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.
The goal of this component of the project is to continue the mooring and ship-based monitoring of the Ocean Acidification-impacted carbonate chemistry of US Pacific coastal waters. This objective will be accomplished by: 1) continued operation of the Oregon Ocean Acidification Mooring Program, including deployment and maintenance of the surface moorings at the established Ocean Acidification (OA) node at NH10 with surface MAPCO2 systems, nearbottom moorings with SAMI-CO2 and SAMI-pH systems at the NH10 site and the shelfbreak in the early stages of the project, followed by a relocation (following validation exercises, see #3) of these assets to a more biologically productive site to the south; 2) measurement support of the West Coast Ocean Acidification Cruise in 2016; and 3) a validation program for moored measurements off the Oregon Coast. The final component will include a parallel deployment of the NOAA-OAP moored assets at NH-10 for 6-12 months following establishment of the OOI node there to ensure consistency between the OAP and OOI platforms, as well as continued opportunistic sample collection for archiving and analyses in Hales; lab at OSU.
This project will deploy two interdisciplinary moorings (CCE1 and CCE2) in the southern California Current System, a key coastal upwelling ecosystem along the west coast of North America. The study region forms the dominant spawning habitat for most of the biomass of small pelagic fishes in the entire California Current System, is important for wild harvest of diverse marine invertebrates and fishes, plays a significant role in the ocean carbon budget for the west coast, and is in close proximity to the Channel Islands National Marine Sanctuary. The offshore CCE1 mooring is located in the core flow of the California Current itself, and represents a key source of horizontal transport of nutrients, dissolved gases, and organisms from higher latitudes. It also represents the offshore atmosphere-ocean gas exchange that occurs over a large area and influences the carbon budget of this Eastern Boundary Current. The CCE2 mooring is located near Pt. Conception, one of the major upwelling centers off the west coast. This is a site of strong, episodic upwelling events that lead to marked increases in pCO2, declines in pH and dissolved oxygen, and intrusion of waters unfavorable to precipitation of calcium carbonate by some shell-bearing marine organisms. The proposed work will regularly deploy and service taut line, bottom-anchored moorings at the two mooring sites, with sensors designed to measure all core carbonate system variables specified by the PMEL OA Monitoring Network. The data will be validated with shipboard measurements and rigorous QC procedures, and made freely available via Iridium satellite telemetry. Complementary measurements made by partners in this region include Spray glider-based assessments of calcium carbonate saturation state, CalCOFI shipboard hydrographic and plankton food web measurements, process studies conducted by the CCE-LTER (Long Term Ecological Research) site, and a new experimental Ocean Acidification facility.
PI: Uwe Send