Monitoring Performance of Shallow, Subtidal Restoration Oyster Reefs Using Advanced Technologies: A Case Study of Felgates Creek Reef (York River, Va) (original) (raw)
Related papers
2007
The decline of the Eastern oyster, Crassostrea virginica, once a dominant feature of most Atlantic and Gulf coast estuaries, has led to large-and small-scale restoration efforts throughout the oyster's range (Kirby 2004, National Research Council 2004). Successes and failures in reef restoration have varied throughout the region. Understanding why different restoration projects succeed or fail is critical to the future optimal use of limited resources (e.g., shells, manpower) and the deployment of cost-effective, successful reef restoration projects. Communicating the results of ongoing oyster reef construction and assessment efforts also is vital (Coen and Luckenbach 2000). Leading oyster reef restoration practitioners from throughout the Gulf of Mexico and eastern U.S. coastal states met to discuss restoration goals, site selection parameters, metrics to assess success, and associated monitoring methods at a South Carolina Sea Grant sponsored workshop held in Myrtle Beach in May, 2004. This document summarizes the results of that workshop, providing a concise and non-technical explanation of the current state of knowledge regarding the why, where, what, and how of oyster reef restoration. We also expand on the workshop results to include information and approaches developed since 2004. Restoration Project Goals Workshop participants identified six major goals of oyster reef restoration projects: habitat creation, shoreline stabilization, water quality improvement, harvesting enrichment, broodstock enhancement, and educational outreach. Any restoration project can include one or more of these goals. Habitat creation: Oyster reefs provide habitat for fish and invertebrates (e.g., crabs and shrimps) that require structural complexity for foraging, nesting and refuge from predators (reviewed in ASMFC 2007). Fish associated with oyster reefs range from residents that use the reef as a primary habitat to transient species that are wide ranging and may forage on or near the reef (Breitburg 1999, Coen et al. 1999b, ASMFC 2007). Some fish species, such as oyster toad fish, gobies, and blennies, attach eggs to the undersides of oyster shells, relying on reef architecture or microhabitat for reproductive success. Crabs commonly are found in greater densities on oyster reefs than on surrounding open-bottom habitat where vulnerability to predation is greater and prey resources are less abundant (Glancy et al. 2003, Grabowski 2004, Tolley and Volety 2005, Hosack et al. 2006). Bivalves including clams and mussels also may utilize reefs as a refuge from predators (e.g., Grabowski 2002, 2004) enabling populations within reefs to act as a source for mudflat and marsh populations that may be depleted more easily by predators.
Oyster Habitat Restoration Monitoring and Assessment Handbook
Oyster reefs or beds are a globally imperiled marine habitat, with degradation primarily driven by anthropogenic factors such as overharvest, changes to hydrology and salinity regimens, pollution and introduced disease. While oyster restoration efforts have historically focused on improving harvests, in recent decades there has been an increasing recognition and better quantitative description of a broader array of ecological services provided by oysters. This has prompted many agencies and conservation organizations to re-focus their attention on restoring oyster habitat for these broader ecological functions and societal benefits. Benefits include production of fish and invertebrates of commercial, recreational and ecological significance, water quality improvement, removal of excess nutrients from coastal ecosystems, and stabilization and/or creation of adjacent habitats such as seagrass beds and salt marshes. Increasingly, these ecosystem services are cited as the principal or exclusive goal(s) of oyster restoration projects. Despite increased restoration the restored reefs have often not been monitored to an extent that allows for comparison. A recent meta-analysis of oyster restoration projects in the Chesapeake Bay examined the available datasets from 1990 to 2007, analyzing over 78,0000 records from 1035 sites (Kramer and Sellner 2009, Kennedy et al. 2011). The analysis found that relatively few of the restoration activities were monitored, and that the restoration goals of many of the projects were not well-defined, with only 43% of the datasets including both a restoration and monitoring component. The authors concluded that the monitoring of this large body of work was inadequate, and they were unable to assess changes in oyster populations on the constructed reefs. Their recommendations were to implement all oyster restoration projects using experimental designs with robust sample size replication and quantitative pre-and post-restoration monitoring. Sufficient monitoring would allow for adaptive management during the post-construction phase, for assessing whether the project met its goals and related performance criteria or to determine whether restored reefs are achieving the stated ecosystem-based restoration goals. To address this critical gap, a working group was formed that consisted of restoration scientists and practitioners from the Atlantic, Pacific, and Gulf coasts of the US. The aim of the group was to recommend monitoring techniques and performance criteria for both the eastern oyster (Crassostrea virginica) and the Olympia oyster (Ostrea lurida) that would allow for more extensive and consistent post-restoration assessment between projects on varying geographic scales. With additional expert input, the working group developed recommendations for a set of Universal Metrics that should be monitored for all oyster restoration projects. The working group also developed guidelines for assessing optional Restoration Goal-based Metrics. The Goal-based Metrics were not meant to be monitored for all projects, but could be monitored as needed to measure project performance and to advance the science of oyster habitat restoration depending on the availability of the necessary funding, capacity, and expertise. The Universal Metrics allow for the systematic assessment of the basic performance of restoration projects, whereas the Restoration Goal-based Metrics would allow practitioners to assess the performance of the restored reefs in meeting the ecosystem service-based restoration goal(s) associated with a project. Together, these metrics allow for the comparison of projects across a variety of scales and restoration approaches. Monitoring of the Universal Environmental Variables will also aid in the interpretation of Universal and Restoration Goal-based Metrics data collected through both pre-and post-restoration monitoring. The Universal Metrics that should be monitored for every oyster restoration project include: (1) reef areal dimension; (2) reef height; (3) oyster density; and, (4) oyster size-frequency distributions. Performance criteria for the Universal Metrics are based on emergent structure (assessed as reef height), successful recruitment, and oyster density present at both shortand mid-term post-construction time frames. The following Universal Environmental Variables should also be monitored for every oyster restoration project to aid with interpretation of Universal Metrics data: (1) water temperature; (2) salinity; and, (3) dissolved oxygen (for subtidal reefs). Restoration practitioners that lack the equipment or capacity to conduct the minimum required monitoring should collaborate with others able to provide this capability such as local researchers from academic institutions and local, state or federal agencies. Along with the Universal Metrics, the Restoration Goal-based Metrics are an optional set of monitoring guidelines provided to enable project managers to assess the following ecosystem service-based restoration goals: (1) brood stock and oyster population enhancement; (2) habitat enhancement for resident and transient species; (3) enhancement of adjacent habitats; and (4) water clarity improvement. This handbook is meant to be a living document that allows for future updates as monitoring methodologies and the state of the science evolve, and as meta-analyses of comparable data are undertaken. Restoration practitioners and other interested parties may at any time submit their comments and any suggestions for improvement to the handbook to ormetrics@gmail.com for consideration in future editions. The establishment of standardized restoration metrics has been a priority within the oyster restoration community for many years, and this handbook is built upon previous work (e.g.,
Ecological Engineering, 2000
Habitat restoration encompasses a broad range of activities, emphasizing very different issues, goals, and approaches depending on the operational definition of 'restoration'. This is particularly true for many shellfish (molluscan) dominated systems (e.g. oyster reefs, mussel beds, vermetid gastropod reefs). In contrast to other well-studied biogenic habitats, such as seagrasses, mangroves, or salt marshes, bivalves are directly consumed as a resource. Hence resource extraction has direct consequences for habitat health. Restoration objectives have typically included reduction of public health risks through improved water quality to increase harvest. Restoration or enhancement of populations of commercially exploited shellfish depressed by overharvesting and/or reduced environmental quality remains the principal motivation behind most shellfish 'restoration' efforts. Direct and indirect ecosystem services (e.g. filtering capacity, benthic-pelagic coupling, nutrient dynamics, sediment stabilization, provision of habitat, etc.) derived from oyster habitat have been largely ignored or underestimated. Only recently, the restoration of lost ecological function associated with shellfish communities has been included in our discussions and related research examining habitat development and function through a scientific approach. The former area has been reviewed extensively and will not be our focus here. In this review, we examine some of the restoration efforts made in the name of fisheries enhancement, address their effectiveness, and discuss some of the issues associated with realizing the broader goal of ecological restoration. We note the importance of linking success criteria to specific goals and make the case for a greater need in clarifying the ecological functions of shellfish and shellfish habitats. We recognize the limitations of existing datasets and summarize ongoing attempts to address oyster habitat restoration throughout the broad geographic distribution of the American oyster, Crassostrea 6irginica (Gmelin). In many ways this topic parallels the ongoing debate over 'attraction versus production' associated with artificial reef management. We consider how local conditions (e.g. tidal range, bottom topography, turbidity, salinity) and resulting habitat traits affect restoration strategies. We also discuss the underappreciated value of shellfish populations from those areas
Environments
Intertidal reefs of Crassostrea virginica (eastern oyster) provide ecologically valuable habitat in estuaries along the Atlantic coast of North America. In Mosquito Lagoon, a shallow-water estuary on the east coast of central Florida, USA, historical aerial imagery was used to document a 24% decline in the live C. virginica reef area between 1943 and 2009. Using 2021 imagery, every living and dead reef in the same region was manually digitized to identify changes during the intervening 12 years. Positive impacts of C. virginica reef restoration that took place between 2007 and 2021 were also digitized to quantify long-term restoration impact. Natural, live C. virginica reef coverage throughout the system was found to have decreased by 50.6% between 2009 and 2021 and, thus, 62.6% between 1943 and 2021. This was attributed to reef fragmentation, reef footprint loss, boating activity, and mangrove expansion. Of the 2542 live reefs identified using 2009 imagery, 219 reefs fragmented, 98...
Evaluating Intertidal Oyster Reef Development in South Carolina Using Associated Faunal Indicators
Restoration Ecology, 2010
Eastern oyster (Crassostrea virginica) habitat is increasingly being restored for the ecosystem services it provides rather than solely as a fishery resource. Community-based projects with the goal of ecological restoration have successfully constructed oyster reefs; however, the habitat benefits of these restoration efforts are usually not assessed or reported. In this study, we examined oyster habitat development at five community-based oyster restoration sites in South Carolina using oyster population parameters, resident fauna densities, and sedimentation (percent sediment coverage) as assessment metrics. All sites included multiple-aged reefs (1-3 years old) at the time of the fall 2004 sampling. Resident crabs and mussels were abundant at all five sites and crab assemblages were related to the size structure of the oyster microhabitat. Scorched mussel (Brachidontes exustus) abundances were most frequently correlated with oyster and other resident species abundances. Associations among oysters and resident crabs and mussels were not evident when analyses were conducted with higher level taxonomic groupings (e.g., total number of crabs, mussels, or oysters), indicating that species-level identifications improve our understanding of interactions among reef inhabitants and oyster populations. Community-based restoration sites in South Carolina provide habitat for mussels and resident crabs, in some cases in the absence of dense populations of relatively large oysters. Monitoring programs that neglect species-level identifications and counts of mussels and crabs may underestimate the successful habitat provision that can arise independent of large, dense oyster assemblages.
Oyster reef restoration in the northern Gulf of Mexico: Extent, methods and outcomes
2014
Available online a b s t r a c t Shellfish reef restoration to support ecological services has become more common in recent decades, driven by increasing awareness of the functional decline of shellfish systems. Maximizing restoration benefits and increasing efficiency of shellfish restoration activities would greatly benefit from understanding and measurement of system responses to management activities. This project (1) compiles a database of northern Gulf of Mexico inshore artificial oyster reefs created for restoration purposes, and (2) quantitatively assesses a subset of reefs to determine project outcomes. We documented 259 artificial inshore reefs created for ecological restoration. Information on reef material, reef design and monitoring was located for 94, 43 and 20% of the reefs identified. To quantify restoration success, we used diver surveys to quantitatively sample oyster density and substrate volume of 11 created reefs across the coast (7 with rock; 4 with shell), paired with 7 historic reefs. Reefs were defined as fully successful if there were live oysters, and partially successful if there was hard substrate. Of these created reefs, 73% were fully successful, while 82% were partially successful. These data highlight that critical information related to reef design, cost, and success remain difficult to find and are generally inaccessible or lost, ultimately hindering efforts to maximize restoration success rates. Maintenance of reef creation information data, development of standard reef performance measures, and inclusion of material and reef design testing within reef creation projects would be highly beneficial in implementing adaptive management. Adaptive management protocols seek specifically to maximize short and long-term restoration success, but are critically dependent on tracking and measuring system responses to management activities.
Fish Utilization of Created vs. Natural Oyster Reefs (Crassostrea virginica)
Estuaries and Coasts, 2018
Once viewed as an inexhaustible fishery resource, eastern oyster reefs (Crassostrea virginica) have been dramatically depleted. In North Carolina alone, eastern oyster harvests have declined by 90% since the early 1900s. However, eastern oyster restoration and management efforts have substantially increased since the 1970s. Oyster reefs provide habitat and refuge for organisms, improve water quality, and decrease erosion. Oyster restoration projects aim to construct reefs that function similarly to their natural counterparts. Therefore, post-creation monitoring of these reefs is crucial in determining restoration success. However, monitoring is often lacking or focused only on oyster density and size rather than ecosystem functions such as nekton utilization. This study examines nekton utilization among created reefs compared to natural reefs in an estuary in Wilmington, North Carolina. The objective was to determine whether the created reefs function similarly to the natural reefs in abundance, species richness, and fish size. Using seine nets and Breder traps, reefs were sampled over a 5-month period. No significant difference was detected among reefs for nekton abundance, species richness, and standard length. This is a promising result for future management, indicating that created and natural reefs can support similar communities of fishes and shrimp.
Oyster reefs at risk and recommendations for conservation, restoration, and management
Bioscience, 2011
kay, hunteR s. lenihan, MaRk W. luckenBach, caitlyn l. toRopova, guofan zhang, anD XiMing guo Native oyster reefs once dominated many estuaries, ecologically and economically. Centuries of resource extraction exacerbated by coastal degradation have pushed oyster reefs to the brink of functional extinction worldwide. We examined the condition of oyster reefs across 144 bays and 44 ecoregions; our comparisons of past with present abundances indicate that more than 90% of them have been lost in bays (70%) and ecoregions (63%). In many bays, more than 99% of oyster reefs have been lost and are functionally extinct. Overall, we estimate that 85% of oyster reefs have been lost globally. Most of the world's remaining wild capture of native oysters (> 75%) comes from just five ecoregions in North America, yet the condition of reefs in these ecoregions is poor at best, except in the Gulf of Mexico. We identify many cost-effective solutions for conservation, restoration, and the management of fisheries and nonnative species that could reverse these oyster losses and restore reef ecosystem services.
Habitat assessment of a restored oyster reef in South Texas
Ecological Engineering, 2018
Oyster reefs are important foundational habitats and provide many ecosystem services. A century of habitat degradation has resulted in substantial reductions in the extent and quality of oyster reefs in many estuaries, thus spurring restoration efforts. In this study, a 1.5 ha oyster reef complex was constructed in Copano Bay, Texas to restore habitat for oysters and associated fauna. Oysters and resident and transient fishes and crustaceans were monitored at the restored reef as well as at nearby natural oyster reef and unrestored bottom (i.e., dense mud with shell hash) habitats for two years following reef construction. The restored reef had substantial oyster recruitment and growth, with oyster abundance and size comparable to nearby habitats within the first year. Resident and transient fauna communities recruited to the restored reef within six months post-construction, and abundance and diversity were comparable to nearby habitats. Significant changes observed in oyster densities between the first and second year post-restoration demonstrate the importance of monitoring over multiple years to capture multiple recruitment cycles and growth to market size. Nekton densities did not change significantly after the first year, but changes in community assemblages were observed through the end of the study. The high densities of oysters and resident nekton relative to other studies indicate that this restoration project was successful in restoring suitable habitat. The design of the reef complex, consisting of relatively high-relief reef mounds and deeper corridors, likely contributed to the relatively high oyster and nekton densities observed in this study. Overall, the restored reef in this study showed tremendous near-term success in providing important ecological functions associated with habitat provision and oyster production.