Project Abstract and Hypothesis

Nonlinear Transitions in the California Current Coastal Pelagic Ecosystem

We have created an LTER site focusing on the California Current pelagic Ecosystem (CCE). This new site builds on what has been learned from the unparalleled suite of coastal observations developed by CalCOFI (California Cooperative Oceanic Fisheries Investigations) since its inception in 1949, but moves far beyond that program. The CCE site focuses on the mechanisms leading to transitions between ecosystem states. The proposed research program is coordinated with three interwoven components:

  1. Experimental Process Studies focused on hypothesized mechanisms leading to system transitions
  2. Space-resolving Time Series that explore alternate hypotheses through characterization of ecosystem responses on time scales from hours to decades
  3. Integrated Modeling studies that synthesize experimental and observational results, provide a platform for hypothesis-testing and eventually ecosystem forecasting, and help to optimize the sampling program

The California Current System (CCS) is a coastal upwelling biome, as found along the eastern margins of all major ocean basins. These are among the most productive coastal ecosystems in the world ocean. The CCS sustains active fisheries for a variety of finfish and marine invertebrates, modulates weather patterns and the hydrologic cycle of much of the western United States, and plays a vital role in the economy of myriad coastal communities. El Niño, the Pacific Decadal Oscillation, and a secular warming trend are known to alter the structure and dynamics of the CCE, leading to the following central questions:

  • What are the mechanisms leading to different ecosystem states in a coastal pelagic ecosystem?
  • What is the interplay between changing ocean climate, community structure and ecosystem dynamics?

We focus on four principal hypotheses generating changes in this ecosystem:

  1. In situ food web changes in response to altered vertical stratification and nutrient supply
  2. Alongshore advection of different assemblages
  3. Changes in cross-shore transport and loss/retention of organisms
  4. Altered predation pressure

We have developed research approaches that address these hypotheses, while concurrently addressing the five core research themes that are held in common across all LTER sites. We are also conducting comparative studies with sites having interests in alternate stable states, El Niño and lower-frequency climate 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 high-frequency (e.g., El Niño) and low-frequency climate forcing on pelagic ecosystems of the California Current and similar biomes.