Data from: Comparison of shallow water seston among biogenic habitats (eelgrass, oysters, bare) on tidal flats
Description
Hypothesis: Biogenic species (eelgrass, oysters) influence water properties such as velocity and particulates, especially in shallow water. We tracked parcels of water across tidal flats using custom Lagrangian drifters and collected samples of water at the start and end of drifts across different habitat types. The study design was nested, including 5 coastal sites in Washington State, USA, 3 subsites per site, each habitat type at a subsite (eelgrass, oysters, bare), and three water levels at each habitat patch. Density and biomass of benthic organisms were evaluated in 10 quadrats per patch. We measured water velocity based on the distance per duration of each drift, chlorophyll-a concentrations, total suspended solids, and organic content near the water surface. Shallowest depths were 0.1 m of water, and most drifts occurred in <2 m of water. These response variables were examined for main effects of water depth and habitat type, as well as depth x habitat interactions that would indicate that water properties become more homogeneous as the distance to the bottom increases. We found that water over eelgrass patches contained higher concentrations of total suspended solids and chlorophyll-a, as well as higher chlorophyll-a per suspended solids, than did bare habitat. In all habitat types, total suspended solids were inversely related to water depth; that is, shallower water contained higher particulate loads. Water velocity slowed at shallow water depths near low tide, as well as over eelgrass patches relative to other habitats. No depth x habitat interactions were detected.