Histopathological lesions, pathogens and parasites as health indicators of an edible clam (Protothaca thaca) inhabiting a bay exposed to anthropogenic activities in Northern Chile

摘要

San Jorge Bay (23 degrees S) is characterised by a permanent coastal upwelling front and a thermal front that influence water circulation into the bay. This bay constantly receives effluents from different mining activities. Several studies have demonstrated different levels of heavy metals in waters and sediments within the bay. The clam Protothaca thaca is a bivalve with sedentary habits, which is distributed along the Peruvian and Chilean coasts and is exploited commercially. During 2010, clams were collected inside the bay: north (La Chimba), centre (Paraiso) and south (Llacolen), as well as from a site outside the bay (Bolsico). Haematological parameters, condition factor index, lesions, parasites and pathogens and heavy metal concentrations in clam tissues were determined. The health indicators of clams inhabiting the bay varied between sites. Clams inside the bay showed higher prevalence and intensity of parasites and lesions than those clams inhabiting the site outside the bay, which could be indicating the presence of some environmental stressor (e.g. heavy metals). This study is the first to evaluate the health status of organisms from San Jorge Bay, and our results support the hypothesis that clams P. thaca can be used to evaluate environmental quality.