Low incidence and limited effect of the oyster pathogen dermo (<Emphasis Type="Italic">Perkinsus marinus</Emphasis>) on an artificial reef in Delaware's Inland Bays

Delaware's Inland Bays comprise a large estuarine system with a restricted access to the Atlantic Ocean (Indian River Inlet). As part of a local oyster stock enhancement and restoration effort, we conducted a survey for the protozoan pathogenPerkinsus marinus (Dermo) in oysters from a newly established reef. Using standardized methods for the polymerase chain reaction (PCR) amplification of the non-transcribed spacer (NTS) region, we were surprised to find no detectable titers of this pathogen in the 30 oysters sampled in the first year of the project. The detection threshold of the PCR coupled with chemiluminescent detection was 30 fgP. marinus NTS DNA. We were able to detect a trace presence of this pathogen in a few hard clams (Mercenaria mercenaria) from the same locale, indicating that aPerkinsus sp. was present in the Inland Bay system. Subsequent monitoring of the reef system using a fluid thioglycollate assay over 3 yr revealed no epizootic outbreaks of this pathogen within the planted oyster population. Two large mortality episodes that did appear in the oyster population were attributable to abiotic conditions and not pathogen exposure. This study emphasizes that all potential sources of mortality in the environment are important to consider when designing oyster seeding projects. In the Delaware Inland Bays,P. marinus does not appear to have a large enough oyster host population to become a significant disease threat at present. Because of the low parasite incidence levels in the Inland Bay system in 2000, the James Farm oyster reef restoration project presents an ideal model system to follow the population dynamics between an oyster-host population and a latent or reservoir pathogen population.     

Fractal dimension of faults network in the upper silesian coal basin (Poland): Preliminary studies

Fractal analysis of faults network, tremor foci spatial distribution as well as the Gutenberg-Richter relationship could further explain whether the biggest seismic events are connected with recent tectonic activity. Fractality of fault systems geometry, as a first step of the analysis, was tested fro a part of the USCB embodying the main structural units. The cluster analysis and the box counting methods were employed.The calculated fractal dimension of fault network was 1.98 for the whole area yet for considered structural units it was close to 1.6. The results point to similarity of studied fault pattern to river network. Faults within selected tectonic units make separate sets which have a distinct geometry and origin. The value of 1.6 is an upper limit to the fracture geometry of rocks that can be explained on the basis of Griffith energy balance concept.     

Tracking deepwater oxygen recovery using sedimentary chironomid assemblages: Peninsula Lake revisited

Journal of Paleolimnology - Peninsula Lake, Ontario, Canada, is a Precambrian Shield lake that has experienced many environmental stressors since European settlement of the watershed in the...     

Assessing professional benefits of GIS certification

ABSTRACT

The certification of geographic information system (GIS) professionals remains a contentious topic. After more than 25 years, the GIS community remains divided over the need to formally recognize GIS professionals who maintain standards of professional competency and conduct. Unfortunately, few studies have examined individuals who have become certified or the professional benefits of certification. This study explores GIS certification through a survey of 1731 geospatial professionals who became geographic information systems professionals (GISPs) between 2003 and 2014. A web-based questionnaire asked GISPs about the certification process, its influence on their compensation and advancement, and other issues. Quantitative and qualitative findings suggest that perceptions about certification fall along a wide spectrum with GISPs employed in private industry seeing fewer benefits compared with those employed in government or not-for-profit organizations. While a large number of respondents conveyed pride in completing the certification process, others expressed frustration over the program’s lack of visibility, standards that have enabled less qualified peers to become certified, and the slow progress at which GIS certification has achieved respect compared with programs administered in other fields such as engineering and planning.     

Pāwehe Ke Kai a‘o Hā‘ena: Creating State Law based on Customary Indigenous Norms of Coastal Management

Much research has demonstrated the effectiveness of customary indigenous management at conserving natural resources. However, little is known about integrating customary management with state-level institutions. We present a model case study of collaborative rulemaking based upon customary norms for interacting with resources. We explore the efforts of one Hawai‘i community to create formal state law based on customary norms to understand: (1) What is needed to integrate customary norms into state law? (2) What factors influence this integration? (3) What lessons emerge for similar efforts in other locations? First, we find that implementing some norms of customary management requires fundamental changes to state-level institutions. Second, communities can overcome institutional constraints by identifying substitutes for those customary norms that cannot be implemented directly. And third, formal regulation must be supplemented with educational and social programs. Based on these findings, we offer suggestions to integrate customary and state management in other geographies.     

The Shape of Mobility: Measuring the Distance Decay Function of Household Mobility

A well-known challenge to studies examining the distance of residential mobility patterns is that the estimates are often constrained to patterns only within a particular metro area or between metro areas. Thus, studies are unable to estimate the entire distance decay functional form. Using a unique data set on the distance of the most recent move for a large sample of households in twenty-three metropolitan areas in the United States over three waves, we flexibly estimate the distance decay function for the entire sample, as well as for a series of subpopulations based on key demographic information.     

An experimental study of two garnet pyroxenite xenoliths from the Bullenmerri and Gnotuk Maars of western Victoria,Australia

Experiments were conducted at 6–30 kb and 875–1200°C on two garnet pyroxenite xenoliths from the Bullenmerri and Gnotuk Maars of western Victoria, Australia. The (garnet + clinopyroxene + plagioclase + spinel) assemblage of DR9734 was stable between 10 and 12.5 kb, and 950 and 1,050°C. The compositions of its natural mineral phases were most closely approximated in experiments at 12.5 kb and 1,000–1,050°C. The (garnet + spinel + clinopyroxene + orthopyroxene + amphibole) assemblage of DR10165 was stable at pressures > 8 kb and temperatures > 950°C. However, differences between natural and experimental mineral compositions indicate that the mineral assemblage of this xenolith persisted metastably after cooling below 950°C with chemical exchange continuing down to approximately 850–900°C. When the experimental data for DR9734 and DR10165 are applied to mineralogical data for other mafic and ultramafic xenoliths from the Bullenmerri and Gnotuk Maars, they indicate that previous pressure and temperature estimates for individual xenoliths are 2–3 kb and 50°C too high. These corrections increase average temperatures for the geotherm beneath western Victoria by about 50°C over a depth range of 30–45 km and confirm its perturbed (high-temperature) character.This paper is a contribution to IGCP Project 304 (Lower Crustal Processes)     

Velocity measures in the sunspot Rome no. 7490 (July 5, 1979)

Material motions on the solar surface have been deduced from the wavelength shift of Fe i 6302.5 Å, measured over the umbra and inner penumbra of a spot for which the magnetic field configuration has already been established with some confidence. The two vector fields are considered together in detail and the results support the convective roll sunspot model (Spruit, Galloway). For the magnetic field regions, both material flow along the field lines and field line motions are derived. A small upward motion only is deduced for the field free regions.     

Components of suction caisson capacity measured in axial pullout tests

Suction caissons are the foundation of choice for offshore structures in deep water. Systematic study of caisson behavior is relegated to the laboratory due to the high cost of full-scale testing. Our laboratory caisson was installed in normally consolidated clay using dead weight and suction. Tensile axial capacity was measured with the top cap vented or sealed, and with the soil undrained or drained. For the common case of rapid pullout with a sealed top, the test results indicate an external side resistance factor (α) of 0.5–0.8 and a reverse end bearing factor (N_c) of 13–21.