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Sean R. Brennan Diego P. Fernandez Jennifer M. Burns Stephanie Aswad Daniel E. Schindler Thure E. Cerling 《Conservation biology》2019,33(6):1415-1425
Human activities threaten the biodiversity of aquatic mammals across the globe. Conservation of these species hinges on the ability to delineate movements and foraging behaviors of animals, but gaining such insights is hampered by difficulties in tracing individuals over their lives. We determined isotope ratios in teeth (87Sr/86Sr, 13C/12C, and 18O/16O) to examine lifelong movement and resource-use patterns of a unique freshwater population of a wide-ranging pinniped species (harbor seal [Phoca vitulina]) that resides in Iliamna Lake, Alaska (U.S.A.). This population's potentially unique migratory behavior and use of different trophic resources are unknown. The isotope ratios we measured in teeth showed that seals were born in the lake, remained lifelong residents, and relied principally on resources produced from in the lake, even when seasonally abundant and nutrient-dense spawning anadromous fish (i.e., sockeye salmon [Oncorhynchus nerka]) were available in the lake. Our results illustrate how serial isotope records in teeth, particularly 87Sr/86Sr ratios, can be used to quantify how coastal mammal populations exploit both freshwater and marine ecosystems. Understanding lifelong patterns of habitat and resource use is essential information when designing effective conservation plans for threatened coastal mammals. We present the Iliamna Lake harbor seals as a unique case study into how isotope records within teeth can help reveal the cryptic ecology of such a population residing in an intact ecosystem. The results also provide critical baseline information for the Kvichak River system, which is facing an uncertain future due to proposed large-scale industrial development and a rapidly changing climate. 相似文献
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Heather E. Harper Paul L. Pennington Jennifer Hoguet Michael H. Fulton 《Journal of environmental science and health. Part. B》2013,48(6):476-483
This study investigated the lethal and sublethal effects of the pyrethroid insecticide bifenthrin on adult and larval grass shrimp, Palaemonetes pugio, and adult sheepshead minnows, Cyprinodon variegatus. The effects were determined by conducting 96-h aqueous static renewal tests and 24-h static tests with sediment. Oxidative stress biomarkers, lipid peroxidation, glutathione, and catalase were also assessed. The 96-h aqueous LC50 value for adult shrimp was 0.020 μ g/L (95% CI: 0.015–0.025 μ g/L) and for larval shrimp was 0.013 μ g/L (95% CI: 0.011–0.016 μ g/L). The 96-h aqueous LC50 for adult sheepshead minnow was 19.806 μ g/L (95% CI: 11.886–47.250 μ g/L). The 24-h sediment LC50 for adult shrimp was 0.339 μ g/L (95% CI: 0.291–0.381 μ g/L) and for larval shrimp was 0.210 μ g/L (95% CI: 0.096–0.393 μ g/L). The oxidative stress assays showed some increasing trends toward physiological stress with increased bifenthrin concentrations but they were largely inconclusive. Given the sensitivity of grass shrimp to this compound in laboratory bioassays, additional work will be needed to determine if these exposure levels are environmentally relevant. 相似文献
167.
Bayesian analysis of abundance for binomial sighting data with unknown number of marked individuals 总被引:2,自引:0,他引:2
The mark-resight method for estimating the size of a closed population can in many circumstances be a less expensive and less
invasive alternative to traditional mark-recapture. Despite its potential advantages, one major drawback of traditional mark-resight
methodology is that the number of marked individuals in the population available for resighting needs to be known exactly.
In real field studies, this can be quite difficult to accomplish. Here we develop a Bayesian model for estimating abundance
when sighting data are acquired from distinct sampling occasions without replacement, but the exact number of marked individuals
is unknown. By first augmenting the data with some fixed number of individuals comprising a marked “super population,” the
problem may then be reformulated in terms of estimating the proportion of this marked super population that was actually available
for resighting. This then allows the data for the marked population available for resighting to be modeled as random realizations
from a binomial logit-normal distribution. We demonstrate the use of our model to estimate the New Zealand robin (Petroica australis) population size in a region of Fiordland National Park, New Zealand. We then evaluate the performance of the proposed model
relative to other estimators via a series of simulation experiments. We generally found our model to have advantages over
other models when sample sizes are smaller with individually heterogeneous resighting probabilities. Due to limited budgets
and the inherent variability between individuals, this is a common occurrence in mark-resight population studies. WinBUGS
and R code to carry out these analyses is available from . 相似文献
168.
The commercial sea cucumber species known as Sandfish (Holothuria scabra) occurs intertidally and subtidally in the Northern Territory of Australia, on or adjacent to Aboriginal land. A 4-yr program of community-based fisheries research with Aboriginal Australians was implemented to assess the viability of indigenous Australians' involvement in the wild-stock fishery. The research involved extensive and intensive indigenous participation, unusual in Australian biophysical sciences research, during field survey and habitat mapping, complemented by commercial catch data modelling and discussion of its implications. Field surveys produced Sandfish distribution and site-specific density, and revealed some areas that were not commercially fished. Catch data modelling results suggested that no additional effort could be sustained, however commercial fishers increased their effort, expanding their operations into the newly mapped areas. These actions effectively precluded indigenous peoples' aspirations of entry into the commercial fishery. The efficacy and outcomes of participatory program design with indigenous Australians need critique in the absence of the political will and statutory backing to provide equitable access to resources. 相似文献
169.
The current range of ecological habitats occupied by a species reflects a combination of the ecological tolerance of the species, dispersal limitation, and competition. Whether the current distribution of a species accurately reflects its niche has important consequences for the role of ecological niche modeling in predicting changes in species ranges as the result of biological invasions and climate change. We employed a detailed data set of species occurrence and spatial variation in biotic and abiotic attributes to model the niche of a native California annual plant, Collinsia sparsiflora. We tested the robustness of our model for both the realized and fundamental niche by planting seeds collected from four populations, representing two ecotypes, into plots that fully represented the five-dimensional niche space described by our model. The model successfully predicted which habitats allowed for C. sparsiflora persistence, but only for one of the two source ecotypes. Our results show that substantial niche divergence has occurred in our sample of four study populations, illustrating the importance of adequately sampling and describing within-species variation in niche modeling. 相似文献
170.
Conflicting demands on detoxification pathways influence how common brushtail possums choose their diets 总被引:1,自引:0,他引:1
Most herbivores eat more and survive better when they have access to a variety of foods. One explanation involves the detoxification of plant secondary metabolites (PSMs). By feeding from a variety of plants that contain different classes of PSMs, animals can use multiple detoxification pathways and presumably consume more food. Although popular, this theory is difficult to test because it requires knowledge of the detoxification pathways of each PSM in the diet. We established that common brushtail possums (Trichosurus vulpecula) use various combinations of oxidation, hydrolysis, and conjugation with glucuronic acid (GA) or glycine to detoxify six PSMs. Compared to their ingestion of a single PSM, possums ate more when offered a choice between two diets containing PSMs that require apparently independent detoxification pathways (benzoate and 1,8-cineole, benzoate and p-cymene, benzoate and orcinol, benzoate and salicin, or orcinol and 1,8-cineole). However, possums still did not eat as much of these diets as they did of a basal diet free of PSMs. This suggests that detoxification pathways are never independent, but are separated instead by degrees. In contrast, possums offered a choice of two PSMs that require competing detoxification pathways (1,8-cineole and p-cymene, 1,8-cineole and salicin, or orcinol and salicin) ate no more than when offered diets containing one of the compounds. There was an exception: even though both rutin and orcinol are detoxified via conjugation with GA, the feeding behavior of possums did not suggest competition for detoxification pathways. This implies that the supply of GA is not limiting. This study provides the first convincing evidence that herbivorous mammals can eat more by selecting mixed diets with a diversity of PSMs that make full use of their detoxification potential. It also emphasizes that other behavioral and physiological factors, such as transient food aversions, influence feeding behavior. 相似文献