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11.
Brian M. Shamblin Mark G. Dodd Dean A. Bagley Llewellyn M. Ehrhart Anton D. Tucker Chris Johnson Raymond R. Carthy Russell A. Scarpino Erin McMichael David S. Addison Kristina L. Williams Michael G. Frick Stefanie Ouellette Anne B. Meylan Matthew H. Godfrey Sally R. Murphy Campbell J. Nairn 《Marine Biology》2011,158(3):571-587
The southeastern United States supports one of two large loggerhead turtle (Caretta caretta) nesting aggregations worldwide and is therefore critical to global conservation and recovery efforts for the species. Previous studies have established the presence of four demographically distinct nesting populations (management units) corresponding to beaches from (1) North Carolina through northeastern Florida, (2) peninsular Florida, (3) the Dry Tortugas, and (4) northwest Florida. Temporal and geographic genetic structure of the nesting aggregation was examined utilizing partial mitochondrial control region haplotype frequencies from 834 samples collected over the 2002 through 2008 nesting seasons from 19 beaches as well as previously published haplotype data. Most rookeries did not exhibit interannual genetic variation. However, the interannual variation detected did significantly impact the interpretation of spatial genetic structure in northeastern Florida. Based on pairwise F ST comparisons, exact tests of population differentiation, and analysis of molecular variance, the present study upholds the distinctiveness of the four currently recognized management units and further supports recognition of discrete central eastern, southern (southeastern and southwestern), and central western Florida management units. Further subdivision may be warranted, but more intensive genetic sampling is required. In addition, tools such as telemetry and mark-recapture are needed to complement genetic data and overcome limitations of genetic markers in resolving loggerhead turtle rookery connectivity in the southeastern USA. 相似文献
12.
Stefan Zerbe Peggy Steffenhagen Karsten Parakenings Tiemo Timmermann Annett Frick Jörg Gelbrecht Dominik Zak 《Environmental management》2013,51(6):1194-1209
The restoration of ecosystem services, i.e., production, regulation, and information, is a global challenge, which the federal state of Mecklenburg-Vorpommern in NE Germany addressed in 2000 by rewetting over 20,000 ha of degraded peatlands within the Mire Restoration Program. We evaluated ecosystem services in 23 rewetted sites by assessing the following mire parameters within a ten year period: (a) dominant vegetation at the ecosystem level, (b) peat formation potential at the landscape level, and (c) aboveground biomass and nutrient levels. Seven to 10 years after rewetting, the wetlands formed a mosaic of vegetation types with the highest potential for peat formation and several dominant, peat-forming species accumulated high levels of aboveground biomass and nutrients (C, N, P). Common reed (Phragmites australis) accumulated the most biomass (up to 24 t dry matter/ha), and N+P during the growing season. A future management option is to annually harvest aquatic and wetland plants to reduce nutrient levels in restored mire ecosystems. 相似文献
13.
Literature data for anion diffusion in compacted swelling clays contain systematic inconsistencies when the results of through-diffusion tests are compared with those of out-diffusion or tracer profile analysis. In the present work we investigated whether these inconsistencies can be explained by taking into account heterogeneities in the compacted samples; in particular increased porosities at the clay boundaries. Based on the combined results of out-diffusion, tracer profile analysis and the spatial distribution of the electrolyte anion in the clay, we conclude that the inconsistencies can indeed be resolved by taking into account a heterogeneous distribution of the total and the anion-accessible porosity. This, by definition, leads to a position dependence of the effective diffusion coefficient. Neglecting these effects results in a rather subordinate systematic error in the determination of effective diffusion coefficients of anions from through-diffusion tests with clay thicknesses in the centimetre range. However, stronger errors in terms of absolute values and conceptual interpretation may be introduced in out-diffusion tests and profile analyses of the diffused tracer. We recommend that anion diffusion tests should be accompanied by measurements of the total and anion-accessible porosity as a function of position in the direction of diffusion. 相似文献
14.
Klemens JA Harper RG Frick JA Capparella AP Richardson HB Coffey MJ 《Chemosphere》2000,41(7):1107-1113
Eleven species of Neotropical migrant passerines collected in Illinois (USA) during May 1996, were analyzed for the presence of organochlorine (OC) pesticides. At least one of five OC pesticide residues was detected in 66 of 72 birds, representing all species examined. The contaminants most frequently detected were p,p'-DDE, dieldrin and heptachlor epoxide, all of which were present in the 10-30 ng/g range. Insectivores had significantly higher levels of these compounds than did non-insectivores, while there was no significant main effect of winter habitat (forest and scrub). Future research on OC pesticide contamination in resident New World passerines may allow more accurate predictions regarding the sources of contamination in Neotropical migrants. 相似文献
15.
Michael G. Frick Kerry Kopitsky Alan B. Bolten Karen A. Bjorndal Helen R. Martins 《Marine Biology》2011,158(8):1699-1708
Grapsoid crabs of the genera Planes and Plagusia are commonly referred to as “rafting crabs” due to their propensity to live on flotsam and pelagic marine animals. Planes minutus and Planes major (=Planes cyaneus) are epibionts of sea turtles. Occurrences of grapsoid crabs in the genera Planes and Plagusia were evaluated on a total of 27 olive ridley sea turtles, Lepidochelys olivacea, from the eastern tropic Pacific (1998–2001) and the Hawaiian Islands (2002) captured in July–December each year. This is
the first report of Planes marinus and Plagusia
squamosa on sea turtles, and of P. major, P. marinus, and P. squamosa in sympatry on a confined substrate. Stomach content analyses showed P. major and P. marinus consumed a variety of neuston and marine vegetation, with the former consuming considerably more animal material. Epibiotic
P. squamosa consumed mostly plant material. The three Planes species had distinctive differences in gastric mill tooth morphology. The versatile mouthparts of P. marinus are described and resemble those of their congeners. Most female P. major and P. marinus collected were ovigerous and present in all survey months. 相似文献
16.
Kimberly J. Reich Karen A. Bjorndal Michael G. Frick Blair E. Witherington Chris Johnson Alan B. Bolten 《Marine Biology》2010,157(1):113-121
To determine whether loggerhead turtles (Caretta caretta) nesting in southeastern USA exhibit polymorphic foraging strategies, we evaluated skin samples for stable isotopes of carbon
(δ13C) and nitrogen (δ15N) from 310 loggerheads from four locations on the east coast of Florida and epibionts from 48 loggerheads. We found a dichotomy
between a depleted δ13C cluster and an enriched δ13C cluster. Epibionts from oceanic/pelagic or neritic/benthic habitats were largely consistent with this dichotomy. The bimodal
distribution of δ13C could reflect a bimodal foraging strategy or—because of the potential for confounding among four gradients of δ13C in marine environments—a polymodal foraging strategy. We integrate our results with results from other stable isotope studies,
satellite telemetry, and flipper tags to evaluate potential foraging strategies. Understanding foraging strategies is essential
for development of management plans for this endangered species that has suffered a 43% population decline over the last decade. 相似文献
17.
Kaj Frick 《Safety Science》2011,49(7):974-987
Voluntary management systems (MS) might improve occupational health and safety (OHS). MSs, as with any OHS management, requires worker influence (and management commitment) to reduce risks at work. Influence through union backed safety representatives (or similar) achieves the best OHS results. However, a MS guarantees neither effective OHS management nor strong worker influence. Systematic violations of legal requirements have repeatedly caused accidents at workplaces with certified MSs. Why employers introduce MS’s can affect their implementation and outcomes. Internal objectives, of productivity and/or work-related health, require upstream prevention and a genuine influence by workers and their safety representatives. However, managers with external objectives for a MS, such as brand images or low reported accident figures, may pursue such objectives through downstream control of safe behaviour – sometimes suppressing accident reporting – and with little attention to more serious long-term diseases. Worker consultation may then be a limited means of enhancing safety, or to one-way communication on safety rules. Such consultation may even be used for union busting. Many trade unions welcome MSs as possible improvement instruments, but they are also wary of what MSs employers are actually trying to implement. Unions try to support their safety representatives’ influence in a MS by enhancing their rights and their competences. If the motives for MSs are mainly external and the opportunities for influence too limited, it may be better for unions not to cooperate with management in a MS that may lead more to manipulation than to safe and sound work. 相似文献
18.
Two strains of microorganisms that both use sugar as energy resource, but which may choose between two different pathways of ATP production, are studied from a game-theory point of view. We consider these pathways as distinct strategies to which we assign payoffs that are proportional to the expected steady-state number of individuals sustainable on the basis of these strategies. In a certain parameter range, we find that the payoffs fulfil the conditions for the prisoner's dilemma. Therefore, cooperative behaviour is unlikely to occur, unless additional factors intervene. In fact, the yeast Saccharomyces cerevisiae uses a competitive strategy by fermenting sugars even under aerobic conditions, thus wasting its own resource. The simple quantifiable structure of the model should enable access to an experimentally determined payoff matrix. 相似文献
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Box models for the global CO2-cycle are described by a system of first order linear differential equations with constant coefficients. Conditions for uniquely existing equilibrium states are given and the reaction to disturbances is analysed. Kalman filtering techniques are applied to uncertainty problems. Some numerical calculations are presented for illustration purposes. 相似文献