A multibiomarker approach in the clam Ruditapes decussatus to assess the impact of pollution in the Ria Formosa lagoon, South Coast of Portugal

摘要

The Ria Formosa lagoon is an ecosystem whose water quality reflects the anthropogenic influence uponthe surrounding areas. In this lagoon, the clam Ruditapes decussatus has a great economical importanceand has been widely used as a biomonitor. A multibiomarker approach (d-aminolevulinic acid dehy-dratase, metallothionein, lipid peroxidation, acetylcholinesterase, alkali-labile phosphates, DNA damage)was applied to assess the environmental quality of this ecosystem and the accumulation of contaminantsand their potential adverse effects on clams. Clams were sampled in different shellfish beds in the periodbetween July 2007 and December 2008 and abiotic parameters (temperature, salinity, pH and dissolvedoxygen of seawater and organic matter in the sediment), condition index, metals (Cd, Cu, Zn, Ni, Pb), TBTsand PAHs concentrations were measured in clam tissues. Data was integrated using Principal ComponentAnalyses and biomarker indices: IBR (Integrated Biomarker Response) and HSI (Health Status Index). Thismultibiomarker approach enabled discrimination of a time and space trend between sites with differentdegrees of anthropogenic contamination, identifying one of them (site 2) as the most stressful andsummer months as the most critical period for clams due to an increase of environmental stress(anthropogenic pressure along with extreme environmental conditions, e.g. temperature, dissolvedoxygen, organic matter in the sediments, etc). The selected biomarkers provided an integrated responseto assess the environmental quality of the system, proving to be a useful approach when complexmixtures of contaminants occur.