ABSTRACT

This award will create a LTER-Long-Term Ecological Research site in the coastal upwelling biome of the California Current System. The research will focus on mechanisms leading to temporal transitions between different states of the pelagic ecosystem. Observations from the CalCOFI (California Cooperative Oceanic Fisheries Investigations) coastal ocean time series, currently in its 55th year, demonstrate the importance of external forcing of the pelagic ecosystem on multiple time scales, including: El Nino, the multi-decadal Pacific Decadal Oscillation, and a multi-decadal secular warming trend. Interactions of such forcing and biotic interactions can lead to nonlinear ecosystem responses that may be expressed as relatively abrupt transitions. The work will evaluate four hypothesized mechanisms for such ecosystem transitions:?
-Sustained, anomalous alongshore advection of different assemblages;
-In situ food web changes in response to altered stratification and nutrient supply;
-Changes in cross-shore transport and loss/retention of organisms; and
-Altered predation pressure.
The California Current Ecosystem (CCE) LTER site will address these hypotheses with an integrated research program having three primary elements: (1) Experimental Process Studies will initially focus on the hypothesis of in situ food web changes. (2) Time Series Studies will evaluate alternative hypotheses using space-resolving time series measurements, including high frequency temporal measurements at different nearshore locations, satellite remote sensing, and an extensive quarterly measurement program at sea that will capitalize on and significantly enhance the CalCOFI time series. (3) Modeling and synthesis studies will help quantify the dynamics underlying the observations; provide a platform for hypothesis testing through numerical experiments and process models; provide a means for dynamic interpolation between observations in space and time; and help optimize the field program.
The proposed study region is an ideal location for an LTER site: it has 5 decades of climate context provided by CalCOFI; it is in a biogeographic boundary region, making it an early sentinel of climate change; it has pronounced spatial gradients in a relatively small geographic area; its anoxic basins provide a unique connection to paleoceanographic studies; and the extant 4-D physical ocean circulation model of the region will permit rapid advances in the development of coupled bio-physical models of ecosystem transitions. The site will allow the LTER network to compare coastal pelagic upwelling ecosystems with other biomes with respect to: Pattern and control of primary production, Spatial and temporal distribution of populations selected to represent trophic structures, Patterns of inorganic inputs and movements of nutrients, and Patterns and frequency of disturbances.
Broader Impacts: The project will have state of the art Information and Data Management to serve data internally, to LTER partners, educators, the general public, and policy makers. An active Education and Outreach program will team scientists with CA-COSEE and external partners to engage the K-12 community in both the process of and the understanding gained from this research. They will train undergraduates, graduate students, and postdoctoral scholars across disciplinary boundaries. Through collaborations with informal science education organizations, they will reach hundreds of K-12 schoolchildren each year, including local low-income and minority students. Teachers and students will participate in field studies and gain training in oceanographic science. They will also assist in the development of new school curricula.

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