What early life history tells us about restoration success in Olympia oysters

• Main Authors: Becker, Bonnie, Behrens, Michael
• Format: Text
• Language: English
• Published: Western CEDAR 2014
• Subjects: Terrestrial and Aquatic Ecology; Pacific; Pacific oyster
• Online Access: https://cedar.wwu.edu/ssec/2014ssec/Day3/100; https://cedar.wwu.edu/cgi/viewcontent.cgi?article=1561&context=ssec

Native Olympia oysters have been the subject of widespread restoration efforts across the west coast, including in the Salish Sea. The ultimate goal of restoration is to establish populations that are self-sustaining or even exporting new offspring to other appropriate habitats. It is difficult to study the early life history of marine invertebrates, which have a microscopic and planktonic larval form and often episodic settlement pulses. However, being able to predict larval behaviors and settlement preferences can allow practitioners to design habitats, choose sites, and distribute restoration networks more effectively. The purpose of this study, a collaboration among academic and non-profit organizations, was to map the spatial and temporal distribution of oyster larvae and settlers in Fidalgo Bay. This bay has been the subject of restoration work over the past decade and has experienced high levels of settlement since the project began. From April through July 2013, we monitored the reproductive state of adults and the relative abundance and distribution of larvae and spatfall. Larvae were collected in larval tube traps and using a plankton pump; the number of larvae were quantified using real-time quantitative PCR. Settlers were sampled using shell strings made of adult Pacific oyster shells that were examined visually. Analyses are ongoing, although studies of adults show low reproductive synchrony, even during peak spawning. Settler data revealed that juvenile oysters settled preferentially near adult oysters rather than across depths and locations as previous studies have indicated. We will compare larval distribution data to determine if larvae are distributed throughout the area and are preferentially settling in optimal habitat, or if they remain in specific areas throughout the dispersal period. These results will be used to improve restoration efforts and to design future studies of larval dispersal of this important ecosystem engineer.