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Design and Implementation of Environmental DNA Metabarcoding Methods for Monitoring the Southern California Marine Protected Area Network


Marine protected areas (MPAs) are important tools for maintaining biodiversity and abundance of marine species. However, key to the effectiveness of MPAs is monitoring of marine communities. Current monitoring methods rely heavily on SCUBA-based visual observations that are costly and time consuming, limiting the scope of MPA monitoring. Environmental DNA (eDNA) metabarcoding is a promising cost effective, rapid, and automatable alternative for marine ecosystem monitoring. However, as a developing tool, the utility of eDNA metabarcoding requires improved bioinformatic techniques and reference barcode databases. Furthermore, it is important to understand how eDNA metabarcoding performs relative to visual surveys to better understand the strengths and limitations of each approach. This thesis improves eDNA metabarcoding approaches to survey the nearshore rocky reef and kelp forest ecosystems within the Southern California MPA network. It then tests the effectiveness of eDNA metabarcoding against visual surveys conducted by the Channel Islands National Park Service Kelp Forest Monitoring Program and Reef Check California. In Chapter 1, I develop FishCARD, a 12S reference barcode database specific to fishes of the California Current ecosystem. FishCARD improves eDNA metabarcoding taxonomic assignments, resulting in the identification of a broader array of marine vertebrate diversity, including invasive, endangered, and mobile species frequently missed by visual surveys. In Chapter 2, I compare eDNA metabarcoding and visual underwater survey methods inside, on the edge of, and outside the Scorpion State Marine Reserve off Santa Cruz Island. We demonstrate that eDNA captures a broader range of fish taxa than visual surveys and detects fine-scale spatial differences in fish communities. In Chapter 3, I demonstrate that eDNA metabarcoding and visual underwater surveys capture similar biogeographic patterns of fish communities across 44 sites within the Southern California Bight. Importantly, eDNA methods distinguished fish communities inside and outside of Southern California MPAs, finding a greater abundance of target species inside MPAs matching patterns observed through visual surveys. These results built off the collaborative development of the Anacapa Toolkit metabarcoding pipeline. Together I demonstrate the utility of eDNA metabarcoding for monitoring MPAs, providing an important complementary tool to visual methods, helping expand MPA monitoring across space, time, and depth.

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