Benthic macrofauna associated with intertidal Zostera noltei beds in Atlantic (Arcachon Bay, France) and Mediterranean ecosystems (Kneiss Islands, Tunisia): comparative study

Abstract

The present study aim to compare between two distinct and distant geographical ecosystems; the Kneiss Islands (Tunisia) and Arcachon Bay (France), which formed by extensive large mudflats with the intertidal Zostera noltei beds, hosted a greater diversity of waterbirds and provides socio-economic importance. In order to determine the response of benthic communities’ structure and functioning to climate variation, the two eelgrass ecosystems constitute a natural laboratory to infer climate warming. The macrobenthic fauna community of Zostera (Zosterella) noltei beds in Kneiss Islands was studied by sampling 34 stations and 48 stations for Arcachon Bay. A total of 148 taxa were identified in Kneiss Islands and 117 species for Arcachon Bay, but only 23 species are common in the both separate ecosystems. Diversity, abundance and community structure are significantly different between the two study areas, could be explained by differences between Mediterranean and Atlantic climatic conditions and by anthropic factors (e.g. fishing pressure, pollution, nutrient inputs) present in each ecosystem. Multidimensional scaling (n-MDS) analysis identified two distinct geographical station groups on the basis of species and families abundance. Save that, three assemblages were identified between the separated ecosystems on the basis of trophic groups.