Caracterização ambiental e distribuição espaço-temporal da biodiversidade de ovos e larvas de peixe no estuário Guajará-Mirim (Pará-Brasil).

Abstract

The estuaries are transitional ecosystems and between the continent and adjacent coastal zone where rivers meet the sea. This study was conducted to determine the composition and distribution of larval fish (ichthyoplankton) estuary Guajará-Mirim. To this were collected bimonthly over a year in less rainy season and rainy, variations mare during daytime, nighttime and diurnal collections. Were pre-established four stations along the estuary to evaluate the effect of tides and a fixed station to collect diurnal. Were determined pH, salinity, temperature, conductivity and dissolved oxygen. To collect the material faunal subsurface trawls were performed with the aid of plankton nets with mesh of 300 and 500μm and 50 cm mouth opening, which was coupled a flow meter, the samples were preserved in 4% formalin. 7,217 larvae were collected, and 1,242 larvae in tidal ebb, 1,896 larvae in tidal flood, 3509 larvae in gathering night, 303 larvae in nictemeral the rainy season and 267 larvae in less rainy season. 3,869 larvae in plankton net mesh of 300μm and 3,348 larvae in plankton net mesh 500μm. The larvae were in 07 orders, 17 families and 33 species were collected and further 121 eggs. The order Clupeiformes and their families Engraulidae and Clupeidae were the most abundant throughout the study, with development in pre-bending as more abundant and species Rhinosardinia Amazon, with the highest densities recorded in the less rainy season and Anchovia clupeoides higher densities in rainy season. In the collections of tidal variation in collecting nocturnal and Diel in the greatest density of species was Anchoa hepsetus. The ordering has identified influences of environmental factors, and seasonality, while the variance characterized partition the variables test (environmental and temporal) together cause an influence on larval dispersion and principal component analysis identified the seasonal influences, collections both in daytime as night, the tidal cycle, and gathering nictemeral.