Variabilidade espacial e temporal na estrutura da comunidade de larvas de peixe e sua relação com os parâmetros físico-químicos na Plataforma Continental Pará-Maranhão (PCPM).

Abstract

This work aims to analyze the ecology of ichthyoplankton from coastal and oceanic regions of the Brazilian Amazon. For this, the samples were collected under the Project Characterization of Strategic Areas in the Amazon, coordinated by PETROBRAS/CENPES. The campaigns took place in two different periods, the first from 05/26 to 07/10, 2012, and the second from 10/02 to 11/28, 2012. The sampling strategy considered four profiles perpendicular to the coast with the station placement on predetermined isobaths between depths of 25 and 3,000 m. To collect ichthyoplankton, horizontal hauls were made using a multiple opening and closing net – Mocness with 300 and 500 μm meshes, being dragged at different depths (-1, -50, -250, -800 and -2300 m). In situ environmental parameters were acquired by a CDT/Rosette and satellite images were acquired from their specific sites. The number of collected larvae was converted into abundance (ind/m3) to then calculate the frequency of occurrence and relative (F.O and F.R) and relative abundance (A.B). The in situ environmental data were visualized in the format of vertical and horizontal profiles, and surface data acquired by satellite were prepared in the Surfers 16 program. The coastal-ocean-depth environmental gradient and its implication in the distribution of larvae were analyzed using nodal analysis (Q and R mode cluster), Canonical Redundancy Analysis – RDA and variance partition. There were differences in environmental parameters between campaigns mainly between temperature, which may be a trigger for the spawning of G. oceanicus in the ocean where it was the most abundant species. The strength of the surface current has a great influence on the water masses, causing a layer of mixture between AT and ACAS, which occasionally generated a pool of species in this region, which can be a spawning site for several marine/estuarine demersal species and pelagic. The species C. pseudopallida was the most frequent and abundant species in deep samples (mesopelagic and bathipelagic).