Insights into the impact of marine litter on coralligenous structuring species in Apulia (Italy)

The accumulation of abandoned fishing gear and litter is considered one of the most important factors contributing to marine environmental degradation worldwide. In the Adriatic and Ionian Seas, little is known about their effect on coralligenous habitats, one of the most important benthic ecosystems in the Mediterranean. In this study, four sites off the Apulian coast (south-eastern Italy), were quantitatively surveyed for marine litter and lost fishing gear through the use of a remotely operated vehicle (ROV), with the aim of evaluating the impact of anthropogenic pressure on the structural diversity and integrity of coralligenous habitats. A positive correlation was detected between the number of litter items observed in each area and the total percentage of individuals of structuring species affected by necrosis, suggesting that human activities such as fishing along the coast and indirect human pressure are negatively affecting these habitats. Lines and ropes were overall the most abundant marine debris found at all four sites surveyed, confirming the impact of maritime activities in the area. The most affected areas were near important ports, while the lowest abundance of fishing gear and marine litter was recorded in the two sites along the Adriatic coast, which were away from major populated centres. In summary, this study provides new insights into the anthropogenic impact of marine litter and fishing on Mediterranean coralligenous bioconstructions as well as useful data for establishing appropriate conservation measures and long-term monitoring programmes to protect one of the most vulnerable and valuable habitats in the Mediterranean sea.