Complex Interactions in a Rapidly Changing World: Responses of Rocky Shore Communities to Recent Climate Change

Vol. 37: 123–133, 2008 CLIMATE RESEARCH Published October 21 doi: 10.3354/cr00768 Clim Res

Contribution to CR Special 18 ‘Effects of climate change on marine ecosystems’ OPENPEN ACCESSCCESS Complex interactions in a rapidly changing world: responses of rocky shore communities to recent climate change

S. J. Hawkins1, 2, P. J. Moore1, 3,*, M. T. Burrows4, E. Poloczanska5, N. Mieszkowska1, R. J. H. Herbert6, S. R. Jenkins2, R. C. Thompson3, M. J. Genner1, 7, A. J. Southward1,†

1Marine Biological Association of the UK, Citadel Hill, Plymouth PL1 2PB, UK 2School of Ocean Sciences, University of Wales Bangor, Menai Bridge, Anglesey LL59 5AB, UK 3Marine Biology and Ecology Research Centre, University of Plymouth, Plymouth PL4 8AA, UK 4Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban PA37 1QA, UK 5Wealth from Oceans Flagship, CSIRO Marine and Atmospheric Research, Hobart, Tasmania 7001, Australia 6School of Conservation Sciences, Bournemouth University, Talbot Campus, Fern Barrow, Poole BH12 5BB, UK 7School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK

ABSTRACT: 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 experi- mental 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 inexpen- sive 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 emphasis- ing the value of long-term studies in informing adaptation to climate change.

KEY WORDS: Climate change · Rocky shores · Time series · Grazer-algae interactions · Ecological forecasting · Adaptational policy · Europe

Resale or republication not permitted without written consent of the publisher

1. INTRODUCTION grand & Ibanez 2004, Hays et al. 2005), fish (Brander et al. 2003, Beare et al. 2004, Genner et al. 2004), and off- Warming of the planet has accelerated in the last few shore benthic organisms (Hiscock et al. 2004). Some of decades (IPCC 2007). Some of the most rapid changes the most marked and best-documented changes have are occurring in the NE Atlantic (IPCC 2007), where in- been seen on rocky shores in Europe (Herbert et al. creases of up to 1°C have been recorded in areas such 2003, Mieszkowska et al. 2005, Simkanin et al. 2005, as the Western English Channel (Hawkins et al. 2003). Lima et al. 2006, Mieszkowska et al. 2006, Herbert et al. Marine ecosystems have responded to this warming 2007, Lima et al. 2007a), the United States (Barry et al. with changes in abundance and shifts in geographic 1995, Harris et al. 1998, Sagarin et al. 1999, Zacherl et ranges of plankton (Beaugrand & Reid 2003, Beau- al. 2003, Harley et al. 2006) and South America (Ri-