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Death by dissolution : sediment saturation state as a mortality factor for juvenile bivalves
Get PDFWe show that death by dissolution is an important size-dependent mortality Utilizing a new experimental design, we were able to replicate saturation states frequently encountered by Mercenaria mercenaria in coastal deposits mercenaria were reared in sediments at Ωaragonite = 0.4 and 0.6, significant occurred (14.0% and 14.4% d⁻¹, respectively), relative to supersaturated-control mm M. mercenaria, significant mortality occurred under the most mortality = 9.6% d⁻¹), although mortality at Ωaragonite = 0.6 was not significant (mortality = 2.7% d⁻¹; control-saturated mortality = 0.2% d⁻¹). For the largest size- clams under the most undersaturated sediments (Ωaragonite = 0.4, 2.8% d⁻¹). To increase survivorship of juvenile bivalves during periods of recruitment, we saturation state by adding crushed Mya arenaria shell to a mud flat in West Bath, increased the average sediment saturation state within retrieved cores from Ω = numbers of live M. arenaria in buffered sediment increased almost three-fold in the metabolic acids that cause lowered saturation states may represent a strategy to decrease dissolution mortality.Keywords: Sediment saturation state, Dissolution, Mortality factors, Juvenile bivalve
Bisphenol A Exposure During Early Development Induces Sex-Specific Changes in Adult Zebrafish Social Interactions
Get PDFDevelopmental bisphenol A (BPA) exposure is associated with adverse behavioral
effects, although underlying modes of action remain unclear. Because BPA is a
suspected xenoestrogen, the objective was to identify sex-based changes in adult
zebrafish social behavior developmentally exposed to BPA (0.0, 0.1 or 1 μM) or one of
two control compounds (0.1 μM 17β-estradiol [E2], and 0.1 μM GSK4716, a synthetic
estrogen-related receptor γ ligand). A test chamber was divided lengthwise so each
arena held one fish unable to detect the presence of the other fish. A mirror was
inserted at one end of each arena; baseline activity levels were determined without mirror. Arenas were divided into 3, computer-generated zones to represent different
distances from mirror image. Circadian rhythm patterns were evaluated at 1-3 (= AM)
and 5-8 (= PM) hr postprandial. Adult zebrafish were placed into arenas and monitored
by digital camera for 5 min. Total distance traveled, % time spent at mirror image, and
number of attacks on mirror image were quantified. E2, GSK4716, and all BPA
treatments dampened male activity and altered male circadian activity patterns; there
was no marked effect on female activity. BPA induced non-monotonic effects (response
curve changes direction within range of concentrations examined) on male % time at
mirror only in AM. All treatments produced increased % time at the mirror during PM.
Male attacks on the mirror were reduced by BPA exposure only during AM. There were
sex-specific effects of developmental BPA on social interactions and time-of-day of
observation affected results.Keywords: social behavior, bisphenol A, agonistic behavior, developmental exposure, zebrafish, circadian rhythms, sex-specific behavio
A critical scale in plankton aggregations across coastal ecosystems
Get PDFWe examined the characteristics of biological patches at four different locations to assess the relationship of patch vertical scale, amplitude, and persistence. In contrast to patches of larger animals, we found that the majority of coherent aggregations of plankton at each site were vertically compressed, with most smaller than 5m vertically. A subset of these layers, often referred to as thin layers in the literature, was distinguished by high intensity and greater persistence but not thickness. Our results suggest that similar to 5m is a critical vertical scale below which aggregations of plankton frequently occur, pointing toward a controlling characteristic or a process common to a variety of regions and organism types. Given the commonality of this scale, insights into physical-biological dynamics gleaned from previous studies of the most intense and persistent of these patches may be applied more generally, leading to a better understanding of the ecosystem effects of heterogeneous plankton distributions.Keywords: spatial structure, patchiness, scale, plankto
Intra‐populational variation of ejaculate traits and sperm depletion in red‐sided garter snakes
Get PDFFemale sexual promiscuity is a prevalent element of mating systems. One consequence of female sexual promiscuity is that male‐male competition often continues post‐copulation within the female’s reproductive tract. According to theory, the number of sperm a male inseminates relative to his rivals strongly predicts his fertilization success. However, sperm quality is also important, especially when males are sperm limited and female sperm storage is prevalent. In this study, we examined intrapopulational variation in sperm numbers and ejaculate quality (sperm mobility) in male red‐sided garter snakes (Thamnophis sirtalis parietalis) and determined whether these traits varied with male body size and condition over successive matings. We obtained sperm by dissolving copulatory plugs collected from natural matings, which enabled us to also test whether males allocated more sperm to larger, more fecund females. We found significant variation in ejaculate quality among males and that small males transferred as many sperm as large males. Total sperm numbers declined significantly from a male’s first to second ejaculate suggesting that males may become significantly sperm depleted across successive matings. The mass of the relatively sperm‐free posterior portion of the copulatory plug that remained after liberation of sperm was correlated with copulation duration. Males copulated longer with larger females; however, longer copulation durations did 1 not correlate with total sperm. Thus, males may allocate more copulatory plug material to larger females to guard against her remating, instead of allocating more sperm.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The article is copyrighted by the Zoological Society of London and published by John Wiley & Sons, Inc. It can be found at: http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291469-7998.Keywords: sperm mobility, copulatory plug, sperm depletion, ejaculate traits, sperm competitio
Mineral changes in cement-sandstone matrices induced by biocementation
No full textPrevention of wellbore CO₂ leakage is a critical component of any successful carbon capture, utilization, and storage program. Sporosarcina pasteurii is a bacterium that has demonstrated the potential ability to seal a compromised wellbore through the enzymatic precipitation of CaCO₃. Here we investigate the growth of S. pasteurii in a synthetic brine that mimics the Illinois Basin and on Mt. Simon sandstone encased in Class H Portland cement under high pressure and supercritical CO₂ (PCO₂) conditions. The bacterium grew optimum at 30 °C compared to 40 °C under ambient and high pressure (10 MPa) conditions; and growth was comparable in experiments at high PCO₂. Sporosarcina pasteurii actively induced the biomineralization of CaCO₃ polymorphs and MgCa(CO₃)₂ in both ambient and high pressure conditions as observed in electron microscopy. In contrast, abiotic (non-biological) samples exposed to CO₂ resulted in the formation of surficial vaterite and calcite. The ability of S. pasteurii to grow under subsurface conditions may be a promising mechanism to enhance wellbore integrity.This is the publisher’s final pdf. The article is published by Elsevier and can be found at: http://www.journals.elsevier.com/international-journal-of-greenhouse-gas-control/Keywords: Supercritical CO₂, Biofilm, Biomineralization, Bioprecipitation, Carbon sequestration, Sporosarcina pasteuri
Living in Non-Parental Care Moderates Effects of Prekindergarten Experiences on Externalizing Behavior Problems in School
Get PDFThe current study examines the effects of prekindergarten quality and quantity on externalizing
behavior problems for children living in non-parental care, compared to other children from
socioeconomically at-risk backgrounds. Data were obtained from the Head Start Impact Study.
Non-parental care was defined as a primary caregiver other than a biological, adoptive, or step-parent.
The sample included 3029 children who attended center-based prekindergarten. Teacher-child
conflict and more hours of prekindergarten predicted increased externalizing behavior
problems for the full sample. Teacher-child closeness and overall process quality were only
associated with externalizing behavior for children in non-parental care. Findings are discussed
within a goodness-of-fit perspective in which the vulnerabilities of children in non-parental care
explain how they respond to their prekindergarten experiences.Keywords: teacher-child relationships, early care and education quality, non-parental care, school readiness, externalizing behavior problems, prekindergarte
A Numerical Modeling Study of the Upwelling Source Waters along the Oregon Coast during 2005
Get PDFRegional ocean circulation along the Oregon coast is studied numerically for forcing fields derived from year 2005 and climatological-mean conditions. The primary object is to study directly the Lagrangian pathways by which fluid arrives in the Oregon upwelling zone. Roughly half of the upwelling fluid is found to arrive in the regional domain from alongshelf source points, primarily north but also south of the Oregon upwelling zone, while the other half ultimately arrives from points offshore and west of the zone. For both the year 2005 and the climatological simulations, different regimes of dominant alongshelf source waters are found, with Cape Blanco being a dividing point for northern versus southern sources, and with the water parcels coming primarily from depths below 100 m. For the offshore sources, most upwelling fluid originates from depths between 150 and 250 m during 2005, but from within the upper 150 m for the climatological simulations. In both cases there are specific regions along the shelf of enhanced vertical motion, which appear to be associated with topographic features such as submarine banks and canyons. A perhaps surprising result is the apparently small role played by the poleward undercurrent as a direct, immediate source of upwelling fluid; on the seasonal time scale considered here, most trajectories are found to move southward over the slope and shelf, with weaker northward motion only farther offshore, in the deep interior. In 2005 the water parcels cover distances longer than in the climatology, and the meridional exchange along their paths is more vigorous. These differences are likely associated in part with the presence of mesoscale vortical structures seaward of the shelf, which are largely absent in the climatological simulation, perhaps because their formation may depend on the large-amplitude, short-time-scale wind variations and reversals that occur in the year 2005 wind field but not in the multiyear mean climatological wind field.Keywords: Upwelling, Model error
Recreational swimmers' exposure to Vibrio vulnificus and Vibrio parahaemolyticus in the Chesapeake Bay, Maryland, USA
Get PDFVibrio vulnificus and Vibrio parahaemolyticus are ubiquitous in the marine–estuarine environment, but the magnitude of human non-ingestion exposure to these waterborne pathogens is largely unknown. We evaluated the magnitude of dermal exposure to V. vulnificus and V. parahaemolyticus among swimmers recreating in Vibrio-populated waters by conducting swim studies at four swimming locations in the Chesapeake Bay in 2009 and 2011. Volunteers (n = 31) swam for set time periods, and surface water (n = 25) and handwash (n = 250) samples were collected. Samples were analyzed for Vibrio concentrations using quantitative PCR. Linear and logistic regressions were used to evaluate factors associated with recreational exposures. Mean surface water V. vulnificus and V. parahaemolyticus concentrations were 1128 CFU mL⁻¹ (95% confidence interval (CI): 665.6, 1591.4) and 18 CFU mL⁻¹ (95% CI: 9.8, 26.1), respectively, across all sampling locations. Mean Vibrio concentrations in handwash samples (V. vulnificus, 180 CFU cm⁻² (95% CI: 136.6, 222.5); V. parahaemolyticus, 3 CFU cm⁻² (95% CI: 2.4, 3.7)) were significantly associated with Vibrio concentrations in surfacewater (V. vulnificus, p < 0.01; V. parahaemolyticus, p < 0.01), but not with salinity or temperature (V. vulnificus, p = 0.52, p = 0.17; V. parahaemolyticus, p = 0.82, p = 0.06). Handwashing reduced V. vulnificus and V. parahaemolyticus on subjects' hands by approximately one log (93.9%, 89.4%, respectively). It can be concluded that when Chesapeake Bay surface waters are characterized by elevated concentrations of Vibrio, swimmers and individuals working in those waters could experience significant dermal exposures to V. vulnificus and V. parahaemolyticus, increasing their risk of infection.This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/environment-internationalKeywords: Vibrio parahaemolyticus, Recreational exposure, Vibrio vulnificus, Chesapeake Bay, Exposure assessment, Waterborne illnes
Practical Modeling for Wind Load Paths in a Realistic, Light-Frame Wood House
Get PDFThe objective of this study was to develop and validate practical modeling methods for investigating load paths and system behavior in a realistic, light-frame wood structure. The modeling methods were validated against full-scale tests on sub-assemblies and an L-shaped house. The model of the L-shaped house was then modified and used to investigate the effects of re-entrant corners, wall openings and gable-end retrofits on system behavior and load paths. Results from this study showed that the effects of adding re-entrant corners and wall openings on uplift load distributions were dependent on the orientation of the trusses with respect to the walls. Openings added to walls parallel to the trusses had the least effect on loads carried by the remaining walls in the building. Varying re-entrant corner dimensions under ASCE 7-05 (ASCE 2005) design wind loads caused increasing degrees of torsion throughout the house, depending on the relative location and stiffness of the in-plane walls (parallel to the wind loads) as well as the assumed direction of the wind loads. Balancing the stiffness of the walls on either side of the house with the largest re-entrant corner helped to decrease torsion in the structure under lateral loads. Finally, although previous full-scale tests on gable-end sections verified the effectiveness of the gable-end retrofit that was recently adopted into the 2010 Florida building code, questions remained about the effects of the retrofit on torsion in a full building. The current study found that adding the gable-end retrofits to the L-shaped house did not cause additional torsion.Keywords: wall openings, gable-end retrofits, structural models, reentrant corners, system behavior, residential buildings, structural system
Optimizing conservation practices in watersheds: Do community preferences matter?
Get PDFThis paper focuses on investigating (a) how landowner tenure and attitudes of farming communities affect the preference of individual conservation practices in agricultural watersheds, (b) how spatial distribution of landowner tenure affects the spatial optimization of conservation practices on a watershed scale, and (c) how the different attitudes and preferences of stakeholders can modify the effectiveness of alternatives obtained via classic optimization approaches that do not include the influence of existing social attitudes in a watershed during the search process. Results show that for Eagle Creek Watershed in central Indiana, USA, the most optimal alternatives (i.e., highest benefits for minimum economic costs) are for a scenario when the watershed consists of landowners who operate as farmers on their own land. When a different land-tenure scenario was used for the watershed (e.g., share renters and cash renters), the optimized alternatives had similar nitrate reduction benefits and sediment reduction benefits, but at higher economic costs. Our experiments also demonstrated that social attitudes can lead to alteration of optimized alternatives found via typical optimization approaches. For example, when certain practices were rejected by landowner operators whose attitudes toward practices were driven by economic profits, removal of these practices from the optimized alternatives led to a setback of nitrates reduction by 2–50%, peak flow reductions by 11–98%, and sediments reduction by 20–77%. In conclusion, this study reveals the potential loss in optimality of optimized alternatives possible, when socioeconomic data on farmer preferences and land tenure are not incorporated within watershed optimization investigations.This is the publisher’s final pdf. The article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1944-7973.Keywords: watershed restoration, multiple objectives, conservation practices, social attitudes, optimization, SWA