Clam Transplantation and Stress- Related Biomarkers as Useful Tools f Assessing Water Quality in Coastal Environments C. NASCI *, L. DA ROS , G. CAMPESAN , E. S. VAN VLEETà, M. SALIZZATO§, L. SPERNI§ and B. PAVONI§ Istituto di Biologia del Mare C.N.R., Castell 1264/a, 30122 Venezia, Italy àUniversity of South Florida, Marine Science Dept. St. Petersburg, 140 Seventh Av. South, FI, USA §Dipartimento di Scienze Ambientali, Universit a di Venezia, Calle Larga Santa Marta, 30123 Venezia, Italy In this study, the Active BioMonitoring (ABM) approach has been investigated using species of indigenous (from a pristine site) and transplanted (to a polluted area) hard clam Mercenaria mercenaria as an indicator organism of water/sediment pollution in Tampa Bay, Florida, a highly urbanized and industrialized subtropical estuary. A range of possible induced stress indices was selected and used on the basis ofpotential pollutantoxicity mechanisms in- cluding speci®c enzymatic responses (MFO as BPH and NADPH cytochrome c reductase, antioxidant enzymes as SOD and caltalase, PDH) and general cellular damage (lysosomalatency,histopathological lesions).The or- ganic sediment contamination compared to the animal body burden revealed bioaccumulation activity in trans- planted clams. The marked increases of BPH and catalase activities, together with the signi®cant reduction of lyso- somalmembrane stability in transplanted animals, sug- gested their potentialfor application asbiomarkers in subtropical coastal pollution monitoring. Ó 1999 Elsevier Science Ltd. All rights reserved. Keywords: Mercenaria mercenaria; Tampa bay; biomark- ers; PCBs; PAHs; metals. Introduction In recentyears,severalstudies highlighted the impor- tance of an integrated approach when assessing the en- vironmentalquality and the eectsof toxicantson organisms. With reference to these ®ndings, the dier- ence in natural variables (i.e. sample site, exposure du- ration,population variation, temperature, salinity etc.) could make it dicult to understand the biological re- sponses to the toxic substance. The use of `active' bio- monitoring (ABM) in which samples are collected from a population at one location hand translocated to the monitoring sitesprovidestheadvantageof ensuring comparable biological samples, reducing the variability of resultsusually encountered in ®eld sampling pro- grammes. Although successful attemptsusing ®sh as eective monitoring means have also been described, th ABM focuses mainly on bivalves (De Kock and Kra- mer, 1994). In marine pollution monitoring, suspension-feeding bivalves (namely Mytilus sp.) have been selected as the most useful `sentinel' organisms, due to their ability to bioaccumulate and concentrate pollutants and to their sedentary habits, thus providing natural and temporal integrated levelsof contaminants in coastal waters (Goldberg et al., 1978).However,the extento which toxic eects may result from contaminated sediments is relatively less known, even though a similar approach using ®lter-feeding and bottom-living bivalves could be adopted. The hard clam Mercenaria mercenaria, which lives buried in sandy and/or muddy sediments, appears to be usefulin providing indications on sedimentpollutant burden.Adults are toleranto salinity variations and spawning begins as the water temperature nears 23°C. Naturalpopulation of M.mercenaria have been found along the North America Atlantic coasts, in Californian waters and along the west coast of Florida. Fewer surveyshave been conducted in tropical or subtropical environments, where high temperatures and increased metabolic rates may enhance damage to ma- rine biota.For this purpose, the integrated use of bio- markersand chemicalcontaminantlevelshas been applied for better comprehension of contaminant im- pact on organisms. PII: S0025-326X(99)00094-6 Marine Pollution Bulletin Vol. 39, Nos. 1±12, pp. 255±260, 1999 Ó 1999 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0025-326X/99 $ - see front matter *Corresponding author. 255