SUMMARY:The southern Brazilian coast is the major fishery ground for the Brazilian sardine (Sardinella brasiliensis), a species responsible for up to 40% of marine fish catches in the region. Fish spawning and recruitment are locally influenced by seasonal advection of nutrient-rich waters from both inshore and offshore sources. Plankton communities are otherwise controlled by regenerative processes related to the oligotrophic nature of the Tropical Water from the Brazil Current. As recorded in other continental margins, zooplankton species diversity increases towards outer shelf and open ocean waters. Peaks of zooplankton biomass and ichthyoplankton abundance are frequent on the inner shelf, either at upwelling sites or off large estuarine systems. However, meandering features of the Brazil Current provide an additional mechanism of upward motion of the cold and nutrient-rich South Atlantic Central Water, increasing phyto-and zooplankton biomass and production on mid-and outer shelves. Cold neritic waters originating off Argentina, and subtropical waters from the Subtropical Convergence exert a strong seasonal influence on zooplankton and ichthyoplankton distribution towards more southern areas. This brief review highlights the need for further experimental studies on zooplankton life cycle strategies in order to understand the major processes controlling food web dynamics in this shelf ecosystem.Keywords: zooplankton, ichthyoplankton, distribution, biomass, water masses, upwelling, continental shelf, south-western Atlantic Ocean. RESUMEN: INFLUENCIA DE LOS PROCESOS FÍSICOS EN LA DISTRIBUCIÓN DEL ZOOPLANCTON E ICTIOPLANCTON: UNA REVISIÓN DE LOS ESTUDIOS REALIZADOS ENLA COSTA SUR DE BRASIL. -La costa sur de Brasil representa la principal zona de pesca de la sardina brasileña (Sardinella brasiliensis), especie responsable de más del 40% de las capturas de especies marinas de la región. El desove y el reclutamiento están influenciados localmente por la advección estacional de aguas ricas en nutrientes procedentes tanto de fuentes costeras como oceánicas. Por otro lado, las comunidades planctónicas son controladas por procesos regenerativos asociados a la naturaleza oligotrófica del Agua Tropical procedente de la Corriente de Brasil. Como se ha observado para otros márgenes continentales, la diversidad de especies del zooplancton aumenta hacia las aguas de la plataforma externa y de océano abierto. Máximos en la biomasa de zooplancton y la abundancia de ictioplancton son frecuentes en la plataforma interna, tanto en afloramientos como en grandes sistemas estuáricos. No obstante, la formación de meandros en la Corriente de Brasil proporciona un mecanismo adicional para la ascensión de las aguas frías y ricas en nutrientes del Atlántico Sur Central, aumentando la biomasa fito-y zooplanctónica y la producción en la plataforma media y externa. Las aguas neríticas frías procedentes del estuario de La Plata y las aguas subtropicales de la Convergencia Subtropical ejercen una fuerte influencia en la distribución del zoopl...

RESUMOEm forma sintética são apresentadas a classificação sistemática, chaves, diagnoses, dados biológicos e distribuição geográfica de 82 espécies de Cladocera e Copepoda da região estuarina da Lagoa dos Patos (Rio Grande, Brasil). A informa ção é complementada com desenhos das espécies e ou das partes diagnosticas. ABSTRACTSystematic classification, keys, diagnosis, biological data and geografic distribution of 82 Cladocera and Copepoda species of the estuary of Lagoa dos Patos (Rio Grande, Brasil) are presented in a short form. This information is com pleted with designs of species and/or diagnostic parts.

Hatching and larval development of the semiterrestrial tropical brachyuran Sesarma angustipes were studied in relation to salinity in laboratory experiments. Adults were found in southern Brazil living in terrestrial habitats and in freshwater creeks When a free choice was offered in the laboratory, females hberated their larvae indscriminately in freshwater or seawater Rearing experiments were carried out at 0, 3, 10, 20, and 32 %O S. Unlike in other manne and brackish water species, freshly hatched zoea I larvae remained actively swimming in freshwater, where they survived for almost 2 d. Maximum survival time of zoea I exposed to 3 %O S was ca 3.5 d The larvae were able to pass through some or all developmental instars (4 zoeal stages and 1 megalopa) only at higher salinities. The zoea I at all salinities 2 10% S had a h g h sunival rate to the second stage. Its minimum duration of development (with 100 % survival), however, was observed at 20 :L S. From the zoea I1 stage, survival was in general highest and development shortest at 32" S, whilst l O I n S allowed only occasional development to later stages. This indicates a decreasing tolerance to low salinities and a shift in optimum salinity toward seawater in successive zoeal instars. Only 2 megalopae successfully reached metamorphosis to the juvenile crab, both at 20 M, S. These results may reflect the following hypothetical patterns in larval development of S. angustipes under field conditions: (1) the zoea I may hatch in freshwater or brackish water; (2) if hatching takes place in freshwater, the larva has 1 to 2 d to be transported by currents to brackish water or seawater; (3) the major part of zoeal development (from the zoea I1 or 111 stage) takes place in lower estuaries and coastal ocearuc waters with >20% S; (4) the megalopa may return to less saline environments. It remains unknown whether the megalopa can successfully metamorphose in freshwater, or if recruitment in rivers and other freshwater biota takes place by upstream migration of juveniles. Our results show that S. angustipes must be considered a marine species that has only started its transition to terrestrial and freshwater habitats. Larval morphology of S. angustipes was practically identical with that presented in a prevlous description of Sesarma ricordj larvae, confirming the hypothes~s that these 2 species are synonyms.

Larvae of the Chinese mitten crab Eriocheir sinensis were reared in the laboratory from the time of hatching and through metamorphosis. Development normally consists of a Prezoea, 5 Zoea stages, and a Megalopa. Occasionally, an additional (stage VI) Zoea and, in one case, an additional Megalopa (transitional to the first crab stage) were observed. Detailed morphological descriptions of all larval and the first two juvenile instars are given, and larval morphology is compared with that of two closely related species, Eriocheir japonicus and Eriocheir rectus, descriptions of which have recently become available. The zoeal stages of these species can be distinguished by their different number of aesthetascs and setae on the antennules, and different setation of maxillipeds 1 and 2. The Megalopa shows differences in the shape of the rostrum and again in the morphology of the antennule. These and other morphological differences (mainly in setation and spinulation of the zoeal carapace) between E. sinensis and E. japonicus larvae suggest that they may be very closely related but separate species; this contradicts a recent study of adult morphometrics and molecular genetics (Li et al., 1993), suggesting that they are only varieties of a single species.

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