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The French experiments of artificial reefs started in the 60's, mainly on the Mediterranean coast. This study focused on two main sites along the Atlantic coast (Aquitaine): the Porto artificial reef, located at Mimizan (1989) and the artificial reefs of Capbreton (1999). Both have been placed off the sandy coast at depths of 12–25 m. A standardized monitoring by visual censuses has been performed since 2009–2010 with 4 sampling points placed on different substrates (barge and concrete pipes) to cover the whole Porto site and 2 sampling points on concrete pipes and Typi unit at Capbreton. Twenty-two taxa were recorded on the Porto artificial reef, dominated by benthic fishes. First results indicated differences in taxa richness between the sampling points: the barge had a more important diversity than the assemblage of concrete modules. Hence, a gradient of habitat complexity is discussed in light of results on taxa richness and biomass assessments. Visual censuses revealed a specific richness of 36 taxa on artificial reefs of Capbreton with a significant difference between concrete pipes and Typi unit. Five taxa were counted every year on both sites and could be considered as more representative of these artificial reefs: Trachurus trachurus, Umbrina sp., Trisopterus luscus, Conger conger, Blenniidae. Despite sharing common species, each site had its own species showing their complementarity. Different temporal variations were found on both sites, in particular at Capbreton where pelagic fishes in 2010 have been replaced in 2013 by benthic fauna. These pioneering analyses on the Aquitaine coast require further research, particularly on the temporal evolution of abundances and biomass. [ABSTRACT FROM AUTHOR]

The benthic community on the rocky foreshore of Guéthary (France) has been monitored since 2002. The standardized and quantitative monitoring method counts 20 geographically referenced quadrats spread on three littoral zones: upper mediolittoral, lower mediolittoral and infralittoral zones. The setting up of this monitoring occurred when the “Prestige” sunk close to the Finistere Cape in Galicia (Spain). The oil slick following the shipwreck impacted the Guéthary foreshore in early 2003. After the “Prestige” oil spill, the taxonomic richness decreased in the studied area with a loss of 16 species – from 57 in 2002 (before the shipwreck) to 41 species in 2004. Two or 3 years later, taxonomic richness increased to a level observed prior to the oil spill. Along the years, temporal variations in community structure of benthic macrofauna are revealed by detailed analysis. Some polluo-sensitive species disappeared after 2002 and have not reappeared yet ( e.g. : Hymeniacidon perlevis ). Some others reappeared two or three years after the spill or even later ( e.g. : Amphipholis squamata , Botryllus schlosseri , Calliostoma zizyphinum , Echinus esculentus , etc. ). Noteworthy changes were found in 2004 driven by the sudden increase in abundance of grazers. The following years, these abundances went back to a stable level. The benthic community seemed to recover almost 5 years later, although a new composition of macrofauna populations was observed. In overall aspect, the complexity of the benthic ecosystem response to oil spills confirms the need of regularly updated baselines to assess the impact of pollutions and more generally to maintain marine biodiversity. [ABSTRACT FROM AUTHOR]

Methylmercury (MeHg) is the most bioavailable and toxic form of the globally distributed pollutant Hg. Organisms of higher trophic levels living in aquatic ecosystems have potentially higher concentrations of MeHg. In this work, we analysed both MeHg and inorganic Mercury (Hg(II)) concentrations from dorsal feathers of chicks from ten colonies of Yellow-legged Gull (Larus michahellis) in the south-eastern part of the Bay of Biscay. Overall, we detected a high mean MeHg concentration that, however, differed among colonies. Additionally, based on stable isotopes analysis (δ13C and δ15N) and conducting General Linear Mixed Models, we found that chicks which were mostly/mainly fed with prey of marine origin had higher levels of MeHg. We propose Yellow-legged Gull as a reliable biomonitor for Hg species, as it is easy for sampling and in compliance with the Minamata convention on Mercury. • Methylmercury (MeHg) is the most bioavailable and toxic form of Hg. • MeHg and Hg(II) concentrations were analysed from chicks' feathers of Larus michahellis. • A high mean MeHg concentration was detected that, however, differed among colonies. • Chicks which were mostly/mainly fed with prey of marine origin had higher levels of MeHg. • Yellow-legged Gull is proposed as a reliable biomonitor for Hg species. [ABSTRACT FROM AUTHOR]