Impact of breakwater relocation on benthic biodiversity associated with seagrass meadows of northern Adriatic Sea

Abstract

Breakwaters are man-made constructions utilized for preventing coastal erosion primarily from wave action. At the same time, defence structures, modifying currents and circulation can affect water quality and benthic assemblages. Assessing and minimizing the impact of these structures is a priority in human-modified coastal ecosystems, such as the central northern Adriatic where breakwaters extend for hundreds of kilometres. We investigated the effects of breakwater relocation on benthic features and meiofaunal diversity. To do this, we conducted a before–after comparison of (2011–2017) the relocation, which occurred in 2015. The analysis was conducted comparing a sheltered site, characterized by the presence of seagrass meadows and a wave-exposed site. Sediment features and meiofaunal variables were altered by the relocation, especially in the areas colonized by seagrass meadows. Results presented here pointed out to an enrichment in organic matter, the loss of two sensitive taxa (Cumacea and Ostracoda) and a shift in the assemblage structure with the increase of the relevance of Copepoda and Polychaeta. These results indicate that the careful management of breakwater is crucial for planning adequate conservation practices and protecting seagrass habitats and their biodiversity.