Abstract:
The dynamics of predator-prey interaction between the invasive Rapa whelk R. venosa and the black mussel M. galloprovincialis in the coastal zone of the Black Sea shapes the structure of the benthic hard rock ecosystems in the littoral area of the basin. Applying a combination of observational methods (transects, photo surveys) and exclusion ’cage’ experiments we tracked the rapid increase in Rapa whelks population density (from 1.1 ind.m2 up to 13 ind.m-2) and the destruction of infralittoral mussel communities by the Rapa whelks in the study area (from up to 2469.95±1184.82 g.m-2 wet biomass and 1054.66±228.19 ind.m-2 to practically none). A rapid recovery was noted just 6 months later in caged experimental plots where R. venosa could not reach the newly settled mussels, in contrast to open plots where no new mussel colonies developed. The importance of harvesting of Rapa whelks by divers as means of local control of their populations, and of the preservation of natural circalittoral M. galloprovincialis populations as sources of larvae for the resettlement of coastal habitats is also discussed.