DREDGING IN THE ITAQUI PORT AREA, MARANHÃO - BRASIL: EFFECTS ON THE COMPOSITION AND ABUNDANCE OF ICHTHYOPLANKTON

Abstract

Assessments of the effects of dredging on biological resources show decreases in density and abundance of species as a result of dredging activity in port areas. Ichthyoplankton samples were taken before, during and after dredging at the Itaqui port complex west of the Golfão Maranhense. The trawls were drawn horizontally on the surface with a duration of 5 minutes. A plankton net of cone-cylindrical type was used, equipped with a flow meter. 677 fish larvae were collected, obtaining a total of 17 species. Significant effects of dredging were observed on species richness during the three stages. The species Anchoviella lepidentostole was dominant before dredging and its abundance reduced during the dredging, which is causing as consequence behavioral disturbance of these organisms. The Engraulidae family was dominant in this study and this may be a consequence of the greater resistance of their representatives to the changes in the environment caused by dredging. However, the results showed us that dredging activity influences the composition, density and abundance of these organisms.