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M B Meyers - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic simulation of Littoral Zone habitats in lower Chesapeake Bay. II. Seagrass habitat primary production and water quality relationships
    ESTUARIES, 1998
    Co-Authors: C. P. Buzzelli, R L Wetzel, M B Meyers
    Abstract:

    Seagrasses are indicators of ecosystem state because they are sensitive to variations in water composition and clarity resulting from watershed-level impacts. A simulation model designed to study Zostera marina (eelgrass) habitat dynamics in a variable Littoral Zone environment was used to address the potential ecological responses to eutrophication in lower Chesapeake Bay. The adjacent channel boundary environment is a source of dissolved and particulate materials to the Littoral Zone. In the simulations, concentrations of key water quality variables in the adjacent estuarine channel boundary were either halved or doubled relative to the base case to investigate light versus nitrogen effects. The role of the seagrass meadow in Littoral Zone carbon and nitrogen dynamics was evaluated when meadow size was changed in the model. Particulate and dissolved organic carbon accounted for 83% of the submarine light attenuation in the seagrass meadow In all model runs, the water column concentrations of chlorophyll a and dissolved inorganic nitrogen (DIN) were below the habitat criteria proposed as critical to seagrass survival. Eelgrass community production was carefully regulated by the interactive effects of light, nitrogen, and grazing on epiphyte growth. Increased eelgrass coverage in the Littoral Zone led to a simulated doubling of ecosystem primary production but reduced the fraction of production by planktonic and sediment microalgae. The simulation model presented here demonstrated the importance of material input from the channel in Littoral Zone biogeochemical dynamics. Submarine light regulated primary production more strongly than inorganic nitrogen concentrations in the model. External DIN concentrations influenced seagrass survival indirectly: enrichment stimulated growth of epiphytes and phytoplankton and promoted shading of the seagrass leaf. The model was based upon a unimpacted ecosystem and deteriorated water quality negatively influenced primary production greater than the increases triggered by improved conditions. Increased material loading to the Littoral Zone reduced submarine light availability, increased phytoplankton production, lowered ecosystem production, and reduced subtidal vegetated habitat. This simulation model of the estuarine Littoral Zone model combines hydrodynamics, biogeochemical sources and sinks, and living resources in order to better understand structure, function, and change in aquatic ecosystems.

C. P. Buzzelli - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic simulation of Littoral Zone habitats in lower Chesapeake Bay. II. Seagrass habitat primary production and water quality relationships
    ESTUARIES, 1998
    Co-Authors: C. P. Buzzelli, R L Wetzel, M B Meyers
    Abstract:

    Seagrasses are indicators of ecosystem state because they are sensitive to variations in water composition and clarity resulting from watershed-level impacts. A simulation model designed to study Zostera marina (eelgrass) habitat dynamics in a variable Littoral Zone environment was used to address the potential ecological responses to eutrophication in lower Chesapeake Bay. The adjacent channel boundary environment is a source of dissolved and particulate materials to the Littoral Zone. In the simulations, concentrations of key water quality variables in the adjacent estuarine channel boundary were either halved or doubled relative to the base case to investigate light versus nitrogen effects. The role of the seagrass meadow in Littoral Zone carbon and nitrogen dynamics was evaluated when meadow size was changed in the model. Particulate and dissolved organic carbon accounted for 83% of the submarine light attenuation in the seagrass meadow In all model runs, the water column concentrations of chlorophyll a and dissolved inorganic nitrogen (DIN) were below the habitat criteria proposed as critical to seagrass survival. Eelgrass community production was carefully regulated by the interactive effects of light, nitrogen, and grazing on epiphyte growth. Increased eelgrass coverage in the Littoral Zone led to a simulated doubling of ecosystem primary production but reduced the fraction of production by planktonic and sediment microalgae. The simulation model presented here demonstrated the importance of material input from the channel in Littoral Zone biogeochemical dynamics. Submarine light regulated primary production more strongly than inorganic nitrogen concentrations in the model. External DIN concentrations influenced seagrass survival indirectly: enrichment stimulated growth of epiphytes and phytoplankton and promoted shading of the seagrass leaf. The model was based upon a unimpacted ecosystem and deteriorated water quality negatively influenced primary production greater than the increases triggered by improved conditions. Increased material loading to the Littoral Zone reduced submarine light availability, increased phytoplankton production, lowered ecosystem production, and reduced subtidal vegetated habitat. This simulation model of the estuarine Littoral Zone model combines hydrodynamics, biogeochemical sources and sinks, and living resources in order to better understand structure, function, and change in aquatic ecosystems.

R L Wetzel - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic simulation of Littoral Zone habitats in lower Chesapeake Bay. II. Seagrass habitat primary production and water quality relationships
    ESTUARIES, 1998
    Co-Authors: C. P. Buzzelli, R L Wetzel, M B Meyers
    Abstract:

    Seagrasses are indicators of ecosystem state because they are sensitive to variations in water composition and clarity resulting from watershed-level impacts. A simulation model designed to study Zostera marina (eelgrass) habitat dynamics in a variable Littoral Zone environment was used to address the potential ecological responses to eutrophication in lower Chesapeake Bay. The adjacent channel boundary environment is a source of dissolved and particulate materials to the Littoral Zone. In the simulations, concentrations of key water quality variables in the adjacent estuarine channel boundary were either halved or doubled relative to the base case to investigate light versus nitrogen effects. The role of the seagrass meadow in Littoral Zone carbon and nitrogen dynamics was evaluated when meadow size was changed in the model. Particulate and dissolved organic carbon accounted for 83% of the submarine light attenuation in the seagrass meadow In all model runs, the water column concentrations of chlorophyll a and dissolved inorganic nitrogen (DIN) were below the habitat criteria proposed as critical to seagrass survival. Eelgrass community production was carefully regulated by the interactive effects of light, nitrogen, and grazing on epiphyte growth. Increased eelgrass coverage in the Littoral Zone led to a simulated doubling of ecosystem primary production but reduced the fraction of production by planktonic and sediment microalgae. The simulation model presented here demonstrated the importance of material input from the channel in Littoral Zone biogeochemical dynamics. Submarine light regulated primary production more strongly than inorganic nitrogen concentrations in the model. External DIN concentrations influenced seagrass survival indirectly: enrichment stimulated growth of epiphytes and phytoplankton and promoted shading of the seagrass leaf. The model was based upon a unimpacted ecosystem and deteriorated water quality negatively influenced primary production greater than the increases triggered by improved conditions. Increased material loading to the Littoral Zone reduced submarine light availability, increased phytoplankton production, lowered ecosystem production, and reduced subtidal vegetated habitat. This simulation model of the estuarine Littoral Zone model combines hydrodynamics, biogeochemical sources and sinks, and living resources in order to better understand structure, function, and change in aquatic ecosystems.

Hélène Cyr - One of the best experts on this subject based on the ideXlab platform.

John A. Downing - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Cover on the Spatial Distribution of Littoral-Zone Fishes
    Canadian Journal of Fisheries and Aquatic Sciences, 1994
    Co-Authors: Wafa Aboul Hosn, John A. Downing
    Abstract:

    Littoral-Zone fish are thought to reduce predation pressure by seeking refuge within macrophyte beds or near the lake bottom, or by aggregating. We used underwater video to measure the spatial aggregation of prey fishes in the Littoral habitat. At low density, fish were more aggregated off the bottom in open habitats than when found off the bottom within macrophyte beds. At high densities, fish were primarily observed near the lake bottom, and the presence or absence of macrophyte beds had little influence on spatial behavior. No difference could be detected in the degree of aggregation seen in fish on the lake bottom inside or outside macrophyte beds. Our results lend field support to theoretical and laboratory research that suggests aggregative behavior in Littoral-Zone fish is strongly influenced by fish density and by habitat structure.