Continuing increase in atmospheric CO₂ consequent ocean acidification is resulting in globally decreasing carbonate saturation states. At high latitudes, aragonite is already nearing undersaturation in surface waters and becomes undersaturated at relatively shallow depths (due to the negative effect of pressure and low temperatures). Carbonate chemistry time series have revealed alarmingly rapid shoaling rates of the aragonite saturation horizon (ASH) in the Iceland Sea. Olafsson et al. 2009 reported a shoaling rate of 4 meters per year, with ASH presently at 1700 m depth. Thus, based on the Iceland Sea topography, 800 km² of benthic habitat is added to undersaturated areas every year.

Gastropoda and Bivalvia are highly diversified classes from the phylum Mollusca that commonly inhabit benthic substrates. Majority of species within both classes produce aragonitic shells, either partly (in addition to calcite) or purely. Along with other various invertebrate fauna, molluscs were sampled and identified in relation to a benthic sampling program (BIOICE), conducted around Iceland over the years 1994 to 2004 with ~1200 samples collected from a depth range of 20-3000 meters. In this study data from the BIOICE program is used to analyse the distribution of Gastropoda and Bivalvia around Iceland in relation to various environmental parameters including aragonite saturation.

Olafsson, J., Olafsdottir, S. R., Benoit-Cattin, A., Danielsen, M., Arnarson, T. S., & Takahashi, T. (2009). Rate of Iceland Sea acidification from time series measurements. Biogeosciences, 6(11), 2661-2668.