Impact of boat anchoring on the Mediterranean endemic bivalve Pinna nobilis : an experimental approach

Abstract

The impact of boat anchoring on the Mediterranean endemic bivalve Pinna nobilis Linnaeus (1758) was assessed experimentally in the field by installing non-biological mimic units of the bivalve in the islands of Mallorca and Malta. In each of these two Mediterranean localities, two study areas having different levels of boat anchoring activities: ‘control’ (no anchoring allowed) and ‘impacted’ (anchoring allowed), were used for the field experiment. A significant number of P. nobilis mimic bivalves were affected by boat anchoring in the impacted areas; the impact was 3 times higher in impacted areas compared to control areas. Boat anchoring also had an adverse impact on Posidonia oceanica meadows, since seagrass cover was lower in the impacted areas.