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Document Type

Book Chapter


Virginia Institute of Marine Science


Paula Hill and Steve Nelson, editors.

Publication Date


Book Title

Toward a Sustainable Coastal Watershed: The Chesapeake Experiment. Proceedings of a Conference 1-3 June 1994. Norfolk, VA


Chesapeake Research Consortium


Edgewater, MD


Chesapeake Research Consortium Publication No. 149


Beds of submerged aquatic vegetation (SAY) may moderate or enhance the standing stocks of dissolved oxygen, nutrients, suspended particulates, and chlorophyll in water masses that are exchanged with adjacent channel areas of the Bay or its tributaries. This study investigated the short-term variability in commonly measured water column parameters at four stations located along a 1 km transect across a polyhaline SAV bed in the lower Bay. Data were collected for 10-day periods during June, August, and October 1993 at 15 min to 3 hr intervals using automated water samplers, arrays of spherical PAR quantum sensors, and Hydrolab datasondes. A similar companion study was conducted at the head of the Bay during these same periods.

Dissolved inorganic oxygen (DIN) and Dissolved inorganic phosphorus (DIP) levels were generally quite low in this polyhaline region of the Bay during most periods ( < lOμM and <1 pM, respectively), however concentrations varied from 1-fold to 10-fold for DIN and 1-fold to 2-fold for DIP at intervals of hours to days. Similar short-term pulses of suspended particles and chlorophyll were also observed. Effects of the SAV meadow on the water column varied with season and the associated meadow development. During June, at maximum SAV biomass, the bed acted to moderate pulses of suspended particles and nutrients, although dissolved oxygen levels varied considerably on a diel basis as a result of the high macrophyte productivity. During August, when bed development was reduced and large amounts of detrital macrophyte production were present, the vegetated shoal appeared to be a source of DIN (especially NH4), and elevated levels of total suspended solids and Chlorophyll and community respiration were evident compared to channelward stations. During October, when secondary regrowth of SAV was observed and detritus was largely gone, SAV and channel areas were most similar.

Effects Of A Polyhaline SAV Bed On Spatial And Temporal Variability In Water Quality