Bivalves, such as oysters, clams, and mussels, have critical roles to play in both the food chain and water quality in Puget Sound. However, if adult bivalve populations are faltering, it is imperative that we learn more about their larval phase, to ensure that the population is sustained. Bivalve larvae are not sessile, and they are not completely mobile, but can orient and move themselves on small scales. The purpose of this project is to determine if bivalve larvae prefer to stay within eelgrass beds depending on the time of day. It is hypothesized that bivalve larvae may stay within eelgrass beds to hide from potential predators. In order to better understand the habitat-level behavior of bivalve larvae, samples were collected during the summer of 2015 at 4 locations around Washington State: Fidalgo Bay, Port Gamble, Case Inlet, and Willapa Bay. Besides the location, key sampling variables included: time of day (light or dark), and substrate (eelgrass or bare). Samples were analyzed by hand-counting all bivalve larvae found through polarized light microscopy. Counts of both specific species, and total bivalves found were collected. The results of this project are still pending; however, this data could be useful to shellfish growers, and any persons responsible for identifying areas for habitat restoration work. With increasing world water temperatures and acidity due to climate change, eelgrass beds, have the potential to be a refuge from these effects. Therefore, this data would be important to predict the effects of ocean acidification and warming on all species of bivalves in all life stages. 

Olympia oysters (Ostrea lurida) are the only native oyster species in Washington State. Over the past 100 years populations have dwindled, but due to restoration efforts, Olympia oysters are slowly recovering. So far there is limited information about the behavior during the larval stage. Previous observations suggest that larvae would be more abundant at the surface compared to the bottom of the water column. In this study, we measured the spatial distribution of larvae at surface and bottom depths in Fidalgo Bay, WA during the Summer of 2013. Plankton samples were taken from 4 intertidal and 2 subtidal stations pumping 100L of seawater through a 75 µm sieve. Olympia oyster larvae were identified using light microscopy, measured for shell height and length, and tallied to determine abundance and distribution. As predicted, larvae were not randomly distributed across the bay, and more larvae were found at the surface for each site. We found an order of magnitude of more larvae at surface depths during ebb tide, indicating that larvae are being transported out of the bay. These results are being combined with additional temporal and spatial sampling, as well as environmental data, to fully describe the larval distribution of oysters in the bay. This study will improve restoration efforts as well as inform researchers and local communities about the early life stages of Olympia oysters.