Chair: Andrew McMinn
Samuel P.S. Rastrick1,2, Chris Hauton2, Cinzia Aless3 Camilla Bertolini4, Andy Foggo5, Helen E. Graham6, Marco Milazzo3, Daniel P. Small7, Jason M Hall- Spencer5, Martin Solan2
1) Institute of Marine Research, PO Box 1870 Nordness, 5870 Bergen, Norway
2) School of Ocean and Earth Science, National Oceanography Centre, University of Southampton Waterfront Campus, European Way, Southampton SO14 3ZH,UK
3) Dipartimento di Scienze della Terra e del Mare, Università degli Studi di Palermo, via Archirafi 28, 90123 Palermo, Italy
4) School of Biological Sciences, Queen’s University Belfast, Belfast, BT9 7BL, Northern Ireland, UK
5) Marine Biology and Ecology Research Centre, School of Marine Science & Engineering, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
6) Uni Research Environment, Postboks 7810, 5020 Bergen, Norway.
7) Biology Department, St. Francis Xavier University, Antigonish, NS, B2G 2W5, Canada
The function and fitness of benthic invertebrates is dependent on energetic trade-offs between the physiological costs of maintaining cellular homeostasis and other energetically demanding processes that determine life-history traits and, therefore, performance, fitness and how organisms regulate their environment. By modeling these trade-offs in life-history, we have also started to investigate how future ocean acidification and warming may affect the population dynamics of key individual species that are important to ecosystem function and services. However, despite these advances in understanding the energetic trade-offs that determine species sensitivity in the laboratory, we have only just started to understand how these trade- offs will be affected in natural systems where species are subject to additional environmental stressors that modify energy availability (e.g. food quality, species interactions/competition). To address this we determined shifts in the physiological responses (oxygen uptake, acid-base status and Na+/K+-ATPase activity), life-history trade-offs (body mass and gonad somatic index) and function (food choice and grazing rate) of the sea urchins P. lividus and Arbacia lixula acclimatised/adapted to a natural pH gradient associated with a shallow water CO2 vent system (Vulcano, Italy). By performing transplantation experiments we also demonstrate how multiple ecological stressors (food quality and species interaction/ composition) associated with naturally assembled systems also affect physiological trade-offs compromising function. In comparing these responses across a natural pCO2 gradient to responses derived from long-term (1 year) laboratory incubations in the same species, we extend beyond previ+ously assumed trade-offs established in the laboratory and discuss the pros and cons of both laboratory and natural gradient experiments in determining the future function and fitness key benthic species.