ICTIOFAUNA DO GOLFÃO MARANHENSE – AMAZÔNIA ORIENTAL: DIVERSIDADE, DISTRIBUIÇÃO E CONCENTRAÇÃO DE METAIS NA ÁGUA E NOS PEIXES.

Abstract

The objective of this study was to identify and describe the spatial and seasonal variation, as well as the levels of contamination in the water and muscle tissue of fish in the Guf of Maranhão, in areas characterized by the confluence of the water masses of São José and São Marcos Bays. Additionally, a systematic review of articles on fish biodiversity in the Amazon was conducted, based on the principles of the Universal Declaration of Bioethics and Human Rights. The methodology involved a systematic search on the basis of the Scientific Electronic Library Online (Scielo) using Boolean descriptors and operators. The review involved the period from 2006 (year immediately following the publication of the statement) to 2018. The spatio-temporal variation study used a sampling design spatial and seasonally stratified with bimonthly samples from November 2015 to July 2018 along 4 collection points (P1, P2, P3 and P4) distributed in the Perízes and Mosquitos estuary, with sections P1 and P2 upstream and P3 and P4 downstream. The biological material was obtained from the installation of multifilament block nets with a 20 - 30 mm mesh. The water and fish contamination levels were evaluated along the Cachorros River, also characterized by stratified design with point distribution following a decreasing saline gradient (P1, P2 and P3), involving sampling in the rainy season. (April and June / 2014) and drought (September and November / 2014).The results indicated a low number of articles related to fish biodiversity of the Amazon region, with contributions of only 7.3% when compared to the total of studies with thematic areas in diversity and conservation of the Amazon. The ichthyofauna in the Perizes and Mosquitos estuary was represented by 52 species. The families Sciaenidae and Ariidae were the most outstanding, both in terms of richness and abundance. Shannon-Wiener and Simpson diversity indices showed higher values during the drought period and at the most upstream points of the estuary. Multivariate analyzes indicated a change in species composition as a function of rainfall intensity. Canonical Correspondence Analysis indicated the predominance of Clupeiformes and Perciformes associated with high level of salinity. The concentration of metals in estuarine water revealed high Fe and Al values, with levels above the limits defined by Brazilian legislation. For the concentration of metals in fish muscle tissue, significant values were detected for Pb and Cd, mainly in carnivorous and detritivorous fish.Therefore, there is a central portion of the Gulf that still has conserved area status, however, with heavy metal contamination patterns with potential to compromise biodiversity and, consequently, fishing that represents an important source of economic and protein resources for the population of Maranhão. In addition, the scenario in the bioethical context of fish biodiversity research in the Amazon makes imperative the wide dissemination of the principles of the Universal Declaration of Bioethics and Human Rights, as well as the implementation of financing policies of projects with requirement, in their edicts, of studies with approaches linked to the principles of the UNESCO declaration.