BENTHIC PRIMARY PRODUCTION IN THE EELGRASS MEADOW AT THE PADILLA BAY NATIONAL ESTUARINE RESEARCH RESERVE, WASHINGTON

Ronald M. Thom

 

February 1988

 

Bibliographic Citation
Thom, Ronald M. 1988. Benthic primary production in the eelgrass meadow at the Padilla Bay National Estuarine Research Reserve, Washington. Report to NOAA/OCRM/MEMD by University of Washington, Fisheries Research Institute (FRI-UW-8808). 33 pp. Seattle, Washington. Padilla Bay National Estuarine Research Reserve Reprint Series No. 10.

Abstract
The spatial patterns of standing stock and productivity of benthic autotrophic components (Zostera marina and Zostera japonica, epiphytic algae and benthic sediment associated algae) of the eelgrass meadow in Padilla Bay, Washington, were studied seasonally for one year. Eelgrass extended from approximately 1.0m above MLLW down to subtidal depths. However, standing stock decreased at depths below -0.5m MLLW. Z. japonica formed a band at upper elevations, and mixed with Z. marina at about 0.3m to 0.6m MLLW. Epiphytic algae were abundant in the meadow, and reached greatest standing stock between 0.3 and -0.4m MLLW. Sediment associated algae were abundant at all elevations as indicated by chlorophyll a concentrations. The standing stock of all components varied seasonally. Sediment algae reached peak abundance in early spring, followed by rapid growth of epiphytic macroalgae in early summer. Eelgrass biomass was greatest in early to late summer depending upon depth. Annual net primary productivity (NPP) for the system was 351 gC m-2. Epiphytic algae, Z. japonica and Z. marina were responsible for 50, 2 and 48% of this production, respectively. NPP by sediment algae was negligible due to high sediment associated respiration rates. Total annual production from the 3,000ha system was approximately 28,000 mt dry plant matter.