Micro-and mesozooplankton were studied in the Sergipe estuary, northeastern Brazil, in order to assess the temporal variability in abundance and biodiversity under stressed conditions (urban pollution). Zooplankton samples and abiotic data were collected at one station during a full tidal cycle in July 2001 and in February 2002, corresponding to the rainy and dry seasons, respectively. The salinity regime was euhaline-polyhaline. Phosphate and dissolved oxygen were higher in July 2001, and nitrite, nitrate and ammonia in February 2002. Chlorophyll-a concentrations were low as a result of light limitation, with 1.18 ± 0.88 µg.m -3 in February and 1.53 ± 1.48 µg.m -3 in July. Fifty-nine zooplankton taxa were identified. Microzooplankton were abundant, mainly the tintinnid Favella ehrenbergii, and ranged from 18,649 ind.m -3 in July to 678,009 ind.m -3 in February. Mesozooplankton ranged from 1,537 ind.m -3 in July to 37,062 ind.m -3 in February and were dominated by barnacle nauplii in July and by copepods in February. The cluster analysis by taxa revealed the existence of three distinct groups: resilient species, characteristic of estuarine areas and occurring during all the year; species mainly more abundant in July (indicators of a healthier environmental condition); and species more abundant in February (tolerant to poor water quality). em fevereiro e foi dominado por náuplios de Cirripedia em julho e por Copepoda em fevereiro. A análise de agrupamento por taxa revelou a existência de três grupos: espécies resilientes, características de áreas estuarinas de ocorrência contínua; espécies que dominaram em julho (indicadores de uma melhor condição ambiental); e espécies mais abundantes em fevereiro (tolerantes à baixa qualidade da água). KeywordsPalavras-chave: zooplâncton, estuário tropical, variação sazonal, nordeste do Brasil. Araujo, HMP. et al. 752

The spatial and seasonal distribution of the Paracalanidae species were studied in eighteen stations in the continental shelf off Sergipe and Alagoas States, northeast Brazil, in December, 2001 and 2003, and in June, 2002 and 2003. The Paracalanidae family was constituted by coastal and shelf species such as Parvocalanus crassirostris, Paracalanus quasimodo, P. indicus and P. aculeatus and oceanic species, Calocalanus pavo and Acrocalanus longicornis. Density values were higher in stations located at 10 m isobath with respect to those located at 20 and 30 m depths. Paracalanidae abundance presented differences between seasons with values higher in June (2002, 2003) than in December (2001, 2002). All species were more abundant in the rainy season except Parvocalanus crassirostris. Paracalanus quasimodo was the dominant species with average densities of 949, 740 and 41 ind.m-3 in December months and 4231, 2389 and 1185 ind.m-3 in June months, at stations with local depths of 10, 20 and 30 m, respectively. Canonical correspondence analysis showed that salinity and temperature were the environmental variables that presented significant correlation with the distribution of Paracalanidae species, probably because these variables are influenced by the estuarine waters and by the dynamic of oceanic water masses in the continental shelf.
A distribuição espacial e sazonal das espécies de Paracalanidae foram estudadas em dezoito estações na plataforma continental dos Estados de Sergipe e Alagoas, nordeste do Brasil, em dezembro de 2001 e 2003 e junho de 2002 e 2003. A família Paracalanidae esteve constituída por espécies costeiras e de plataforma tais como Parvocalanus crassirostris, Paracalanus quasimodo, P. indicus e P. aculeatus e por espécies oceânicas, Calocalanus pavo e Acrocalanus longicornis. Os valores de densidade total foram mais elevados nas estações localizadas em isóbata de 10 m decrescendo nas estações localizadas em profundidades de 20 e 30 m. A abundância de Paracalanidae apresentou padrão de flutuação sazonal, com valores mais elevados em junho (2002, 2003) do que em dezembro (2001, 2002). Todas as espécies foram mais abundantes no período chuvoso com exceção do Parvocalanus crassirostris. Paracalanus quasimodo foi a espécie dominante, com densidades médias de 949, 740 e 41 ind.m-3, nos meses de dezembro e de 4231, 2389 e 1185 ind.m-3, nos meses de junho, em isóbatas de 10, 20 e 30 m, respectivamente. A análise de correspondência canônica mostrou que a salinidade e a temperatura foram os fatores ambientais que apresentaram relação significativa com a distribuição das espécies de Paracalanidae, provavelmente porque estes fatores foram influenciados pelas águas estuarinas e pela dinâmica das massas de água oceânicas na plataforma continental

A new species of ergasilid copepod, Ergasilus foresti, is described from the zooplankton communities of the upper reaches of Piauí river estuary in northeastern Brazil, and of the Patos lagoon and the Taim hydrological system in southern Brazil. The establishment of the new taxon is justi ed by comparisons with all congeners exhibiting a 2-segmented endopod in the rst leg. This endopod is elongate and bears a unique rosette of spinules on the posterior surface of the distal segment. RÉSUMÉUne nouvelle espèce de copépode de la famille des Ergasilidae, Ergasilus foresti, est décrite, en provenance des communautés zooplanctoniques de l'estuaire du euve Piauí, au nord-est du Brésil, et de la lagune Patos et du système hydrologique de Taim au sud du Brésil. L'établissement de ce nouveau taxon est justi é par comparaison avec tous les congénères ayant une première paire de pattes à endopodite bisegmenté. Dans la nouvelle espèce, cet endopodite porte une rosette de spinules sur la face postérieure du segment distal.

A new species of Acusicola is described based on adults of both sexes taken from plankton samples collected in the upper reaches of the Piauí River estuary, in the northeast of Brazil. Ovigerous females were present in the plankton. The new species, Acusicola minuta n. sp., can be distinguished from its congeners by its small body size, female antennal morphology and leg setation. The male described here as A. minuta n. sp. is the first known male attributed to the genus.

The purpose of this work was to study the composition and abundance of the mesozooplankton at two stations at the continental shelf off Sergipe. At each station, oblique plankton tows were carried using plankton nets with 200 µm mesh size, in six hours intervals during three consecutive days. One hundred and three taxa were identified and Copepoda was the dominant group with fifty one species. The mesozooplankton assemblage was composed by coastal, neritic and oceanic tropical species. There were significant differences in composition and abundance between the two studied stations (p<0,05) but not between tidal stages. At station 1, the most abundant species were Creseis acicula, Oikopleura spp., Temora stylifera, Paracalanus quasimodo and Aglaura hemistoma, and at station 2 Paracalanus quasimodo, Paracalanus spp., Siphonophora, Gastropoda and Decapoda larvae. Coastal species such as Parvocalanus crassirostris, Acartia lilljeborgi, Euterpina acutifrons and Corycaeus giesbrechti occurred only at the last station, located close to the mouth of the São Francisco River, where surface salinity and transparency values were low. In this station the salinity average value at surface was 30,8±1,9 and at the bottom layer was 35.0±0.3 PSU. Mesozooplanhton density values ranged between 124 ind.m -3 and 2,658 ind.m -3 at station 1, and from 734 ind.m -3 to 3,061 ind.m -3 at station 2. A Monte Carlo test based on a canonical ordination revelead that local depth and water transparency were significantly correlated to the mesozooplankton distribution.Key words: zooplankton community, Copepoda, shelf off Sergipe, tropical. DISTRIBUIÇÃO DO MESOZOOPLÂNCTON NA PLATAFORMA CONTINENTAL DE SERGIPE, BRASIL RESUMOA proposta desse trabalho foi estudar a composição e abundância do mesozooplâncton em duas estações, na plataforma continental de Sergipe. Em cada estação, arrastos oblíquos de plâncton foram feitos utilizando-se uma rede de plâncton de 200 µm de abertura de malha, em intervalos de seis horas, durante três dias consecutivos. Cento e três táxons foram identificados e Copepoda foi o grupo dominante com cinqüenta e uma espécies. A assembléia mesozooplanctônica foi composta por espécies tropicais costeiras, neríticas e oceânicas. Houve diferença significativa na composição e abundância entre as duas estações estudadas (p<0,05), mas não entre os estágios tidais. Na estação 1 as espécies mais abundantes foram Creseis acicula, Oikopleura spp., Temora stylifera, Paracalanus quasimodo e Aglaura hemistoma e na estação 2, Paracalanus quasimodo, Paracalanus spp., Siphonophora e larvas de Gastropoda e Decapoda.