THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE SPATIAL AND TEMPORAL DISTRIBUTION OF MARINE CLADOCERANS (CRUSTACEA, BRANCHIOPODA) IN AN ESTUARY OF UBATUBA, SP / INFLUÃNCIA DE FATORES AMBIENTAIS SOBRE A DISTRIBUIÃÃO TEMPORAL E ESPACIAL DE CLADÃCEROS MARINHOS (CRUSTACEA, BRANCHIOPODA) EM UM ESTUÃRIO DE UBATUBA, SP

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The aim of the present study is to analyse the occurrence and the horizontal-temporal distribution of marine cladocerans in a shallow estuarine region associated to a mangrove forest, and to verify the possible influence of environmental factors on the temporal variation of the species. In the period from July 2004 to June 2005, zooplankton samples were taken during the flood tide of sizygia in two sampling stations located on Praia Dura estuary, Ubatuba city, SP. The samples were collected in triplicates through horizontal hauls using a planktonic conic net with a fluxometer attached to determine the filtered water volume and, the sampled zooplankton was immediately preserved with 4% neutral formaldehyde solution. Simultaneously with the sampling, temperature, salinity, pH and dissolved oxygen of the water were measured. In the laboratory, subsamples were taken from the original collected samples and the zooplankton were analised under a stereomicroscope. So, the marine cladocerans were identified at species level and quantified. The zooplankton abundance was expressed by individuals per cubic meter. Three marine cladocerans species were registered in the Praia Dura estuary. Penilia avirostris was the dominant species and appeared throughout of the year. Pseudevadne tergestina and Pleopis polyphemoides were the less frequent species, but this later showed a ix seasonal variation occurring in the spring and summer months. The occurrence of P. polyphemoides presented negative correlationship with the temperature and a positive correlationship with the dissolved oxygen. The abiotic factors and the species abundances didnât show any statistical difference between the sampling stations (always p >0,05). The Component of principal Analysis presented that the species P. avirostris, P. tergestina and P. polyphemoides, had organized as an group, being 60% of the variance was explained by the dissolved oxygen.

ASSUNTO(S)

branchiopoda environmental factors estuÃrio cladÃceros marinhos fatores ambientais marine cladocerans estuary ubatuba aquicultura branchiopoda ubatuba

ACESSO AO ARTIGO

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