Novel microcosm system for investigating the effects of elevated carbon dioxide and temperature on intertidal organisms

In addition to the predicted rise in temperature, a recognised consequence of increased atmospheric CO 2 is ocean acidification.The response of marine organisms to the stresses associated with acidification is still not understood, and a number of recent experiments have addressed this problem.The starting point for many of these studies has been the development of a system by which seawater pH can be altered and then maintained.The current paper presents details of a temperature-and pH-controlled microcosm system, which enables the establishment of a tidal regime, for the experimental investigation of intertidal organisms.Two climate scenarios were simulated to evaluate the system's precision and accuracy; Year 2008 ('low' [CO 2 ]: 380 ppm and 14°C) conditions and Year 2100 ('high' [CO 2 ]) conditions (based on the IPCC -Intergovernmental Panel on Climate Change -2007 A2 scenario, 'high' [CO 2 ]: 1250 ppm and 2.0 to 5.4°C warming).The temperature and seawater carbonate chemistry were reliably maintained for 30 d during which time newly settled barnacle cyprids were allowed to metamorphose into juveniles, then grow and develop.The pH and [CO 2 ] had 95% confidence intervals of ± 0.03 units and ±17 ppm, respectively, under low [CO 2 ] conditions, and of ± 0.02 units and ± 43 ppm, respectively, under high [CO 2 ] conditions.The tidal regime is fully adjustable, and on this occasion was set to a 6 h cycle.These microcosms have proved ideal for studying benthic organisms from a variety of near-surface environments and at different stages of their life-cycle.