Impacts of Paired Olympia Oyster (Ostrea lurida) and Eelgrass (Zostera marina) Restoration on Fish Movement and Habitat Utilization

• Main Author: Taylor, Alyssa
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01.01.2024
• Subjects: Biology; Ecology
• ISBN: 9798383580189

Wetlands are extremely valuable ecosystems that have experienced significant declines over time. To preserve wetlands and the functions they provide, restoration is often used. Olympia oysters (Ostrea lurida) and eelgrass (Zostera marina) were restored as part of a living shoreline restoration, separately and paired, at four sites in Newport Bay, California, in 2016 and 2017. I monitored fish communities using baited remote underwater videos (BRUVs) deployed at both the intertidal and subtidal level. Additionally, fish were caught using hook-and-line, tagged with external color-coded tags, and then BRUVs were deployed for the next 3 days to assess whether fish populations were more resident or transient within the embayment. I hypothesized that fish abundance within restored habitats would be highest at paired oyster and eelgrass treatments due to the structure, shelter, and foraging grounds provided by the oyster and eelgrass beds. I found that community composition and abundance varied by season and within season by site (which correlates with available habitat parameters of oyster and eelgrass density). No individual habitat parameter was predictive of fish abundance, but the consideration of site, season, and habitat parameters together allowed for visualization of trends in fish communities. In spring, summer, and fall, the PCH site had the highest fish abundance; of all the sites, PCH was at the intersection of eelgrass and oyster habitat parameters in principle component analyses more than any other site. The fishing and tagging study resulted in the capture of 108 fish from 11 different species, none of which were ever seen again. This suggests that fish are moving among habitats within the bay more than anticipated and speaks to the success of the restoration since it created large patches of valuable intertidal habitat for fish to move between. Future restorations can be informed on the basis that increasing the microhabitat diversity in the overall habitat supports a varied fish community composed of many guilds.