POTENTIAL IMPACT OF MUSSEL FARMING ON THE ECOLOGY AND BIOLOGY OF MARINE-COASTAL AREAS

The seasonal variability of physico-chemical and biological parameters was observed from October 2012 to October 2013 inside and outside a farming area in the Southern Adriatic sea (Italy), to assess the impact of the mussel farming on ecology and biology of the area. Temperature showed a typical seasonal trend from 7°C to 27°C, while the salinity range was 34-39 psu. Oxygen saturation was close to 100% at the surface layers and decreased up to 60% near the bottom during the spring, suggesting its consumption by organic matter mineralization processes, which affected ammonia and phosphorous, with the highest concentrations measured outside area (4.73 ?M and 2.12 ?M, respectively). Increased values of oxidative nitrogen in winter (12.01 ± 3.67 ?M) were highlighted. A typical seasonal trend was observed for silicates from 5.59 ± 2.36 ?M in winter to 0.45 ± 0.28 ?M in spring. Chlorophyll a values reflected mixing and upwelling processes, with a peak of 6.70 ?g.l-1 in March, characteristic of the maximum phytoplankton production (1.53 x 106 cell.l-1). Diatoms represented the predominant taxonomic group (52%) in abundance and number of species for all the period, suggesting constant eutrophic conditions in both sites. The temporal trend of diatoms is roughly similar for both the sites, except for the spring-summer period, when a decrease of 50% of diatoms abundance was observed outside and a greater deviation of 80% was found inside the farming area.