Environmental quality improvement of a mariculture plant after its conversion into a multi-trophic system

Integrated Multitrophic Aquaculture (IMTA) seems to be one of the best solutions for sustainable aquaculture. Within the Remedia LIFE Project, an experimental IMTA plant was put in place in the Mar Grande of Taranto (Mediterranean Sea, Southern Italy). The polyculture of several bioremediating organisms, such as mussels, tubeworms, sponges, and sea-weeds, was combined with a coastal cage fish farm, in order to remove organic and inorganic wastes coming from the fish's metabolism. To verify the effectiveness of the system, the ex ante measurement of chemical-physical variables, tro-phic status, microbial contamination, and zoobenthos community health was compared with the results of the same mea-surement performed one year and two years after the implementation of the experimental IMTA plant. The results were encouraging, since a reduction in total nitrogen concentration in the seawater (from 43.4 +/- 8.9 to 5.6 +/- 3.7 mu M/l), a reduction in microbial pollution indicators in the seawater (total coliforms: from 280 +/- 18 MPN/100 mL to 0; E. coli: from 33 +/- 1.3 MPN/100 mL to 0) and in the sediments (total coliforms: from 230 +/- 6.2 MPN/100 g to 170 +/- 9; E. coli: from 40 +/- 9.4 MPN/100 g to 0), an enhancement of the trophic status (TRIX: from 4.45 +/- 1.29 to 3.84 +/- 0.18), and an increase in the zoobenthic quality indices and biodiversity were recorded (AMBI: from 4.8 to 2.4; M-AMBI: from 0.14 to 0.7). These results prove that the Remedia LIFE project's purpose was achieved. The selectedbioremediators worked synergistically, improving water and sediments quality within the fish farm area. Moreover, bioremediating organisms increased their weight as a result of wastes uptake, producing, as co-products, large amounts of additional biomass. This could be commercially exploited, thus being an added value of the IMTA plant. Based on our findings, the promotion of eco-friendly practices to ameliorate ecosystem health should be encouraged.

Automated summary

Integrated Multitrophic Aquaculture (IMTA) is a sustainable solution that combines various bioremediating organisms with fish farming to remove waste. The Remedia LIFE Project established an experimental IMTA plant in the Mediterranean Sea and achieved positive results in water quality improvement, reduction of microbial pollution, enhancement of trophic status, and increase in biodiversity. The project also highlighted the commercial potential of the additional biomass produced by bioremediating organisms.