Complex interactions in a rapidly changing world: responses of rocky shore communities to recent climate change

Warming of the planet has accelerated in recent years and is predicted to continue over the next 50 to 100 yr. Evidence of responses to present warming in marine ecosystems include Shifts in the geographic range of species as well as in the composition of pelagic and demersal fish, benthic and intertidal assemblages, Here we provide a review of the changes, in geographic distributions and population abundance of species detected on rocky shores of the NE Atlantic over the last 60 yr. This period encompassed the warm 1950s, a colder period between 1963 and the late 1980s and the recent period of accelerating warming to levels above those of the 1950s. The likely consequences of these responses are then explored. To do this, a summary of the dynamic balance between grazers, macroalgae and barnacles in structuring mid-shore communities is given before outlining experimental work on interactions between key components of rocky shore communities. Modelling and quantitative forecasting were used to predict changes in community composition and dynamics in a warmer world and their consequences for ecosystem functioning discussed. We then identify areas that need further work before making a case for the use of rocky shore species not just as inexpensive indicators of change offshore, but as tractable models to explore the direct and indirect effects of climate change in marine and coastal ecosystems, We also provide a societal perspective emphasising the value of long-term Studies in informing adaptation to climate change.