Submarine Groundwater Discharge in North Monterey Bay— The Fuel Sustaining the Algal Incubator

Northern Monterey Bay is subject to recurrent diatom and dinoflagellate blooms. Theories as to why these blooms occur in Northern Monterey Bay include the creation of retention zones within the inner shelf, which accumulate nutrients and phytoplankton, and pumping of nutrient-rich deep water from Monterey Canyon onto the inner shelf. The scientists of this project propose that submarine groundwater discharge is a yet unidentified source of nutrients to Monterey Bay that may contribute to sustaining the phytoplankton in the coastal area. Preliminary results indicate that submarine groundwater discharge is continuous throughout the year, adding nutrients into Northern Monterey Bay, and mixing models of nutrients and radium isotopes show the greatest influence of submarine groundwater discharge on the bay is in the nearshore, with nutrient- rich deep water influencing areas of the continental shelf further from shore. An incubation experiment with Monterey Bay seawater and phytoplankton populations showed additions of local groundwater elicited a positive growth response from diatoms, further strengthening the theory that submarine groundwater discharge plays a role in phytoplankton ecology of Northern Monterey Bay.