Larval connectivity, which quantifies the intensity and pathways of connections among populations through the dispersal of larvae, is a critical factor in marine population dynamics and has broad reaching consequences for marine spatial planning and fisheries management. Biophysical models, consisting of ocean circulation models combined with Lagrangian particle tracking, are now widely used to provide insights into the spatial and temporal dynamics of larval connectivity that remain unobtainable through empirical approaches. However, many of the biological assumptions used to characterize larval life history in these models are quite general and the impacts of these assumptions have yet to be rigorously tested. The goal of this project is to quantify How important are the details of larval biology in estimates of connectivity and long-term population dynamics? To answer this question, the investigators will study the spatial and temporal impacts of larval biological factors on site-to-site connectivity and long-term population growth using a biophysical model for near shore species in the Southern California Bight (SCB). Four major, larval biological factors will be investigated: (1) temperature effects on larval growth, maturation and mortality, (2) vertical swimming behavior, (3) spatial/temporal variability in larval production, and (4) role of habitat on settlement. Using a biophysical model of the SCB, differences in larval connectivity due to the biological factors will be assessed statistically by comparing connectivity estimates that incorporate the additional biological factors to a baseline of connectivity estimates calculated from passive, neutrally buoyant particles. The investigators will also employ a spatial demographic model, driven by the connectivity estimates, to quantify the influence of biological factors on long-term population dynamics. The project will generate significant insights into the various aspects of larval biology that are critical for determining larval connectivity and for projecting population dynamics into the future. The results of this project will improve the credible application of biophysical modeling approaches to scientific studies of coastal species as well as to marine spatial planning and fisheries management.
BROADER IMPACTS The results of this study will contribute greatly to our scientific understanding of the role of circulation in dynamics of marine organisms and population connectivity. As importantly, the results will have direct management applications. Siegel and Kendall have both been involved in the Channel Islands National Marine Sanctuary's and the State of California's processes to designate marine protected areas (MPAs) and this study is expected to contribute as the State's Marine Life Protection Act (MLPA) process moves into its monitoring and evaluation phase in the Southern California Bight. The PIs have extensive experience involving undergraduate and graduate students in research and ~20 students a year from diverse backgrounds participate in research in their labs. This project will also maintain diversity in the sciences by supporting the research of one female PI with no prior NSF support (Simons) and a female graduate student. The investigators will continue weekly group meetings in spatial marine ecology at UCSB that have become a nexus of activity for graduate students, postdocs and faculty. In addition, the connectivity estimates produced for the SCB from this project will be made freely available to all interested investigators via the SBC LTER information management system (http://sbc.lternet.edu/data). There is a great need for these connectivity estimates by both academics and resource managers throughout the SCB. This collaboration with SBC LTER will also expand the types of analyses they can conduct and provide added value to both the present project and the SBC LTER.
