Local Anthropogenic Nutrients Effects on Coastal Acidification and Hypoxia in Southern California Bight: A Case Study Linking Integrated Systems Modeling to Support Management Decisions

Martha Sutula1, Faycal Kessouri2, James C McWilliams3, Daniele Bianchi4, Curtis A. Deutsch5, Nina Bednarsek6, Evan M Howard7, Lionel Renault8, Karen McLaughlin1, Minna Ho1, Richard A Feely9 and Stephen Weisberg10, (1)Southern California Coastal Water Research Project, Costa Mesa, CA, United States, (2)Southern California Coastal Water Research Project, Costa Mesa, United States, (3)University of California, Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, United States, (4)University of California Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, (5)University of Washington Seattle Campus, School of Oceanography, Seattle, United States, (6)Southern California Coastal Water Research Project, Biogeochemistry, Costa Mesa, United States, (7)WHOI, Woods Hole, MA, United States, (8)University of California Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, United States, (9)NOAA PMEL, Seattle, United States, (10)SCCWRP, Costa Mesa, CA, United States
Abstract:
Coastal oceans are increasingly experiencing acidification and hypoxia (CAH) events severe enough to affect biotic resources. Three phenomena have been implicated: 1) large scale acidification and deoxygenation associated with climate warming and increased atmospheric CO2, 2) natural climate variability, and 3) coastal eutrophication, driven by anthropogenic nutrient inputs. Disentangling the magnitude and interaction of these factors requires an integrated systems modeling approach carefully validated against available datasets; use of this information to drive management conversations about climate change adaptation and local pollution management requires an active and engaged stakeholder community and scientific consensus on the import of these changes to nearshore biological communities. This talk presents a case study of how these components are being used to support management conversations on feasibility of local pollution management to reduce CAH stress in the Southern California Bight (SCB) nearshore, a large marine embayment on the US West Coast. In the SCB, where the primary or secondary treated wastewater from a population of 20 million people are discharged via ocean outfalls, we employ an ecophysiological framework for evaluating marine habitat suitability that utilizes synergistic thresholds of pH, DO and temperature to investigate the biological impact of local pollution sources. These biologically-relevant thresholds are being applied to numerical simulations of a Regional Oceanic Modeling System (ROMS), comprising circulation, biogeochemical cycles, and lower-trophic ecosystem of the SCB to quantify the impact of anthropogenic nutrients and to determine appropriate management actions. This talk will summarize key components of ongoing investigations that are important for management acceptance and consideration of possible actions.
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