Guest Artist Recital:Mark Kellog, Alto & Tenor Trombone

Kemp Recital Hall Saturday Afternoon April 7, 2001 5:00p.m

An updated model for estimating the TMDL-related benefits of oyster reef restoration Harris Creek, Maryland, USA

In 2014, a user-friendly, web-accessible model was developed that allowed restoration practitioners and resource managers to easily estimate the TMDLrelated benefits of oyster reef (Crassostrea virginica) restoration per unit area, run restoration scenarios in Harris Creek, MD to optimize restoration planning and implementation, and calculate the benefits of the chosen plan. The model was rooted in scientifically defensible data and was readily transferrable to systems throughout the Chesapeake Bay and Eastern Shore. The model operated in five vertically well-mixed boxes along the main axis of the creek. Exchanges among creeks were computed using a tidal prism approach and were compared to exchanges provided from a high resolution 3D hydrodynamic model. Watershed inputs for the model were obtained for the Harris Creek sub-watershed from the Phase V Chesapeake Bay Program Watershed Model. The base model simulated daily concentrations over an annual cycle of chlorophyll-a, dissolved inorganic nitrogen (N) and phosphorus (P), dissolved oxygen, total suspended solids, the biomass of benthic microalgae, and the water column and sediment pools of labile organic carbon (C) and associated N and P. Water quality data for model forcing and calibration were obtained from the Chesapeake Bay Program, the Choptank Riverkeeper, the University of Maryland Center for Environmental Science, and the Maryland Department of Natural Resources. An oyster sub-model was coupled to this base model to compute the volume of water filtered, removal of phytoplankton, suspended solids, and associated nutrients via filtration, recycling of nutrients and consumption of oxygen by oyster respiration, production of feces, N and P accumulation in oyster tissues and shell, oyster-enhanced denitrification, and N and P burial associated with restored reefs. The completed model was served online and operated through a web browser, enabling users to conduct scenario analysis by entering box-specific values for acres restored, restored oyster density, and restored oyster size, as well as the economic value of associated N and P removal. The updated model incorporates all aspects of the previous model but replaces oyster related data collected outside Harris Creek with site-specific data, and now includes restored oyster populations and water quality data through 2016. It also incorporates the impacts of two common, reef-associated filter feeding organisms: the hooked mussel Ischadium recurvum and the sea squirt Molgula manhattensis. Additional data collected in Harris Creek and incorporated into the model include: biomass of benthic microalgae, biogeochemical fluxes in relation to oyster biomass, and the biomass density and distribution of the dominant non-oyster reef filter feeders (I. recurvum, and M. manhattensis). The revised model incorporates an improved estimate of annual oyster growth, uses an improved method for estimating N and P sequestered in tissues and shells, and accounts for the prerestoration oyster population in Harris Creek. The model also incorporates data on the filtration capacity of I. recurvum and M. manhattensis in relation to C. virginica collected as part of a previous study (not in Harris Creek) by Kellogg and Newell (unpublished data)

A model for estimating the TMDL-related benefits of oyster reef restoration : Harris Creek, Maryland, USA

A user-friendly, web-accessible model has been developed that allows restoration practitioners and resource managers to easily estimate the TMDL-related benefits of oyster reef restoration per unit area, run restoration scenarios in Harris Creek, MD to optimize restoration planning and implementation, and calculate the benefits of the chosen plan. The model is rooted in scientifically defensible data and is readily transferable to systems throughout the Chesapeake Bay and Eastern Shore. The model operates in five vertically well-mixed boxes along the main axis of the creek. Exchanges among creeks are computed using a tidal prism approach and were compared to exchanges provided from a high resolution 3D hydrodynamic model. Watershed inputs for the model were obtained for the Harris Creek sub-watershed from the Phase V Chesapeake Bay Program Watershed Model. The base model simulates daily concentrations over an annual cycle of chlorophyll-a, dissolved inorganic nitrogen (N) and phosphorus (P), dissolved oxygen, total suspended solids, the biomass of benthic microalgae, and the water column and sediment pools of labile organic carbon (C) and associated N and P. Water quality data for model forcing and calibration were obtained from the Chesapeake Bay Program, the Choptank Riverkeeper, the University of Maryland Center for Environmental Science, and the Maryland Department of Natural Resources. An oyster sub-model has been coupled to this base model and computes the volume of water filtered, removal of phytoplankton, suspended solids, and associated nutrients via filtration, recycling of nutrients and consumption of oxygen by oyster respiration, production of feces, N and P accumulation in oyster tissues and shell, oyster-enhanced denitrification, and N and P burial associated with restored reefs. The completed model is served online and operates through a web browser, enabling users to conduct scenario analysis by entering box-specific values for acres restored, restored oyster density, and restored oyster size, as well as the economic value of associated N and P removal

Potential Effects of Endocrine Disrupting Compounds on Bivalve Populations in Chesapeake Bay: A Review of Current Knowledge and Assessment of Research Needs

Numerous compounds in the environment interfere with normal endocrine function in humans and other animals. These compounds, which include heavy metals, a wide variety of anthropogenic organic compounds, steroids and steroid-mimicking compounds, are collectively termed endocrine disrupting compounds (EDCs). Over the past 20 years, research on the impacts of EDC exposure has identified a range of effects on growth, development, and reproduction in humans and wildlife

AXAF VETA-I mirror encircled energy measurements and data reduction

The AXAF VETA-I mirror encircled energy was measured with a series of apertures and two flow gas proportional counters at five X-ray energies ranging from 0.28 to 2.3 keV. The proportional counter has a thin plastic window with an opaque wire mesh supporting grid. Depending on the counter position, this mesh can cause the X-ray transmission to vary as much as +/-9 percent, which directly translates into an error in the encircled energy. In order to correct this wire mesh effect, window scan measurements were made, in which the counter was scanned in both horizontal (Y) and vertical (Z) directions with the aperture fixed. Post VETA measurement of the VXDS setup were made to determine the exact geometry and position of the mesh grid. Computer models of the window mesh were developed to simulate the X-ray transmission based on this measurement. The window scan data were fitted to such mesh models and corrections were made. After this study, the mesh effect was well understood and the final results of the encircled energy were obtained with an uncertainty of less than 0.8 percent

Linking structural and functional characteristics of restored oyster reefs : A Restoration Project in the Virginia Coast Reserve

Eighteen native oyster reefs (16-m2 each) were restored using six oyster densities (0, 10, 25, 50, 100 and 250 adult oysters m-2) with three replicates of each density at an intertidal site in The Nature Conservancy’s Virginia Coast Reserve. Reef construction was successful and continues to provide a range of oyster biomass densities useful for exploring relationships between oyster reef structural and functional parameters. Between April 2012 and July 2013, a science-based monitoring program explored quantitative relationships between structural and functional characteristics of these restored reefs. Structural parameters examined included oyster abundance, oyster size/biomass, surface shell volume, reef topographic complexity and sediment characteristics. Functional parameters included denitrification rates and macrofaunal abundance and biomass. Relationships between reef structural parameters and functional parameters were complex and variable. As of July 2014, these reefs continue to serves as a platform for continued studies of the relationships between reef structural and functional characteristics

The Spectra of Star Forming Galaxies at High Redshift

We review the spectral properties of the population of star forming galaxies at z = 3 discovered using a colour selection technique which targets the Lyman discontinuity at 912 Angstroms. The UV luminosity of the typical z = 3 galaxy exceeds by more than one order of magnitude that of the most luminous starbursts in the nearby universe, although the maximum star formation intensity (SFR per unit area) is within the limits found in local surveys. We consider in detail the likely magnitude of dust extinction and conclude that published estimates of the volume-averaged star formation rate at high z need to be revised to higher values by a factor of about 3. This correction improves the agreement between the observations and recent theoretical predictions. Lyman alpha emission is generally weak, most likely as a result of resonant scattering. The large equivalent widths of the strongest interstellar lines and their systematic blueshift (by up to several hundred km/s) relative to the Lyman alpha emission line are indicative of highly energetic outflows in the interstellar medium. Pilot observations have detected the redshifted Hbeta and [O III] emission lines in the K band. The widths of these features imply dynamical masses of approximately 10^{10} solar masses for the innermost star forming regions; the total masses involved are likely to exceed 10^{12} solar masses.Comment: 11 pages, LaTeX, 5 Postscript Figures. To appear in `The Ultraviolet Universe at Low and High Redshift', ed. W. Waller, (Woodbury: AIP Press