Ictoplâncton do complexo estuarino de Itapessoca norte de Pernambuco - PE.
Abstract
The present study was carried out in the estuarine complex of Itapessoca, located on the north
coast of Pernambuco (PE) Brazil, at latitudes 07º 37 - 07º 41 S and the longitudes 034º 50 -
34º 55 W, from April 2001 to April 2002. The purpose was to characterize the environment
and the ictioplanktonic community, attempting to recognize the distributional trends of these
organisms, in order to evaluate the estuary s role as a site for the fish initial development
phases. The water temperature, salinity and transparency were measured and the collected
samples of the water where analyzed in order to estimate the levels of nitrite, nitrate and
dissolved phosphate, ammonia, alkalinity and chlorophyll-a. The ictioplankton was collected
through horizontal hauls with plankton net with 500 µm mesh. The hauls had a standard
duration of 10 minutes, with the approximate speed of two knots. It was calculated the
specific diversity of the fish larvae and the biotic and abiotic data were statistically related. A
total of 87,758 eggs and 6,677 larvae were sampled corresponding to a total density of
39,445.34 eggs.100m-3 and 3,001.17 larvae.100m-3. The eggs and the larvae were present in
all months and sampling stations. In relation to the fish larvae a total of 8 orders and 19
families were identified. The Engraulidae family was the most abundant (69,53%), followed
by Eleotridae (7,73%) and Gobiidae (6,53%). Despite of the considerable integrity state of the
Itapessoca estuary, the values of the diversity family indexes were low, in comparing to other
estuarine areas. These low values can be explained by the dominance of the Engraulidae
family, in all months and sampling stations. It was verified that the environment is rich in
phosphate, with high levels of alkalinity; the levels of chlorophyll-a were in accordance with
productive environments, but the low values of nitrite, nitrate and ammonia can indicate that
nitrogen is a limiting factor of the local productivity, reflecting in the low occurrence levels
of ictioplanktonic organisms at the estuarine complex of Itapessoca.