Estimation Of Oyster Shell Surface-Area Using Regression Equations Derived From Aluminum Foil Molds

A method is described for estimation of surface area of shells of the American oyster, Crassostrea virginica (Gmelin 1791), as an alternative to direct measurement of surface area with aluminum foil molds. It is based on computation, from a small sample of shells, of the equation for regression of area of aluminum foil molds of shells on area enclosed within tracings of the shell outline. Area of other shells is then predicted from their shell outline area using the equation. Accuracy of the regression method in spatfall studies was established using data from shellstring collectors suspended in the Piankatank River, Virginia. For the most part, differences between foil mold area of individual shellstring shells and the area predicted from regression equations were small, and spat densities on individual shells, as computed from foil mold area and from regression-predicted area, were almost identical

A survey for oysters and shell in the vicinity of the proposed construction site for a city of Norfolk water line across the Lafayette River near the Hampton Boulevard bridge

At the request of the Department of Utilities of the City of Norfolk, the Virginia Institute of Marine Science conducted a survey of the oyster ground in the Lafayette River in the immediate vicinity of the proposed construction site for a 20 11 water line across the river just below the Hampton Blvd. bridge and in front of the Norfolk Yacht and Country Club (Figure 1). The section of river bottom surveyed was delineated by the Department of Utilities engineers on their site plans. It consisted of a strip across an oyster ground leased by Holland Fisheries. Inc. (Virginia Marine Resources Commission Plat File No. 1403), with boundaries parallel to the proposed water line, approximately 680 ft long on the SE side and 550 ft long on the NV side (Figure 2). The strip was approximately 35 ft wide on the NW side of the proposed water line and 82 ft wide on the SE side. The total area surveyed was estimated to be 1.8 acres. Overall area of the oyster ground lease is 33.80 acres

The Role of Filter-Feeding Organisms in Concentration of Suspended Solids Containing Kepone Into Bottom Deposits

Filter-feeding marine animals such as molluscs, tunicates and barnacles filter particles as small as 1 micron from suspension during their feeding process and void them as fecal pellets. These settle at much faster rates than their component particles. Feces or pseudofeces which settle are termed biodeposits. Eighty-two to 93 percent by volume of the particles in the biodeposits of several species of molluscs are smaller than 4 microns; the range in size of those particles is about 1 to 10 microns (Haven and Morales-Alamo, 1973). (...

Anatomical features in histological sections of Crassostrea virginica (Gmelin, 1791) as an aid in management of gonad area for reproductive assessment

The relationship between gonad area in transverse histological sections of the American oyster Crassostrea virginica (Gmelin 1790) and body location from which the section was cut was studied in specimens collected from four stations in the James River, Virginia in 1984 and 1986. Gonad area, expressed as percentage of total body area, increases in an antero-posterior direction; this requires use of sections from the same body location in comparisons between oysters. Approximate body locations, identified according to the anatomy and arrangement of the internal organs in the sections, were grouped into five types with similar gonad area percentages. One of those types is uniquely suitable for identification of a specific body location because it includes an easily recognizable pair of H-shaped structures corresponding to the posterior appendix of the anterior stomach caecum; furthermore, the recommended section type can be readily found on the whole oyster because it is located close to the junction of the gills and the labial palps. Gamete volume fraction (GVF) was positively correlated with percent gonad area (PGA) in most of the section types at three of the stations, suggesting that either measurement may be used to estimate the relative gonadal development in oysters. Differences between collection dates at the fourth station indicated what external factors may disrupt the correlation. It is suggested that gonad area measurements from a series of selected histological sections could be combined with gamete density measurements to estimate total gamete production by an oyster

Aspects of biodeposition by oysters and other invertebrate filter feeders

Quantities of suspended matter removed by oysters (Crassostrea virginica) and deposited as feces or pseudofeces varied seasonally, reaching maxima in September. Below 2.8C, measurable quantities were not produced. At certain seasons, levels of suspended solids influenced quantities of biodeposits. Laboratory studies indicated that the oysters on 0.405 hectare of an estuarine bottom may produce up to 981 kg of feces and pseudofeces weekly. Of the particles, 95% were under 3 µ in diameter. all types of algal cells present in the surrounding water were represented. The deposits contained 77–91% inorganic matter, mostly illite, chlorite, and mixed‐layer clays, 4–12% organic carbon, and 1.0 g/kg phosphorus. biodeposits of filter feeders such as barnacles, tunicates, and other lamelli‐branchs were similar to those of oysters. Filter feeders may influence deposition, transport, and the composition of suspended sediments in estuaries. A possible relationship between the removal from suspension and the subsequent deposition of radionuclides associated with particles of clay, silt, or planktonic algae and feces or pseudofeces is suggested

Recruitment and growth of oysters on shell planted at four monthly intervals in the lower Potomac River, Maryland

Oyster shells were planted on four successive months (May to August 1986) in contiguous plots at Jones Shore Bar in the Potomac River, Maryland, to study the effect of differences in time of cultch planting on settlement and survival of oyster spat. The plots were usually sampled at two-week intervals from time of planting through November, 1986, and once in June, 1987. A massive concentration of the tunicate Molgula manhattensis covered the bottom in all plots within four to six or eight weeks following shell planting. A commercially acceptable number of spat per shell, between 1.8 and 2.2 (approximately equivalent to 900-1200 spat per bu), was recorded at three of the plots on June 26, 1987, in spite of the heavy tunicate fouling of 1986. Recruitment of oyster spat was lower in the plot on which cultch was planted earliest, on May 13, than in the other three plots on which cultch was planted 1-3 months later. Number of spat was highest in the plot on which shells were planted on July 14; accidental planting of cultch into two elongated mounds on that plot may have contributed to the high recruitment of spat observed. Mean spat height was lowest in the plot on which cultch was planted on August 12 and highest in the plots on which shell was planted on May 13 and June 16. The lower number of spat found on shells planted on May 13 was probably associated with the early planting date. The data suggest that combined maximum recruitment and growth of oyster spat is most likely to occur at Jones Shore on cultch planted between late June and mid-July, although plantings as early as mid-June and as late as early August may also produce commercially-acceptable results

Biodeposition as a Factor in Sedimentation of Fine Suspended Solids in Estuaries

Filter feeders, such as mollusks, tunicates, and barnacles, ingest particles as small as 1 micron during their feeding process and void them in fecal pellets which range from 500 to 3,000 microns in length; these pellets settle at a much faster rate than their component particles. Feces and pseudofeces that settle to the bottom are termed biodeposits. Oyster biodeposits contain 77 to 91 percent inorganic matter, 4 to 12 percent organic carbon, and about 1.0 gram per kilogram of phosphorus. Fecal pellets are alternately deposited and resuspended by tidal currents. They settle and accumulate in areas of estuaries where the fine particles themselves would not. A portion of the biodeposits settling on sediment surfaces is mixed into subsurface deposits and may alter the textural and chemical properties of the original sediments.https://scholarworks.wm.edu/vimsbooks/1017/thumbnail.jp