The California Current Ecosystem (CCE) LTER site is a productive coastal upwelling biome structured by remote and local physical forcing, as well as biotic interactions in the ocean water column. The CCE site, building upon 60 years of extensive time-series measurements by CalCOFI, seeks to understand the mechanisms underlying transitions between different states of this ecosystem, as well as their corollary: ecosystem resilience. In the first phase of CCE funding investigators at this site uncovered a new climate mode for the North Pacific (NPGO); found marked differences in food web structure between the offshore wind stress curl and the classical coastal boundary upwelling domains; detected long-term changes in gelatinous grazers (pelagic tunicates), optical properties, nitracline depths, prevalence of hypoxia, stratification, and other ecosystem characteristics; revealed zones of iron and iron-light co-limitation of primary production; developed a ROMS model and used it in hindcast mode to diagnose causality of ecosystem transitions and forecast mode to guide Lagrangian process cruises; developed an allometric approach to food web modeling; discovered differences between physical and biotic time series in degree of nonlinearities; demonstrated the destabilizing effects of fishing; initiated new data practices; and more. Findings from this first effort point to the importance of spatial structuring of the CCE, especially on the mesoscale. In this renewal the LTER investigators target mesoscale fronts and eddies, which constitute an important part of the CCE ecological disturbance regime. CCE Investigators have found that such features vary on interannual and decadal scales in the CCE region and they hypothesize that their variability over time may contribute to ecosystem transitions.
This project will continue studies at the CCE LTER. The overarching questions posed in this next phase of the study are: What are the mechanisms leading to different states in a coastal pelagic ecosystem? What is the interplay between changing ocean climate, community structure and ecosystem dynamics? To address these questions, the investigators propose to examine 4 mechanisms that could contribute to ecosystem transitions: anomalous alongshore advection; in situ food web changes in response to stratification and nutrient supply; changes in cross-shore transport; and altered predation pressure. They will also test 3 hypotheses related to the role of mesoscale processes, specifically concerning their role in altering nutrient fluxes and predator-prey interactions, the integrated biogeochemical effects of mesoscale fronts and eddies over the CCE region and the relationship of such features to larger scale climate variability. A combination of Lagrangian process cruises, experimental work, time series measurements, modeling, data synthesis, and a coupled human-natural system study will be used to address these questions. The project will also continue to measure the 5 LTER core variables.
Broader Impacts: Notable among the ecosystem services furnished by the coastal ocean off southern California is the region?s importance for spawning and/or harvesting of many commercially important fishes and marine invertebrates. This research will provide a key scientific foundation for understanding time and space variability of properties relevant to ecosystem-based fisheries management. This information is essential as managers begin to address the consequences of changing ocean acidity, stratification, and hypoxia for resource populations and communities. ISSE (Integrated Science for Society and the Environment) studies will partner an economist, graduate student, and scientists in the development of a bioeconomic model to examine the interplay between ecosystem variability and fishers? decision-making and resource allocation. In addition, the CCE Investigators will further develop and enhance DataZoo, the information system central to our Information Management and data sharing environment. They will implement new web-accessible tools to facilitate data visualization and communication of CCE results to students, teachers across all levels, scientists, managers, policy-makers, and the broader public. An Education, Outreach, and Capacity Building (EOCB) program will include a vigorous program of involvement of tens of graduate students in site science and communication. A graduate student will serve as a research liaison with the EOCB coordinator, to help translate CCE science into K-12 lesson plans. CCE LTER will work with local teachers in a diverse urban school district to bring CCE science into the classroom, and will continue outreach and coastal ocean time series activities with the nonprofit Ocean Institute. This LTER site will expand their successful RET and Teacher-at-Sea programs, to enable teachers to communicate the process of science inquiry directly to students. Their REU program will continue targeting under-represented undergraduates to expand the pipeline into the ocean sciences.
