Efeitos da obra de engorda sobre a macrofauna bentônica da zona de surfe das praias do Meireles e de Iracema, em Fortaleza, Ceará - Brasil

Abstract

Beach nourishment is a method used to replace the sediment that has suffered from erosive processes, caused by both natural factors and anthropogenic interventions. The beaches of Meireles and Iracema, in the city of Fortaleza, Ceará, are examples of beaches that have suffered from beach nourishment, as both places faced an intense erosion process, influenced by the presence of constructions, such as Porto do Mucuripe, which were responsible for changing the sediment flow in the region. However, beach nourishment can alter the physical characteristics of the beach, such as its topographic profile and the size of the sediment grains, which, consequently, affects the fauna that inhabits this environment. Benthic macrofauna, which consists of invertebrates that live associated with the substrate, is formed by organisms that are highly sensitive and vulnerable to changes in the beach environment, with their richness and distribution being directly influenced by changes in physical factors. In this regard, the purpose of this research is to evaluate the effects of the beach nourishment at the beaches of Meireles and Iracema on the benthic macrofauna of the surf zone. Five monitoring campaigns were carried out in order to characterize the benthic macrofauna in the phases before, during and after the beach nourishment. In each campaign, five stations were sampled using a biological trawl dredge. After the field procedure, the material collected was sent to the laboratory, where it was sorted, identified and analyzed. A total of 416 specimens were recorded, distributed among 40 different taxa. There was significant variability in richness throughout the campaigns, with the last campaign showing the highest number of taxa. Molluscs were the most frequent taxon, followed by polychaetes, crustaceans and echinoderms. In relation to the sediment, there was a gradual increase in the average grain size over the campaigns, although no significant difference was recorded. From the results obtained, it can be concluded that the beach nourishment of Meireles and Iracema beaches has caused a disturbance in the environment, altering the physical characteristics of the ecosystem. Thus, the intervention was responsible for causing a restructuring of the benthic community, which gradually recolonized the surf zone as the beach recovered its original morphodynamics.