DISTRIBUIÇÃO ESPACIAL DE PEIXES ESTUARINOS NO LITORAL AMAZÔNICO BRASILEIRO.

Abstract

Estuaries as freshwater and marine interactive ecosystems comprise important zones for refuge, growth and development of fish and other animals. This study was conducted concerning the estuarine icthyofauna spatial distribution from Brazil’s Amazonian coast at the Gulf of Maranhão. Fish sampling was carried out using trawl net with 6.0m long by 3.0m wide and 1cm mash size between knots. For each trawling, the mean distance traveled was 300m at an average depth of 5.8 meters with an estimated duration of 5 minutes each, totaling 132 samplings. Afterwards each trawling, fish were placed into tagged plastic bags under refrigeration and transported to the laboratory. A total of 4.400 fish, belonging to 11 orders, 23 families and 66 species were collected. Ten species contributed to more than 82% from the total sampling. Orders Siluriformes and Perciformes were the most representative with 84.9%, while species of Scianidae and Ariidae were the most numerous. Small individuals were predominant in the captures, suggesting that estuaries may work as nursery areas for several species at juvenile stages. Analyzing environmental parameters it was demonstrated that the Gulf of Maranhão is stratified, comprising heterogeneous habitats. The canonic correspondence analysis (CCA) indicated that temperature, dissolved oxygen, and total suspended solids were the most important environmental parameters affecting fish distribution. Therefore, the observed pattern for the estuarine fish community structure seems to be strongly influenced by fish physiological responses as function of the species plasticity regarding such environmental variations.