahnon et al., 1986). The present study reports its association with Mnemiopsis mccradyi (Mayer, 1910) observed on live specimens captured during the austral summer of 2000 in the harbour of Mar del Plata, Argentina ( g. 1). Sixty-eight specimens of Amphipoda were found among the tissues, in cavities of the body, and over the surface of 24 ctenophores, with an average of 2-3 individuals per host. These observations were complemented aboard the RV “Canepa”, with fixed samples taken during December 1999 in coastal waters of the district of Buenos Aires, between 36º 30'S and 38º 30' S ( fig. 1). These specimens were identi ed on board, previous to their conservation with formalin.Fil: Sorarrain, Dora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Ramírez, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Mianzan, Hermes Walter. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; Argentin

¿Un Mar de gelatina?

Los celentéreos o celenterados forman un gran grupo de invertebrados marinos que incluye a hidras, corales, pólipos y medusas. Hasta el siglo XVIII se los consideraba plantas. El público que concurre a balnearios marinos suele tener dolorosos encuentros con las últimas.Fil: Mianzan, Hermes Walter. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Ramírez, Fernando. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Costello, John. University of Southern California; Estados UnidosFil: Chiaverano, Luciano. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentin

Influence of a tidal front on zooplankton abundance, assemblages and life histories in Península Valdés, Argentina

The complex biophysical interactions that occur in Península Valdés tidal front offer an appropriate scenario to study how zooplankton species respond to the environmental setting. In that sense, we studied why some zooplankton assemblages come to dominate in certain areas, focusing on the differential use that each life history stage makes on the hydrodynamic regimes. Environmental data and zooplankton samples were taken across the tidal front, covering well-mixed, frontal and stratified waters. Zooplankton abundance, assemblage structure, specific composition and life histories were analyzed in relation to depth, temperature, stratification level of the water column and chlorophyll a. Zooplankton-specific composition did not vary across the different zones of the front but, due to differences in relative abundance, three assemblages were detected in coincidence with the three zones analyzed. Most zooplankton adult groups and early life stages were related to the stratification level of the water column. This environmental factor best explained the coupling of the three different zooplankton assemblages with the three zones of the frontal system. This distributional pattern was clearly observed in the copepods group. Despite different copepod species prevailing in different parts of the tidal front, the frontal interface appears to be an important breeding area for all copepod species. The stratification level would be the main factor responsible for the zooplankton distributional pattern across the tidal front, although other physical and biological processes, such as transport, retention and life history strategies could be conditioning the establishment of different zooplankton populations in this complex frontal system.Fil: Derisio, Carla María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Alemany, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Acha, Eduardo Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Mianzan, Hermes Walter. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Jellyfish bycatch diminishes profit in an anchovy fishery off Peru

Peru supports one of the world’s largest single-species fisheries based on the Peruvian anchovy (Engraulis ringens L. Jenyns, 1842), and bycatch of the scyphomedusa Chrysaora plocamia (Lesson, 1832) affects this fishery. Medusae display strong seasonal fluctuations, with peak abundances during summer. Off southern Peru and during the austral summer 2008–2009, C. plocamia were >30% of the catch in 5% of the hauls, which was enough to cause economic losses of more than 200,000 US$ in only 35 d of fishing. Fishery factories refused to receive the catch if jellyfish bycatch was >40% ofthe catch in weight. Economic losses could substantially increase during warm periods like El Nino, ˜ during which C. plocamia medusa abundances greatly increase. This study was the first attempt to quantify economic losses due to jellyfish through the use of bycatch rates and interviews with employees of fishery factoriesFil: Quiñones Dávila, Javier. Instituto del Mar del Perú; PerúFil: Monroy, Aldrin. Instituto del Mar del Perú; PerúFil: Acha, Eduardo Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mianzan, Hermes Walter. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin