PI: Mark Ohman
Research Institution: Scripps Institution of Oceanography, UC San Diego
PI: Mark D. Ohman
The California Current Ecosystem (CCE) Long Term Ecological Research (LTER) site is a productive coastal upwelling biome structured by remote and local physical forcing, as well as biotic interactions in the ocean water column. The CCE-LTER site, building upon >62 years of extensive ocean measurements by CalCOFI, seeks to understand the mechanisms underlying transitions between different states of the pelagic ecosystem, as well as the corollary: ecosystem resilience. This interdisciplinary research group is investigating the ecological effects of long-term forcing by a secular warming trend, the North Pacific Gyre Oscillation and Pacific Decadal Oscillation, and El Niño in altering the structure and dynamics of the pelagic ecosystem. The research program includes extensive time series measurements (shipboard, gliders, moorings, remote sensing, nearshore piers), Lagrangian-design experimental process cruises, coupled circulation-food web models, information management, and an education, outreach, and capacity-building program. A current focus of the process cruise component of the CCE-LTER site is the role of mesoscale and sub-mesoscale fronts and eddies in altering nutrient fluxes, predator-prey interactions, and biogeochemistry, and the relationship of such features to larger scale climate variability.
An aspect of the changes in the California Current System whose consequences are largely unknown is the effects of changing ocean chemistry on organisms in the water column. These processes include altered ocean acidity, hypoxia, and trace metal availability. Research pertaining to ocean acidification in the CCE-LTER site includes: (1) Two interdisciplinary moorings in collaboration with colleagues at PMEL and the Southwest Fisheries Science Center. These moorings (CCE-1 in the offshore, low salinity core of the California Current, and CCE-2 in the coastal upwelling region off Pt. Conception) include measurements of pCO2, pH, dissolved O2, meteorological variables, 7-wavelength irradiance, phytoplankton fluorescence, nitrate+nitrite, acoustic backscatter due to macrozooplankton and fish, Doppler currents, and CTD’s. Partner moorings include HARP measurements of marine mammal vocalizations. (2) Spray ocean gliders along CalCOFI lines 80 and 90. The line 80 glider intersects the CCE-1 and CCE-2 mooring sites, and includes dissolved oxygen and temperature, from which aragonite saturation state is estimated, zooplankton acoustic backscatter, Doppler currents, phytoplankton fluorescence, and CTD. (3) Quarterly shipboard measurements of pH and carbon system variables from CalCOFI, accompanied by extensive hydrographic, plankton, fish egg, and multi-frequency acoustic measurements. (4) Studies of long-term variability in calcifying holozooplankton (esp. pteropods, heteropods, and planktonic foraminifera), and the relationship of their vertical distributions to calcium carbonate saturation state. (5) Experimental studies.
KEYWORDS: ecosystem state changes, climate change, multi-decadal variations, ENSO, ocean acidification, autonomous gliders, moorings
FUNDING AGENCY: NSF (LTER), NOAA (moorings, gliders)