Reprint Series No. 13

PLANT STANDING STOCK AND PRODUCTIVITY ON TIDAL FLATS IN PADILLA BAY, WASHINGTON: A TEMPERATE NORTH PACIFIC ESTUARINE EMBAYMENT

Ronald M. Thom

 

July 1989

Bibliographic Citation
Thom, Ronald M. 1989. Plant standing stock and productivity on tidal flats in Padilla Bay, Washington: a temperate north Pacific estuarine embayment. Report to NOAA/OCRM/MEMD by University of Washington, Fisheries Research Institute (FRI-UW-8909). 37 pp. Seattle, Washington. Padilla Bay National Estuarine Research Reserve Reprint Series No. 13.

Abstract
The standing stock productivity and respiration rates of sediment associated microalgae and macrophytes occurring in (a) sparse pickleweed (Salicornia virginica) marsh, (b) sand-mudflat, and (3) gravel patch habitats located in a Pacific Northwest estuarine bay were measured over an annual cycle in 1987 to 1988. Annual gross primary productivity (GPP) for the sand-mud flats, marsh habitat and gravel patch was 149, 277 and 355 g C m-2. Biomass, net primary productivity and respiration (R) were greatest in spring, intermediate in summer and lowest in autumn-winter in all habitats. The seasonality was related to varying irradiance, temperature and inorganic nutrient concentrations (particularly nitrate nitrogen). Sites with the coarsest sediments had the greatest productivity rates, and sites with the finest sediments had the greatest R. The data from the present study were combined with data from the eelgrass system in the bay. The greatest proportion of total bay annual GPP was attributed to the Zostera marina system (59%), followed by the Zostera japonica system (23%), the sand-mud habitat (8%), the gravel patch (0.2%) and the marsh habitat (0.1%). NPP, respiration and GPP averaged 166, 211 and 377 g C m-2 yr -l, respectively. GPP:R ratio (1.8) indicated that the bay system was autotrophic and exported 44% of the annual productivity. All component systems except the eelgrass meadow sediments were autotrophic on an annual basis. The bay system had an annual turnover rate of 7.0.