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Several researches have been conducted to explain patterns of the abundance, richness and taxonomic diversity of benthic polychaetes; however, such analyses have ignored the functional diversity of polychaete communities, especially feeding guilds in intertidal rocky shores. The present study was carried out to describe and analyse the polychaete feeding guilds on intertidal rocky shores and then examine the effects of environmental factors. Twelve intertidal rocky shores from the coastal protected area of Essaouira (Atlantic coast of Morocco) were sampled during the summer of 2016. A total of 42 polychaete species belonging to 29 genera and 16 families were identified among the 4517 specimens collected. The medium biomass per sampling site was found to be 37.61 ± 15.80 g.m -2 . The polychaete species were classified into five feeding guilds, and nine feeding modes. The filter feeders were the dominant feeding guild (32%) followed by omnivores (23%), burrowers (20%), carnivorous (15%) and surface deposit-feeders (10%). The FDT (filter feeder, discretely motile, with tentacles) was the most abundant feeding mode, accounting for 24% of abundance (mainly represented by Sabellaria alveolata), followed by the ODJ feeding mode (omnivorous, discretely motile, with jaw apparatus) with 22%, and the SDT feeding mode (surface deposit feeder, discretely motile, with tentacles) with 18.9%. The highest trophic importance index and index of trophic diversity values were recorded in the southern region of Essaouira coastline. Based on the canonical correspondence analysis, composition and spatial distribution of polychaete feeding guilds were mainly related to the length of rocky shores and water temperature.

Valve activity was measured in the Mediterranean mussel Mytilus galloprovincialis in response to sublethal concentrations of four metals (Hg, Cu, Zn and Cd) and two phosphate industry effluents from the Atlantic coast of Morocco. Valve movements were monitored using a proximity inductive sensor which could display all activity figures from full closure to wide opening of the shell valves. In a 1 h exposure experiments, all metals induced a decrease in the time of normal opening and the appearance of sequences of stress behaviour, including enhanced valve adductions and complete closure at high concentrations. Mercury (tested from 5 to 75 microg Hg l(-1)) was the most toxic to the valve activity, with a threshold effective concentration at 10 microg Hg l(-1) and full valve closure occurring at 50 microg Hg l(-1). Copper (15-150 microg Cu l(-1)) showed a toxic effect starting at threshold concentration of 20 microg Cu l(-1) and induced full valve closure at 150 microg Cu l(-1). Zinc (100-500 microg Zn l(-1)) was effective in reducing the time of normal opening (threshold concentration at 100 microg Zn I(-1)) but no complete closure was recorded in any of the tested concentrations. For cadmium (1000-5000 microg Cd l(-1)), the valve activity was insensitive for exposures under 2000 microg Cd l(-1). Results for the testing of several samplings of the phosphate industry effluents (Safi and Jorf Lasfar) showed that their toxicity varied over the time. The effluent of the Jorf Lasfar plant (2-9.4%) was, however, more toxic than that of Safi (1-25%). In the light of these results, the sensitivity of the valve activity of Mytilus galloprovincialis to pollutants and its usefulness for in situ monitoring of coastal pollution in Morocco are discussed.

Les organismes utilisés dans les tests de toxicité des sédiments doivent être sensibles aux substances toxiques et capables de s'adapter à différents types de sédiments.La toxicité aiguë des sédiments a été étudiée chez l'amphipode d'eau douce, Gammarus gauthieri. Des sédiments de référen-ce et de composition très variable ont été testés pour déterminer les effets liés aux caractéristiques naturelles des sédiments sur G. gauthieri. Une bonne survie des gammares a été obtenue après 10 jours d'exposition à ces sédiments, la variation entre les différents types de sédiments n'est pas significative au seuil de 5 %.D'autre part, cette espèce a montré une forte sensibilité vis-à-vis des sédiments contaminés prélevés dans l'Oued Boufekrane (Maroc) ; les CL50 lOj ont varié entre 11 % et 80 %.Ainsi, G. gauthieri paraît une espèce utile pour les tests de toxicité des sédiments des eaux douces. Use of the Amphipod Crustacean Gammarus gauthieri Pinkster in freshwater sediment toxicity testsKeywords : Gammarus gauthieri, lethal toxicity, sediments, Morocco.The organisms selected for the toxicity tests of sediments must be sensitive to toxicants and tolerant to natural sediment characteristics.In this study, lethal sediment toxicity has been tested with the freshwater amphipod Gammarus gauthieri. Tests were conducted with control sediment varying in composition to determine the effects of natural environmental variables to G. gauthieri. The organisms survival was higher than 90 % in the control sediment over 10 days periods ; no significant differences were observed among different types of sediments.On the other hand this species was sensitive to the contaminated sediments collected in the Boufekrane river (Morocco), the LC50 lOd ranged from 11% to 80 %.G. gauthieri appears to be useful for testing the toxicity of freshwater sediments.

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