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The Guana-Tolomato-Matanzas (GTM) system is a well-flushed estuary in Northeastern Florida, USA, and characterized as having an extraordinarily high abundance of oysters that resembles the populations described by Euro-American settlers. Historically, dense populations of oysters, such as those found in GTM, are believed to play an important role in water filtration; however, most research teams seeking to simulate this role have not had access to such robust populations to parametrize their models. To quantify the filtration service (FS) of Eastern oysters (Crassostrea virginica) in GTM at several spatial scales (i.e., reef, watershed, estuary), we implemented a model that solves for the hydrodynamics and depletion of particulate matter passing over model oyster populations, the latter of which were derived from detailed bay-wide surveys. The model results suggested that oyster reefs populating the GTM play an important role in water quality by filtering ~60% of the estuary’s volume within its residence time. Our approach teases apart the role of reef size, residence time, particle concentration, and other physical factors on the generation of FS at different spatial scales. Downstream effects were found to be very important for estuary FS, which depend on the spatial distribution of the reefs in the GTM and local and estuarine-scale hydrodynamics. Therefore, the difference between “realized” FS and the “potential” FS of a given reef may be substantial when considering the complex hydrodynamic and connectivity among populations at several scales. Our model results provide clear and actionable information for management of these oyster populations and conservation of their ecosystem services.

Research on the effects of bivalve filtration emphasizing oysters has mainly involved extrapolations from laboratory based measurements on individual oysters to potential whole-ecosystem impacts, with only a few studies on reef-scale processes and less using direct measurements. This study characterized spatial effects of whole-reef (oysters, Crassostrea virginica, and other filter feeders on the reef) filtration in the water immediately above and adjacent to a small (∼300 m2) intertidal reef in Tarpon Bay, Sanibel, Florida. Changes in water column parameters were measured in 2010 (chlorophyll a only) and 2013 (chlorophyll a and turbidity) by slowly paddling a kayak back-and-forth across the reef while logging position and water data. Although oysters were the dominant filter feeder, mussels, slipper shells, sponges, and a filter-feeding crab also occurred on the reef. Ambient water flow speed and direction were concurrently determined in 2013 by an acoustic-doppler current profiler. Measurements were made on two days (1–2 June) in 2010, and two days (November 15 and December 9) in 2013. ArcGIS software was used to plot the data and construct two-dimensional maps showing changes in chlorophyll a and turbidity, which clearly indicated the spatial extent of decreases in both as water flowed across the reef. Seston decrease (interpreted as depletion) levels were spatially variable, averaging 23–25% but as high as 68% in some areas directly over the reef. The extent of detectable depletion usually extended 10–20 m beyond the edge of the reef, potentially increasing light levels and thereby providing enhanced growth conditions for adjacent seagrasses and algae, suggesting that restoration success of macrophyte habitats could be enhanced by close spatial coupling with oyster reef restoration.

Grizzle, R.E.; Bricelj, V.M.; AlShihi, R.M.; Ward, K.M., and Anderson, D.M., 2018. Marine molluscs in nearshore habitats of the United Arab Emirates: Decadal changes and species of public health significance. This paper describes the results of three qualitative surveys of marine molluscs conducted in December 2010 and May 2011 and 2012 in nearshore benthic habitats along the Arabian Gulf and Gulf of Oman coasts of the United Arab Emirates. Findings are compared with historical studies, focusing on extensive surveys from the 1960s and 1970s. Molluscan species of public health significance are identified on the basis of their potential as vectors of algal toxins in light of the recent occurrence of harmful algal blooms (HABs) in the region. Habitats sampled included intertidal sand or gravel beaches, rocks and jetties, sheltered soft-sediment flats and mangroves, and shallow subtidal coral reefs. The present study showed differences in taxonomic composition and decreased species richness of gastro...

Interest and investment in constructing living shorelines rather than harder engineering structures are on the rise worldwide. However, the performance of these interventions in rejuvenating coastal habitats, depositing fine sediments with elevated organic content, and reducing erosion varies widely and is often low along energetic shorelines. In this study, we test the efficacy of a living shoreline design that couples breakwalls and oyster restoration structures, in protecting coastal estuarine ecosystems and their services along energetic shorelines. A field experiment was conducted between 2015 and 2019 along a section of the Atlantic Intracoastal Waterway in northeast Florida, which experiences commercial and recreational vessel traffic. We discovered that organic matter, silt and clay content all increased in sediments collected in the living shorelines compared to paired control treatments. In addition, oysters established and developed into robust reefs on the gabions – wire cages filled with seasoned oyster shells - that were used to facilitate oyster recovery within this living shorelines design, although oyster growth was highest where the gabions were placed at lower intertidal elevations. Additionally, salt marsh cordgrass along shoreline margins protected by the living shoreline structures remained stable or began advancing toward the Intracoastal Waterway channel at rates of ~1 m per year, whereas cordgrass in control treatments retreated at rates approaching 2 m per year. This study provides powerful evidence that vessel wake stress is indeed driving ecosystem loss and that simple nature-based living shoreline structures designed to dissipate this energy can slow or reverse ecosystem decline. More research is needed to optimize these nature-based solutions for shoreline protection in coastal and estuarine settings, and to improve their durability.

Coral reefs of the United Arab Emirates were once extensive, but have declined dramatically in recent decades. Marine management and policy have been hampered by outdated and inaccurate habitat maps and habitat quality information. We combined existing recent datasets with our newly mapped coral habitats to provide a current assessment of nation-wide extent, and performed quantitative surveys of communities at 23 sites to assess coral cover and composition. Over 132 km(2) of coral habitat was mapped, averaging 28.6 ± 3.8% live coral cover at surveyed sites. In the Arabian Gulf low cover, low richness Porites dominated communities characterized western Abu Dhabi, while reefs northeast of Abu Dhabi city generally contained higher richness and cover, and were dominated by merulinids (formerly faviids). Distinct communities occur in the Sea of Oman, where cover and richness were low. We provide management recommendations to enhance conservation of vulnerable coral reefs in the UAE.

The spatial relationship between adult eastern oyster Crassostrea virginica populations and recruitment to the benthos of their offspring is not well understood. It is well established that larvae can be widely dispersed, but the relationship between dispersal potential and actual recruitment patterns across the full range of spatial scales involved remains unknown. To explore this relationship, spat collectors were deployed on and near (up to 1 km distance) three natural oyster reefs in New Hampshire in 2014 and 2015. Spat densities on the reefs and within 400 m of the reefs were nearly 10-fold higher than densities more distant. These data do not negate the potential importance of widespread dispersal and recruitment, but they do indicate a surprising level of recruitment very near their likely source. Additional research is needed in other areas to test the generality of the findings and to assess potential causal factors for the observed patterns. The overall implication for choosing sites for oyster reef restoration projects, particularly in recruitment-limited areas, is that they may need to be located much closer to spawning adults than previously thought to maximize the likelihood of adequate natural recruitment and reef development.

The seaweed communities that developed on oyster farm gear in the Great Bay Estuary in New Hampshire (NH) were compared to three adjacent natural subtidal habitats: an oyster reef, eelgrass bed, and a mudflat. Both farm gear and oyster reefs have received little attention with respect to associated seaweeds. Comparisons were based upon replicate quadrat samples taken during August, and October 2014, plus August 2015. Mean species richness (all dates combined, N = 12) was significantly and substantially lower on the mudflat (2.86 ± 0.56 SE taxa/0.25 m2), but not different among the other three habitats (range: 9.00 ± 0.97 to 11.00 ± 1.41 taxa/0.25 m2). Mean biomass was also statistically different across habitats (P

Habitat loss and disturbance are ranked globally as the greatest threats to biodiversity. Development and coastal population growth are the leading causes for habitat losses. Recently, the restoration of marine habitats has increased, especially with the goal of increasing non-consumptive ecosystem services derived from mangrove and submerged aquatic vegetation (SAV) along with biogenic oyster reefs. Habitats reside in landscapes dominated by multiple species. Rather than focusing on a single habitat such as oysters or mangroves or SAV, we took an approach restoring multiple adjacent habitats to accelerate restoration in a Florida embayment that had been significantly degraded prior to the restoration of natural tidally generated flows. After a multiple habitat die-off, a project was initiated in 2006 to reintroduce tidal flushing. The re-introduction of tidal flushing, however, did not result in immediate recovery of mangrove shorelines or oyster-dominated reefs. There was a lack of mangrove propagule production and significant substrate limitation in areas with appropriate salinity, sediment and tidal flows. From 2009–2012, red mangrove (Rhizophora mangle) propagules were collected (over 500,000) and planted for a total area of 3.24 ha. From 2009–2010, five intertidal reefs were constructed by adding bagged and fossil shell (54 MT) for Crassostrea virginica larvae to recruit onto totaling over 779 m2. Monitoring of planted mangrove versus unplanted shorelines demonstrated that prop root and drop root densities were higher where propagules were planted (28 m−2) versus unplanted (2.3 m−2). Oyster densities and mean sizes (multiple year classes) at new and natural reefs were measured after 8, 12, and 24, and 36 months. An initial settlement pulse was observed in the first 8 months followed by an increase in the density of greater than 1-year old oysters. Xanthid crab densities (Eurypanopeus depressus and Panopeus spp.) in restored reefs and natural reefs were similar, while Petrolisthes armatus densities were lower in restored reefs. Whole reef seston filtration rates over restored reefs were −26 to 157 L m−2 h−1 when measured at 4, 15, 28, and 40 months. A multiple habitat approach may be useful in accelerating the natural ecological succession, especially if the project site has reached a degraded, alternate ecological state. These results suggest a multiple habitat approach can be useful in providing non-provisioning ecosystem services to a Florida embayment.

Restoration of degraded ecosystems is an important societal goal, yet inadequate monitoring and the absence of clear performance metrics are common criticisms of many habitat restoration projects. Funding limitations can prevent adequate monitoring, but we suggest that the lack of accepted metrics to address the diversity of restoration objectives also presents a serious challenge to the monitoring of restoration projects. A working group with experience in designing and monitoring oyster reef projects was used to develop standardized monitoring metrics, units, and performance criteria that would allow for comparison among restoration sites and projects of various construction types. A set of four universal metrics (reef areal dimensions, reef height, oyster density, and oyster size–frequency distribution) and a set of three universal environmental variables (water temperature, salinity, and dissolved oxygen) are recommended to be monitored for all oyster habitat restoration projects regardless of their goal(s). In addition, restoration goal-based metrics specific to four commonly cited ecosystem service-based restoration goals are recommended, along with an optional set of seven supplemental ancillary metrics that could provide information useful to the interpretation of prerestoration and postrestoration monitoring data. Widespread adoption of a common set of metrics with standardized techniques and units to assess well-defined goals not only allows practitioners to gauge the performance of their own projects but also allows for comparison among projects, which is both essential to the advancement of the field of oyster restoration and can provide new knowledge about the structure and ecological function of oyster reef ecosystems.

Benthic deposition of carbon (C) and nitrogen (N)-rich oyster biodeposits may increase denitrification, or anaerobic respiration of nitrate (NO3 −) to di-nitrogen gas (N2). However, environmental drivers of C and N dynamics in oyster biodeposits and reef-adjacent sediments require clarification. In July 2012, we collected intact sediment cores adjacent to and 15–20 m away from two oyster reefs (Crassostrea virginica) in Great Bay, New Hampshire, USA: one reference site and one site with cultural eutrophication. We also measured seston, chlorophyll a, and in situ oyster feeding and biodeposition. Cores were incubated in continuous-flow chambers where inflow water received 15N-ammonium (NH4 +), 15NO3 −, or no isotopes (control). We quantified fluxes of dissolved nutrients and gasses (oxygen, 28N2, 29N2, 30N2, and argon) after 24 h. Finally, we measured size-fractionated sediment organic matter. At the eutrophic site, abundant phytoplankton in the 5–28 µm size range was correlated with enhanced oyster feeding rates and biodeposit quality (lower C:N). This site had greater denitrification rates in reef-adjacent cores relative to distal cores. Low production of 29,30N2 in 15NH4 + amended cores suggested water column or biodeposit NH4 + were unlikely to be converted to N2. At both sites, reef-adjacent cores had more shell and higher 29,30N2 production with 15NO3 − addition relative to distal cores, suggesting direct denitrification enhancement near reefs. Oysters likely increased sediment N2 production via high quality biodeposits (eutrophic site), and NO3 − diffusion via structural complexity of reef-adjacent sediment (both sites). Overall, results suggest oyster-mediated ecosystems services may be expected to vary with environmental conditions.

The Eastern Oyster Crassostrea virginica is an important component of the ecology of Apalachicola Bay, Florida, and the economy of the region. Although oyster reefs in the Bay occur in both tidal zones, subtidal reefs have received the most attention because they support most of the oyster fishery. The present study provides new information on the distribution, condition, and ecology of the intertidal reefs, and assessed the general utility of high-resolution satellite imagery for routine monitoring of the extent and condition of intertidal oysters. Using online, freely available color imagery and manual interpretation, a total of 782 individual reefs ranging in size from ∼3 m2 to 3.9 ha (= 9.7 acres) and covering a total of 94 ha (233 ac) of bottom area were mapped. Field inspection and sampling of 100 individual intertidal reefs on November 12–16, 2016, confirmed wide differences in the number and areal coverage of reefs in the three major geographic regions in the Bay: 433 reefs covering a total of 56 ha (139 acres) in the western area (St. Vincent Sound); 113 reefs covering 8 ha (19 acres) in the central area; and 236 reefs covering 30 ha (75 acres) in the eastern area (St. George Sound). Most reefs in the western portion of the bay consisted of recently dead (“box”) oysters in all size classes, suggesting a recent massive mortality event. Mean densities (all size classes combined) of live oysters in the central and eastern areas were 42.9/m2 (±7.39; 1 SE) and 99.3/m2 (±13.22; 1 SE), respectively, with an overall mean shell height of 23.6 mm. Size-frequency histograms indicated only two year classes of live oysters, and the largest oyster collected was 84 mm. Although detailed quantitative comparisons with subtidal reefs were not possible, data from the present study suggest that intertidal reefs cover much less bottom area of the bay, but may contain much higher live oyster densities. The present study also demonstrated the use of high-resolution satellite imagery for mapping reefs as small as a few square meters in surface area, and the potential for estimating relative reef condition measured by live oyster density.

It was with great excitement that we planned the combined meetings of Northeast Aquaculture Conference and Exposition (NACE) and the International Conference on Shellfish Restoration (ICSR) with the 33rd Milford Aquaculture Seminar (MAS). Bringing these different but complementary audiences together resulted in a meeting that combined many different aspects of fisheries restoration and aquaculture under one umbrella.Four hundred attendees including government representatives, research scientists, industry, and academia at both the university and vocational high school levels attended this event. The meeting commenced on Wednesday December 12th 2012, with over eighty people attending seven field trips to area aquaculture farms and research facilities. The formal program began on Thursday, December 13th with a plenary session including invited speakers Eric Schwabb, Acting Assistant Secretary for Conservation and Management at NOAA; Sebastian Belle, Executive Director of the Maine Aquaculture Association and Boze Hancock from the Nature Conservancy, who discussed the role of aquaculture in fisheries restoration. John Bullard, the Northeast Regional Administrator of NOAA Fisheries Service, addressed the group during the luncheon the following day. The technical papers and workshops presented were divided into 35 sessions over three days of the meeting and included topics such as the history of aquaculture, aquaculture hatchery innovations, siting and planning issues, risk management, aquaculture business management, ocean acidification, climate change, as well as aquaculture disease issues and potential remedies. Having persons present who have experienced problems and successes, along with those in manufacturing and government responsible for addressing concerns and sharing best practices, was invaluable. Discussions among this cross-section of persons who represent different aspects of aquaculture were as important as the well-presented and interesting formal papers and poster sessions. These discussions were facilitated by the many opportunities presented during the large trade show, reception, breaks, lunches, banquet and lobster bake held throughout the meeting.The importance of and need for aquaculture were made evident by all who were in attendance. We are grateful to the twenty four meeting sponsors and to all those who participated and made this such an important and memorable meeting.While oyster restoration efforts have been under way in the Chesapeake Bay for more than two decades, until recently, varying reporting methods and success criteria made it difficult to determine how much progress had been made. A goal to “Restore native oyster habitat and populations in 20 out of 35 to 40 candidate tributaries by 2025” was set in the 2010 strategy to implement the Chesapeake Bay Protection and Restoration Executive Order (signed by President Obama in 2009). This goal made it a priority for state and federal fishery managers, academics, and scientists working on oyster restoration to collaboratively define a “restored tributary” and a “restored reef” to enable them to track progress. A team of these people, led by NOAA staff, agreed on “oyster metrics” in 2011 (http//preview.tinyurl.com/8kmbdpm) that specify key metrics and target ranges for them, including tributary size, how to determine how much restorable bottom a tributary contains, how much of that restorable bottom needs to be restored, and the minimum oyster density and biomass in that restored bottom to count a tributary as restored. These new metrics enable experts to clearly see how oyster restoration efforts are working and use adaptive management to improve these efforts. These metrics serve as a tool to plan and evaluate oyster restoration consistently across the Chesapeake Bay, and the consensus-based framework used to develop them may have broader application to other restoration activities.In the past, oyster restoration in Maryland was performed primarily

The oyster habitat in the USA is a valuable re- source that has suffered significant declines over the past century. While this loss of habitat is well documented, the loss of associated ecosystem services remains poorly quan- tified. Meanwhile, ecosystem service recovery has become a major impetus for restoration. Here we propose a model for estimating the volume of water filtered by oyster popula- tions under field conditions and make estimates of the contribution of past (c. 1880-1910) and present (c. 2000- 2010) oyster populations to improving water quality in 13 US estuaries. We find that filtration capacity of oysters has declined almost universally (12 of the 13 estuaries exam- ined) by a median of 85 %. Whereas historically, oyster populations achieved full estuary filtration (filtering a vol- ume equivalent or larger than the entire estuary volume within the residence time of the water) in six of the eight estuaries in the Gulf of Mexico during summer months, this is now the case for only one estuary: Apalachicola Bay, Florida. By contrast, while all five estuaries on the North Atlantic coast showed large decreases in filtration capacity, none were achieving full estuary filtration at the time of our c. 1900 historic baseline. This apparent difference from the Gulf of Mexico is explained at least in part by our North Atlantic baseline representing a shifted baseline, as sur- veyed populations were already much reduced by exploita- tion in this region.

A numerical bioenergetics simulation model based on the physiological processes affecting individual clams across a range of phenotypes describing a cohort has been developed and applied to the conditions in Great South Bay, New York. The clam population is relatively sensitive to food and to a lesser extent to temperature within this system. The timing of temperature and food in the spring, and more importantly in the fall, can increase population sensitivity beyond the effects of one factor operating alone. The effects of fishing on the stocks in proportion to the size structure present, and as directed fisheries on various size classes (littleneck, cherrystone, chowder) was simulated. Recruitment overfishing was responsible for the stock decline in the 1970s and 1980s, but the continued decline into the late 1990s and 2000s cannot be attributed to fishing alone. Recruit-per-adult declined after the mid 1990s. Modeled stock recovery times under constant environmental conditions are on order of ...

Little is known about the distribution and ecology of intertidal oysters in northeastern North America. North of Chesapeake Bay, intertidal oysters have either been previously reported as non-existent or only occurring as single oysters or sparse clusters. In the present study, we report the occurrence of dense populations of inter-tidal oysters at several estuarine sites within New Hampshire and mid-coastal Maine, with these growing under dense canopies of the long-lived Ascophyllum nodosum (fucoid alga). The densities of these northern intertidal oysters rival subtidal populations in the same geography, and their sizes suggest a persistence of 5 or more years.

Towed underwater video has become a widely used method for bottom habitat mapping in coastal waters, but very little has been published on this relatively new and effective approach. We use a case study on two oyster reefs to illustrate the pros and cons of towed video, visualization techniques, and future research topics. Towed video is deployed in similar fashion to single-beam sonars, yielding narrow swaths of video imagery that are recorded concurrently with global positioning system (GPS) data for georeferencing. The major advantages over acoustic (sonar) methods are that image processing and interpretation are relatively simple, and there is little or no need for subsequent ground-truthing. The system used in the present study consists of an underwater black and white camera mounted on a steel frame, differential GPS unit, and digital video camera for recording. It was assembled from off-the-shelf items, and total cost was approximately $3500 (2006 US$). The imagery from both study reefs wa...

Growth of fouling organisms on suspended fish cages is an impediment to aquaculture projects in coastal waters around the world. The present study characterized ecological succession of fouling communities on the netting of fish cages at an open ocean aquaculture site 10 km east of New Hampshire, USA in the western Gulf of Maine. Ecological succession can be defined as the process by which a community moves from a simple level of organization to a more complex community. Routine cleaning of the cages causes loss of organisms and initiation of ecological succession. Experimental panels of nylon net material were deployed at different times of the year and for different durations from September 2002 to September 2003 (eleven sets of 1-month panels, four sets of 3-month panels, two sets of 6-month panels, and one set of 1-year panels), with four replicates of each deployment. Panels were randomly arranged on a grid that was attached to a fish cage at a water depth of ∼ 15 m. There were substantial and significant differences in density and biomass of the total communities of most successional sequences when comparing panels deployed during May–September to those deployed during the cooler months, October–April. However, the blue mussel, Mytilus edulis, dominated in density and biomass in almost every sequence, regardless of time of initiation or duration. Other species that occurred in high numbers and/or biomass were the amphipods Caprella sp. and Jassa marmorata, the molluscs Hiatella arctica and Anomia sp., the seastar Asterias vulgaris, and the anemone Metridium senile. Juveniles and adults of some species were also present in some early (1-month) successional sequences, indicating that migration may be an important process in community development. Some of the dominant species listed above were present in all successional stages (early, intermediate and late), differing only in relative abundances in the community. The consistent dominance of M. edulis, and other differences in successional patterns compared to what has been typically observed for epifaunal communities in the region, were hypothesized to be the result of a combination of factors: a lack of predators such as seastars and fish that typically consume mussels in natural communities, excessive predation by nudibranchs on those species (e.g., Tubularia sp.) normally abundant in early successional stages, year-round availability of mussel larvae, and cage cleaning protocols that do not remove all the organisms present. The introduction of predatory fishes or seastars into or onto the cages might provide some amount of control on the growth of fouling organisms.

The importance of restoring filter-feeders, such as the Eastern oyster Crassostrea virginica, to mitigate the effects of eutrophication (e.g. in Chesapeake Bay) is currently under debate. The argument that bivalve molluscs alone cannot control phytoplankton blooms and reduce hypoxia oversimplifies a more complex issue, namely that ecosystem engineering species make manifold contributions to ecosystem services. Although further discussion and research leading to a more complete understanding is required, oysters and other molluscs (e.g. mussels) in estuarine eco- systems provide services far beyond the mere top-down control of phytoplankton blooms, such as (1) seston filtration, (2) benthic-pelagic coupling, (3) creation of refugia from predation, (4) creation of feeding habitat for juveniles and adults of mobile species, and for sessile stages of species that attach to molluscan shells, and (5) provision of nesting habitat.

The most commonly used methods for measuring the amount of seston removed from the water column (uptake) by populations of suspension-feeding bivalve molluscs involve taking discrete water samples followed by laboratory analyses. Here we describe a new method based on in situ fluorometry that provides rapid measurement of seston removal rates. The new system is comprised of two identical units, each consisting of an in situ fluorometer, data logger and peristaltic pump with plastic tube attached to a deployment device. The deployment device allows precise placement of the fluorometer probe and intake end of the plastic tube so that in situ fluorescence (chlorophyll a) can be measured and water can be sampled for seston analyses in the laboratory from the same height. The typical setup involves placing one unit upstream and the other downstream of the study area and sampling the water at periodic intervals. Changes in seston concentration are revealed in the field by the fluorometers, and the sampled water can be analyzed in the laboratory for various seston parameters. Comparisons of the in situ data with data from laboratory analyses of pumped water samples were made for three species at four study sites: the eastern oyster (Crassostrea virginica), hard clam (Mercenaria mercenaria), and blue mussel (Mytilus edulis). Comparisons of measured upstream versus downstream seston concentrations indicated significant (t-tests, P < 0.05) differences (uptake) for six of eight trials based on in situ fluorometry, but only marginally significant (P < 0.10) differences at two of the four trials using laboratory chlorophyll a measurements. These data demonstrate that compared with sampling methods requiring laboratory analyses, the new in situ method provides much more rapid quantitative assessments and may provide more accurate estimates.

Along the east coast of central Florida in the Indian River Lagoon system, intense recreational boating activity occurs year-round, and intertidal reefs of the eastern oyster Crassostrea virginica (Gmelin) with dead margins (mounds of disarticulated shells) on their seaward edges are commonly found adjacent to major boating channels. These dead margins are caused, at least in part, by boat wakes and extend significantly higher above the high water line than reefs lacking dead margins (pristine reefs). To determine if these “impacted” oyster reefs alter recruitment and subsequent survival of C. virginica, three 8-wk field trials were run between May 2001 and April 2002 in Mosquito Lagoon. During each trial, data were also collected on total sediment loads, silt/clay fractions and relative water motion. Although recruitment did not differ between impacted and pristine reefs, juvenile survival was significantly reduced on impacted reefs. Additionally, larval recruitment and subsequent mortality were...

Nematode assemblages were studied from four sublittoral sites at 50–56 m depth in the Gulf of Maine, north-eastern coast of the USA, within the context of an open ocean aquaculture experimental site. All four sites, two potential impact and two control sites, had a similar muddy–sand bottom and low organic content. Seventy genera in 27 families were recorded from a total of 1072 individuals. All but one taxa could be related to known genera. Family Comesomatidae was the most dominant with close to a third (27·6%) of the total individuals. At the genus level Sabatieria and Setosabatieria were most dominant with a quarter of the total number of individuals. Composition of dominant families from the Gulf of Maine differed from all hitherto reported sublittoral or deep-sea communities from both sides of the Atlantic, and most similar with European estuaries.Nematode diversity at the genus-level was reasonably high and was comparable with Mediterranean samples. Most diversity indices ordered the four sites similarly with Site 2 as the most diverse followed by Site 5 and then Site 6. By contrast the relative diversity of Site 4 depended on the index employed and its k-dominance curve crossed that of the others. Furthermore based on clustering the community at Site 4 was least similar to the others. Although these observations could be related to the fact that Site 4 is within the expected impact zone of the fish cage, the low number of fish introduced by the time of sampling and the lack of any difference in the maturity index among all the sites argue that these results can be considered before-impact data for further monitoring of the open ocean aquaculture experiment.A new paradigm where morphological information is documented and communicated using digital multifocal images is introduced. Each video image is comparable with visualization of a specimen under a microscope where the movie can be played back and forth to mimic focusing through a specimen. Web-based and openly accessible digital multifocal images were used to document and effectively communicate the morphology of all the identified genera in this study. This approach for documenting and communicating survey results is proposed as a benchmark for future similar studies that would enhance standardization and quality control of meiofaunal taxonomy, ecology and biodiversity studies.

Christopher B. Barrett Raymond E. GrizzleDepartment of Economics Randall Environmental Studies CenterUtah State University Taylor UniversityLogan, UT 84322-3530 Upland, IN 46989-1001cbarrett@b202.usu.edu rygrizzle@tayloru.eduAbstract: This paper advances a holistic ecological approach based on a three-compartmentmodel. This approach favors policy initiatives that lie at the intersection of thethree major areas of concern common to most environmental controversies:environmental protection, provision of basic human needs, and advancingeconomic welfare. In support of this approach, we propose a "pluralisticstewardship” integrating core elements of anthropocentrism, biocentrism, andecocentrism. After presenting the basics of our model, we then explain why it isimportant to identify and promote a holistic ecological approach to sustainability. Here we employ the economic concept of path dependence, emphasizing that thereexist multiple paths society can follow in environmental ethics and policy but onceone has been chosen, implicitly or explicitly, there may be little opportunity toreverse such choices.

Using a conceptual model consisting of three intersecting spheres of concern (environmental protection, human needs provision, and economic welfare) central to most environmental issues, we map six major Christian traditions of thought. Our purpose is to highlight the complementarities among these diverse responses in order to inform a more holistic Christian environmentalism founded on one or more of the major tenets of each of the six core traditions. Our approach also incorporates major premises of at least the more moderate versions of biocentrism, ecocentrism, and anthropocentrism. We label this holistic approach “cosmocentrism” and use it as the basis for a preliminary description of the notion of “pluralistic stewardship.” We argue that only such holistic environmental perspectives, where societal needs are more directly coupled with environmental protection, and a pluralism of worldviews are acknowledged as potentially contributing to such efforts are capable of successfully addressing the complex issues we face today. We note that, at the international level in particular, Christian thought and secular environmentalism already have been moving in such a direction.

Underwater observations of eelgrass (Zostera marina L.) beds at the mouth of the Jordan River, Maine, USA, indicated that the eelgrass blades gently undulated with low-amplitude movements under low current speeds. When the above-canopy speeds exceeded 10 cm s−1, dramatic large-amplitude waving of many blades in synchrony occurred. The eelgrass waving caused wide variability in horizontal water current speeds measured above the canopy. During three summers (1986, 1989, 1990), the blade tips (distal 30 cm) had an average of about 3 × more recently settled (plantigrade) blue mussels (Mytilus edulis) compared to regions lower (30–90 cm) on the blade. Because waving of seagrass blades results in the blade tips moving through much more of the water column than lower regions of the blade and in enhanced turbulent mixing above the plant canopy, we hypothesize that such movements increase the likelihood of blade encounter with mussel larvae, and explain enhanced mussel abundances on blade tips. We further hypothesize that the enhanced mixing may direct larvae into seagrass beds generally. Large-amplitude, synchronous waving of terrestrial grasses has been termed ‘honami,’ (Japanese: ho = cereal; nami = wave) and has been shown to dramatically alter aerodynamical conditions within and above the grass canopy. We suggest that ‘monami’ (mo = aquatic plant) is important in coastal hydrodynamics and has major implications for larval settlement and recruitment.

Historic baselines are important in developing our understanding of ecosystems in the face of rapid global change. While a number of studies have sought to determine changes in extent of exploited habitats over historic timescales, few have quantified such changes prior to late twentieth century baselines. Here, we present, to our knowledge, the first ever large-scale quantitative assessment of the extent and biomass of marine habitat-forming species over a 100-year time frame. We examined records of wild native oyster abundance in the United States from a historic, yet already exploited, baseline between 1878 and 1935 (predominantly 1885–1915), and a current baseline between 1968 and 2010 (predominantly 2000–2010). We quantified the extent of oyster grounds in 39 estuaries historically and 51 estuaries from recent times. Data from 24 estuaries allowed comparison of historic to present extent and biomass. We found evidence for a 64 per cent decline in the spatial extent of oyster habitat and an 88 per cent decline in oyster biomass over time. The difference between these two numbers illustrates that current areal extent measures may be masking significant loss of habitat through degradation.

Experiments were conducted in a multiple-flume apparatus to determine the effects of water flow (current speed) on individual growth of the infaunal siphonate Mercenaria mercenaria (hard clam) and the epibenthic nonsiphonate Crassostrea virginica (eastern oyster). During summer 1990 there were no significant differences in shell growth rate or final soft tissue weights of either species over a 24-day period for mean flow treatment levels of ≈2, 4 and 8 cm s −1 mid-depth (≈ffree-stream) speeds. The overall trends were a positive relation between growth and flow speed for clams, and a negative relation for oysters. A 28-day experiment in summer 1991 tested for the effects of four flow speed levels: 0, 1, 2 and 4 cm s −1 . There were substantial and marginally significant differences in shell growth rates for oysters (ANOVA, P = 0.042) and clams (ANOVA, P = 0.063). Growth response patterns were different for the two taxa, with clams showing a consistent positive relation between flow speed and growth (maximal growth at 2 to 4 cm s −1 ), and oysters showing maximal growth (average three-fold increase over other flow speeds) at 1 cm s −1 with decreased growth at 0 cm s −1 and > 1 cm s −1 . We hypothesize that the differences in growth response patterns may be explained by differences in inhalant pumping speeds, with maximal individual growth expected for suspension-feeding bivalves at ambient flow speeds that approximate the inhalant pumping speed. Because siphonate taxa typically have greater inhalant pumping speeds, we predict that ambient flow speeds optimal for individual growth will generally be several cm s −1 greater than those for nonsiphonate taxa.

Sediment profile imaging (SPI) is a technique that involves collecting data In the field on sedimentary conditions, particularly vertical variations at and below the sed imen tha te r interface SPI approaches were developed nearly 20 yr ago, but have not been widely used in routine pollution monitoring efforts, although their potential for saving time and money is great. The present report is a comparison of SPI and 'traditional' (which involves excising a sediment sample, removing the organisms, and identifying and further processing them in the laboratory) benthic sampling techniques used along an organic enrichment gradient in a temperate coastal lagoon. Twenty-four core samples were taken in summer 1985 along an enrichment gradient mainly resulting from the discharge of sewage effluents, and processed by traditional rnacrofaunal benthic methods. Coincidental with these cores, sediment samples were taken for various physicochemical analyses, and optically clear acrylic box core samples were taken and analyzed in the field for changes in redox potential, dominant benthic taxa and their relative abundances, and sedimentary features. Various univariate and multivariate analyses of the benthic and sedimentary data showed substantial, and expected, changes along the pollution gradient. The changes were similar to those reported from other coastal waters affected by organic wastes: an area nearest the pollution source with lowest taxa numbers (S), abundances (A) and biomass (B); and increased S, A and B with increasing distance from the pollution source. Small near-surface polychaetes (capitellids and Streblospio benedicti) and the amphipod Ampelisca sp , were numerical dominants at all sites, and large, deep-burrowing species (e.g. Asychis elongata) were only found at the least-enriched sites SPI allowed identification of the dominant benthic taxa to useful levels ( e g . 'small near-surface dwelling annelids', 'large deep-burrowing polychaetes'), and location of the apparent color redox potential discontinuity (RPD) layer depth. The RPD ranged from about 1 cm at the site nearest the pollution source to 2 4 cm at the 2 sites farthest away. The SPI data were a s useful a s the traditional data in delimiting the spatial extent of the pollution-impacted benthos. It is suggested that a variety of coring devices presently exist for quickly and efficiently obtaining SPI data, especially in shallow waters.

An individual-based model was developed to simulate growth of the hard clam, Mercenaria mercenaria, in response to temperature, salinity and food supply conditions. Unique characteristics of the model are that: (1) length and tissue weight are related only by condition index, so that weight, up to a point, can vary independently of length, and (2) age is decoupled from length. Tissue weight changes result from the difference in assimilation and respiration. Changes in hard clam condition are determined from a standard length-weight relationship for average hard clam growth. Changes in hard clam length (growth) occur only when condition index is greater than zero, which happens when excess weight for a given length is attained. No change in length occurs if condition index is zero (mean case) or negative (less weight than expected at a given length). This model structure resolves limitations that accompany models used to simulate the growth and development of shellfish populations. The length-frequency distribution for a cohort was developed from the individual-based model through simulation of a suite of genotypes with varying physiological capabilities. Hard clam populations were then formed by the yearly concatenation of cohorts with partially independent trajectories that are produced by cohort- and population-based processes. Development and verification of the hard clam model was done using long-term data sets from Great South Bay, New York that have been collected by the Town of Islip, New York. The ability to separately track length and age in the simulations allowed derivation of a general mathematical relationship for describing age-length relationships in hard clam populations. The mathematical relationship, which is based on a twisted bivariate Gaussian distribution, reproduces the features of age-length distributions observed for hard clam populations. The parameters obtained from fitting the twisted bivariate Gaussian to simulated hard clam length-frequency distributions obtained for varying conditions yield insight into the growth and mortality processes and population-dependent processes, compensatory and otherwise, that structured the population. This in turn provides a basis for development of theoretical models of population age-length compositions. The twisted bivariate Gaussian also offers the possibility of rapidly and inexpensively developing age-length keys, used to convert length-based data to age-based data, by permitting a relatively few known age-length pairs to be expanded into the full age- and length-frequency structure of the population.

Publisher Summary This chapter discusses the physiological ecology of Mercenaria mercenaria with emphasis on feeding, nutrition, growth, and production. It also includes a review of whole-organism behavior relevant to feeding. A consideration of energy flow through the organism provides the organizing framework. The major terms that deal with energetic are also introduced in the chapter. The various anatomical structures and associated physiological processes are considered in the chapter. The aspects of energy acquisition, which include feeding and various post-ingestion processes, are also reviewed. Energy expenditures such as biodeposition, excretion, and other metabolic “costs” such as respiration are described in the chapter. The vast majority of the research on hard clams is concerned with growth and factors that influence it. The extrinsic (environmental) factors affecting growth are also emphasized. The feeding responses largely explain the patterns of individual growth responses. The chapter also reviews the whole-organism behavior and provides a fluid mechanical perspective on the feeding environment experienced by clams in nature. Feeding occurs close to the bottom, well within the benthic boundary layer, because of the hard clam's infaunal life habit and the relatively short length of its siphons.

This chapter describes recommended techniques for collecting quantitative samples of infauna and small epifauna for the determination of abundance and biomass. The fauna of seagrass beds can be classified based on where they live. Infauna lives within the bottom sediments and epifauna lives above the bottom, among the plant leaves and stems. The major kinds of quantitative sampling devices for infauna are grabs, corers, dredges, and suction samplers. Each includes a wide variety of different models and variations on the basic design. Several environmental characteristics typical of seagrass habitats contribute to the superiority of corers and suction samplers for quantitative sampling of the infauna. Although some species of seagrasses occur at water depths of 60 m or more, most species are restricted to much shallower depths. Hence, most seagrasses can be sampled with hand-held devices, such as corers or suction samplers while wading at low tide, or from a boat, or by divers. In contrast, many grabs and dredges are heavy, cumbersome devices that require a boat and winch for deployment. Ease of operation probably has been a major factor in the choice of corers over other methods. The combination of the environmental characteristics of seagrass beds (shallow waters, adequate visibility, and accessibility) and the structural and functional properties of a small beam net make it the most convenient sampler for small epifauna.

This paper advances a holistic ecological approach based on a three-compartment model. This approach favors policy initiatives that lie at the intersection of the three major areas of concern common to most environmental controversies: environmental protection, provision of basic human needs, and advancing economic welfare. In support of this approach, we propose a "pluralistic stewardship" integrating core elements of anthropocentrism, biocentrism, and ecocentrism. After presenting the basics of our model, we then explain why it is important to identify and promote a holistic ecological approach to sustainability. Here we employ the economic concept of path dependence, emphasizing that there exist multiple paths society can follow in environmental ethics and policy but once one has been chosen, implicitly or explicitly, there may be little opportunity to reverse such choices.

Several field experiments have shown that bottom sediment type affects growth of the hard clam, Mercenaria mercenaria. A previous manipulative field experiment carried out within a moderate range of tidal current speed/seston concentration regimes in Great Sound, a coastal lagoon in southern New Jersey, USA, indicated that growth of M. mercenaria was more influenced by horizontal seston fluxes than sediment type. The present descriptive/correlative study was also conducted at Great Sound, during 1985 and 1986, and was designed to quantify the relationships between shell growth of M. mercenaria and a wide range of levels of tidal currents, seston, and bottom sediments. It showed: (1) near-bottom tidal currents and seston were best correlated with growth when combined as a horizontal seston flux rate, [i.e., current speed (cm s-1) x seston concentration dry wt cm-3=dry wt seston cm-2 s-1]; (2) the correlation between seston fluxes and growth was positive to some point, then became negative with further increases in seston fluxes; (3) sediment characteristics were correlated with growth; and (4) there may be an interaction between sediment characteristics and seston fluxes as they affect growth. These findings suggested a statistical model of the general form: $$\eqalign{ & SG = B_0 + B_1 (X_1 ) + B_2 (X_1 )^2 \cr & {\rm{ }} + B_3 (X_2 ) + B_4 (X_1 )(X_2 ) + E, \cr}$$ where SG=shell growth; B o=y-intercept; B i =coefficient of the ith term; X 1=mean horizontal seston flux; X 2=sediment characteristic; E=error term. Multiple regression techniques were used to determine values for the coefficients in the model, and associated R 2 values. R 2 values for models using various shell growth measurements, seston fluxes, and bottom sediment characteristics ranged from 0.69 (P=0.35) to 0.90 (P=0.07). Maximum growth occurred at moderate seston flux rates (e.g. 90 to 130 mg particulate organic matter cm-2 s-1) combined with sand sediments. Increased or decreased (relative to moderate rates) seston fluxes, and/or decreased grain size of the bottom sediments, resulted in reduced growth.

Southern New Jersey is a barrier island coast, characterized by a tide-dominated hydrographic regime. Great Sound, a shallow, open lagoon which is fed by tidal channels within the back-barrier salt marsh complex, is a sediment sink, apparently for detritus imported from the inner continental shelf through two tidal inlets. Study of the system tidal hydrodynamics and sediment accumulation patterns provides the basis for a numerical sedimentation model. This model predicts rapid accumulation of coarse-grained (> 20 μm) sediment near the Intracoastal Waterway which cuts through Great Sound, and dominance of storm-related sedimentation events. Observations generally confirm the model predictions. Sands are deposited rapidly on flood tidal deltas associated with the two major channels, Great Channel and Ingram Thorofare, and along the Intracoastal Waterway. Finer detritus is transported predominantly as organic-mineral aggregates, and accumulates slowly (< 2.7 mm/yr) in the southwestern and eastern parts of the sound. Resuspension of bottom sediments is common in the shallow (0.6 m) sound due to wave action and flood tidal currents on the deltas (U0.4 d max ≲ 42 cm/s). Low tidal flow velocities (U0.4 d max < 18 cm/s) over much of Great Sound and the presence of macroalgae in some locations, however, promote net accumulation. Although sediment deposition and accumulation data are variable, the range of accumulation rates suggests that recent accretion in Great Sound is approximately equivalent to the local sea-level rise of 4 mm/yr.

Great Sound is a 6 km 2 shallow (average depth = 0.6 m) lagoon fringed by salt marsh and connected directly to the ocean by two large (5 and 10 km long) flood-dominated tidal channels which enter at opposite ends. The lagoon can be divided into three subenvironments: flood tidal delta and channel, transition area, and basin. Tidal deltas containing several distributary channels are deposited from expanding jet flow as tidal currents enter the lagoon. A physical process study (velocity profiles, salinity, temperature, suspended load and box cores) indicated that sedimentation patterns are determined by: (1) proximity to the point sources of sediment, the tidal channels, (2) spatial changes in tidal current strength and abundance of benthic organisms (primarily sand-trapping macroalgae), (3) dispersion of particulates by tidal and wave-generated currents, and (4) postdepositional processes including bioturbation and resuspension by waves. Tidal currents ranged from U max > 40 cm/s ( U ∗ max = 4.0 cm/s ) in the tidal delta channels, to U max U ∗ max = 2.6 cm/s ) in transition areas to U max U ∗ max cm/s ) in the basins. U max , U ∗ max = maximum current velocity and maximum shear velocity respectively. Typical suspended sediment loads were 10–50 mg/l near the bottom; however, sediment transport was enhanced by wind-generated waves (up to 0.5 m wave height) which eroded the bottom creating concentration spikes of greater than 300 mg/l. Bottom sediments ranged from well-sorted fine sand in most delta and channel areas to basins composed of 90% silt and clay. Factors affecting sediment supply, transportation, deposition and resuspension interact in complex ways so that wide variability in the textural characteristics of deposited sediment occurs and no single factor (e.g., velocity) is well correlated with sediment characteristics. A conceptual model illustrating these spatial relations between hydrodynamics, benthos and sedimentation in the Great Sound system, was developed. The model should be useful in other tide-dominated coastal lagoons as a guide for design of benthic and sedimentary studies.

Life history differences and effects of physicochemical changes on macrobenthos of coastal lagoons were studied for 2 yr'at one site in the sewage-polluted, moderately enriched Sykes Creek and a comparison site in the less-polluted Banana River, Florida, USA. Monthly and bi-monthly quantitative sediment samples for faunal analyses were taken from the natural substratum, and recolonization of defaunated sediments set out at 4 different times in 1 yr was monitored concurrently. The top 4 numerical dominants in natural substratum samples from Sykes Creek, i.e. the indicator species, were: Corophium ellisi, Haploscoloplos foliosus, Capitella capitata, Anomalocardia auberiana. Based on recolonization experiments all 4 were identified as opportunistic. However, the top 2 numerical dominants in the Creek (C. ellisi, H. foliosus) also relied on their abilities to exploit food and/or space. Banana River benthos contained a greater relative abundance of equilibrium species and fewer opportunistic species compared to Sykes Creek, suggesting that there has been a shift toward a life history strategy of opportunism in the enriched area. With a lag shift of 2 mo, dissolved oxygen and temperature from the Creek were strongly correlated with macrobenthic density. Also, drastic declines involving most species present were observed in early summer in 1978 and 1979 coinciding (no 2-mo lag) with oxygen/temperature extremes of < 2.5 mg 1'129 OC. These data suggest that the pollution indicator species were as intolerant of oxygen/temperature extremes as non-indicator species. Thus, the numerical dominance of the indicator species in shallow water and sand sediments in Sykes Creek can likely be explained by some combination of superior abilities related to quick invasion and exploitation of food and/or space, competitive interactions could be important. Further concurrent testing of hypotheses is needed. Investigation of the indicator concept was posed as one of the best ways to determine the effects of organic pollution on benthos.

Tidal currents, seston, and sediments separately influence growth of the hard clam, Mercenaria mercenaria, but it is uncertain how these factors may interact. A 3×3 factorial field experiment, carried out in Great Sound, a coastal lagoon in Southern New Jersey, USA, between May and September 1986, determined the relative effects of three sediment types and three site-specific seston/tidal current regimes on the individual growth of M. mercenaria. Analysis of variance of the change in shell length after 15 wk (differences in initial and final lengths) demonstrated a significant difference (P=0.0064) in growth among sites, but no significant differences (P=0.1331) for growth in different sediments, although trends were evident. Effects of sites were independent of sediment type (P=0.2621). Shell growth rates differed by 10.7% between the slowest and fastest sites, but only differed by 5.7% between sediment types, with fastest growth in sand and slowest in mud. Tidal current speeds and four measures of seston (chlorophyll a, particulate inorganic and organic matter, PIM and POM, and energy content) were measured >20 times in near-bottom waters at each site. Horizontal fluxes of POM exhibited higher correlation coefficients with growth rates, than did seston concentrations or current speeds alone. We attribute significant “site” differences to differences in horizontal seston fluxes fluxes among sites. We suggest that horizontal seston fluxes may be a major factor affecting individual growth of suspension-feeding bivalves.

Callinectes bocourti, a large, swimming crab of some commercial importance, is found predominantly throughout the West Indies and down to Brazil. Holt huis (1959) noted that the species was the most abundant portunid found in Surinam, probably because it was able to tolerate lower salinities than other swimming crabs in the region. Provenzano (1961) recorded the species for the first time in the continental United States based on a mature male specimen deposited in the University of Miami Marine Laboratory Museum; the specimen was collected at Matheson Hammock, Biscayne Bay, Florida. Recently, Perry (1973) reported a second specimen, from Biloxi Bay, Mississippi, thus extending the known range of the species to the northern Gulf of Mexico. We report here yet a third specimen, a mature male, which was collected in the Indian River, Indian River County, Vero Beach, Florida, during the summer of 1973 by Mr. Gerald Herting then with the Florida State Department of Natural Resources. The Indian River record is approximately 150 miles (250 km) north on the central eastern coast of Florida from the specimen-locality reported by Proven zano, though not as far north latitudinally as Perry's record. Our specimen, as Provenzano's and Perry's material, also agrees well with the description provided by Rathbun (1930: 128) although we noted several apparently minor differ ences. In her diagnosis, Rathbun noted the lateral spine as less than twice as long as the preceding tooth. In our specimen, the posterolateral spine was 10.9 mm long, whereas the penultimate lateral tooth was 5.0 mm long. Strict adherence to Rathbun's key would place the species as Callinectes toxotes Ordway, 1863, an eastern Pacific species and the possible analog of C. bocourti. However, all other features, including intramedial ratios, frontal teeth, and male gonopods were in agreement with that indicated by Rathbun in her description for C. bocourti. Neither Provenzano nor Perry gave color notes for their respective specimens. The coloration in our specimen, only recently preserved, was noteworthy. Holt huis (1959: 203) stated that the color pattern for this species was remarkable, the palm of the chela being dark reddish brown above and whitish below, the