Amostragens quantitativas de plâncton foram desenvolvidas no sistema estuarino de Itamaracá durante baixa-mares diurnas de fevereiro de 1995 a maio de 1996. Utilizou-se uma rede de plâncton de 300µm de abertura de malha e 60cm de diâmetro de boca. Foram registrados 49 taxa, inclusive 29 taxa de Decapoda. Os taxa mais abundantes foram Copepoda, zoeas de Brachyura, náuplios de Cirripedia, adultos de Lucifer faxoni, Chaetognatha, Appendicularia, ovos de peixe, Gastropoda, e zoeas de Upogebiidae. As zoeas de Brachyura examinadas (N=265) pertenceram ás famílias Ocypodidae, Grapsidae, Xanthidae e Leucosiidae. Larvas do caranguejo-uçá (Ucides cordatus) e de caranguejos chama-maré (Uca spp.), foram encontrados somente na área estuarina, indicando que não houve exportação de larvas destes grupos do estuário para a plataforma continental. Zoeas de Xanthidae e Grapsidae foram encontradas nas plumas estuarinas e na plataforma, porém em numero inferior. Análise de agrupamento e MDS (escala multidimensional), baseados em dados de abundância, não demonstraram nenhum padrão claro de agrupamento das estações ou dos taxa, indicando a existência de uma comunidade relativamente homogênea. Análise de correlação realizada com dados log10(x+1)- transformados de 19 taxa mostrou 39 correlações significantes entre os grupos. A alta variabilidade geral dos dados, tanto como a ocorrência de correlações positivas entre as abundâncias de muitos grupos na área de Itamaracá provavelmente são o resultado da agregação de macrozooplâncton em áreas de convergência. Palavras chave: Zooplâncton tropical, manguezal; larvas de Curstáceo Decapoda

ABSTRACT

ABSTRACT. Studies were carried out to assess the macrozooplankton small-scale temporal and spatial variability at three stations in three hours intervals, during 24 hours in July 1996 (rainy season) and December 1996 (dry season). A plankton net 300µm mesh size was hauled at surface during three minutes. Water samples for salinity, temperature, dissolved oxygen and pH were taken simultaneously with the zooplankton samples. Sixty-five macrozooplankton taxa were registered. Copepoda constituted the most common taxon and comprised 58% of the total zooplankton counts. Brachyuran zoeae, cirripedian larvae, Larvacea (Oikopleura dioica Fol, 1872), and Gastropoda veligers were abundant at some tidal cycles, mainly during the night. Species diversity average was 2.0 bits . ind -1 . The mean density ranged from 23 ind . m -3 to 5,201 ind . m -3 . The rainy season presented greater numerical abundance. A regular temporal zooplankton cycle was not observed. Instead, there was a large stochastic variation between samples.

This study provides baseline information on the hydrological conditions and on the coral and plankton communities at the Maracajaú reef ecosystem (Northeastern Brazil

This study was carried out to assess the diversity and the abundance of the reef zooplankton in the Maracajaú reefs. Samples were collected with two plankton nets (65 and 300 micrometers mesh size, each) from February to June/2000 at three stations in a transect perpendicular to coast. Plankton biomass in the 65 µm fraction varied from 45.19 mg.m -3 to 316.45 mg.m . In the 300 µm fraction biomass varied from 9.33 mg.m -3 to 43.16 mg.m -3 . Zooplankton presented 61 taxa. Copepods were the most diverse taxa with 23 species. Euterpina acutifrons, Oithona oswaldocruzi, Oithona hebes, Oithona sp., Parvocalanus crassirostris, Acartia lilljeborgi, Bivalvia and Gastropoda larvae, Trilocularina sp., Balanus sp. larvae, Spirillina sp., Polychaeta larvae, Brachyura (zoea) and Oikopleura longicauda occurred in more than 75% of the samples. The zooplankton followed a seasonal pattern, with the highest numbers occurring during the rainy season (February). A high density of microzooplankton was found which varied from 1,917 ind.m and a maximum of 1,617 ind.m -3 . Species diversity was intermediate (~2 bits.ind -1 ) and eveness relatively high (~0.78). Samples could be joined into 3 groups, mainly influenced by rainfall. Species similarity presented 5 groups: oceanic, neritic, a mixture of neritic and oceanic, reef and estuarine. Our data suggest a dynamic relationship between the zooplankton communities characteristic of inshore water trapped by the coastal boundary layer and more offshore plankton communities.