Potential range of the zebra mussel, Dreissena polymorpha, in and near Virginia

This publication is devoted to predictions of the probability of invasion by the zebra mussel, Dreissena polymorpha (and the quagga mussel, Dreissena sp.) to specific bodies of water in Virginia. Probability of invasion is divided into risk and susceptibility. Risk refers to the chance, relative to other sites, that a body of water will be inoculated with Dreissena, in sufficient number to establish a population. Inoculation can occur by natural dispersal, but in the mid-Atlantic region is most likely to-occur though accidental introduction by humans, especially via boat traffic. Susceptibility of a body of water refers to the probability, based on known physiological requirements, that Dreissena could survive and reproduce. In this publication predictions are made, concerning both risk and susceptibility, for several bodies of water in Virginia

Habitat Requirements for the Softshell Clam, Mya arenaria in the Chesapeake Bay

Large populations of softshell clams persist only in relatively shallow, sandy. mesohaline portions of Chesapeake Bay. These areas are mostly in Maryland, but can also occur in the Rappahannock River. Virginia. In some other portions of the bay, especially polyhaline portions. sparse populations of soft shell clams persist subtidally. Restricted populations exist intertidally. Softshell clams grow rapidly in Chesapeake Bay, reaching commercial size in two years or less. They reproduce twice per year, in spring and fall, but probably only fall spawnings are important in maintaining population levels. Major recruitment events do not occur in most years. despite heavy annual sets. Softshell clams are a major food item for many predator species. Major predators on juveniles include blue crabs. mud crabs, flatworms. mummichogs. and soot. Major predators on adults include blue crabs, eels. and cownose rays. Some other species that may depend heavily on softshell clams include overwintering and migrating ducks. geese, and swans. and estuarine populations of muskrats and raccoons. Diseases may play an important role in regulating populations of adult softshell clams, and hydrocarbon pollution is linked to increased frequency of disease. Oil pollution does the most widespread and persistent damage to softshell clams. and may also induce disease. Heavy metals. pesticides, and other contaminants can be extremely toxic, but the harmful effects to clams do not last when the contamination abates . The main concern with these toxin compounds is the chance of bioaccumulation by softshell clams, thereby passing the compounds on to predators or to humans. Siltation caused by storm events. dredging operations. or erosion, can smother clam populations. Eutrophication, enhanced by nutrient inputs from sewage or agriculture. is not yet known to have affected softshell clam populations. but the danger exists

Response Of Settling Oyster Larvae, Crassostrea Virginica, To Specific Portions Of The Visible Light Spectrum

Settlement site choice was used to rest the ability of competent-to-settle oyster (Crassostrea virginica) larvae to detect specific portions of the visible light spectrum. Larvae were permitted to settle on illuminated or shaded sides of vertically oriented settlement substrates. Five light treatments were used, including white light (400-700 nm), three fractions of white light; red light (600-700 nm), green light (450-575 nm, peak at 525 nm), blue light (400-500 nm, peal; at 425 nm); and total darkness. In total darkness, no settlement preference for either side of the substrates was detected. In all light treatments, larvae settled in significantly higher numbers onto shaded surfaces than illuminated surfaces. Crassostrea virginica larvae respond to most portions of the visible light spectrum, unlike many previously studied marine invertebrate larvae. This ability may reflect the diverse light conditions in the largely estuarine habitat of this species

Soft Shell Clam Mya arenaria

Large populations of soft shell clams persist only in relatively shallow, sandy, mesohaline portions of the Chesapeake Bay. These areas are mostly in Maryland, but also occur in the Rappahannock River, Virginia. In some other portions of the Bay, especially polyhaline portions, low populations of soft shell clams persist subtidally. Restricted populations persist intertidally. Soft shell clams grow rapidly in the Chesapeake Bay, reaching commercial size in two years or less. They reproduce twice per year, in spring and fall, but probably only fall spawnings are important in maintaining population levels. Major recruitment events do not occur in most years, despite heavy annual sets. Soft shell clams are important food for many predators. Major predators on juveniles include blue crabs, mud crabs, flatworms, mummichogs, and spot. Major predators on adults include blue crabs, eels, and cownose rays. Some other species that may depend heavily on soft shell clams include ducks, geese, swans, muskrats, and raccoons. Diseases may play an important role in regulating adult populations of soft shell clams; hydrocarbon pollution is linked to increased frequency of disease. Oil pollution does the most widespread and persistent damage to soft shell clams through toxicity, aside from its role in inducing disease. Heavy metals, pesticides, and similar pollutants can be extremely toxic, but the harmful effects to clams do not last if the pollution abates. The main concern with the latter toxicants is bioaccumulation by soft shell clams, with the potential for passing toxic contaminants on to predators or to humans. Siltation caused by storm events, dredging operations, or erosion, can smother clam populations. Eutrophication, enhanced by nutrient inputs from sewage or agriculture, is not known to have affected soft shell clam populations.https://scholarworks.wm.edu/vimsbooks/1019/thumbnail.jp

The Decline Of The Virginia Oyster Fishery In Chesapeake Bay Considerations For Introduction Of A Non-Endemic Species, Crassostrea gigas (Thunberg, 1793)

The Chesapeake Bay oyster fishery for Crassostrea virginica (Gmelin) is in a state of continuing decline. Two diseases, Haplosporidium nelsoni and Perkinsus marinus have effectively eliminated oysters from many sections of the Bay. Despite over 30 years of disease activity the native oysters have developed neither tolerance nor absolute resistance to these diseases, and do not exhibit any recovery in disease endemic areas in Virginia. Repletion programs have completely failed to recover to permanent production areas lost to disease. Present fishery management activities are limited to a controlled retreat away from the disease in an arena where disease distribution is salinity and temperature (and hence climate) related and, therefore, beyond human influence. Disease resistance is the pivotal issue. This commentary builds on the reality that without resistance to both diseases no recovery to sustained, stable production on all formerly productive oyster bottom is possible. It is improbable that such resistance can be developed in Crassostrea virginica. A consideration is made of the case for introduction of a non-endemic species, Crassostrea gigas (Thunberg) to assist in attaining this goal

Correlation of a-Amylase Inhibitor Content in Eastern Soft Wheats with Development Parameters of the Rice Weevil (Coleoptera: Curculionidae)

The a-amylase inhibitor content in saline extracts of 104 Eastern soft wheat cultivars was determined by assay against a purified a-amylase preparation from the rice weevil, Sitophilus oryzae (L.). A two-fold range of inhibitor levels, expressed as amylase inhibitor units per gram of dry weight (AID/g), was found across all cultivars. Inhibitory activity was lowest in cultivar \u27Augusta\u27 (5,084 ± 124 AIU/g) and highest in cultivar \u27Logan\u27 (10,410 ± 61 AID/g). No correlation of inhibitor content with progeny production (r = -0.161) or rate of emergence (r = -0.292) was found among weevils reared on 30 cultivars having relatively low, medium, and high inhibitor levels, but there was a positive correlation between inhibitor content and average number of days to adult emergence (r = 0.569). Although mean development times were significantly different on cultivars with low and high AIU/g (35.9 ± 0.2 and 36.6 ± 0.1 d, respectively), the differences were only slight and indicated that, for these cultivars of soft wheats, a-amylase inhibitors have little practical effect on initial population reductions. Nevertheless, based on a population model for S. oryzae developing on wheat at 25°C and 75% RH, the slight delay in mean development time (0.7 d) on cultivars with relatively high AIU/g results in a 20.9% reduction in total number of weevils after 180 d. Simulations also indicate that physical or biochemical resistance factors in wheat have to delay development time for about 6.2 d or reduce fecundity by about 40% to prevent wheat from being graded weevily 180 d after a single pair of weevils infests a hypothetical 6,000-bushel wheat bin

Formation of Uniaxial Molecular Films by Liquid-Crystal Imprinting in a Magnetic Field

Scanning tunneling microscopy was used to study molecular order in monolayer organic films formed by solution-phase growth from thermotropic liquid crystal solvents. The films develop macroscopically uniaxial alignment, with adlayer orientation controlled by an external magnetic field through interactions mediated by the liquid crystal. Results are presented for two films deposited from nematic and smectic- A solvents, along with a discussion of the alignment mechanism

Treatment Intensification in Patients With Kawasaki Disease and Coronary Aneurysm at Diagnosis.

BackgroundCoronary artery aneurysms (CAA) are a serious complication of Kawasaki disease. Treatment with intravenous immunoglobulin (IVIg) within 10 days of fever onset reduces the risk of CAA from 25% to <5%. Corticosteroids and infliximab are often used in high-risk patients or those with CAA at diagnosis, but there are no data on their longer-term impact on CAA.MethodsRetrospective multicenter study including children who had CAA with a z score ≥2.5 and <10 at time of diagnosis and who received primary therapy with IVIg alone or in combination with either corticosteroids or infliximab within 10 days of onset of fever.ResultsOf 121 children, with a median age of 2.8 (range 0.1-15.5) years, 30 (25%) received primary therapy with corticosteroids and IVIg, 58 (48%) received primary therapy with infliximab and IVIg, and 33 (27%) received primary therapy with IVIg only. Median coronary z scores at the time of diagnosis did not differ among treatment groups (P = .39). Primary treatment intensification with either corticosteroids or infliximab were independent protective factors against progression of coronary size on follow-up (coefficient: -1.31 [95% confidence interval: -2.33 to -0.29]; coefficient: -1.07 [95% confidence interval: -1.95 to -0.19], respectively).ConclusionsAmong a high-risk group of patients with Kawasaki disease with CAA on baseline echocardiography, those treated with corticosteroids or infliximab in addition to IVIg had less progression in CAA size compared with those treated with IVIg alone. Prospective randomized trials are needed to determine the best adjunctive treatment of patients who present with CAA

Jack superpolynomials with negative fractional parameter: clustering properties and super-Virasoro ideals

The Jack polynomials P_\lambda^{(\alpha)} at \alpha=-(k+1)/(r-1) indexed by certain (k,r,N)-admissible partitions are known to span an ideal I^{(k,r)}_N of the space of symmetric functions in N variables. The ideal I^{(k,r)}_N is invariant under the action of certain differential operators which include half the Virasoro algebra. Moreover, the Jack polynomials in I^{(k,r)}_N admit clusters of size at most k: they vanish when k+1 of their variables are identified, and they do not vanish when only k of them are identified. We generalize most of these properties to superspace using orthogonal eigenfunctions of the supersymmetric extension of the trigonometric Calogero-Moser-Sutherland model known as Jack superpolynomials. In particular, we show that the Jack superpolynomials P_{\Lambda}^{(\alpha)} at \alpha=-(k+1)/(r-1) indexed by certain (k,r,N)-admissible superpartitions span an ideal {\mathcal I}^{(k,r)}_N of the space of symmetric polynomials in N commuting variables and N anticommuting variables. We prove that the ideal {\mathcal I}^{(k,r)}_N is stable with respect to the action of the negative-half of the super-Virasoro algebra. In addition, we show that the Jack superpolynomials in {\mathcal I}^{(k,r)}_N vanish when k+1 of their commuting variables are equal, and conjecture that they do not vanish when only k of them are identified. This allows us to conclude that the standard Jack polynomials with prescribed symmetry should satisfy similar clustering properties. Finally, we conjecture that the elements of {\mathcal I}^{(k,2)}_N provide a basis for the subspace of symmetric superpolynomials in N variables that vanish when k+1 commuting variables are set equal to each other.Comment: 36 pages; the main changes in v2 are : 1) in the introduction, we present exceptions to an often made statement concerning the clustering property of the ordinary Jack polynomials for (k,r,N)-admissible partitions (see Footnote 2); 2) Conjecture 14 is substantiated with the extensive computational evidence presented in the new appendix C; 3) the various tests supporting Conjecture 16 are reporte