PMEL's surface observational network, consisting of the complementary moorings and underway observations, is designed to quantify the temporal and spatial scales of variability of carbon species, pH, and aragonite saturation in surface waters. To assess spatial dynamics in OA and evaluate the synergistic effects of coastal processes along the coasts and in the open ocean, we will leverage our Ship of Opportunity Program (SOOP) infrastructure along the U.S. west coast. Underway observations have been enhanced by the collection and analysis of discrete DIC and TA samples beginning in FY 2010.
The primary objectives of our underway OA FY 2015–2017 sustained investment work plan are to maintain existing underway observations on NOAA Ships Oscar Dyson and Bell Shimada with autonomous pCO2, pH, and ancillary sensors that cover the continental shelf regions of Alaska, Washington, Oregon, and California. We plan to work with Dr. Rik Wanninkhof''s group at AOML to ensure that the underway OA system on NOAA Ship Ronald Brown is working well for the FY2016 West Coast Ocean Acidification cruise. In addition to making ongoing observations from existing OAP-funded CO2/pH SOOP platforms, during this funding period we are placing a major emphasis on finalizing QC on backlogged underway pH and DO data, distributing the final data to CDIAC and NODC data archives, and data synthesis and publication efforts. These efforts are being undertaken in conjunction with other members of the PMEL Carbon Group, the PMEL Science Data Integration Group, our AOML sister group, and Dr. Todd Martz at Scripps Institution of Oceanography. Finally, under the OAP SI FY15-17 work plan, we will continue to maintain the pH and O2 sensors that are presently on the container ship Cap Blanche and contribute to the trans-Pacific decadal time-series.
Since ocean acidification (OA) emerged as an important scientific issue, the PMEL Carbon Group has been augmenting and expanding our observational capacity by adding pH and other biogeochemical measurements to a variety of observing platforms. In particular, high-frequency observations on moorings provide valuable information for better understanding natural variability in inorganic carbon chemistry over daily, seasonal, and interannual cycles. The current NOAA OA mooring network consists of 21 moorings in coral, coastal, and open ocean environments (Figure 1). At present, the OA mooring network includes surface measurements of CO2 (seawater and atmospheric marine boundary layer), pH, temperature (T), salinity (S), dissolved oxygen (DO), fluorescence, and turbidity at all sites. The main objective of this network is to quantify temporal variability in the ocean carbon system. This includes describing how annual, seasonal, and event-scale variability impacts air-sea CO2 flux and ocean acidification; providing the carbon chemistry baseline that informs biological observations and research; and contributing to the validation of ocean biogeochemical models and coastal forecasts. Sustained investments in the OA mooring network maintain long-term time series of OA variability and change, allow the PMEL Carbon Group and partners to provide analyses and comparisons of patterns and trends across the network, and make these mooring data available to the public and the broader scientific community.
The main hypothesis that motivates this mooring network is that the range of natural variability as well as the rates and magnitude of acidification will vary across time, space, and depth as a consequence of local and regional geochemical, hydrological, and biological mechanisms. Similar to the iconic Mauna Loa atmospheric CO2 time series, the “ocean observatories” in the NOAA OA/CO2 mooring network gain importance with time as they, in this case, begin to distinguish ocean carbon uptake and ocean acidification from the large natural temporal variability in the marine environment. The main objective of the NOAA OA/CO2 mooring network is to quantify temporal variability in the ocean carbon system. This includes describing how annual, seasonal, and event-scale variability impacts CO2 flux and OA; providing the carbon chemistry baseline that informs biological observations and research; and contributing to the validation of ocean biogeochemical models and coastal forecasts.
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.