Who is contributing where? Predicting ecosystem service multifunctionality for shellfish species through ecological principles

In situ habitat clearance rates and particle size preference of indigenous Olympia oysters (Ostrea lurida) and non-native Pacific oysters (Magallana gigas) in North American Pacific coast estuaries

The Olympia oyster, Ostrea lurida, is the target of many restoration projects along estuaries on the North American Pacific coast, while the non-native Pacific oyster, Magallana gigas, dominates oyster aquaculture globally. Both species provide filtration functions that were investigated in three California bays using a whole-habitat, in situ approach, a laboratory particle selection experiment, and a regional physiological comparison. Measurements of chlorophyll α, temperature, salinity, and turbidity upstream and downstream, as well as point samples of seston total particulate matter and organic content to estimate habitat clearance rates (HCR, L hr-1 m-2) were collected. From February 2018 to June 2019, twenty-two trials were conducted across four sites. HCRs were highly variable within and among sites, ranging from site averages of -464 to 166 L hr-1 m-2, and not significantly different among sites, indicating field filtration performance of O. lurida habitat and M. gigas aquaculture is similar. Using a random forest regression, site was the most important predictor of HCR, with a variable importance score of 25.7 % (SD = 4.6 %). O. lurida and M. gigas had significantly different particle size selection preferences, likely affecting the quality of their filtration. This study's findings suggest that restoring O. lurida habitat may provide similar filtration benefits as M. gigas aquaculture, but the unique hydrodynamics and food quality of individual bays, as well as regional differences in filter feeder communities, must be considered in managing oyster habitat for filtration functions.

Estimating Effects of Sea Level Rise on Benthic Biodiversity and Ecosystem Functioning in a Large Meso-Tidal Coastal Lagoon

Estuaries are among the world's most productive ecosystems, but due to their geographic location, they are at the forefront of anthropogenic pressures. Sea level rise (SLR) is one major consequence of climate change that poses a threat to estuaries with extensive intertidal habitats. The ecological implications of intertidal habitat loss have been largely overlooked despite their likely significance. We aimed to address this knowledge gap by investigating how benthic macroinvertebrate communities and their contributions to ecosystem function are likely to respond to SLR. Based on a spatially extensive dataset (119 sites) from a large coastal lagoon, depth, sediment chlorophyll concentrations, mud content, and average current speed were identified as the main drivers of community compositional turnover. Shifts in benthic community structure and associated functional implications were then evaluated using depth as a proxy for SLR. Three main macrofaunal groups representing intertidal, shallow subtidal, and deep subtidal habitats were identified. Functional trait analysis indicated low functional redundancy for a key intertidal suspension-feeding bivalve (Austrovenus stutchburyi) and the lack of a shallow subtidal functional replacement should intertidal habitats become inundated. These findings strongly suggest SLR and the associated environmental changes will alter estuarine macroinvertebrate communities, with implications for future ecosystem function and resilience.