Materials Processing by Oysters in Patches: Interactive Roles of Current Speed and Seston Composition

Filtration rates for oysters have typically been measure in still water laboratory experiments and ecosystem-level effects estimated by extrapolation. With the exception of in situ measures of oyster filtration by Dame (1999, Chapter 18, this volume and references cited therein) these estimates have failed to account for the effects of hydrodynamic effects on oyster filtration rates and on physical redistribution of particles. In this chapter we report on a series of experiments conducted in a recirculating seawater flume designed to address the effects of flow speed and seston composition on filtration rates in a bed of oysters. In six separate experiments ninety oysters were arranged in the bed of the flume, flow speed adjusted to one of eight levels (0.65, 1.0, 2.1, 4.2, 6.0, 10.4, 13.7 or 22.0 cm s·1 ), seston added to the flume and particle concentrations upstream and downstream of the oyster bed determined from vertically-arrayed samples. Four experiments investigated the effects of each flow speed on the filtration of a unialgal diet, while two experiments utilized the algal diet in combination with inorganic particles. Control experiments sought to estimate the effects hydrodynamic effects on particle distribution by measuring filtration rates over beds of ninety pairs of empty oyster valves. Our findings reveal effects of flow speed and, less evidently, seston composition on particle filtration by oysters. More importantly, our results point to the importance of hydrodynamically-mediated particle redistribution of particles over patches of oysters, and portend sampling difficulties associated with quantifying oyster filtration rates in the field.https://scholarworks.wm.edu/vimsbooks/1089/thumbnail.jp

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

Settlement and survival of the oyster Crassostrea virginica on created oyster reef habitats in Chesapeake Bay

Efforts to restore Crassostrea virginica oyster reef habitats in Chesapeake Bay typically begin with the placement of hard substrata, such as oyster shell, in the form ofthreedimensional mounds on the seabed to serve as a base for oyster recruitment and growth. A shortage of sufficient volumes of oyster shell for creating large-scale reefs has led to widespread use of other materials, such as surf clam (Spisula solidissima) shell, as a substitute for oyster shell. We monitored oyster recruitment, survival, and growth on intertidal and subtidal reefs constructed shucked oyster and surf clam shell. Results indicate that oyster settlement occurred on both substrate types throughout the monitoring period but high levels of postsettlement mortality occurred on clam shell mounds. On the subtidal clam shell mound, the quality of the substrate material varied with reef elevation with large shell fragments and intact valves scattered around the reef base and small, tightly packed shell fragments paving the crest and flank of the reef mound. The abundance of oysters on this reef reflected this distribution where oysters were more abundant and larger at the reef base and less abundant and smaller on the crest of the reef. Oyster shell reefs supported greater oyster growth and survival and offered the highest degree of structural complexity. We suggest that the availability of interstitial space and appropriate settlement surfaces account for the observed differences in oyster abundance across the reef systems. The patterns observed give context to the importance of substrate selection in similar restoration activities

Filtration by oysters : interactive effects of water flow, seston composition and filtration rate

Filtration by suspension-feeding bivalves affects water quality and the postulated impacts include increased light penetration and enhanced benthic primary production. Such system-level predictions are extrapolated fiom still water experiments which neglect the effects of flow, seston composition, turbulent mixing and refiltration by oysters within groups. Flume experiments were used to investigate the effects of varying flow speed and seston composition on filtration capacity of oysters. Six groups of 90 oysters were used in treatments which varied concentrations of the algae Ekalassiosira weisj70grgrsie parately and in combination with inorganics; four sets of shell only controls were used to evaluate hydrodynamic effects. The results indicate the importance of morphological differences in bed structure on turbulence and particle redistribution which may obscure biological effects and of the importance of the physiological condition of oysters on filtration capacity. Field transplants of eelgrass, Zostera marina, and American oysters, Crassostrea virgmica, were used to evaluate interactions between oyster filtration, water quality and plant survival in the field. Abnormally poor water quality forced the early termination of these experiments, but in conjunction with the flume results they indicate a strong effect of physical forces on seston distribution against which impacts of suspension feeders must judged

Oyster Reef Restoration: Convergence Of Harvest And Conservation Strategies

Oyster reef restoration, protection, and construction are important to meeting harvest, water quality, and fish habitat goals. However, the strategies needed to achieve harvest and conservation goals have often been considered to be at odds. We argue that these goals are. in fact, compatible and that the same strategies will promote a sustainable harvest of the resource, increased filtration of estuarine waters, and increased provision of structured habitat for finfish, crabs, and other organisms that utilize oyster reefs or receive benefit indirectly from them. Creation or designations of unharvested sites (refuge sites) are key components of these strategies. Unharvested reefs have the potential to provide vertical relief, which is typically destroyed by harvest practices, to act as a source of larvae, which potentially increases the supply of harvestable oysters, and to protect those individuals most likely to have some resistance to disease. Furthermore. proper monitoring and design of refuge and restoration efforts are critical to providing information needed to improve the success of future restoration efforts, and will simultaneously enhance the basic information needed to understand the ecology of oysters and their role in estuarine and coastal systems

Millennial-scale sustainability of the Chesapeake Bay Native American oyster fishery

Estuaries around the world are in a state of decline following decades or more of overfishing, pollution, and climate change. Oysters (Ostreidae), ecosystem engineers in many estuaries, influence water quality, construct habitat, and provide food for humans and wildlife. In North America\u27s Chesapeake Bay, once-thriving eastern oyster (Crassostrea virginica) populations have declined dramatically, making their restoration and conservation extremely challenging. Here we present data on oyster size and human harvest from Chesapeake Bay archaeological sites spanning similar to 3,500 y of Native American, colonial, and historical occupation. We compare oysters from archaeological sites with Pleistocene oyster reefs that existed before human harvest, modern oyster reefs, and other records of human oyster harvest from around the world. Native American fisheries were focused on nearshore oysters and were likely harvested at a rate that was sustainable over centuries to millennia, despite changing Holocene climatic conditions and sea-level rise. These data document resilience in oyster populations under long-term Native American harvest, sea-level rise, and climate change; provide context for managing modern oyster fisheries in the Chesapeake Bay and elsewhere around the world; and demonstrate an interdisciplinary approach that can be applied broadly to other fisheries

The spatiotemporal expression of multiple coho salmon ovarian connexin genes and their hormonal regulation in vitro during oogenesis

BACKGROUND: Throughout oogenesis, cell-cell communication via gap junctions (GJs) between oocytes and surrounding follicle cells (theca and granulosa cells), and/or amongst follicle cells is required for successful follicular development. To gain a fundamental understanding of ovarian GJs in teleosts, gene transcripts encoding GJ proteins, connexins (cx), were identified in the coho salmon, Oncorhynchus kisutch, ovary. The spatiotemporal expression of four ovarian cx transcripts was assessed, as well as their potential regulation by follicle-stimulating hormone (FSH), luteinizing hormone (LH) and insulin-like growth factor 1 (IGF1). METHODS: Salmonid ovarian transcriptomes were mined for cx genes. Four gene transcripts designated cx30.9, cx34.3, cx43.2, and cx44.9 were identified. Changes in gene expression across major stages of oogenesis were determined with real-time, quantitative RT-PCR (qPCR) and cx transcripts were localized to specific ovary cell-types by in situ hybridization. Further, salmon ovarian follicles were cultured with various concentrations of FSH, LH and IGF1 and effects of each hormone on cx gene expression were determined by qPCR. RESULTS: Transcripts for cx30.9 and cx44.9 were highly expressed at the perinucleolus (PN)-stage and decreased thereafter. In contrast, transcripts for cx34.3 and cx43.2 were low at the PN-stage and increased during later stages of oogenesis, peaking at the mid vitellogenic (VIT)-stage and maturing (MAT)-stage, respectively. In situ hybridization revealed that transcripts for cx34.3 were only detected in granulosa cells, but other cx transcripts were detected in both oocytes and follicle cells. Transcripts for cx30.9 and cx44.9 were down-regulated by FSH and IGF1 at the lipid droplet (LD)-stage, whereas transcripts for cx34.3 were up-regulated by FSH and IGF1 at the LD-stage, and LH and IGF1 at the late VIT-stage. Transcripts for cx43.2 were down-regulated by IGF1 at the late VIT-stage and showed no response to gonadotropins. CONCLUSION: Our findings demonstrate the presence and hormonal regulation of four different cx transcripts in the salmon ovary. Differences in the spatiotemporal expression profile and hormonal regulation of these cx transcripts likely relate to their different roles during ovarian follicle differentiation and development

Restoration of seagrass habitat leads to rapid recovery of coastal ecosystem services

There have been increasing attempts to reverse habitat degradation through active restoration, but few largescale successes are reported to guide these efforts. Here, we report outcomes from a unique and very successful seagrass restoration project: Since 1999, over 70 million seeds of a marine angiosperm, eelgrass (Zostera marina), have been broadcast into mid-western Atlantic coastal lagoons, leading to recovery of 3612 ha of seagrass. Well-developed meadows now foster productive and diverse animal communities, sequester substantial stocks of carbon and nitrogen, and have prompted a parallel restoration for bay scallops (Argopecten irradians). Restored ecosystem services are approaching historic levels, but we also note that managers value services differently today than they did nine decades ago, emphasizing regulating in addition to provisioning services. Thus, this study serves as a blueprint for restoring and maintaining healthy ecosystems to safeguard multiple benefits, including co-benefits that may emerge as management priorities over time

Scaling Ecosystem Services to Reef Development : Effects of oyster density on nitrogen removal and reef community structure

Eighteen native oyster experimental 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 each of two sites: one subtidal site in Onancock Creek, Virginia and one intertidal site in Hillcrest Oyster Sanctuary within The Nature Conservancy’s Virginia Coast Reserve. 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. Data were collected from the intertidal site during six sampling periods between April 2012 and July 2013 and from the subtidal site in April and June 2012. Relationships between reef structural parameters and functional parameters were complex and variable. As of July 2014, the intertidal reefs continue to serve as a platform for continued studies of the relationships between reef structural and functional characteristics