The causes and consequences of patchiness in kelp forests and implications for coastal marine reserve design (Hosted by NCEAS)
- Ellen I. Damschen
|Center Associate||1st November 2005—31st October 2006||Participant List|
Human-induced change has led to the rapid loss of global biodiversity and the alteration of local species assemblages through habitat destruction and degradation, the introduction of novel species, alteration of biogeochemical cycles, and the over-consumption of resources. In marine systems, these effects have recently become disturbingly apparent. 60% of the world¿s fisheries today are fully- or over-exploited and the trophic structure of marine communities has undergone dramatic changes as a result of the loss of top predators. Marine reserves are quickly becoming one of the major strategies for ameliorating these negative impacts. Like terrestrial reserves, marine reserves are based on fundamental theory provided by island biogeography and metapopulation biology that predict species persistence and colonization rates will increase in larger and less isolated habitats. Marine systems, however, differ from their terrestrial counterparts, which has led to the general belief that landscape structure (i.e., habitat area, patch shape, proximity, and the use of movement corridors and stepping stones) is generally a non-issue in marine ecosystems. However, the usefulness of theory originating from terrestrial reserve design may largely depend on the specific habitat types chosen. There are strong similarities between nearshore coastal habitats and terrestrial plant communities, making it likely that the effects of connectivity and patch shape also operate similarly in these systems.
I propose the first test of large-scale habitat configuration effects on species diversity and composition over time in kelp forests using rare long-term datasets from the Santa Barbara Channel. This project will determine the effects of the spatial arrangement of habitat in kelp forests on community composition and species abundances and distributions and will provide a differential tool that can be used to assess the importance of connectivity and patch shape for species with different life history traits at two different scales. I will use a combination of traditional multivariate statistics and Hierarchical Bayesian Modeling (a new computational statistical technique to assess complex spatiotemporal problems) to determine if the degree of patchiness at two different spatial scales (between- and within-reefs) has increased over time due to human-induced impacts (e.g., urchins, pollution, climate variability). Using a cross-disciplinary approach, I will apply tools from terrestrial landscape ecology to quantify suitable habitat for kelp and determine if the area, isolation, and shape of available substrate affects kelp colonization and turnover. I will use this same approach to determine if kelp forest patchiness affects the distribution and abundance of marine species and whether life history traits (reproductive mode, planktonic larval duration, vagility) can predict species responses. Finally, I plan to then use existing global datasets to determine if the local findings are generalizable across kelp forests.
To meet these proposed goals, I will utilize my strong background in terrestrial reserve design, dispersal dynamics, database management, and multivariate spatial statistics. I will develop collaborations with leaders in bioinformatics, biogeography, and marine reserve design at the University of California-Santa Barbara and the National Center for Ecological Analysis and Synthesis (NCEAS), which will allow me to complete the proposed research successfully in fellowship time frame. My sponsoring scientist, Steve Gaines, is a leader in marine population dynamics, larval dispersal, biogeography, and the design of marine reserves, and has been an active participant in ecoinformatics at the NCEAS, making him an ideal mentor and collaborator. This project uniquely synthesizes large-scale data to inform reserve designers at a critical time about the optimal size, shape, and placement of habitats for different marine organisms.