Settlement Patterns Of Crassostrea virginica (Gmelin, 1791) Larvae In Relation To Tidal Zonation

Experiments were conducted to determine the settlement distribution of the oyster Crassostrea virginica (Gmelin) in relation to tidal zonation in an area where adult populations are largely confined to the intertidal zone. Hatchery-reared pediveliger larvae were interned in PVC tubes positioned at known tidal heights. The influence of non-tidal factors was limited: mesh covering the ends of the tubes prevented loss of larvae to dispersal or predation, the settling substrate was not colonized by competitors, and the effects of light and horizontal currents were minimized. Settlement was found to occur throughout the intertidal zone but predominated at the bottom of the tidal-depth gradient. Few oysters settled in the zone occupied by the adult populations, the intertidal position of which is hypothesized to be controlled by predation

Hard Clam Mercenaria mercenaria

The hard clam is found along the eastern coast of North America from the Gulf of St. Lawrence to Texas. In Chesapeake Bay, the hard clam is restricted to salinities above approximately 12 ppt. An extensive survey of hard clam resources is overdue. Statements concerning long term trends in populations are not feasible. Hard clams ·grow to a maximum shell length of about 120 mm. There are few documented cases of diseases in wild hard clam populations. Parasitic infestations are also slight. The life cycle of the hard clam includes a pelagic larval phase and a relatively sedentary benthic juvenile and adult phase. In Chesapeake Bay, ripe gametes can be found between May and October, and spawning commences when temperatures rise above 20-23 ·c. The larvae are planktotrophic (feeding). Metamorphosis usually commences at a shell length of 200-210 mm. Predation on new recruits is very high; dense aggregations of hard clams have been found in the absence of predators. Aside from predation and fishing pressure, the natural mortality of larger clams appears very low. Hard clams are important suspension-feeding infauna, thus they are important in grazing of primary production, transfer of carbon and nitrogen to benthic food chains, and, through excretion, rapid recycling of particulate nitrogen as ammonia. The major food source for hard clams is planktonic microalgae. In Chesapeake Bay, growth occurs in spring and fall, when optimum water temperatures coincide with abundant food. Clams are capable of living in a variety of sediment types, but higher abundances are found in coarse-grained sediments. Hard clam stocks are susceptible to overfishing. Recruitment rates are poorly understood, as are possible reestablishment periods if areas are depleted through commercial harvesting, and factors influencing larval settlement rates. Hard clam mariculture is well established and could easily be expanded into sites within the Bay. Given the ability of clams to bioaccumulate toxic substances, adequate monitoring should be maintained. The sub lethal effects of toxic material readily found in the lower James River should be examinedhttps://scholarworks.wm.edu/vimsbooks/1018/thumbnail.jp

Wavefronts and modal structure of long surface and internal ring waves on a parallel shear current

We study long surface and internal ring waves propagating in a stratified fluid over a parallel shear flow. The far-field modal and amplitude equations for the ring waves are presented in dimensional form. We re-derive them from the formulation for plane waves tangent to the ring wave, which opens a way to obtaining important characteristics of the ring waves (e.g. group speed) and to constructing more general `hybrid solutions' consisting of a part of a ring wave and two tangent plane waves. The modal equations constitute a new spectral problem, and are analysed for a number of examples of surface ring waves in a homogeneous fluid and internal ring waves in a stratified fluid. The detailed analysis is developed for the case of a two-layered fluid with a linear shear current where we study their wavefronts and two-dimensional modal structure. Comparisons are made between the modal functions of the surface waves in a homogeneous and two-layered fluids, as well as the interfacial waves described exactly and in the rigid-lid approximation. We also analyse the wavefronts of surface and interfacial waves for a family of power-law upper-layer currents, which can be used to model wind generated currents, river inflows and exchange flows in straits. A global and local measure of the deformation of wavefronts are introduced and evaluated.Comment: 35 pages, 21 figure

Scientific Bounty Among Meteorites Recovered from the Dominion Range, Transantarctic Mountains

The US Antarctic Meteorite Pro-gram has visited the Dominion Range in the Transantarctic Mountains during several different sea-sons, including 1985, 2003, 2008, 2010, 2014 and 2018. Total recovered meteorites from this region is close to 3000. The 1985 (11 samples), 2003 (141 samples), 2008 (521 samples), 2010 (901 samples), 2014 (562 samples) seasons have been fully classified, and 2018 (865 samples) are in the process of being classified and characterized. Given that close to 2200 samples have been classified so far, with more expected in 2020, now is a good time to summarize the state of the collection. Here we describe the significant samples documented from this area, as well as a large meteorite shower that dominates the statistics of the region

Investigating the role of calibration of hygrothermal simulations in the low carbon retrofit of solid walls

Solid masonry buildings account for around 20% of the UK building stock. As a traditional building material in the UK, stone could enhance the architectural style of buildings and last for thousands of years. However, historic buildings inevitably face the issue of diminished performance over hundreds or thousands of years. For these historic buildings whose appearance is protected, internal wall insulation (IWI) is a possible solution for protecting the façade while saving energy, improving indoor thermal comfort, and reducing carbon emissions. Of concern is that IWI could alter the drying capacity of the structure, thereby increasing moisture accumulation and causing durability issues such as freeze-thaw damage and mould growth. Hygrothermal simulations is one of the most commonly used methods to compare the performance and feasibility of different IWI assemblies. However, an inadequate assessment could lead to the specification of inappropriate IWI, prompting an incorrect choice of retrofit strategy. This study investigates the role of calibration in the assessment of moisture risks and durability of a solid masonry wall. The calibration of a hygrothermal model was performed using in-situ monitoring data; the model can be used for the comparison of IWI systems. According to the results, the selection of material properties had the highest impact in the calibration

Infectious reservoir of Plasmodium infection in Mae Hong Son Province, north-west Thailand

BACKGROUND: It was unknown whether the main reservoir of Plasmodium falciparum and Plasmodium vivax, which infects mosquitoes in Thailand, was (a) in people feeling sufficiently ill with malaria to come to a clinic or (b) in people who had remained in their home villages with some fever symptoms or with none. METHODS: Mass surveys were carried out in Thai villages to identify people with Plasmodium infections and with fever. Malaria patients were also located at a clinic which served these villages. Adults from both sources whose blood slides registered positive for Plasmodium spp. were requested to allow laboratory-bred Anopheles minimus to feed on them. Seven to nine days after the blood feeds the mosquitoes were dissected and checked for presence of oocysts. RESULTS AND DISCUSSION: There were higher rates of Plasmodium infection among people in the villages with fever than without fever and much higher rates of infection among clinic patients than among people who had remained in the villages. People with malarial infections identified via the clinic and the village surveys could infect mosquitoes, especially, but not only, if their blood slides showed visible gametocytes. Because only a very small minority of the village populations were visiting the clinic on any one day, assessment indicated that the main reservoir of infection was not primarily among clinic patients but among those in the villages, especially those feeling feverish. CONCLUSIONS: Efficient use of an anti-gametocyte drug to suppress the parasite reservoir in a population requires that it be given, not just to clinic patients, but to infected people located by mass surveys of the villages, especially those feeling feverish

Data for the Desert Citrus Industry

This item is part of the Agricultural Experiment Station archive. It was digitized from a physical copy provided by the University Libraries at the University of Arizona. For more information, please email CALS Publications at [email protected]

Patterns of Lakeshore Usage Around Lake Bemidji

ABSTRACT - The eutrophication of lakes has been the subject of much discussion in scientific journals and the popular press .. Usually the e.utrophication process is accelerated by human activities. This study evaluates the extent of lakeshore development and recreational use of Lake Bemidji in north central Minnesota and examines the willingness of lakeshore residents to be assessed for corrective measures to halt deterioration of this valuable recreational lake. The shoreline of Lake Bemidji is highly developed, and the high density human habitation represents a potential source of nutrients from percolation through the sand and gravel soils which surround the lake. Residents around Lake Bemidji believe that growth of algae and aquatic vascular plants is not now severe and that it does not affect their use of the lake for recreational purposes. Although seventy-five percent of the residents favor regulation of lakeshore use and development, only 37 percent indicate willingness to be assessed for construction of a sewer line surrounding the lake

Normative Findings for Periocular Anthropometric Measurements among Chinese Young Adults in Hong Kong

Measurement of periocular structures is of value in several clinical specialties including ophthalmology, optometry, medical and clinical genetics, oculoplastic surgery, and traumatology. Therefore we aimed to determine the periocular anthropometric norms for Chinese young adults using a noninvasive 3D stereophotography system. Craniofacial images using the 3dMDface system were acquired for 103 Chinese subjects (51 males and 52 females) between the ages of 18 and 35 years. Anthropometric landmarks were identified on these digital images according to standard definitions, and linear distances between these landmarks were calculated. It was found that ocular measurements were significantly larger in Chinese males than females for intercanthal width, biocular width, and eye fissure lengths. No gender differences were found in the eye fissure height and the canthal index which ranged between 43 and 44. Both right and left eye fissure height-length ratios were significantly larger in females. This is the first study to employ 3D stereophotogrammetry to create a database of anthropometric normative data for periocular measurements. These data would be useful for clinical interpretation of periocular pathology and serve as reference values when planning aesthetic and posttraumatic surgical interventions

De Facto New Federalism and New England: A Discussion

Using John Shannons paper as a broad frame of reference (see previous article), a panel discussion titled The Changing Nature of FederalI State Relations: The Fiscal Impact on New England took place on 18 November 1985 at the University of Massachusetts at Boston. The discussion was sponsored by the John W. McCormack Institute of Public Affairs and was presented in a roundtable forum. The members of the panel were Kenneth Curtis, former governor of Maine; Chester Atkins, member of Congress from the Massachusetts Fifth Congressional District; Richard Licht, lieutenant governor of Rhode Island; David Walker, professor of political science at the University of Connecticut and former assistant director of the Government Structure and Function Section, Advisory Commission on Intergovernmental Relations; and Roger Porter, professor of government and business at the John F. Kennedy School of Government and former special assistant to President Reagan. The following are excerpts from their remarks