Metal pollution influences on the razor clam scrobicularia plana population from the Sancti-Petri saltmarsh (Southwest Iberian Peninsula)

Abstract Metal pollution provokes alteration at several levels of biological response in many saltwater organisms. In order to archive the influ- ence of metal pollution on the S. plana population, a suite of biolog- ical responses to metal pollutants were evaluated in organisms collected from ten sampling points along the main channel of the Sancti-Petri saltmarshes. Three levels of biological organization were selected: population and physiological (abundance, length, resistance to anoxia and condition index), histological (gills and digestive diverticulum) and biochemical (metallothionein). The re- sults showed that, (1) the geographical scale utilized in this study was adequate for the lower levels of biological organization as his- tological and biochemicals are more sensitive. However, for the higher levels of biological organization for population parameters (abundance and length), a larger geographical scale should be used. (2) Using three levels of biological organization is adequate for the ecotoxicology studies, because they vary independently and are complementary, not redundant. (3) The metals present in S. plana do not cause important histopathological alterations in the gills and digestive diverticulum. (4) The metals and/or stress factors pro- duce lipofuscin, which corroborate the digestive gland as a target organ and lipofuscin as good biomarker of exposure and stress. (5) The metal contamination activates the digestive diverticulum (gemulation and exocitosis) and the cellular mechanisms (brown cells and haemocytes) of detoxification and elimination. This work has been funded by CAPES and Consejeria Medio Ambiente (Junta de Andalucia) in the framework of the project ''Estudio de la recu- peración de las marismas del Caño de Sancti-Petri tras el cese de los vertidos residuales de la ciudad de San Fernando".