The working hypothesis of this project is that low pH/low oxygen conditions generate distinctive chemical signatures in the carbonate structures of marine invertebrates and thus can be used as proxies for detecting exposure to ocean acidification/low-oxygen conditions that may occur off upwelling coasts such as California. In the project’s final year, scientists will conduct controlled tank experiments to compare the effects of ambient and low pH/low oxygen conditions on larval mussels and market squid embryos. The tank conditions will simulate scenarios for San Diego coastal waters. Trace element fingerprinting and boron isotope analyses of mussel shells and squid statoliths (carbonate structures similar to otoliths in fish) will establish whether chemical fingerprinting can be done and is suitable for environmental monitoring.