Assessment of ecological quality status along the Apulian coasts (eastern Mediterranean Sea) based on meiobenthic and nematode assemblages

Coastal environments may be impacted by several anthropogenic activities such as sewage discharges, fish-farming and hydrocarbons along with seaside tourism activities, all proved to have an effect on benthic and, particularly, meiobenthic assemblages. An ecological survey was conducted along the Apulian coast (South Italy) to explore potential relationships between the degree of human disturbance and meiobenthic communities which are still unexplored. Sediment samples were collected in triplicate from 3 stations along each of 16 transects and at a different depth gradient (from similar to 10 to 50 m). The levels of taxa richness and biodiversity of the meiobenthic and nematode assemblages were overall high. The Water Framework Directive and Marine Strategy Framework Directive suggest the creation of specific thresholds to define the EcoQ (Ecological Quality) status of marine coastal systems. The thresholds applied on the meiobenthos showed the worst conditions at Brindisi harbour and at the mussel farm infrastructure of Castro. An overall moderate impact was also detected at the multiple-use Marine Protect Area of Porto Cesareo, likely due to the overwhelming number of tourists leading to an increase of organic enrichment (sewage discharge) negatively affecting the benthic communities assemblages. The main representatives of the nematode assemblages were taxa known as typical of muddy sediments. When EcoQ was assessed with the nematode thresholds, the worst EcoQ was found at Brindisi Harbour, Torre Specchia, and Alimini Lakes. The ecological conditions revealed by meiobenthic and nematode assemblages were generally consistent and seem to highlight a greater alteration of the meiobenthic communities assemblages along the Adriatic than the Ionian coasts.