Potential changes in benthic macrofaunal distributions from the English Channel simulated under climate change scenarios

Climate-induced changes in the distribution of species are likely to affect the functioning and diversity of marine ecosystems. Therefore, in economic and ecological important areas, such as the English Channel, projections of the future distributions of key species under changing environmental conditions are urgently needed. Ecological Niche Models (ENMs) have been applied successfully to determine potential distributions of species based on the information of the environmental niche of a species (sensu Hutchinson). In this study, the niches of two commercially exploited benthic species, Pecten maximus and Glycymeris glycymeris, and two ecologically important species, Abra alba and Ophelia borealis were derived using four contemporary hydrographic variables, i.e. sea surface temperature, sea surface salinity, water depth and sediment type. Consequently, using these ecological envelopes, the Non-Parametric Probalistic Ecological Niche model (NPPEN) was applied to calculate contemporary probabilities of occurrence for each species in the North East Atlantic and to predict potential re-distributions under the climate change scenario A2 for two time periods 2050–2059 and 2090–2099. Results show general northern displacements of the four benthic species from the English Channel into the North Sea and southern Norwegian coast. The projections mostly indicate a reduction of suitable habitat for benthic species with a notable disappearance of their distributions in the English Channel, except for A. alba. However, interpretations should be treated with caution since many uncertainties and assumptions are attached to ecological niche models in general. Furthermore, opening up potential habitats for benthic species does not necessarily imply that the species will actually occupy these sites in the future. The displacement and colonisation success of species are a function of many other non-climatic factors such as species life histories, dispersal abilities, adaptability and community interactions.