In 2012, NOAA funded three multi-year research projects that link ocean acidification (OA) with fisheries and the coastal economies. Some results from these projects are now available. These research findings complement ongoing work within NOAA that monitors OA and determines the impacts on marine populations. “Predicting how marine ecosystems will respond to rising levels of CO2 in the years to come is an extremely challenging task.” says Libby Jewett, director of the NOAA Ocean Acidification Program. “We are excited to strengthen our approach through the development of these cutting edge forecasting tools.”

1. At the Woods Hole Oceanographic Institution, Dr. Sarah Cooley and her colleagues used a series of models on environmental changes, scallop populations, and economic conditions to show the effects of future carbon dioxide (CO2) scenarios on scallop harvests. Learn more here.

Image from Cooley et al. 2015.

2. At the State University of New York at Stony Brook, Dr. Chris Gobler and colleagues examined two species with contrasting susceptibility to OA: scallops and hard clams. These studies provide guidance on sustainable shellfish harvest levels and identify regions of estuaries that are most vulnerable to OA. Learn more here.

3. A team of scientists from the Northwest Fisheries Science Center, University of Washington, and Australia’s CSIRO led by Dr. Isaac Kaplan linked a large climate model with ecosystem and economic models. They are using these linked models to project future OA conditions, and trace the impacts of OA through the California Current food web into fish harvests and regional port communities. Learn more here.

These research awards complement ongoing work within NOAA that monitors ocean acidification and determines the impacts on marine populations.

NOAA Scientists Look at Potential Ocean Acidification Impacts on the Puget Sound Food Web

NOAA scientists at the Northwest Fisheries Science Center are beginning to understand future impacts of ocean acidification on Puget Sound’s food web. Drs. Shallin Busch, Chris Harvey, and Paul McElhany applied ocean acidification scenarios to a food web model to explore how the estuary’s food web and its ecosystem services (i.e., fisheries yield and ecotourism) may change over the next fifty years. The scenarios focused on species that calcify (i.e. shrimp, copepods and sea urchins), as they are most likely to respond to changes in carbon chemistry. Furthermore, the scenarios were designed to identify which acidification-sensitive species and groups the food web responds to most, information which can inform experiments and field investigations on the impacts of acidification.  Scenarios of ocean acidification on crustaceans affected the food web more than scenarios on echinoderms and molluscs, and results indicate that the food web is most sensitive to ocean acidification scenarios on copepods, an abundant group of zooplankton. This study demonstrates that the direct effects of ocean acidification can ripple through the food web to cause both negative and positive effects on other species groups, including those that are harvested and provide ecosystem services, and can restructure the food web, redirecting the flow of energy to species like polycheates and small gelatinous zooplankton.

Figure: Food web model of Puget Sound's central basin, with 65 functional groups (Harvey et al., 2010).  Box size is proportional to biomass, and the width of connecting lines is proportional to energy flow from prey to predator. Functional groups included in ocean acidification scenarios are circled. Single line = crustaceans, double line = molluscs, dashed line = echinoderms. 

This work highlights the complexity of interactions among and between species in an ecosystem and the difficulties inherent in understanding the impacts of ocean acidification on entire food webs. More accurate predictions of impacts will require better information on the relative sensitivity of local species to ocean acidification and how the changes in chemistry could alter species interactions. Important lessons emphasized by the study are that the effects of ocean acidification will be mediated by predator-prey interactions, the impacts of ocean acidification on a community cannot necessarily be predicted by a community’s or group of species’ average direct responses to ocean acidification, and, in some systems, the groups that seem most susceptible to ocean acidification (e.g. some molluscs) may influence the food web less than the groups that are less sensitive to acidification. Results from modeling exercises such as this can help inform resource managers about the types of changes in marine ecosystems that could occur under ocean acidification and can guide scientists developing monitoring activities and experimental work to explore the impacts of acidification.

This work was funded by NOAA's Northwest Fisheries Science Center and Ocean Acidification Program.