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The eastern oyster (Crassostrea virginica), has experienced dramatic declines throughout its range, and most U.S. states along the Atlantic and Gulf of Mexico coasts have restoration programs. Oyster restoration in the Hudson River Estuary has been a focus of management agencies for over two decades. The present project was initiated in 2013 after sampling for replacement of the Tappan Zee bridge determined live oysters would be lost during bridge construction, thus requiring mitigation measures. Preliminary studies identified three areas for pilot studies to inform the design of full‐scale efforts. A pilot study involving deployment of oyster shell‐filled gabions and two styles of Reef Balls, found all substrates supported oyster recruitment and growth but there were higher oyster densities on gabions. Some of the gabions, however, failed structurally necessitating a need for new design. For full‐scale restoration, a total of 422 modified gabions and 881 Mini‐Bay style Reef Balls were deployed across three sites which totaled approximately 2.4 ha (6 ac) in seafloor area. Both substrate types were heavily colonized by oysters and several other species at all three sites, essentially duplicating the findings of the pilot study. The final monitoring event in 2020 indicated a total of approximately 5.8 million live oysters were on the substrates deployed in 2018. This mitigation effort was the largest oyster habitat restoration project in, or north of, the New York Harbor region in recent decades based on restoration area and several oyster metrics of early success. [ABSTRACT FROM AUTHOR]

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 [m.sup.2] 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/[m.sup.2] ([+ or -]7.39; 1 SE) and 99.3/[m.sup.2] ([+ or -]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.KEY WORDS: aerial imagery, coastal habitat, estuaries, mapping, shellfish management, Crassostrea virginica, oyster, INTRODUCTIONIn their global assessment which estimated declines in oyster habitat at 85%, Beck et al. (2011) noted the need for more mapping efforts to facilitate management, and lamented the fact [...]

When harvested, oysters represent a removal from the ecosystem of nutrients such as nitrogen (N) and carbon (C). A number of factors potentially affect nutrient content, but a quantitative understanding across the geographical range of the eastern oysters is lacking. This study was designed to quantify the relationships among various metrics of farmed eastern oysters near its northern geographical range focusing on nutrient content. Hatchery-reared oysters were deployed in polyethylene bags at six sites, and were measured on multiple occasions from 2010 to 2012. A quadratic polynomial fit to the combined datasets for shell height indicated that on average a 'cocktail' size oyster (63 mm shell height) would be reached after 2 year, and 'regular' size (76 mm) would require 3 year. There were significant differences in growth rates and oyster nutrient content among the sites; means for %N in soft tissue ranged from 6.9 to 8.6, and 0.07 to 0.18 in shell. Per cent N in soft tissue and shell were highest at two sites at the mouths of rivers with elevated dissolved inorganic N concentrations in the water. Grand means (all sites, seasons and years combined) of soft tissue N and C for regular size oysters were 7.3% and 38.5%, respectively; and for shell N and C were 0.13% and 12.0% respectively. Our study extends the range of data on nutrient content of the eastern oyster to northern New England, and indicates that oyster size, seasonality, and nutrient concentration in ambient water potentially affect %N and %C content of oysters. [ABSTRACT FROM AUTHOR]