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41.
Summary In 1981–1985, we studied territory dynamics in a southeastern Idaho sage sparrow population to evaluate the hypothesis that territory shifts represent adaptive adjustments in site use. We predicted that shifts should (1) result in changes in territory characteristics, (2) be influenced by previous reproductive success and result in greater success, and (3) decline in magnitude for individual males over time. Habitat features of territories changed little as a result of shifts, but territory size increased. Correspondingly, habitat features of territories were unrelated to reproductive success, whereas territory size was positively related. The magnitude of territory shifts was negatively correlated with preshift fledging success, and after shifts, males experienced greater average reproductive success than before. Successive territory shifts by individual males became progressively smaller. Thus, territory shifting by sage sparrows seems to be adaptive behavior aimed primarily at increasing territory size. 相似文献
42.
Gunderson MP Bermudez DS Bryan TA Degala S Edwards TM Kools SA Milnes MR Woodward AR Guillette LJ 《Chemosphere》2004,56(4):335-345
This 3-year study was designed to examine variation in plasma sex steroids, phallus size, and the standard error (S.E.) associated with these endpoints in juvenile alligators collected from 3 sites within the Kissimmee-Everglades drainage (Florida, USA) with varying concentrations of sediment organochlorine contaminants. We hypothesized that decreased plasma sex steroid concentrations and phallus size would be observed in the higher contaminant site when compared to the intermediate and lower contaminant sites. Furthermore, we hypothesized that greater S.E. associated with these endpoints would be observed for the populations from more contaminated sites. We found that differences existed with females from the higher contaminant site exhibiting lower plasma estradiol-17beta (E2) and testosterone (T) concentrations. Males from the higher contaminant site exhibited smaller phallus sizes than males from the intermediate and lower contaminant sites. Smaller phallus size in this case differed from that reported in Lake Apopka male alligators [Gen. Comp. Endocrinol. 116 (1999) 356] in that a significant positive relationship between body size and phallus size existed. No difference among sites was observed in plasma T for males. Lower S.E. was associated with E2 and T concentrations in females from the higher contaminant site and in phallus size in males from the higher contaminant site. This pattern was opposite to what we had hypothesized. We concluded that variation in plasma E2 and T concentrations, phallus size, and the S.E. associated with these endpoints exists among the 3 sites with the patterns matching the patterns of organochlorine contamination, although S.E. patterns were opposite to what was predicted. 相似文献
43.
Exposure to environmental contaminants has been shown to alter normal thyroid function in various wildlife species, including the American alligator (Alligator mississippiensis). Abnormalities in circulating levels of the thyroid hormone thyroxine (T4) have been reported in juvenile alligators from several contaminated lakes in Florida. To further elucidate these functional thyroid abnormalities, this study examines the structure of thyroids and circulating T4 concentrations from juvenile alligators collected from three sites of varying contamination on Lake Okeechobee, Florida. The following variables were used to characterize thyroid morphology: epithelial cell height, width and area, percent colloid, and follicle area. These variables were compared among study sites and between genders. No difference was detected in epithelial cell height, epithelial cell area, or follicle area among the sites, whereas significant differences in epithelial cell width (p=0.02) and percent colloid (p=0.008) were found. Animals from the most contaminated site (Belle Glade) had significantly greater epithelial cell widths and significantly less colloid present in their follicles compared to animals from the reference site (West). Gender did not have a significant interaction with site for any variable measured. Thyroxine (T4) concentrations were elevated in the intermediately contaminated site (Conservation Area 3A) compared to the other sites (p<0.0001). It is proposed that the disruptions seen in Lake Okeechobee alligators are due to disruptions at both the thyroid and extra-thyroidal tissues. 相似文献
44.
Sami A. Fam David M. Falatko Glenn McGillicuddy George Pon Louis J. Burkhardt Jonathan Hone 《补救:环境净化治理成本、技术与工艺杂志》2012,22(2):33-47
Bioremediation of 1,1,1‐trichloroethane (TCA) is more challenging than bioremediation of other chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE). TCA transformation often occurs under methanogenic and sulfate‐reducing conditions and is mediated by Dehalobacter. The source area at the project site contains moderately permeable medium sand with a low hydraulic gradient and is approximately 0.5 acre. TCA contamination generally extended to 35 feet, with the highest concentrations at approximately 20 feet. The concentrations then decreased with depth; several wells contained 300 to 600 mg/L of TCA prior to bioremediation. The area of treatment also contained 2 to 30 mg/L of TCE from an upgradient source. Initial site groundwater conditions indicated minimal biotic dechlorination and the presence of up to 20 mg/L of nitrate and 90 mg/L of sulfate. Microcosm testing indicated that TCA dechlorination was inhibited by the site's relatively low pH (5 to 5.5) and high TCA concentration. After the pH was adjusted and TCA concentrations were reduced to less than 35 mg/L (by dilution with site water), dechlorination proceeded rapidly using whey (or slower with sodium lactate) as an electron donor. Throughout the remediation program, increased resistance to TCA inhibition (from 35 to 200 mg/L) was observed as the microbes adapted to the elevated TCA concentrations. The article presents the results of a full‐scale enhanced anaerobic dechlorination recirculation system and the successful efforts to eliminate TCA‐ and pH‐related inhibition. © 2012 Wiley Periodicals, Inc. 相似文献
45.
The landscape epidemiology of foot-and-mouth disease in South Africa: A spatially explicit multi-agent simulation 总被引:1,自引:0,他引:1
This study aimed at understanding how landscape heterogeneity influences outbreaks of contagious diseases in southern Africa. Landscape attributes influence patterns of movement and behaviour of animal hosts, virus spread and survival, as well as land use practices. A multi-agent simulation was developed to represent the spatial and temporal dynamics of pathogens between human-livestock and wildlife interfaces at the fringe of large wildlife conservation areas. The model represents the three main elements associated with epidemics - populations, space, and time - to simulate direct contacts between wildlife and livestock. The dynamics of these populations emerge from interactions between agents and the landscape. The model was calibrated to represent the transmission of foot-and-mouth disease through direct contact at the border of the Kruger National Park in South Africa. In the region, African buffaloes (Syncerus caffer) act as reservoirs of the virus and spread the infection to domestic cattle bordering the park. We tested the sensitivity of various factors influencing contact rate between buffaloes and cattle, and thus the risk of foot-and-mouth disease transmission. Results show that cattle-buffalo contacts mostly depend on the range of displacements of cattle and buffaloes, as influenced by the landscape configuration, and on the number of fence breakages multiplied by the time between breakage and repair. Contacts take place not only close to water-points but also in grazing areas, within an area up to 6 km from the fence. 相似文献
46.
Stephane Denis Roberto Renzoni Jean L. Fontaine Albert Germain Louis Corman Pierre Gilson 《毒物与环境化学》2013,95(3-4):155-163
Cement industry is an interesting way to eliminate combustible wastes. Thermal valorization is maximal, conditions of combustion are especially favorable to the destruction and the trapping of pollutants, and there are neither ultimate residues (slag) nor aqueous rejects. Moreover the properties of the cement are not modified. Nevertheless the increased use of substitution fuel may lead to deal with unusual amounts of heavy metals. Tests were realized on several rotary cement kilns with varying substitution ratios of fossil fuels by wastes. Mass balances were fitted over the whole plant, and emission factors were explained. 相似文献
47.
Marine reserves are an increasingly important tool for the management of marine ecosystems around the world. However, the effects of proposed marine reserve configurations on sustainability and yield of populations are typically not estimated because of the computational intensity of direct simulation and uncertainty in larval dispersal and density-dependent recruitment. Here we develop a method for efficiently assessing a marine reserve configuration for persistence and yield of a population with sedentary adults and dispersing larvae. The method extends the familiar sustainability criteria of individual replacement for single populations based on eggs-per-recruit (EPR) to spatially distributed populations with sedentary adults, a dispersing larval phase, and limited carrying capacity in the settlement-recruit relationship. We refer to this approach as dispersal-per-recruit (DPR). In some cases, a single DPR calculation, based on the assumption that post-settlement habitat is saturated (i.e., at maximum recruitment), is sufficient to determine population persistence, while in other cases further iterative calculations are required. These additional calculations reach an equilibrium more rapidly than a full simulation of age- or size-structured populations. From the DPR result, fishery yield can be computed from yield-per-recruit (YPR) at each point. We assess the utility of DPR calculations by applying them to single reserves, uniformly distributed systems of reserves, and randomly sized and spaced systems of reserves on a linear coastline. We find that for low levels of EPR in fished areas (e.g., 10% or less of the natural, unfished EPR when post-settlement habitats are saturated by 35% of natural settlement), a single DPR calculation is sufficient to determine persistence of the population. We also show that, in uniform systems of reserves with finite reserve size, maximal fisheries yield occurs when the density of reserves is such that all post-settlement habitat is nearly saturated with settlers. Finally, we demonstrate the application of this approach to a realistic proposed marine reserve configuration. 相似文献
48.
Amanda Xuereb Cassidy C. D'Aloia Marco Andrello Louis Bernatchez Marie-Josée Fortin 《Conservation biology》2021,35(3):909-920
The availability of genomic data for an increasing number of species makes it possible to incorporate evolutionary processes into conservation plans. Recent studies show how genetic data can inform spatial conservation prioritization (SCP), but they focus on metrics of diversity and distinctness derived primarily from neutral genetic data sets. Identifying adaptive genetic markers can provide important information regarding the capacity for populations to adapt to environmental change. Yet, the effect of including metrics based on adaptive genomic data into SCP in comparison to more widely used neutral genetic metrics has not been explored. We used existing genomic data on a commercially exploited species, the giant California sea cucumber (Parastichopus californicus), to perform SCP for the coastal region of British Columbia (BC), Canada. Using a RAD-seq data set for 717 P. californicus individuals across 24 sampling locations, we identified putatively adaptive (i.e., candidate) single nucleotide polymorphisms (SNPs) based on genotype–environment associations with seafloor temperature. We calculated various metrics for both neutral and candidate SNPs and compared SCP outcomes with independent metrics and combinations of metrics. Priority areas varied depending on whether neutral or candidate SNPs were used and on the specific metric used. For example, targeting sites with a high frequency of warm-temperature-associated alleles to support persistence under future warming prioritized areas in the southern coastal region. In contrast, targeting sites with high expected heterozygosity at candidate loci to support persistence under future environmental uncertainty prioritized areas in the north. When combining metrics, all scenarios generated intermediate solutions, protecting sites that span latitudinal and thermal gradients. Our results demonstrate that distinguishing between neutral and adaptive markers can affect conservation solutions and emphasize the importance of defining objectives when choosing among various genomic metrics for SCP. 相似文献
49.
Véronique Thériault Louis Bernatchez Julian J. Dodson 《Behavioral ecology and sociobiology》2007,62(1):51-65
Salmonids are known for the occurrence in sympatry of two life-history forms, one that undergoes migration to sea before returning
to freshwater to reproduce (anadromous) and one that inhabits freshwater without a migration phase (resident). Whereas one
breeding population is often suggested by population genetic studies, mating patterns have rarely been directly assessed,
especially when both sexes are found within each life-history form. By using highly polymorphic microsatellite loci and parentage
analysis in a natural population of sympatric anadromous and resident brook charr (Salvelinus fontinalis), we found that gene flow occurred between the two forms and was mediated by resident males mating with both resident and
anadromous females. Determinants of reproductive success, estimated by the number of surviving juveniles (ages 1 and 2 years),
differed between the sexes. No strong evidence of the influence of size on individual reproductive success was found for males,
whereas larger females (and hence most likely to be anadromous) were more successful. The higher individual reproductive success
of anadromous fish compared to residents was mainly explained by this higher reproductive success of anadromous females. We
suggest that resident males adopt a “sneaking” reproductive tactic as a way of increasing their reproductive success by mating
with females of all sizes in all habitats. The persistence of the resident tactic among females may be linked to their advantage
in accessing spatially constrained spawning areas in small tributary streams unavailable to larger females. 相似文献
50.
Sulphate, Nitrogen and Base Cation Budgets at 21 Forested Catchments in Canada, the United States and Europe 总被引:1,自引:0,他引:1
Watmough SA Aherne J Alewell C Arp P Bailey S Clair T Dillon P Duchesne L Eimers C Fernandez I Foster N Larssen T Miller E Mitchell M Page S 《Environmental monitoring and assessment》2005,109(1-3):1-36
To assess the concern over declining base cation levels in forest soils caused by acid deposition, input-output budgets (1990s
average) for sulphate (SO4), inorganic nitrogen (NO3-N; NH4-N), calcium (Ca), magnesium (Mg) and potassium (K) were synthesised for 21 forested catchments from 17 regions in Canada,
the United States and Europe. Trend analysis was conducted on monthly ion concentrations in deposition and runoff when more
than 9 years of data were available (14 regions, 17 sites). Annual average SO4 deposition during the 1990s ranged between 7.3 and 28.4 kg ha−1 per year, and inorganic nitrogen (N) deposition was between 2.8 and 13.8 kg ha−1 per year, of which 41–67% was nitrate (NO3-N). Over the period of record, SO4 concentration in deposition decreased in 13/14 (13 out of 14 total) regions and SO4 in runoff decreased at 14/17 catchments. In contrast, NO3-N concentrations in deposition decreased in only 1/14 regions, while NH4-N concentration patterns varied; increasing at 3/14 regions and decreasing at 2/14 regions. Nitrate concentrations in runoff
decreased at 4/17 catchments and increased at only 1 site, whereas runoff levels of NH4-N increased at 5/17 catchments. Decreasing trends in deposition were also recorded for Ca, Mg, and K at many of the catchments
and on an equivalent basis, accounted for up to 131% (median 22%) of the decrease in acid anion deposition. Base cation concentrations
in streams generally declined over time, with significant decreases in Ca, Mg and K occurring at 8, 9 and 7 of 17 sites respectively,
which accounted for up to 133% (median 48%) of the decrease in acid anion concentration. Sulphate export exceeded input at
18/21 catchments, likely due to dry deposition and/or internal sources. The majority of N in deposition (31–100%; median 94%)
was retained in the catchments, although there was a tendency for greater NO3-N leaching at sites receiving higher (<7 kg ha-1 per year) bulk inorganic N deposition. Mass balance calculations show that export of Ca and Mg in runoff exceeds input at
all 21 catchments, but K export only exceeds input at 16/21 sites. Estimates of base cation weathering were available for
18 sites. When included in the mass balance calculation, Ca, Mg and K exports exceeded inputs at 14, 10 and 2 sites respectively.
Annual Ca and Mg losses represent appreciable proportions of the current exchangeable soil Ca and Mg pools, although losses
at some of the sites likely occur from weathering reactions beneath the rooting zone and there is considerable uncertainty
associated with mineral weathering estimates. Critical loads for sulphur (S) and N, using a critical base cation to aluminium
ratio of 10 in soil solution, are currently exceeded at 7 of the 18 sites with base cation weathering estimates. Despite reductions
in SO4 and H+ deposition, mass balance estimates indicate that acid deposition continues to acidify soils in many regions with losses of
Ca and Mg of primary concern.
The U.S. Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.
The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright. 相似文献