In 2010 and 2011, Alaska Fisheries Science Center (AFSC) scientists at the Kodiak Laboratory in Alaska tested the effects of lower pH due to increased carbon dioxide (CO2) on the survival, condition, and growth of red king crab (Paralithodes camtschaticus). Commercially important shellfish are a priority for AFSC research related to ocean acidification because of their economic value and because calcifying species are likely to suffer direct effects due to increased acidity (and a decrease in calcium carbonate saturation state) of our oceans.
The multi-year project objectives are to test the effects of CO2 enrichment (which leads to decreasing pH and lower saturation state) across a range of commercially important crab species and life stages (embryo, larvae, juveniles, and adults). The response variables currently measured include mortality, condition, growth, and calcification of the shell.
We will examine the effects of OA conditions (elevated pCO2) on the adaptive response of a potentially vulnerable native marine mollusc species with ecological, economic and social importance in the Pacific Northwest: geoduck clams (Panopea generosa). Geoduck clam larvae will be exposed to normal and elevated pCO2 and surviving larvae will be assessed using genomic sequencing to determine changes in allele frequencies at single nucleotide polymorphisms throughout the genome, and changes in the frequency of methylation states (epialleles) throughout the epigenome. Existing ecosystem models of OA consider a species' response to increased pCO2 as a fixed attribute; however, interpretations of the effects of OA at the population level may shift substantially if species adapt to the new environment. Furthermore, we will gain a better understanding of how specific genetic and epigenetic variations influence phenotype and the ability of an organism to respond, giving us new insights into fundamental aspects of species adaptation to environmental change.
Assessing a species’ risk to ocean acidification (OA) will depend on their duration of exposure to low pH/low saturation state conditions and their sensitivity to low pH conditions. Lab species exposure experiments attempt to measure species sensitivity to low pH. This modeling project estimates species exposure. In FY13, we started using an existing circulation/water quality of model of the Salish Sea and Washington/B.C. Coasts developed by the Pacific Northwest National Laboratory to understand carbonate chemistry exposure of zooplankton species. We are using empirical relationships between carbonate chemistry, oxygen, temperature and salinity to add carbonate chemistry to the circulation model. We then use an individually-based model to simulate the movement of various zooplankton species in this environment. In FY15-FY17, we will continue development and publication of results from this model, including exploration of current and future CO2 scenarios. Results from the model will inform the Dungeness crab exposure experiments planned for FY16, as well as general zooplankton vulnerability to OA.
Ecosystem models are used to estimate the potential direct and indirect effects of ocean acidification (OA) on marine resources. The population abundance and distribution of species that are sensitive to seawater carbonate chemistry can experience the direct effects of OA. Even species not sensitive to carbonate chemistry can have indirectly changes in abundance and distribution as a result of changes in their prey, predators, competitors or critical habitat forming organisms that are sensitive. Ecosystem models use information on food webs and other relationships to estimate these ripple effects of OA on important ecosystem services like fisheries.
Species exposure experiments that measure the response of organisms reared in seawater with manipulated carbonate chemistry are an important way to learn about the potential effects of ocean acidification (OA). Experimental systems that closely mimic the natural environment (e.g. with multiple stressors) can lead to studies with greater ecological relevance. Using a combination of NWFSC and OAP funds, the NWFSC built a facility for conducting species exposure experiments at the Montlake Lab, and has started a new facility at the Mukilteo Field station. The facilities include both rearing aquaria and a lab for carbon chemistry analysis (DIC, alkalinity, spectrophotometric pH). The NWFSC experimental systems are considered “shared-use” facilities, in that the systems are available for NWFSC research teams and outside collaborators as capacity allows. In the past, we have worked on collaborative projects with PMEL, University of Washington, Oregon State University, Suquamish Tribe, Evergreen State University, Cal Poly and Western Washington University. These collaborators often provide external funding for experiments, greatly increasing the research that can be conducted.