The bivalves Amarilladesma mactroides and Donax hanleyanus as bioindicators of the impact of vehicles on Cassino Beach, southern Brazil.

Sandy beaches are the main recreational ecosystems of the world, enabling high ecological impacts, especially on the benthic macrofauna, which inhabit the sandy matrix and have a low capacity of locomotion. Cassino Beach, located in southern Brazil, has intense vehicle traffic during the summer, so the purpose of this study was to evaluate the impact of vehicles on the key species Amarilladesma mactroides and Donax hanleyanus. For this purpose, samplings were performed in three sectors of this beach (High Impact, Moderate Impact and Control) during six periods of the year. The results showed lower densities of both bivalves in the High Impact sector than in to the other sectors in all periods, except in first summer sampling, and a predominance of recruits throughout the study. Thus, it suggests that the two species were influenced by the intense vehicle traffic, especially in the most impacted sector. In this way, we conclude that these bivalves could be used as good indicators of pulse disturbance by vehicle traffic on this beach and the results can support in management plans regarding the use of Cassino Beach, considering ecological aspects of this ecosystem in addition to economic and cultural demands.