Clam population dynamics as an indicator of beach urbanization impacts

Abstract

Modification of natural environments due to human activities has become an issue of great concern in the last years. In this study, beach urbanization impact was assessed through population dynamics of two dominant infaunal clam species: Amarilladesma mactroides and Donax hanleyanus. The beaches used as sampling sites were characterized by an urbanization index, which exhibited three levels of urbanization. Recruits and juveniles of both studied species were collected monthly during a two years sampling. Results showed that beach urbanization reduces A. mactroides recruits and juveniles’ abundances, whereas the abundance of D. hanleyanus juveniles increased with higher urbanization degree. Also, the observed effects were limited to summer and autumn, coinciding with the time of higher impact due to recreation activities. The interspecific differences found and the importance of the sampling period when studying anthropic impacts over beaches, are discussed.