HUMAN TRAMPLING EFFECT ON BENTHIC FAUNA OF SANDY BEACHES WITH DIFFERENT INTENSITIES OF USE IN RIO DE JANEIRO, BRAZIL

Abstract

About 75% of the world’s shoreline is composed of beach environments. Among them, the sandy beach is a familiar environment and used for tourism and recreation. The organisms that live in these environments, as polychaetes, crustaceans and mollusks, are almost unknown by people because they live buried. Thus, many time people could cause damage to these organisms without their own knowledge. Trampling is one of the human-induced impacts to those organisms, destroying their bodies or even dispelling them. Focused on this behavior, this research aims to simulate trampling on two sandy beaches and to observe a real scenario of recreation on weekends and during the week during summer and winter seasons in the Rio de Janeiro state, Brazil. This study verified the changes occurring mainly in the faunal density of these two beaches with different intensities of use, in the predefined situations. Samples were collected during four months, on the second half of year, using simulated treatments and in another two months simple observation of the behavior of tourists was also performed. The simulated treatments did not cause significant changes in any collection except two. One of them was possibly a sampling artifact, which may be due to a low level of impact. The samples on the winter months also did not show significant changes, but the summer samples showed a large decrease in density of organisms during the weekend compared to during the week, probably related to the high intensity of human activity. As this study aimed to verify changes or impacts in organisms at up to 20 cm of depth, we concluded that only high impact activities could affect drastically the faunal density, as observed during the summer season at weekends on the study.