Mechanical grooming and beach award status are associated with low strandline biodiversity in Scotland

Abstract

Beach grooming and beach award status are both shown to be associated with low macroinvertebrate taxon richness in Scotland. Previous studies in California have revealed that mechanical raking to remove wrack from sandy beaches has negative ecological consequences for coastal ecosystems. In the current study the presence and absence of eight common taxa that inhabit beached wrack on sandy beaches in Scotland was assessed at 60 sites, 24 of which were groomed and 29 of which were in receipt of a beach award. On average 4.86 of the eight taxa were found to be present on ungroomed beaches, whereas only 1.13 taxa were present on groomed beaches. Thus, beach grooming seems to be having a major effect on the biodiversity of beach macroinvertebrates in Scotland. Fewer macroinvertebrate taxa were also found on award (1.5) compared to non-award (4.38) beaches. It was also revealed that award beaches were much more likely to be groomed than non-award beaches, with 69% of award beaches surveyed being groomed compared to only 6% of non-award beaches. This pattern is surprising as the awarding bodies discourage the removal of seaweed and regulations state that beached wrack should only be removed if it constitutes a nuisance. It is concluded that award status, not nuisance level, has the main factor driving most beach grooming and that this has resulted in the substantial loss of macroinvertebrate biodiversity from award beaches in Scotland. In conclusion it is shown that beach grooming has a substantial negative impact upon strandline macroinvertebrate biodiversity in Scotland and that grooming is much more likely to occur on award beaches.