Intersite variations of a battery of biomarkers at different levels of biological organisation in the estuarine endobenthic worm Nereis diversicolor (Polychaeta, Nereididae)

Abstract

The ragworm Nereis diversicolor has been proposed as a sentinel species for the assessment of estuarine sediment quality. The aim of this study was to test the responsiveness of the worms using a battery of biomarkers in specimens from a moderately contaminated site (Loire estuary, Fr.) and a comparatively cleaner site (Bay of Bourgneuf, Fr.) as a reference site. Ragworms were collected on 7 occasions from April 2008 to October 2009 for the determination of biochemical (GST, AChE, digestive enzymes), physiological (energy reserves (glycogen, lipids and proteins), relationship between length and weight), and behavioural (feeding and burrowing) biomarkers. The biomarker responses were tentatively interpreted in terms of the concept of cascading events potentially responsible for local depletion/extinction of populations submitted to chemical stress. Impairments of AChE and amylase activities, feeding rate, energy reserve concentrations (glycogen and lipids), and the relationship between length and weight showed up differences between the reference site and the Loire estuary despite the latter being far from the most contaminated estuary in France or internationally. However, no links could be established in the Loire estuary ragworms between effects at infra-individual and individual levels, nor with worm population density, even though a small oil spill had occurred in the Loire estuary only one month before the beginning of sampling.