Oyster Reef Habitat Restoration : a synopsis and synthesis of approaches; proceedings from the symposium, Williamsburg, Virginia, April 1995

This volume has its origin in a symposium held in Williamsburg, VA in April 1995, though most of the chapters have been significantly revised in the interim. The primary purpose of the symposium was to bring together state fisheries managers involved in fisheries-directed oyster enhancement and research scientists to refine approaches for enhancing oyster populations and to better develop the rationale for restoring reef habitats. We could hardly have anticipated the degree to which this been successful. In the interim between the symposium and the publication of this volume the notion that oyster reefs are valuable habitats, both for oysters and for the other ecosystem services they provide, has been gaining wider acceptance. . . . Table of Contents Introduction and Overview by Mark W. Luckenbach, Roger Mann and James A. Wesson Part I. Historical Perspectives Chapter 1 - The Evolution of the Chesapeake Oyster Reef System During the Holocene Epoch by William J. Hargis, Jr. Chapter 2 - The Morphology and Physical Oceanography of Unexploited Oyster Reefs in North America by Victor S. Kennedy and Lawrence P. Sanford Chapter 3 - Oyster Bottom: Surface Geomorphology and Twentieth Century Changes in the Maryland Chesapeake Bay by Gary F. Smith, Kelly N. Geenhawk and Dorothy L. Jensen Part II. Synopsis of Ongoing Efforts Chapter 4 - Resource Management Programs for the Eastern Oyster, Crassostrea virginica,in the U.S. Gulf of Mexico ...Past, Present and Future by Richard L. Leard, Ronald Dugas and Mark Benigan Chapter 5 - Oyster Habitat Restoration: A Response to Hurricane Andrew by William S. Perret, Ronald Dugas, John Roussel, Charles A. Wilson, and John Supan Chapter 6 - Oyster Restoration in Alabama by Richard K. Wallace, Kenneth Heck and Mark Van Hoose Chapter 7 - A History of Oyster Reef Restoration in North Carolina by Michael D. Marshall, Jeffrey E. French and Stephen W. Shelton Chapter 8 - Oyster Restoration Efforts in Virginia by James Wesson, Roger Mann and Mark Luckenbach Part Ill. Reef Morphology and Function - Questions of Scale Chapter 9 - South Carolina Intertidal Oyster Reef Studies: Design, Sampling and Focus for Evaluating Habitat Value and Function by Loren D. Coen, David M. Knott, Elizabeth L. Wenner, Nancy H. Hadley, Amy H. Ringwood and M. Yvonne Bobo Chapter 10 - Small-scale Patterns of Recruitment on a Constructed Intertidal Reef: The Role of Spatial Refugia by Ian K. Bartol and Roger Mann Chapter 11 - Perspectives on Induced Settlement and Metamorphosis as a Tool for Oyster Reef Enhancement by Stephen Coon and William K. Fitt Chapter 12 - Processes Controlling Local and Regional Patterns of Invertebrate Colonization: Applications to the Design of Artificial Oyster Habitat by Richard W. Osman and Robert B. Whitlatch Chapter 13 - Reefs as Metapopulatons: Approaches for Restoring and Managing Spatially Fragmented Habitats by Robert B. Whitlatch and Richard W. Osman Chapter 14 - Application of Landscape Ecological Principles to Oyster Reef Habitat Restoration by David B. Eggleston Chapter 15 - Use of Oyster Reefs as a Habitat for Epibenthic Fish and Decapods by Martin H. Posey, Troy D. Alphin, Christopher M. Powell and Edward Townsend Chapter 16 - Are Three Dimensional Structure and Healthy Oyster Populations the Keys to an Ecologically Interesting and Important Fish Community? by Denise L. Breitburg Chapter 17 - Materials Processing by Oysters in Patches: Interactive Roles of Current Speed and Seston Composition by Deborah Harsh and Mark W. Luckenbach Chapter 18 - Oyster Reefs as Components in Estuarine Nutrient Cycling: fucidental or Controlling? by Richard F. Dame Part IV. Alternative Substrates Chapter 19 - Use of Dredged Material for Oyster Habitat Creation in Coastal Virginia by Walter I. Priest, III, Janet Nestlerode and Christopher W. Frye Chapter 20 - Alternatives to Clam and Oyster Shell as Cultch for Eastern Oysters by Haywood, E. L., III, T. M. Soniat and R. C. Broadhurst, III Chapter 21 - Dredged Material as a Substrate for Fisheries Habitat Establishment in Coastal Waters by Douglas Clarke, David Meyer, Allison Veishlow and Michael LaCroix Part V. Management Options and Economic Considerations Chapter 22 - Managing Around Oyster Diseases in Maryland and Maryland Oyster Roundtable Strategies by Kennedy T. Paynter Chapter 23 - Chesapeake Bay Oyster Reefs, Their Importance, Destruction and Guidelines for Restoring Them by William J. Hargis, Jr. and Dexter S. Haven Chapter 24 - Economics of Augmentation of Natural Production Using Remote Setting Techniques by John E. Supan, Charles A. Wilson and Kenneth J. Robert

Dynamics of a Generalized Cosmological Scalar-Tensor Theory

A generalized scalar-tensor theory is investigated whose cosmological term depends on both a scalar field and its time derivative. A correspondence with solutions of five-dimensional Space-Time-Matter theory is noted. Analytic solutions are found for the scale factor, scalar field and cosmological term. Models with free parameters of order unity are consistent with recent observational data and could be relevant to both the dark-matter and cosmological-"constant" problems.Comment: 13 page

Oyster (Crassostrea Virginica, Gmelin 1791) Population Dynamics On Public Reefs In The Great Wicomico River, Virginia, USA

We describe oyster population trends in the Great Wicomico River, VA, from 2000 through 2009 using quantitative fishery independent survey data collected using a stratified random design. The seven public reefs examined cover a total of 2.8 X 10(5) m(2) and vary in individual size from 1.36 X 10(4) to 7.16 X 10(4) m(2). The river is functionally divided by a sand spit into upriver and downriver regions. Oyster densities on the upriver reefs were typically an order of magnitude higher than densities on the downriver reefs within the same time period. Throughout the system, the highest observed densities were coincident with high annual recruitment events (2002, 2006). Recruitment events were usually followed by high mortality, with small percentages of the population reaching \u3e= 3 y of age. A predictive stock recruit relationship is absent; rather, population demographics appear to be dominated by periodic high recruitment events. In the absence of seed removal, biomass maxima follow 1-2 y after recruitment maxima. Standing stock for the system varied between 1.56 X 10(6) g and 3.63 X 10(7) g in 2005 and 2006. Year-specific age-at-length relationships were estimated from demographics data. Length demographics were recast as age demographics to estimate mortality. Observed proportional mortality between young of the year and age 2 oysters was approximately 0.88 for the 2006-y class, which is slightly higher than the 0.62-0.71 observed for the 2007-y class. The ability to estimate age specific mortality accurately allows the construction of shell (habitat) budgets for the individual reef systems. The Great Wicomico oyster population appears to be maintained by episodic and extraordinary recruitment in the face of high mortality the latter driven by disease (predominantly Perkinsus marinus) epizootics. The shell resource is modest, equivalent to little more than a monolayer several centimeters thick. Over short timescales (years), the available shell resource oscillates in concert with mortality. The shell accretion rate on upriver reefs is consistently 4-5 times greater than that observed on downriver reefs. Periodic modest shell planting has maintained the habitat base (the shell resource) throughout the system over decadal scales

Management Of The Piankatank River, Virginia, In Support Of Oyster (Crassostrea Virginica, Gmelin 1791) Fishery Repletion

The Piankatank River is a trap-type estuary on the western shore of Chesapeake Bay that has been managed for seed oyster production since 1963. Market oyster production in the river is minimal. Repletion efforts include shell planting and seed removal. We describe sequential changes in population demographics and habitat in relation to repletion activities on eight Piankatank River public oyster reefs from 1998 through 2009. Two reef groups (northern and southern) may be distinguished by density (oysters/m(2)), biomass (e dry tissue weight), and shell volume (L/m(2)) data. Age-at-length relationships were estimated from demographic data using a quadratic model. Observed mortality rates were high, and age 3+ oysters were essentially absent. A strong recruitment signal was observed in 1999 and 2002. Between 1998 and 2009, about 30% of the live oysters in the river were harvested as seed, corresponding to similar to 7.5% of the total shell base in an average year. Typically, for every 5 bushels of shell planted, 1 bushel of seed was harvested (20% return). Even with shell planting (similar to 10 L/m(2)/y), the river shell budget showed a deficit with respect to the accretion rate required to balance sea level rise and natural degradation processes. During the study period, the mean river recruit-to-stock ratio was similar to 4. The unusual and consistently high recruit-to-stock ratios suggest that management for modest continuous seed removal may be accomplished without shell planting. Annual stock assessment to identify low recruitment years is recommended as a method to adjust annual seed harvest quotas

Population Studies Of The Native Eastern Oyster, Crassostrea Virginica, (Gmelin, 1791) In The James River, Virginia, Usa

We describe oyster population trends in the James River, VA from 1993 through 2006 using quantitative fishery independent survey data collected using a stratified random design, The 23 reefs contained in the study area cover a total of 2.41 to 4.98 X 10(7) m(2). There is a marked pattern in density of oysters among X 10(7) m(2) and vary in individual size from 1.26 X 10(4) m(2) the reefs: during the Study period a small group of reefs comprising 5.4% of the total a rea consistently contained between 25.7 and 55.5% by number and 35.8 and 54.8% by biomass of the total oyster population. The highest density reefs exhibit, with very few exceptions, mean densities well in excess of 200 oysters m(-2), typically between 300 and 500 m(-2) with a single maximum value of 773 oysters m(-2) in 2002 coincident with the highest annual recruitment observed during the Study period. Recruitment events were usually followed by very high mortality with very small percentages of the population reaching ages \u3e= 3 y of age. A strong stock-recruit relationship is absent; rather population demographics appear to be dominated by periodic high recruitment events. Biomass maxima tended to lag one to two years after recruitment maxima. Standing stock for the total system varied between 1.07 X 10(8) g and 3.31 X 10(8) g (107 and 331 metric tonnes) in 2003 and 2005, respectively as the 2002 recruits grew and suffered mortality. Age-at-length relationships were estimated from demographics: using a July I birth date and a November 1 survey date giving lengths of 37.3 mm at 0.33 y, 58.9 mm at 1.33 y, 80.5 mm at 2.33 y, 102.1 mm at 3.33 y and 123.7 mm at 4.33 y Length demographics were recast as age demographics to estimate annual proportional mortality. Mean proportional mortality values for age 1 oysters range from a low of 0.2-0.4 to a high in excess of 0.7. Age 2 mean proportional mortality values range from a low of 0.41 to a high exceeding 0.75. The proportional mortality for age 3 and 4 y olds generally exceeded mean values of 0.6 with highest values approaching 0.95. In all cases, these values exceeded mortality estimates calculated using traditional box count methods by a considerable margin. The ability to accurately estimate age specific mortality allows the construction of shell (habitat) budgets for the individual reef systems. Shell half-life loss rate estimates in the most productive reefs is between 2 and 3 y and the population is maintained by the continual and extraordinary recruitment in the face of high mortality-the latter driven by disease (predominantly Perkinsus marinus) epizootics. The shell resource, even on the most productive reefs, is modest, equivalent to little more than a monolayer several centimeters thick. Individual reefs demonstrate remarkable stability as either high shell density + high population density associations (high:high) or low shell density + low Population density associations (low:low), even in the face of temporal population and demographic fluctuations associated with disease related mortality. The probability of Manipulating either shell and/or live oyster density to effect the transition of a low:low reef to a high:high reef is considered bleak in the face of extant recruitment and mortality patterns. The primary impediment 10 population expansion or rebuilding is high and uncontrolled mortality rather than a lack of recruitment. Given the large numbers of oysters in low salinity refugia that have the ability to contnually contribute to the larval pool, active selection against disease susceptible oysters on a system wide basis is unlikely

Oyster Planting Protocols To Deter Losses To Cownose Ray Predation

The utility of shell overlays to oyster (Crassostrea virginica) plantings as a cownose ray (Rhinoptera bonasus) predator deterrence mechanism was examined. Typical industry practice of oyster seed planting was followed in an experimental design employing treatment areas of 0.5-1.0 acre (0.2-0.4 hectare). Areas were prepared in the Lower Machodoc Creek, Virginia, by the initial application of shell to insure a stable substrate under planted seed oysters. Seed oysters were planted using standard industry methods. Experimental areas were located, two upstream and two downstream, of a constriction in the Lower Machodoc that dictated differing physical environments in the respective locations with downstream locations being more exposed to northeast wind-driven stresses and, historically, a greater incidence of ray predation. Once oysters were planted, two of the areas, one upstream and one downstream of the aforementioned constriction, were additionally treated with a shell overlay as a predation deterrent. Oyster seed were planted in the experimental plots in February 2012. Market oysters were harvested from the experimental plots in December 2013 and January 2014. Final harvest data demonstrated that shell overlays do not offer additional protection to planted oyster seed with respect to possible cownose ray predation. Evidence of predation in the form of characteristically broken oyster valves were recorded in all treatment areas. Concurrent stomach content analysis of rays captured at the study location and observations of fouling community associated with the cultured oysters taken during the harvest operation indicate broad dietary preferences for rays when such a variety exists in the foraging region. For rays, oysters are not the singular preferred diet item, although localized and intensive feeding on oysters remains an option with a wide foraging range. Areas without overlay demonstrated higher production than those with shell overlay. Shell overlays are not recommended as predator deterrents for cownose rays in large deployments of unprotected oyster seed

Piecing together the puzzle of NGC 5253: abundances, kinematics and WR stars

We present Gemini-S/GMOS-IFU optical spectroscopy of four regions near the centre of the nearby (3.8 Mpc) dwarf starburst galaxy NGC 5253. This galaxy is famous for hosting a radio supernebula containing two deeply embedded massive super star clusters, surrounded by a region of enhanced nitrogen abundance that has been linked to the presence of WR stars. We detected 11 distinct sources of red WR bump (CIV) emission over a 20" (~350 pc) area, each consistent with the presence of ~1 WCE-type star. WC stars are not found coincident with the supernebula, although WN stars have previously been detected here. We performed a multi-component decomposition of the H\alpha\ line across all four fields and mapped the kinematics of the narrow and broad (FWHM = 100-250 km/s) components. These maps paint a picture of localised gas flows, as part of multiple overlapping bubbles and filaments driven by the star clusters throughout the starburst. We confirm the presence of a strong H\alpha\ velocity gradient over ~4.5" (~80 pc) coincident with the region of N/O enhancement, and high gas density known from previous study, and interpret this as an accelerating ionized gas outflow from the supernebula clusters. We measure the ionized gas abundances in a number of regions in the outer IFU positions and combine these with measurements from the literature to assess the radial abundance distribution. We find that the O/H and N/H profiles are consistent with being flat. Only the central 50 pc exhibits the well-known N/O enhancement, and we propose that the unusually high densities/pressures in the supernebula region have acted to impede the escape of metal-enriched hot winds from the star clusters and allow them to mix with the cooler phases, thus allowing these freshly processed chemicals to be seen in the optical.Comment: 16 pages, accepted to A&

Embeddings in Non-Vacuum Spacetimes

A scheme is discussed for embedding n-dimensional, Riemannian manifolds in an (n+1)-dimensional Einstein space. Criteria for embedding a given manifold in a spacetime that represents a solution to Einstein's equations sourced by a massless scalar field are also discussed. The embedding procedures are illustrated with a number of examples.Comment: 17 pages, Plain Latex. Extended discussion on embeddings with scalar fields and further examples included. In press, Classical and Quantum Gravit