Mesozooplâncton do sistema estuarino de Barra das Jangadas, Pernambuco, Brasil

Abstract

r ra a a a a das das das das das J J J J Jangadas, angadas, angadas, angadas, angadas, Per Per Per Per Pernamb namb namb namb nambuco uco uco uco uco, Br Br Br Br Brazil. azil. azil. azil. azil. Mesozooplankton studies were carried out at the Barra das Jangadas estuarine system, Pernambuco, Brazil (8º14'36"S, 34º56'28"W), to assess its community structure. Samples were collected with a plankton net (300 µm mesh size) during the dry (January, 2001) and rainy (July, 2001) seasons, with three hour intervals between each sampling, both in spring and neap tides. Thirty seven mesozooplankton taxa were identified, from which Copepoda were particularly abundant, including the species Pseudodiaptomus acutus (F. Dahl, 1894), Peudodiaptomus richardi (F. Dahl, 1894), Acartia lilljeborgi (Giesbrecht, 1892), Parvocalanus crassirostris (Dahl, 1894), Oithona hebes (Santos, 1973), and Notodiaptomus cearensis Wright, 1936. Total density varied from 69.34 to 8568.34 org.m -3 in the dry season and from 261.98 to 10224.83 org.m -3 in the rainy season. Meroplanktonic crustaceans (brachyuran zoeae) were very frequent and numerically abundant, playing an important role in the pelagic food web. Species diversity varied from 0.44 to 3.13 bits.ind -1 (dry season) and from 0.66 to 2.92 bits.ind -1 (rainy season). Low diversities were caused by the dominance of brachyuran zoeae. Cluster analysis revealed two groups, the first formed by marine euryhaline species and the second by true estuarine species. KEY WORDS. Estuary; Northeastern Brazil; zooplankton.RESUMO. Estudos sobre o mesozooplâncton foram realizados no sistema estuarino de Barra das Jangadas, Pernambuco, Brasil (8º14'36"S, 34º56'28"W) visando analisar a estrutura da comunidade. As amostras foram obtidas com rede de plâncton, com malha de 300 µm, durante os períodos, seco (janeiro/2001) e chuvoso (julho/2001), nas marés de sizígia e de quadratura, em intervalos de três horas. Foram identificados 37 taxa, destacando-se Copepoda com as espécies Pseudodiaptomus acutus (F. Dahl, 1894), Pseudodiaptomus richardi (F. Dahl, 1894), Acartia lilljeborgi (Giesbrecht, 1892), Parvocalanus crassirostris (Dahl, 1894), Oithona hebes (Santos, 1973) e Notodiaptomus cearensis Wright, 1936. A densidade total durante o período seco variou de 69,34 a 8.568,34 org.m -3 . Para o período chuvoso variou de 261,98 a 10.224,83 org.m -3 . Os Crustacea meroplanctônicos (Brachyura zoea) foram muito freqüentes e muito abundantes, destacando seu importante papel na cadeia trófica pelágica. A diversidade específica durante o período seco, variou de 0,44 a 3,13 bits.ind -1 , e para o período chuvoso de 0,66 a 2,93 bits.ind -1 . Os baixos valores de diversidade ocorreram devido à dominância de Brachyura (zoea). A análise de agrupamento revelou a formação de dois grupos. O primeiro formado por espécies marinhas e euri-halinas, e o segundo por espécies indicadoras de ambientes estuarinos. PALAVRAS-CHAVES. Estuário; Nordeste do Brasil; zooplâncton.

Population dynamics of Calanopia americana Dahl F., 1894 (Copepoda, Calanoida) in a reef environment in tropical Brazil

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