Spatio-temporal benthic biodiversity patterns and pollution pressure in three Mediterranean touristic ports

The Mediterranean Sea is one of the busiest areas worldwide in terms of maritime activity, 29 facing considerable anthropogenic disturbances, such as pollution by hydrocarbons and 30 heavy metals. The present study has evaluated the environmental and ecological status of 31 three touristic ports, Cagliari (Sardinia, Italy), Heraklion (Crete, Greece) and El Kantaoui 32 (Tunisia), based on the combined assessment of physical parameters, chemical variables (i.e. 33 nutrients, pigments), sediment pollution and macrobenthic biodiversity. Different port 34 sectors (leisure, fishing, passenger, cargo, shipyard) and different seasons (winter, before 35 touristic period, after touristic period) were compared. Salinity and sediment concentration 36 of copper and antimony were the three environmental parameters most highly correlated 37 with benthic species composition and diversity. Both the environmental variables and the 38 benthic biodiversity patterns were significantly different between the three ports (i.e. 39 different geographical locations). Heraklion port was heavily polluted by AHs in surface and 40 anoxic sediments and had the highest percentage of opportunistic species, while Cagliari had 41 the highest levels of PAHs and UCM and low species richness. El Kantaoui port was less 42 polluted and characterised by a richer biodiversity. The shipyard sector in Heraklion port was 43 significantly different from all other sectors in terms of abiotic and biotic parameters. 44 Physico-chemical and pollution variables recorded during the period after tourism (late 45 summer) were significantly different from the ones recorded in winter. Seasonal differences 46 were not significant between benthic species diversity patterns, but were revealed when the 47 patters derived from the aggregation of higher taxonomic levels were compared. The 48 present study indicates that a regular-basis monitoring plan including evaluation of 49 environmental health based on benthic biodiversity, can provide a basis for perceiving 50 changes and reveal the degree of anthropogenic disturbances in port environments.