| Summary: | Olympia oysters (Ostrea lurida) are a bed-forming oyster and the only oyster native to the west coast spanning from Baja, Mexico to Alaska. A combination of oil spills, waterfront development, and mismanagement has resulted in the local extirpation of Olympia oysters in Fidalgo Bay, Washington. Restoration efforts in Fidalgo Bay dating back to 2002 have augmented the population of adult Olympia oysters. In subsequent years, settlement substrate was increased by adding Pacific oyster shell to the beaches to promote recruitment. Annual observations since then demonstrate an increase in the Olympia oyster population. This project focuses on identifying the spatial and temporal distribution of newly settled Olympia oysters in Fidalgo Bay. The hypotheses being tested are (1) Olympia oysters will have higher rates of settlement near adult populations, and (2) larval abundance will be higher at the surface compared to the bottom of the water column irrespective of tidal direction. To quantify recruitment, eight spat monitoring locations around Fidalgo Bay were monitored bi-weekly, utilizing shellstrings which were constructed from Pacific oyster shell. To quantify Olympia oyster larvae within the water column, weekly plankton samples were collected near the adult Olympia oyster population. Regarding hypothesis (1), results show that Olympia oyster settlement rates are higher in areas which directly neighbor the adult population. Regarding hypothesis (2), larval abundance was found to be significantly greater at the surface compared to the bottom of the water column. Identifying patterns of recruitment is vital to making the best decision possible in Olympia oyster restoration work. This research will provide a framework to monitor rebounding Olympia oyster populations. Results may assist in designing habitat restoration networks for Olympia oysters.
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