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

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

A Survey for Oysters and Shell in the Vicinity of the Proposed Bridge Construction at the Site of the Hampton Boulevard Bridge (Rte. 337) Over the Lafayette River in Norfolk, VA.

At the request of the Virginia Department of Transportation (VDOT), the Virginia Institute of Marine Science (VIMS) conducted a survey of certain parcels of oyster grounds in the Lafayette River in the immediate vicinity of a proposed construction site for a new bridge across the river on Hampton Blvd., east of the present bridge, in Norfolk, Va

Reproductive Activity Of Oysters, Crassostrea-Virginica (Gmelin, 1791) In The James River, Virginia, During 1987-1988

Reproductive activity in oysters, Crassostrea virginica Gmelin, in the James River, Virginia, was examined for 1987 from weekly estimates for fecundity and egg viability in oysters collected from Wreck Shoal, and for 1988 from weekly estimates of fecundity, egg viability, gonad volume fraction, gonad thickness, and mean egg size in oysters collected from Horsehead Reef. Maximum and mean fecundity values from Wreck Shoal oysters were higher than from Horsehead oysters. No relationship was evident between fecundity and egg viability at Horsehead Reef. A strong temporal relationship was observed between egg viability and peak oyster settlement in the James in both years of the study as estimated by off-bottom settlement substrates. In 1987 highest viability occurred from late June through mid August with peak settlement occurring from mid June through late August. In 1988 viable eggs were recorded from late July through the end of August; major settlement occurred from early August through mid September. Fishery independent estimates of oyster population abundance on Horsehead Reef, when combined with concurrent egg production and viability data, illustrate the losses that occur during the early life history stages of oysters in this location

Seasonal abundance of oyster spat and four animal associates on an oyster reef in the James River, Virginia

Five species of invertebrates collected at bi-weekly to monthly intervals from an oyster reef in the James River, Virginia. between September 1984 and August 1985 exhibited similar patterns of fluctuation in abundance throughout most of the period. The species were: spat of the oyster Crassostrea virginica: two species that feed on oysters. the flatworm Stylochus ellipticus, and the gastropod Boonea impressa. as well as two others with no known direct trophic interactions with the oyster. the isopod Cassidinidea lunifrons and the nudibranch Doridella obscura. B. impressa was many times more abundant than S. ellipticus but because of the difference in feeding habits between the two species it is speculated that S. ellipticus has a greater harmful effect on oysters than its abundance would suggest. Densities of all species declined sharply between early October and early November; the decline was probably related to seasonal mortality associated with declining water temperatures. B. impressa and C. lunifrons were the most abundant species throughout most of the sampling period , but only oyster spat showed a definite high peak in recruitment in 1985. Failure of the data to show reproduction peaks for three of the other species was attributed to incomplete retention of smaller individuals in the 0.5 mm-mesh screen used: large variations in density did not permit clear definition of a peak in C. lunifrons. lt is recommended that studies of oysters on their reefs include other abundant noncommercial species to provide a stronger foundation for management of the resource than if only the oyster was studied

The therapeutic relationship in child psychotherapy: integrating the perspectives of children, parents and therapists

OBJECTIVES: To describe and analyse the therapeutic relationship integrating the views of children, parents and therapists. METHODS: This study employs a qualitative methodology, assuming a discovery-oriented approach which draws from grounded theory. Twelve psychotherapy triads participated, composed of children aged 6-10, their parents and psychotherapists. Semi-structured follow-up interviews were conducted (N=36), including a drawing in the case of the children. RESULTS: A positive therapeutic relationship with children and parents was viewed as a gradually constructed process, based on a positive emotional encounter between participants. It was facilitated primarily by the therapist's commitment and playful stance, the child and therapist mutual involvement, and the parent's collaboration. These aspects entailed a trustful, validating and caring relationship, that shaped children and parents' motivations towards therapy and facilitated change. CONCLUSIONS: From a multiple-perspective approach, therapy was conceived as a relational experience. The development of positive relationships required different and evolving dispositions from therapy main actors. Therapists' genuine feelings and engagement in therapeutic activity seem central, underlining the importance of addressing relational aspects in child therapy research and training

The Rich Globular Cluster System of Abell 1689 and the Radial Dependence of the Globular Cluster Formation Efficiency

We study the rich globular cluster (GC) system in the center of the massive cluster of galaxies Abell 1689 (z=0.18), one of the most powerful gravitational lenses known. With 28 HST/ACS orbits in the F814W bandpass, we reach magnitude I_814=29 with >90% completeness and sample the brightest ~5% of the GC system. Assuming the well-known Gaussian form of the GC luminosity function (GCLF), we estimate a total population of N(GC_total) = 162,850 GCs within a projected radius of 400kpc. As many as half may comprise an intracluster component. Even with the sizable uncertainties, which mainly result from the uncertain GCLF parameters, this is by far the largest GC system studied to date. The specific frequency S_N is high, but not uncommon for central galaxies in massive clusters, rising from S_N~5 near the center to ~12 at large radii. Passive galaxy fading would increase S_N by ~20% at z=0. We construct the radial mass profiles of the GCs, stars, intracluster gas, and lensing-derived total mass, and we compare the mass fractions as a function of radius. The estimated mass in GCs, M(GC_total)=3.9x10^10 Msun, is comparable to ~80% of the total stellar mass of the Milky Way. The shape of the GC mass profile appears intermediate between those of the stellar light and total cluster mass. Despite the extreme nature of this system, the ratios of the GC mass to the baryonic and total masses, and thus the GC formation efficiency, are typical of those in other rich clusters when comparing at the same physical radii. The GC formation efficiency is not constant, but varies with radius, in a manner that appears similar for different clusters; we speculate on the reasons for this similarity in profile.Comment: 13 pages, 11 figures; accepted for publication in Ap

Necrotizing pneumonia in children: Chest computed tomography vs. lung ultrasound.

The utilization of contrast-enhanced computed tomography (CT) of the chest for the diagnosis of necrotizing pneumonia (NP), a complication of community-acquired pneumonia, is controversial because of the inherent ionizing radiation involved. Over the past few years, the growing availability of bedside Lung Ultrasound (LUS) devices has led to increased use of this nonionizing imaging method for diagnosing thoracic pathology, including pneumonia. The objectives of this study were as follows: first, to compare the performance of LUS vs. CT in the identification of certain radiological signs of NP, and second, to determine whether LUS could replace CT in the diagnosis of NP. We compared retrospectively the CT and LUS images of 41 patients between 2005 and 2018 in whom at least one contrast-injected chest CT scan and one LUS had been undertaken fewer than 7 days apart. Pleural effusions were demonstrated almost systematically (100% on CT vs. 95.8% on LUS). Visualization of septations in pleural effusions was clearly superior on LUS (20.4% on CT vs 62.5% on LUS). Concerning the detection of necrosis, we observed a strong correlation between LUS and the gold-standard CT (95.8% on LUS vs. 93.7% on CT). Parenchymal cavities were more easily detected on CT than on LUS (79.1 vs. 35.4%). LUS has shown to be as effective as CT in the diagnosis of NP. The use of CT in patients with NP could be limited to the detection of complications such as bronchopleural fistulae in unfavorably evolving diseases