Effects of bait collection on Nereis virens populations and macrofaunal communities in the Solent, UK

Abstract

The Solent European Marine Sites contain many tiers of habitat and species conservation, but also high levels of bait collection. Effective management strategies must be founded on up-to-date and locally based information from relevant studies of the impacts; these have been lacking for the collection of Nereis virens, a key bait species. The impacts on macrofauna were assessed through two approaches; (a) undug and dug sites in the Solent were compared over two years of repeat sampling; and (b) monitoring the long-term effects of simulated bait collection at an undug site through five years of yearly sampling. Dug sites had significantly higher densities of N. virens, but the mean weight was found to be significantly lower than those collected from the undug sites, but percentage maturity was not different. Organic content and sediment particle sizes differed between sites, and only the presence of gravel had a significant positive correlation with density. No clear patterns of other macrofauna species present were evident, although there was a significantly lower density of the terebellid polychaete Neoamphitrite figulus at the dug sites. Simulated bait collection did not alter overall macrofauna diversity, but certain species were affected. Abundance of N. figulus and the commensal Harmothoë glabra remained consistently lower in the dug area, whilst Cerastoderma edule numbers were reduced initially, but recovered. Numbers of Nephtys hombergii declined in both areas, but at a significantly greater rate in the dug area. A general decline in the abundance of many species, irrespective of digging, occurred over the period. The importance of these changes in Nereis virens populations and in the macrofauna community needs to be investigated prior to any management decisions on collection.