We compared behavioural (burrowing speed), biochemical (acetylcholinesterase [AChE] inhibition, activities of digestive enzymes) and physiological (feeding and egestion rates, condition) responses in Nereis diversicolor originating from a multipolluted estuary (Loire estuary) and a relatively clean site (Bay of Bourgneuf) on 3 occasions during spring 2008. Significant inhibition of AChE and digestive enzymes (amylase and carboxymethylcellulase) activities were recorded in individuals from the Loire estuary compared to the reference site. At the individual level no significant intersite differences in burrowing speed were observed when ragworms were exposed to their sediment of origin. No link between AChE activity and burrowing behaviour was found in worms from either site. Cross-tests revealed that behavioural disturbances in locomotion were not due to neurological dysfunction but to avoidance of contaminated sediments. Feeding and egestion rates were depressed significantly in worms originating from the Loire estuary compared to the reference site. These behavioural impairments were accompanied by changes in digestive enzyme activities, which can explain the generally poorer condition of ragworms from the Loire estuary. Temporal changes in responses reported in the present study underline the importance of the fluctuation of environmental factors and thus the need for more than one sampling series to assess the health status of a given site. Disturbances at the different levels of biological organisation are likely explained by environmental contamination either chronic in the Loire estuary or the result of a small oil spill.
KEY WORDS: Nereis diversicolor · Estuarine sediment · Biomonitoring · Behavioural impairments · Biochemical biomarkers
Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 393: [55][56][57][58][59][60][61][62][63][64][65][66][67] 2009 of sediment toxicity tests to examine the impact of pollutants on the aquatic sedimentary environment (DelValls & Conradi 2000, Chapman et al. 2002. In addition, field studies provide information about the biological effects of pollutants at various levels of biological organisation.Although biochemical and physiological biomarkers have been used increasingly in environment toxicology, they are not yet able to predict the effects of contaminants at higher levels of biological organisation. The aim of most ecological risk assessments is to protect populations, communities and ecosystems; only rarely is the goal to protect individuals. Therefore it is important to study the link between the responses of biomarkers at the sub-organismal and supraorganismal levels (Forbes et al. 2006). Studies of biomarkers related to energy metabolism, growth or reproduction (De Coen & Janssen 2003, Durou et al. 2007b as well as behavioural disturbances (Dell'Omo 2002, Amiard-Triquet 2009) appear particularly promising. Behavioural biomarkers are sensitive tools that help us to assess the impact of contaminants at concent...
