Comparative studies across sites with interests in alternate stable states, El Niño and lower-frequency forcing, and the role of top-down impacts on ecosystem dynamics. A long term goal for this site is to develop a mechanistic, coupled bio-physical model for understanding and forecasting the consequences of El Niño and low-frequency climate forcing on pelagic ecosystems of the California Current and similar biomes.
The CCE is an LTER-Long-Term Ecological Research site in the coastal upwelling biome of the California Current 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 its research hypotheses with an integrated research program having three primary elements:
- Experimental Process Studies will initially focus on the hypothesis of in situ food web changes.
- 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.
- 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. Noteworthy is the integration of Information and Data Management as well as of Education and Outreach components within the project so that synergies develop during design and implementation.Read Less
This new site will build on what has been learned from the unparalleled suite of coastal observations developed by CalCOFI (the California Cooperative Oceanic Fisheries Investigations) since its inception in 1949, but move far beyond that program. The new site will focus specifically on the mechanisms leading to transitions between ecosystem states.