Mainland and Island Kelp Forests in Northern Baja California, Mexico: Subtidal Community Structure, Dynamics, and Connectivity for the Design of Marine Protected Areas

The coasts of northwestern Baja California, MEX, are classified as "Marine Priority Zone I" (MPZI) for conservation of biodiversity in Mexico, and their long-term conservation will require maintaining species diversity, habitat quality, and ecological processes as conservation targets. For my dissertation, I examined patterns of spatial and temporal variability in benthic communities from mainland Macrocystis pyrifera kelp forests, and assessed patterns of genetic diversity and connectivity among mainland and island kelp forests in the MPZI. In the first chapter, I examined spatial and short-term temporal changes in benthic community composition from a USA-MEX transboundary group of kelp forests. The benthic communities were similar, but not identical among sites, and temporal changes in species abundances were not consistent across all sites. Further, I observed a significant relationship between substratum rugosity and species richness, and consequently suggest an index of substratum rugosity can serve as a useful surrogate for biological diversity. Next, I investigated the patterns of connectivity among mainland and island kelp forests from the entire MPZI by assessing patterns of genetic diversity for populations of two invertebrate species with different pelagic larval durations. This produced consistent evidence to support a spatial north-south genetic subdivision predicted by persistent oceanographic surface currents. Finally, I explored similarities in community structure within and among kelp forest communities across the entire MPZI, which revealed a north-south differentiation in benthic communities. This also confirmed the relationship between substratum rugosity and species richness, and supported using rugosity as a surrogate for species richness in the MPZI region. Based on these findings, I recommend classifying mainland and island forest habitats as conservation sites from the north and south MPZI regions, and further prioritize site selection in accordance with species richness and connectivity for the future design of conservation networks along the northwestern coasts of Baja California, Mexico.