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13 pages, 5 figures, 4 tables ; Trawling disturbs benthic communities, eliminating the most vulnerable organisms and modifying habitat structure. While the cumulative effects of disturbance resulting from commercial trawling activities are poorly understood, several studies suggest that chronically disturbed communities are dominated by opportunistic organisms. This study focuses on changes in functional components of the benthic community occurring in muddy sediments in a NW Mediterranean trawling ground, including an area that has not been fished for 20 yr. In both disturbed and undisturbed areas, the overall benthic community from the fishing ground was dominated by burrowing epifaunal deposit feeders and predators, and deep burrowing infaunal deposit feeders. The fished area had a higher abundance of burrowing epifaunal scavengers and motile burrowing infauna, while the undisturbed area was characterised by higher abundance of surface infauna, epifaunal suspension feeders and predatory fish. This study clearly demonstrates that changes in the functional components of a benthic community can result from fishing in areas dominated by organisms not considered especially vulnerable to trawling activities. Thus, fisheries managers aiming to reduce ecosystem disturbance must consider the implications of trawling on the structure and functioning of all types of benthic communities. ; The authors thank J. Hewitt and C. Lundquist for their helpful comments on the manuscript. This study was funded by the EU project RESPONSE (Q5RS-2002-00787). We thank the participants in the Response project, as well as all the participants in the 'Veda' cruises and the crew of the RV 'Garcia Del Cid' for their help and enthusiasm. Data were provided by the Fishermen's Association of St. Carles. S. de Juan was supported by a grant from Departament d'Universitats, Recerca i Societat of the Catalan government to study at the National Institute of Water and Atmospheric Research (NIWA), New Zealand. Comments from 3 anonymous reviewers improved the final version of the manuscript. ; Peer reviewed

Long-term variations of ecological status in a Mediterranean coastal lagoon (Sacca di Goro, Northern Adriatic) were investigated, combining data on the concentration of surface sediment contaminants and on the structure of the macrobenthic community. The aim was to assess any amount of chemical contamination and check the response of the macrobenthic community to sediment contamination. Over the studied period, the sediments of the lagoon showed contamination by trace metals and organochlorine pesticides, with most of them exceeding the thresholds indicated by the Italian legislation in many samples. Contamination by polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) instead never exceeded the threshold. The ecological status based on the macrobenthic community, evaluated through biotic indices (AMBI and M-AMBI), fell below the Good/Moderate threshold in most samples. The results indicate a possible influence of toxic compounds in sediment on benthic organisms, but most of the variability shown by the macrobenthic community is probably due to other factors. The difficulty in establishing a cause/effect relationship was due to the co-occurrence and variability of various stressors (both natural and anthropogenic) and their interactions. The methods currently used for monitoring transitional waters thus seem insufficient to disentangle the effect of pollutants and other environmental variables on the benthos. Integrated approaches (e.g., bioaccumulation and toxicity tests) are thus needed for a more precise identification of the risk posed by a high concentration of pollutants in such environments.

Long-term variations of ecological status in a Mediterranean coastal lagoon (Sacca di Goro, Northern Adriatic) were investigated, combining data on the concentration of surface sediment contaminants and on the structure of the macrobenthic community. The aim was to assess any amount of chemical contamination and check the response of the macrobenthic community to sediment contamination. Over the studied period, the sediments of the lagoon showed contamination by trace metals and organochlorine pesticides, with most of them exceeding the thresholds indicated by the Italian legislation in many samples. Contamination by polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) instead never exceeded the threshold. The ecological status based on the macrobenthic community, evaluated through biotic indices (AMBI and M-AMBI), fell below the Good/Moderate threshold in most samples. The results indicate a possible influence of toxic compounds in sediment on benthic organisms, but most of the variability shown by the macrobenthic community is probably due to other factors. The difficulty in establishing a cause/effect relationship was due to the co-occurrence and variability of various stressors (both natural and anthropogenic) and their interactions. The methods currently used for monitoring transitional waters thus seem insufficient to disentangle the effect of pollutants and other environmental variables on the benthos. Integrated approaches (e.g., bioaccumulation and toxicity tests) are thus needed for a more precise identification of the risk posed by a high concentration of pollutants in such environments.