DinÃmica do microzooplÃncton no Canal de Santa Cruz, Pernambuco, Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Studies were carried out to assess the transport dynamics and the microzooplanktonic community structure from the south and north inlets of Santa Cruz Channel (Itamaracà â PE) in relation to the adjacent shelf, considering tidal phases and depth. Plankton samples were taken with a pump at three stations along a transect across the inlets. At the central station (Center or Convergence), three depth levels were sampled (50 cm below the surface, at midwater and 50 cm above the bottom), while at the lateral stations (Continent and Island stations), samples were taken only at subsurface and above the bottom. Samples were taken in 3-hour intervals during spring tide (03 to 04 august â Orange inlet and 05 to 06 August, 2001 â Catuama inlet) and neap tide (09 to 10 august â Orange inlet and 11 to 12 August, 2001 â Catuama inlet). Plankton samples were taken with a pump at three stations along a transect across the inlet. Sample water was pumped on board through a conical 64 μm mesh size plankton net for 3 to 5 minutes per sample, at approximately 100 litres per minute. Before each sampling series, a complete 3-D current profile from one margin to the other was obtained with an ADCP (Acoustic Doppler Current Profiler) probe mounted on a small vessel. Additionally, current velocity and direction was measured continuously with the ADCP (RD Instruments) during all plankton sampling stations. Temperature, salinity and dissolved oxygen data were also obtained at all stations. Wet weight data were obtained in the laboratory. 51 taxa were identified at Catuama and 44 at Orange inlet. The holoplankton presented 70% of total abundance, Copepoda in the naupliar phase dominating at both inlets (50 to 80% of abundance). Among Copepoda, Oithona hebes, Euterpina acutifrons and Parvocalanus crassirostris, dominated which are characteristic of estuarine areas. In samples where Copepoda nauplii were less representative, Protozoa outranked, mainly Favella ehrenbergii. Diversity and evenness were low, indicating an unbalanced system, caused by the increasing anthropic impacts to the region. The dynamic pattern in both inlets in relation to the factors studied (photoperiod, depth, stations, tidal phase and cycle), showed that only the tidal phase and cycle influenced the biotic and abiotic factors, being important in structuring the zooplankton community. In relation to the instantaneous transport were observed positive values showing a net import of microzooplankton during flood tide. This may be caused by the high marine influence, large size of inlets and low freshwater discharge. It can be concluded, for the rainy season, that the adjacent shelf contributes to a higher flux of microzooplankton to the Santa Cruz Channel through the Orange and Catuama inlets

ASSUNTO(S)

oceanografia dinÃmica estuÃrios transport estuary microzooplankton microzooplÃncton transporte dynamic

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