Abstract
The present study analyses the spatio-temporal variability of the macrozoobenthos from the intertidal zone of the Kneiss Islands (Gulf of Gabes, Tunisia). Samples were collected once from 34 stations, while seasonal variations were studied by sampling four times at 12 stations over the period 2013-2014. A total of 159 macrobenthos taxa associated with intertidal Zostera noltei beds are identified from the 34 stations, with a taxonomic dominance of crustaceans (32%), molluscs (29%) and annelids (27%). Abundance varies from 9244 to 36,844 ind·m-2 with a mean value of 14,346 ind·m-2. Analysis of the trophic structure shows that the majority of stations are strongly represented by carnivores (41%), followed by the non-selective deposit feeders (16%). Cluster analysis and multidimensional scaling allow identification of three main benthic assemblages based on species abundance, corresponding to different sediment types and organic matter contents. The seasonal variability in abundance, diversity and community structure is mainly due to spring and summer recruitment. The biotic indices (i.e. AMBI, BO2A and BENTIX) show that the intertidal area of Kneiss Islands exhibits a good ecological status.
Highlights
Owing to their position at the interface of land and sea, shallow waters and coastal areas are generally highly productive and ecologically important [1] [2]
This study reports the spatial and temporal variability of benthic macrofauna communities over the whole intertidal zone of the Kneiss Islands in the Gulf of Gabès, i.e. an inventory of species associated with Zostera eelgrass, distributed in the intertidal ecosystem, along with the spatial distribution of macrobenthic fauna assemblages, as well as the seasonal variations according to the main environmental changes and anthropogenic pressures, especially traditional human activities
Long-term studies are essential for understanding the natural variability of species composition, dominance structure and the functional diversity of benthic communities in relation to natural environmental drivers, all of which are affected by climate change [79]
Summary
Owing to their position at the interface of land and sea, shallow waters and coastal areas are generally highly productive and ecologically important [1] [2]. Coastal ecosystems often form a mosaic of interlinked habitats that should not be considered in isolation. Each habitat has its own characteristics and hosts particular benthic assemblages [3]-[5]. Coastal habitats are threatened by anthropogenic stressors, including coastal development and habitat degradation [6]-[9]. Many human activities (pollution, tourism, clam harvesting, bait digging, commercial fisheries, eutrophication, sediment discharge, sand extraction and marine transportation) have directly and indirectly affected the biodiversity of these ecosystems on a worldwide scale [10]-[13]. Many species and habitats are in jeopardy [14], considering that degradation has modified coastal habitats to such a degree that they no longer fulfill their functional roles as nurseries, in feeding or in reproduction [15] [16]
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