Publications

At the 1992 workshop, participants agreed that the St. Johns river Water Management District (SJRWMD) will complete the 1992 SAV inventory for the Lagoon system and that the analysis of factors causingSAV loss will be addressed by existing and proposed water quality monitoring programs. The last three task will be completed through the SAV Initiative. A consensus was reached at this workshop on the importance of photosynthetically active radiation (PAR) in the Lagoon. PAR is a measure of light available for photosynthesis. All plants, including Submerged species such as seagrasses, require light to survive and flourish.

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A principle conclusion of the Environmental Protection Agency Chesapeake Bay Program Studies (U.S. EPA, 1982) was that deteriorating water quality in the Chesapeake was directly correlated with increased nutrient enrichment over the past few decades. Water quality deterioration was considered to have maj9or detrimental effects on a number of living resources including submerged aquatic vegetation, shellfish and finfish. The point source nutrient control strategies developed both prior to and subsequent to the Bay Program research findings have, however, only focused on phosphorus. As spokepersons for the research community, the Scientific and Technical Advisory Committee to the Chesapeake Bay Program, believes it is vital that the importance of nitrogen control be brought to the attention of the policy making and management segments of the Bay community for use in developing effective nutrient control strategies.

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Hydrological models of nutrient inputs in the Chesapeake Bay watershed seem well developed. Such models can be coupled to phytoplankton production but as production moves to higher trophic levels, the problems of understanding, modeling and managing increase because we are increasingly dealing with critters with minds and agendas of their own. Moreover, tjey interact with eachh other and are directly or indirectly subject to fishing prressure. In short, we moving from physical/chemical problems and into biological and fisheries problems. Interactions between fishermen and the ecosystem: Comfortable single species management tools do not reflect fisheries or biological reality. This is because, in addition to the direct effects of fishing mortality, other interactions occur beteen both sets of players. The workshop presentations have made it clear that multi-species are of two types.

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The Chesapeake Bay Program, in consortium with participating agencies, universities and organizations, has conducted a range of physical, chemical and biological monitoring programs in tidal waters and streams, in the atmosphere, and on the land with the goal of supporting the restoration and protection of the Chesapeake Bay. These programs generally aproach this goal through the fulfillment of the following objectives:

1. characterization of existing conditions;

2. determination of status and trends; and

3. use of monitoring information to further the understanding of processes controlling water quality and the linkage with living resources.

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During 1983 and 1984, information on the distribution and abundance of Hydrilla verticillata, and exotic submerged aquatic macrophyte from Sourtheast Asia, was collected in the tidal Potomac River. Data were collected on four transects established on the Virginia side of the river as well as numerous other transects established for a concurrent submersed aquatic vegetation survey. Depth of water in which Hydrilla occurred, comparative seasonal biomass, tuber production, replacement rate, and competition with other species were measured. Laboratory experiments were conducted on salinity tolerances.

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This report provides a synopsis of material presented to the workshop on current and future capabilities for remote sensing of estuaries. Clearly, this topic was not covered exhaustively in a workshop of this scale. Rather, the meeting highlighted existing technologies and approaches that have direct bearing on management needs for Chesapeake Bay and that have shown promise when applied to estuarine and coastal waters and the watersheds that border them. Recommendations that emerged in the discussion coalesce into several categories:

1. Expand and Better Integrate In-situ Technologies;

2. Expand the Use of Aircraft and Satellite-based Sensors;

3. Increase the Use of Landsat Imagery; and

4. Improve and Expand Wetlands Mapping.

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The distribution and abundance of submersed aquatic vegetation in the tidal Potomac River and Estuary were studied from 1978 through 1981 with asistance of the U.S. fish and Wildlife Service. Sixteen species of submersed aquatic plants were identified, fourteen vascular plants and two species of the algae Chara. Most of the plants were located in the transition zone of the Potomac River and Wicomico Riber tributary, with a few isolated populations in the tidal river and estuary. Vallisneria americana, Zannichellia palustria, Ruppina maritime, and Potamogeton perfoliatus were the most abundant and widespread species. The present distribution and abundance differ considerably from that in the early 1900's when flats in the tidal river were covered with lush vegetation including Vallisneria and Potamogeton spp. the the estuary ahd an abundance of Zostera marina.

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This report documents the distribution of submersed aquatic vegettation collected in the tidal Potomac River and transition zone of the Potomac Estuary during 1987. Maps illustrate the distribution of submersed aquatic plants and Hydrilla verticillata int he tidal Potomac River, based on shoreline surveys. Species of submersed aquatic plants found on vegetated transects in the transition zone of the Potomac Estuary are reported for each transect location. Regrowth of harvested Hydrilla is presented for four mechanically harvested sites. Data on the distance from shore and greatest depth of water in which aquatic plants grew on four transects and on Secchi depths throughout the study reach are reported. These data can be used to quantify changes in water clarity and plant distribution.

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this report summarizes data on the distribution and abundance of submersed aquatic vegetation collected in the tidal Potomac River and Estuary during 1986. Plan species were dientified and dry weight determined for selected sites sampled in spring and fallo. The percentage of each plan speciesn was determined in areas of highplant density in the fall. Water-quality characteristics measure include temperature, specific conductance, dissolved oxygen, pH, and transparency as indicated by Secchi depthy. Maps were made of the distribution of submersed aquatic vegetation based on transect samples and a complete shoreline survey.

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This report summarizes data on the distribution and abundance of submersed aquatic vegetation collected in the tidal Potomac River during 1985. Plant species were identified and dry weight determined for selected sites. Information on competition between Hydrilla verticillata and toher species was collected. Water-quality characteristics measured include temperature, specific conductance, dissolved oxygen, pH, and transparency as indicated by Secchi depth. A map was made of the distribution of submersed aquatic vegetation based on transect samples and a complete shoreline survey.

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