PIER BENEATH: OBSERVATIONS OF THE MARINE FLORA AND FAUNA ASSOCIATED WITH YARMOUTH PIER, ISLE OF WIGHT.

Abstract

With numbers of offshore structures increasing around our coast, it is important to understand how marine organisms might be affected by these developments. Benthic species may benefit from a greater sur face area for colonisation, and it is possible that aggregations of fish, normally associated with rocky reefs, may become established. The extent to which fish utilise structures for grazing on surface benthos, for refuge or to hide in ambush for prey, is poorly understood. Here we present results of survey work conducted at Yarmouth Pier from 2017-2019 during a phase of reconstruction of the pier head. Data from the pier was mostly collected by volunteer Seasearch SCUBA divers and the deployment of Baited Remote Underwater Video (BRUV) from the pier head. Reference sites to the east and west of the pier were also sampled using BRUV to determine whether observed changes in species abundance were confined to the pier or could be generally attributed to the wider locality. A total of 140 species were recorded on the pier structure and seabed immediately below the pier and an additional 5 species were recorded from the Reference sites. BRUV surveys yielded more species from the pier than the Reference sites. During spring and summer 2018, recolonisation of the new pier piles was rapid and included pioneer benthic species not seen in the previous summer. Yet although the mobile fish assemblage differed from that prior to reconstruction of the pier head, this could be attributed to background variation. The pier is clearly attractive to invertebrates and a range of reef fish, including species of wrasse, pout, pollack and bass that individually benefit from the structure in different ways.