VariaÃÃo temporal da meiofauna e da nematofauna em uma Ãrea mediolitorÃnea da bacia do Pina (Pernambuco, Brasil)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The basin of Pina has been studied for many years in order to check the level of organic pollutants. Many rivers are discharged in this basin bringing a big amount of pollutants to it. This affects the quality of organisms fished by the poor population that lives in the neighborhood. Up to now thereâs only one studie on meiofauna, specifically on nematofauna, carried out at this place, despite of its great role for the benthic trophic net. Biosedimentic samples were taken weekly during 3 months at the low pluviosity phase (January, February and March) and 3 months at the high pluviosity (June, July and August) of 1999 in a fixed transect at intertidal area, with 5 random replications, making a total of 120 samples. It was used a corer of 5 cm length and 2.5 cm of internal diameter. Temperature was measured and sediments were taken for granulometric and organic matter analyses. Monthly, on the lowest tide day, water was collected using a bottle of Nanser to verify the amount of dissolved oxygen (BOD) and salinity to follow the variation of polluting loaded in the estuary. The Nematoda were mounted in permanent slides and identified, moreover the population and trophic structures were defined. Statistical programs were used to correlate the non-biotic factors with the meiofauna and the nematofauna. Using the same methodology meiofauna and sediments were collected in 10 sample points covering the entire basin. Qualitatively the meiofauna composition was the same for the two studied phases, composed by 10 taxa: Turbellaria, Gastrotricha, Nematoda, Rotifera, Tardigrada, Polychaeta, Oligochaeta, Acari, Ostracoda e Copepoda. The highest monthly average for the meiofauna was in March (3126.5 ind. 10cm-2) with 90% composed by Nematoda and the lowest was in August (1291.15 ind.10 cm-2) with 97% Nematoda. Weekly the highest density was recorded at the last week of June (4785.2 ind. 10 cm-2) with 84% composed by Nematoda while the lowest was recorded at the first week of January (453.25 ind. 10 cm-2) with 63% Nematoda. The nematofauna was composed by three orders: Enoplida, with trhee families and four genus, Chromadorida, with five families and thirteen genus and Monhysterida, with five families and ten genus. The genera found were: Anoplostoma, Astonema, Axonolaimus. Chromadorita, Chromaspirinia, Daptonema, Desmodora, Halalaimus, Halichoanolaimus, Linhomoeus, Marylynnia, Metachromadora, Oncholaimus, Paracanthonchus, Paracyatholaimus, Paramonohystera, Parodontophora, Pomponema, Prochromadorella, Pseudochromadora, Sabatieria, Spirinia, Terschellingia, Thalassomonystera, Theristus, Tricotheristus e Viscosia. The temporal pattern showed the rainy phase with highest densities, positively correlated to organic matter and grains arrangement. The new species Spirinia n.sp. was very resistant to the physical-chemical conditions of the studied environment, since it was dominant during almost all period of this survey, except when the rain levels lowered (end of July and beginning of August). When this happens Therschelingia and Daptonema change this dominance. The amount of organic matter observed reflects itself on the community structure but there is a combination of effects with the granulometry acting independent of the climatic phase. The dynamic of the non-biotic parameters in an estuary allied with the rapidity of morphological changing of the Nematoda to survive in extreme environments confirms the importance of weekly monitoring this community in order to have more precise answers about these organisms so important in brackish environments

ASSUNTO(S)

oceanografia poluiÃÃo nematoda estuÃrio meiofauna

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