Complex coastal flows and connectivity between kelp forests and the coastal ocean in the Southern California Bight

Libe Washburn, University of California Santa Barbara, Santa Barbara, CA, United States, Nicholas Nidzieko, University of California Santa Barbara, Geography, Santa Barbara, CA, United States, Robert J. Miller, University of California, Marine Science Institute, Santa Barbara, United States, Brian Emery, University of California, Marine Science Institute and Department of Mechanical Engineering, Santa Barbara, United States and Anthony Kirincich, Woods Hole Oceanographic Inst, Woods Hole, MA, United States
Abstract:
As part of the Santa Barbara Coastal Long Term Ecological Research program (SBC LTER) we are examining circulation processes that drive along-shore and cross-shore connectivity between kelp forest ecosystems and the offshore ocean. These process are essential for delivering subsidies that maintain the diverse communities resident in kelp forests. For example, previous research has shown that suspension feeders comprise the most consumer biomass in SBC LTER study sites and that they depend on phytoplankton as their primary external source of dietary carbon. Phytoplankton, along with other subsidies for kelp forest communities, are delivered by a variety of coastal circulation processes. These previous studies have also revealed that internal waves traveling across the inner shelf are important transport mechanisms, but alone are insufficient to supply all of the nutrients and other subsidies required to sustain the kelp forests. This suggests that alternate transport mechanisms contribute to the supply of required subsidies. We are using a variety of observational approaches to understand other complex coastal flows that deliver phytoplankton and other subsidies to SBC LTER study sites. These approaches include oceanographic moorings along the inner shelf for measuring currents and water properties such as chlorophyll fluorescence, pH, and dissolved oxygen. Larger scale, surface flow patterns that drive inner-shelf currents are observed by the oceanographic radar network maintained by the Southern California Coastal Ocean Observing System. Preliminary results indicate that near-shore, anti-cyclonic eddies on scales of 5-15 km occur frequently near study sites. We are using the moored observations to determine if phytoplankton are delivered to SBC LTER kelp forests by these eddies. Future work will examine other possible delivery mechanisms such along-shore current pathways connecting offshore waters to the kelp forests.
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