Anthropic pressure due to lost fishing gears and marine litter on different rhodolith beds off the Campania Coast (Tyrrhenian Sea, Italy)

Impact of fishing gears and marine litter is a recognized global socio-ecological issue. Little is known about the extent of the problem in the Mediterranean seabed; even less information is available regarding litter distribution and its effects on deep rhodolith beds. Indeed, Mediterranean rhodolith beds are often remote and not yet sufficiently explored habitats, despite being internationally protected and recognized among the most important benthic communities for biodiversity maintenance. In this study, a quantitative assessment of marine litter and lost fishing gears, observed using a remotely operated vehicle, was carried out in 6 sites off the Campania Coast (Tyrrhenian Sea) characterized by different rhodolith covers. A negative correlation between abundance and richness of both marine litter and abandoned fishing gears with respect to the rhodolith cover was detected, suggesting that indirect human pressure along the coasts and direct effect of fishing activities might negatively damage these habitats. In fact, a lot of abandoned fishing gears and litter were recorded in all the 4 sites of the Gulf of Naples, confirming the high impact of maritime activities in this overcrowded area. Particularly, the Secchitiello site showed a very low mean cover of rhodoliths (<5%) in concurrence with the highest abundance of lost fishing gears and litter. On the contrary, the lowest abundance of fishing gears and litter was recorded in the 2 sites along the Cilento coast, possibly due to the relatively low maritime activities in this poorly inhabited area. In conclusion, this work gives new insights into the anthropic pressure due to marine litter and fishing on deep Mediterranean rhodolith beds, and provides useful data for their management and conservation.