Meeting Abstract

P2.32  Saturday, Jan. 5  Elevated CO₂, temperature and salinity interactively affect biomineralization and shell properties of hard shell clams Mercenaria mercenaria MATOO, O; DICKINSON, G.; IVANINA, A.; BENIASH, E.; SOKOLOVA, I.*; University of North Carolina at Charlotte; University of Pittsburgh; University of North Carolina at Charlotte; University of Pittsburgh; University of North Carolina at Charlotte isokolov@uncc.edu

Ocean acidification (OA) driven by elevated atmospheric CO2 concentrations has been shown to negatively affect survival, growth and shell formation of marine calcifiers. In estuaries, the effects of OA may be modified by other environmental stressors such as fluctuations in salinity or temperature. We tested the interactive effects of elevated CO2 levels (hypercapnia) combined with increased temperature or decreased salinity on biomineralization and shell properties of the hard shell clam, Mercenaria mercenaria. In adult clams, shell formed during exposure to hypercapnia (800 ppm) at an elevated temperature (27 °C) showed significantly reduced hardness compared to the shells formed in normocapnia (400 ppm CO2 at 22 or 27°C) or hypercapnia at 22°C despite higher aragonite saturation in the high temperature treatments. In juvenile clams, increased CO2 levels (800 and 2000 ppm) led to reduced shell hardness, deterioration of the hinge region, and shell erosion. These effects were considerably more pronounced at the reduced salinity (15 PSU) compared to the normal salinity of 30 PSU. This suggests that hyposalinity and elevated temperature stress may exacerbate the negative effects of OA and compromise growth and survival of hard shell clams under future ocean conditions. Supported by NSF award IOS-0951079.