Figure 1 2 Photo of recruitment of oyster shells cultch as part of SC restoration work Photo. courtesy of Loren Cohen Shellfish Research Section Marine Resources Research Institute South. Carolina Department of Natural Resources Charleston SC. They filter suspended particles excess nutrients and phytoplankton from the water column. to help maintain good water quality Species of oysters native to the United States is the. American oyster Crassostrea virginica In the Pacific Northwest species of oysters that are. commonly grown and eaten include the,Asian oyster Crassostrea ariakensis. Pacific oyster Crassostrea gigas, These species however are non native to the United States In some cases these species of. oysters are used to rebuild reefs along the United States coasts e g Virginia and Maryland. because they grow relatively fast and have a higher tolerance to disease compared to native. species Since these species grow rapidly in suitable conditions they may grow. uncontrollably expanding tremendously along the coast and outgrowing native oyster. species Other species of oysters locally or occasionally seen include the. Olympia oyster Ostrea conchaphila found on the West coast of North America in. areas between Sitka Alaska and Panama Gillespie 2000. Frond oyster Dendostea frons which is located in the tropical West Atlantic e g in. the Caribbean, Oyster reefs form when densely packed individual oysters grow upward and outward. creating a complex hard surface along the coastline as shown in Figure 2 The reefs are a. three dimensional habitat located in intertidal or subtidal zones Shipley and Kiesling 1994. and are particularly abundant in estuarine systems along the Atlantic Ocean and Gulf of. Figure 2 Oyster reefs along the coastline Effects of simulated harvesting evaluating the impacts and. recovery of intertidal fishery practices project followed recovery for 2 or 3 years Photo courtesy of. Loren Cohen Shellfish Research Section Marine Resources Research Institute South Carolina. Department of Natural Resources Charleston SC, Oyster reefs are dominant in estuarine systems along the Atlantic and Gulf of Mexico Oyster. reefs provide habitat for marine organism and birds supply breeding feeding nursery. grounds as well as refuge from predation for some species Additionally the hard structure of. the oyster reef stabilizes sediments to help improve water quality as well as provide shoreline. protection The reefs also have a significant economic value for the United States seafood. industry as they support many recreationally and commercially valuable animals such as fish. crabs shrimp and oysters in parts of the United States such as Louisiana Mississippi and. Figure 3 Picking oysters by hand at low tide Photograph courtesy of Bob Williams Willapa Bay. Washington Publication of the National Oceanic Atmospheric Administration NOAA. NOAA Central Library http www photolib noaa gov fish fish0744 htm. If the reefs are not in good health it will affect faunal abundance and diversity Despite their. importance oyster reef ecosystems have been degraded by various human pressures Lenihan. and Peterson 1998 Gagliano and Gagliano 2002 Since healthy oyster reefs support a. thriving ecosystem and are also economically important to the fishing industry restoration. efforts should be performed to ensure that these habitats are returned to a healthy functioning. state and that they are monitored and properly managed. In bays and sounds along much of the US coast oyster reef restoration efforts are being. performed in order to replace or maintain the critical ecosystem functions provided by both. the oyster organisms and the complex habitat they create When restoring oyster reefs the. primary ecological goals are usually to restore the physical structure and functioning of the. ecosystem promote oyster growth and successfully develop complex ecological. communities Many volunteer groups government agencies local state and federal and. universities have developed management and restoration plans for oyster reefs In figures 4. and 5 there are two methods shown that can be used to create oyster reefs. The individual shown in Figure 4 is using a high pressure water system to distribute oyster. shells from the platform of a boat into the water along the coastline Over time waves will. further distribute shells allowing them to establish themselves along the coast by attaching to. one another or other hard substrates in order to form a reef. Figure 4 1 Large scale reef restoration shell planting in 2002 Folly Creek Charleston Co South. Carolina Andy Jennings running the water pressure nozzle Photo courtesy of Loren Cohen Shellfish. Research Section Marine Resources Research Institute South Carolina Department of Natural. Resources Charleston South Carolina, Figure 4 2 Photo courtesy of Ray Haggerty retired SCDNR large scale reef restoration shell. planting in 2002 Bull Creek Beaufort Co South Carolina. Individuals shown in Figure 5 help to create reefs by transplanting oyster shells along the. coast Here oysters are placed in individual bags and laid down side by side until the selected. area for oyster restoration is filled Over time oysters will grow through the bags and attach. themselves to one another forming a hard reef structure. Figure 5 0 South Carolina Aquarium SCORE reef building project Charleston SC reef bags. Individuals placing bags filled with oyster shells along the shoreline Photo courtesy of Loren Cohen. Shellfish Research Section Marine Resources Research Institute South Carolina Department of. Natural Resources Charleston SC, Figure 5 1 Bags filled oyster shells along the shoreline to form reefs SC Aquarium SCORE reef. building project Charleston SC Photo courtesy of Loren Cohen Shellfish Research Section Marine. Resources Research Institute South Carolina Department of Natural Resources Charleston SC. Organization of Information Following the section titled Human Impacts to Oyster. Reefs the structural characteristics of oyster reefs that are applicable to restoration. monitoring are presented These structural characteristics presented will generally be. monitored first depending on the goals of the restoration project After the structural. characteristics have been addressed the habitat s functional characteristics are discussed later. in the chapter Some of these characteristics if not all should be monitored to ensure the. habitat is functioning efficiently Two matrices are then presented at the end of this chapter to. show the connection between the habitat s structural and functional characteristics to the. parameters that can be considered for monitoring Whenever possible parameters shown in. this list are discussed throughout the text to show how they can be used and factors that may. influence them These parameters are not expected to be monitored in all restoration projects. The information simply presents the role each characteristics plays and how it may be useful. if monitored Some characteristics however can be monitored before the project begins to. gather baseline information on the condition of the habitat and at the end of the project to. assess results Also provided are various types of methods that can be used when monitoring. a specific parameter however one must consider the project goals and what type of data is. expected to be collected Experts in the field must be consulted as to the best method to use. in a specific area Finally an annotated bibliography of monitoring and restoration related. oyster reef literature and a review of technical methods manuals are presented in Appendices. I and II respectively to direct the reader to additional information that can be useful for. developing a restoration monitoring plan,HUMAN IMPACTS TO OYSTER REEFS. Oyster reefs like other coastal habitats are threatened by various stressors such as. coastal development,harvesting techniques,run off from agricultural and industrial sources. over harvesting,oyster diseases, Coastal development in many cases involves the use of heavy machinery which disrupts or. even destroys the oyster reef structure Oyster harvesting techniques such as dredging also. disrupts reef structure and faunal communities that are present Lenihan and Peterson 1998. Over harvesting can also threaten reefs as fishermen remove oysters in large amounts. reducing the size of the reef structure Coen et al 1999 The reduction in oyster reef. structure in turn reduces the abundance and diversity of faunal species many of which are. commercially and recreationally important It is important to understand the structural and. functional characteristics of oyster reefs in order to effectively monitor and restore these. valuable coastal habitats, Oyster harvesting techniques may also impact the reef s structure and faunal community. Popular oyster harvesting techniques such as dredging hand tonging and diver collecting. were investigated to determine how they alter oyster reef morphology and caused incidental. mortality to un harvested oysters in the Neuse River North Carolina Lenihan and Peterson. 1997 Reefs harvested with dredges experienced maximum reduction of reef height. compared to other reefs that used a different technique Harvesting disturbs the reef structure. and may cause ecological changes Reef height controls local hydrology flow which in turn. affects recruitment growth and survival of oysters Reefs that were harvested by divers. rather than dredging experienced the lowest incidental mortality and maximum catch per. unit effort It is therefore important to select carefully the type of oyster harvesting technique. to avoid damaging the reef s structure, Agricultural and industrial run off from various sources affects the survival and growth of. oysters In many cases run off contains toxins or fertilizers which may promote algae. growth and cause a reduction in oxygen levels around the reef As a result oyster s. functional ability such as its ability to filter water efficiently decreases and eventually the. oysters die In the Neuse River in North Carolina oysters declined because of low dissolved. oxygen and environmental disturbances Deep water reefs disturbed by harvesting were. exposed to bottom water with low dissolved oxygen levels throughout estuarine. stratification As a result of low dissolved oxygen oysters and other reef associated. invertebrates and demersal fishes eventually died Lenihan and Thayer 1999 This was. caused by the oyster s inability to filter water and provide nutrients to the species that rely on. Oyster diseases also threaten the survival and recruitment of oysters and have been studied. by many researchers The parasites Perkinsus marinus which causes Dermo and. Haplosporidium nelson resulted in MSX disease that caused oyster mortalities throughout the. east coast of the United States Leonard et al 1999 MSX disease is brought on by a parasite. which was introduced to East coast from Asia The occurrence and intensity of Dermo and. MSX in Eastern oysters found in Rhode Island waters was surveyed by various practitioners. Leonard et al 1999 Perkinsus marinus infection levels were observed at their highest in. August and may have been responsible for the oyster mortalities at several sites Beginning. in the 1950 s along the Chesapeake Bay the native oyster Eastern oyster Crassostrea. virginica was infected by Dermo and MSX diseases Such diseases over time caused a. significant decline in the Chesapeake s native oysters which in turn significantly reduced the. size of the oyster reefs By 1990 these diseases were seen on oyster reefs throughout other. areas such as Delaware Maine Massachusetts and Connecticut causing significant increase. in oyster deaths on a much broader scale Disease infected oysters tend not to filter water. properly causing water quality to deteriorate around the reef In addition decrease in the reef. structure and reduced water quality can cause reef associated fish either to die or migrate to. other areas,Importance of Monitoring Oyster Reefs, Practitioners should conduct monitoring of the oyster reefs structural and functional. characteristics both during and after restoration in order to. evaluate the state of the habitat,understand the functioning of the ecosystem. monitor the interaction of the organisms on and around the reefs. Parameters selected for monitoring should be based on the particular goals and objectives of. the restoration project Monitoring restoration efforts allows the practitioner to determine. whether modifications must be made to the project and to track the success of the restoration. project Molluscan Ecology Program 2002 Monitoring should also be conducted to Coen. 2003 per comm, evaluate stressors at existing but degraded oyster reefs that might be targets for. restoration e g water quality salinity low D O disease. evaluate sites proposed for restoration Some of the most important features here. are bottom condition water quality such as D O harmful algal blooms and natural. recruitment of oysters Note both steps a and b could be combined to a category of. pre restoration monitoring, facilitate adaptive management This means measuring those elements during the. restoration process which will allow practitioners to modify their approach For. instance monitoring the quality of the substrate in the years after initial planting can. reveal whether or not it is necessary to add substrate to provide clean settlement sites. Also monitoring for oyster recruitment during the early years of the restoration. process can indicate whether the site is recruitment limited and brood stock. enhancement might be justified, assess restoration success Most of which is discussed in this chapter. There are various structural and functional characteristics that can be considered to. monitor the success of a restoration project Examples of characteristics that should be. taken into consideration when evaluating and monitoring oyster reef restoration. succession include Coen 2003 per comm, Availability and integrity of substrate for continued oyster settlement. Areas where oyster reef restoration is an issue, o Adequate substrate for settlement may be limited so all restoration efforts. begin with the addition of substrate s or cultch to sites where. oyster recruitment and survival rates are sufficiently high material. is rapidly covered with oysters and provides substratum for. additional oyster recruitment over time, oyster recruitment and survival rates are low competition with. other epifauna often occurs Substrate degradation caused by. boring sponges and sedimentation may reduce the availability of. clean substrate generally oyster shell for oyster settlement. o Assessing the availability of adequate substrate prior to recruitment each. year can provide a basis for making adaptive management decisions such. as whether adding supplemental substrate s is needed. Oyster recruitment levels should be evaluated before during and after the. restoration Without new recruits the restoration effort which in most cases. involves planting some shell is ineffective It is crucial that oyster recruitment be. monitored for a minimum of three to four years following the construction of reef. foundation Coen 2003 per comm, There are several components to this monitoring need that can lead to different. adaptive management decisions and assessments of success This includes. Larval availability settler Early post settlement survival. o traditional spat collectors are o standard stock assessments of. substrates shells tiles or other oysters e g young the year. materials that can be retrieved recruits provides a measure of. on a regular basis throughout the success of the reef substratum and. peak settlement time for oysters may suggest some remediation if. the success is low It is important,o they should be placed in the. to obtain quantitative estimates at,vicinity of reef restoration. sufficient frequency and over more,projects to assess the potential. than one recruitment season,recruits to the reef,o if the number of settling oysters is. o expectations about the,sufficiently high but the number of. abundance of newly settled,surviving new recruits is low then. oysters will vary locally but,it may be possible to identify the. some minimal level of oyster,cause s of this mortality and. recruitment will be required for,changes may result. successful restoration,o if oyster settlement is,unsuccessful the restoration. project must either,be relocated,oyster brood stock in the area. enhanced or,remote set oysters onto,substrates deployed onto reefs. including relaying seed, An example with regard to early post settlement survival was observed in Virginia. where reef bases constructed of alternative substrates surf clam shell and coal ash. pellets intertidal were found to have similar settlement abundances as reefs of oyster. shell but much higher predation induced mortality rates Coen 2003 per comm The. result was that restoration using the alternative substrate as bases was unsuccessful. while that using oyster shells was successful Incidentally a midcourse change. modifications made as needed during the project would be to cap the clam shell and. coal ash bases with a layer of oyster shells Similarly current restoration efforts in. some states are revealing that degradation of shell substrate by boring sponge may. demand fresh shell be added to a restoration site for several consecutive years until a. sufficient number of living oysters establish themselves on the reef Coen 2003 per. Abundance and size frequency distribution of oysters on the reef The size. and frequency of oysters on the reef suggests an age structure critical to. estimating population demographics and its growth potential. Figure 6 A small scale experiments to assess the impact of boat wakes on newly planted. Gulf shell Inlet Creek experiments Photo courtesy of Loren Cohen Shellfish Research Section. Marine Resources Research Institute South Carolina Department of Natural Resources Charleston. Diseases and related monitoring, Oyster diseases are widespread throughout regions where oyster restoration is likely. to be conducted It is important to measure disease prevalence and intensity for two. o because knowing disease levels can play a role in understanding mortality. patterns and affect adaptive management decisions and. o because an important goal of oyster restoration efforts is to develop oyster. populations with greater disease tolerance over a longer period of time. especially in North Carolina NC Virginia VA and Maryland MD It is. necessary to follow disease dynamics to track progress towards this goal. This is currently urging potential introductions of exotic non native oyster species NC. VA In South Carolina a lot of effort is placed on monitoring diseases along with. environmental information temperatures intertidal subtidal pH DO depth salinity. etc expensive,Structural Characteristics of Oyster Reefs. When designing a successful oyster reef restoration monitoring plan one must first. understand the structural characteristics of the habitat and how they relate to the project. goals These structural characteristics include,Biological. o Habitat created by animals,o Topography Bathymetry. o Sediment type and grain size,o Tides and Hydroperiods. o Turbidity Light availability,Hydrological,o Water sources. o Salinity,o Dissolved Oxygen, Since these structural characteristics can influence oyster attachment establishment and. growth practitioners must first monitor them to ensure conditions are favorable for successful. restoration Once reefs have been established the practitioner can begin monitoring the reef s. functioning capacity such as providing breeding feeding and nursery grounds for fish and. other marine organisms Pre restoration monitoring is recommended before restoration is. conducted to determine baseline conditions After restoration efforts post restoration. monitoring is performed to track the success of the project by comparing the restoration site to. reference sites This section however concentrates on the structural characteristics of oyster. reefs and methods that can be used to sample measure and monitor each parameter. BIOLOGICAL,Habitat created by animals, As mentioned earlier in the introduction oyster reefs are formed when individual oysters. accumulate and form a complex structure that rises above the bottom floor Oysters are filter. feeding bivalve molluscs filtering microalgae suspended particulate organic matter and. dissolved organic matter from the water column over their gills Recruitment settlement and. growth of oysters over time increases the size of the reef which supports local and. commercial fisheries such as crabs oysters and fish The structure of the reef forms a three. dimensional biogenic2 habitat in intertidal or subtidal zones composed of multiple year. classes of oysters which also provides microhabitats for many different species of animals. such as polychaetes and shrimps Shipley and Kiesling 1994 Intertidal oyster reefs are. found throughout the entire intertidal zone from near bottom to depths where the reef s top. frequently breaks the surface of the water at low tide Chesapeake Bay Program 2002. Subtidal oyster reef however extends slightly above the bottom yet below the intertidal zone. Monitoring Methods, The NOAA Coastal Services Center and South Carolina Department of Natural Resources. SCDNR have been working together to develop high resolution remote sensing methods. for assessing intertidal oyster reefs along the South Carolina coast Finkbeiner et al 2003. Multiple image processing photography spectral clustering and digital texture analysis are. methods primarily used to determine the boundaries and spatial characteristics of oyster reefs. Finkbeiner et al 2003 Restoration practitioners can also used digital and analog aerial. photography to assess oyster reef conditions during restoration Figure 7 shows an aerial. photograph of intertidal oyster reefs, Figure 7 Represents an aerial photograph of oyster reefs SCDNR reef construction Inlet Creek. SC Charleston Co Photo courtesy of George Steele South Carolina Department of Natural. Resources Charleston SC, For four years side scan surveys were used for rapid and accurate assessment of oyster reefs. in turbid waters in south Louisiana Allen et al 2003 They compared the number of shells. recorded from quadrant sampling in each sampling site Dredge sampling was integrated with. resulting from the actions of living organisms, groundtruth side scan surveys to make results more relevant to the oyster industry. Combining the use of side scan sonar and GIS to monitor oyster productivity is useful for. monitoring and tracking changes to oyster reef communities Allen et al 2003. Topography, Topography of intertidal oyster reef has a distinct three dimensional structure that is. composed of living oyster shell The reefs provide vertical relief and structural heterogeneity. e g the height and width of the oyster shells that form reefs that attracts and sustains fish. population such as,striped bass Morone saxatilis,bluefish Pomatomus saltatrix and. weakfish Cynoscion regalis, The size of vertical relief affects faunal abundance and utilization in oyster reefs Breitburg. and Miller 1998 The complexity of the reef structure and vertical relief increases habitats. for fish and decapods utilizing the reef as refuge Lenihan 1999 Size of the reef s vertical. relief can improve water quality by enhancing the removal of materials from the water near. the reef Along the Neuse River in North Carolina oyster decline and change in topography. results from various environmental disturbances Lenihan and Thayer 1999 Following their. investigations researchers were able to determine that some harvest practices affected the. reef s topography by reducing the height of oyster reefs causing a decrease in flow speeds. across reefs In addition reduced flow speeds caused an increase in sedimentation which. reduced the quality of suspended food material for oysters This explained why oyster s. growth on harvest disturbed reefs was slow their health was relatively poor and mortality. rates were higher,Monitoring and Measuring Methods. Estuarine and coastal benthic habitats are evaluated using underwater acoustic technology. with reflected sound energy to identify surface objects texture and density disturbances and. to classify benthic habitat Smith et al 2001 Researchers have used sub bottom profiling. systems side scan sonar and acoustic seabed classification systems ASCS to successfully. assess oyster reef structures Data collected on the quality and quantity of oyster shell. resources was then integrated with Geographical Information Systems GIS to assess oyster. habitat Smith et al 2001 Using this method can help practitioners evaluate changes in. oyster reef structure over time following restoration efforts A recommended method for. rapidly classifying bottom type navigation is to combine mapping by acoustic profiler to. differentiate substrate type and a fathometer to assess bottom relief and a global positioning. system GPS to determine accurate position Simons et al 1992 This method has. effectively mapped oyster reefs and oyster bottom of Galveston Bay Texas Instruments are. employed using a small research vessel in most weather conditions and in shallow 1 m or.
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tributed routing protocols. We are interested in training neural networks on two important aspects of those network protocols. The first one is the network protocol itself, namely how to distrib-ute topology information among different nodes, and the second one is how to compute routes given a topology and link weights.
[USMLE] Step 1 to evaluate whether this novel learning strategy successfully conveyed basic science core concepts to students. Methods students work together to achieve a common The Duke-NUS Program Duke-NUS was established in 2005 as a collaboration between the Duke University School of Medicine (DSOM) and the National University of Singapore (NUS) to train and cultivate a cadre of physician ...
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