Efeito da obra do aterro sobre a ictiofauna da praia arenosa do Meireles, Ceará

Abstract

Beaches are environments formed by the accumulation of unconsolidated sediments that are influenced by factors such as wave, tide and wind dynamics. They are habitats of several organisms that use their space for feeding, resting, reproduction and foraging. Due to the advance of real estate speculation in coastal areas, occupations close to the sea are becoming increasingly common, as happens in the city of Fortaleza-CE. Currently, a large part of the city beach suffers from erosive processes caused by the accumulation of a series of factors, such as the construction of the port of Mucuripe, occupation of dunes, damming of rivers, etc. As a way to mitigate the erosive processes rigid containment works were installed, however the result was not completely satisfactory and other works to protect the coastal zone were carried out, such as hydraulic embankment. The embankment is a type of coastal work that feeds erosive beaches with sediments similar to their origin, but the effects of this type of work on the marine ichthyofauna are uncertain. Therefore, the objective of this study is to identify the effects of the new landfill at Meireles Beach on the fish assemblage of the region, with the hypothesis that the beach fattening has deleterious effects during and after the work. Fish were collected in 4 beach trawls at each time point (before, during, after) over three years, for a total of 16 trawls. The specimens collected were biometrical and identified to species level when possible. Only changes in the fish assembly at the time during construction were verified. A total of 40,617 fish belonging to 88 species and 29 families were sampled. The most abundant species at the study were Cathorops spixii , Opisthonema oglinum and Opisthonema oglinum. The most dominant species in the moment before were Cetengraulis edentulus, Pellona harroweri, Ophisthonema oglinum and Trichiurus lepturus, during was Trichiurus lepturus and then Ophisthonema oglinum and Chloroscombrus chrysurus. The analysis of the data through the indices of species richness (S), Pielou's equability (J') and Shannon-Wiener diversity (H') and nMDS showed that the differences were significant among the moments, being the moment during the most divergent among the moments, however after the completion of the fattening work the fish assembly reestablished itself. We conclude that beach nourishment can negatively impact the fish assembly of a sandy beach, but further studies in order to measure the degree of impact of this type of work also need to be conducted.