Motile fauna of sub-tidal Zostera marina meadows in England and Wales

Abstract

Despite being under continued anthropogenic threat, there exists limited evidence in the United Kingdom (UK) and northern Europe for the role of sub-tidal Zostera marina meadows in providing habitat in support of economically important fauna. This is a major issue given the need to support fisheries production into the future. Understanding this at a regional and local scale is important given that their ecosystem service value can change with factors such as environmental gradients and anthropogenic impacts. In the present study, we investigate the role of sub-tidal seagrass in supporting motile fauna including juvenile fish and invertebrates of commercial value. Seagrass meadows in three locations in the UK (Porthdinllaen, Tremadog Bay and the Isle of Wight) were examined using stereo Baited Remote Underwater Video systems (BRUVs). Twenty-six taxa were recorded, ten of which were of economic importance, including an abundance of juvenile gadoids. Although the commercially important species that we found as juveniles in seagrass are not obligate seagrass users, the resources that seagrass meadows offer to these fish potentially provide significant long-term fitness benefits, possibly enhancing the whole population. All sites sampled contained economically important fauna, but there existed a significant difference between the assemblages at different locations, with the sites in the Isle of Wight containing an impoverished fauna. Sites sampled in North Wales contained double the abundance of individuals and over three times the number of species than those in the Isle of Wight. This highlights that ecosystem services such as habitat provision are not constant between sites and possibly impacted upon by site condition and locally specific environmental differences. The present study provides evidence of the importance of seagrass meadows in the UK for supporting biodiversity and the need to protect these sensitive habitats.