Which of the following best predicts the effect of the enclosure on the o’neill population?

Abstract

1. The Littoral Ecosystem Risk Assessment Model (LERAM) is described and evaluated using field data from a littoral enclosure study of the effects of the insecticide chlorpyrifos. LERAM is a bioenergetic ecosystem effects model that links single species toxicity data to a bioenergetic model of the trophic structure of an ecosystem in order to simulate community and ecosystem level effects of chemical stressors. It uses Monte Carlo iterations of these simulations in order to calculate probabilistic ecological risk assessments of chemical stressors. 2. The means and standard deviations of the model parameters were calibrated using data from the control enclosures in the field. LERAM produced reasonable representations of the ecosystems in the littoral enclosures. 3. The data from enclosures treated at 0.5, 6.3, and 32.0 μ g l-1 chlorpyrifos (average peak concentration) were then used to evaluate LERAM predictions of the effect of chlorpyrifos on a littoral ecosystem. The LERAM deterministic, time-series predictions were usually within a factor of two for all populations on all field sampling dates. The divergence on a few days, however, was more, with the worst case being a factor of six for a population with very high variability in the field. The LERAM probabilistic predictions of the relative effect on total production, which is the quantity LERAM uses for ecological risk assessment, were not significantly different from the relative effects measured in the field. 4. Recommendations for further evaluation of LERAM and for further research on its components are summarized.

Journal Information

Journal of Applied Ecology publishes novel papers that apply ecological concepts, theories, models and methods to the management of biological resources in their widest sense. The editors encourage contributions that use applied ecological problems to test and develop basic ecological theory, although there must be clear potential for improving management. The journal includes all major themes in applied ecology: conservation biology, global change, environmental pollution, wildlife and habitat management, land use and management, aquatic resources, restoration ecology, and the management of pests, weeds and disease. Articles that interact with related fields are welcomed providing that their relevance to applied ecology is clear. Further details are available at www.journalofappliedecology.org. JSTOR provides a digital archive of the print version of The Journal of Applied Ecology. The electronic version of The Journal of Applied Ecology is available at http://www3.interscience.wiley.com/journal/117972213/home. Authorised users may be able to access the full text articles at this site.

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The British Ecological Society is a welcoming and inclusive home for everyone interested in ecology. The Society was established in 1913 and has over 6,000 members worldwide, bringing people together across regional, national and global scales to advance ecological science. The BES's many activities include the publication of a range of scientific literature, including seven internationally renowned journals, the organisation and sponsorship of a wide variety of meetings, the funding of numerous grant schemes, education work and policy work.

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Journal of Applied Ecology © 1994 British Ecological Society
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Abstract

Assessments of ecological risk require accurate predictions of contaminant dynamics in natural populations. However, simple deterministic models that assume constant uptake rates and elimination fractions may compromise both their ecological realism and their general application to animals with variable metabolisms or diets. In particular, the temperature-dependent metabolic rates characteristic of ectotherms may lead to significant differences between observed and predicted contaminant kinetics. We examined the influence of a seasonally variable thermal environment on predicting the uptake and annual cycling of contaminants by ectotherms, using a temperature-dependent model of 137Cs kinetics in free-living yellow-bellied turtles, Trachemys scripta. We compared predictions from this model with those of deterministic negative exponential and flexibly shaped Richards sigmoidal models. Concentrations of 137Cs in a population of this species in Pond B, a radionuclide-contaminated nuclear reactor cooling reservoir, and 137Cs uptake by uncontaminated turtles held captive in Pond B for 4 yr confirmed both the pattern of uptake and the equilibrium concentrations predicted by the temperature-dependent model. Almost 90% of the variance in the predicted time-integrated 137Cs concentration was explainable by linear relationships with model parameters. The model was also relatively insensitive to uncertainties in the estimates of ambient temperature, suggesting that adequate estimates of temperature-dependent ingestion and elimination may require relatively few measurements of ambient conditions at sites of interest. Analyses of Richards sigmoidal models of 137Cs uptake indicated significant differences from a negative exponential trajectory in the 1st yr after the turtles' release into Pond B. We also observed significant annual cycling of 137Cs concentrations, apparently due to temperature-dependent metabolism and its influence on ingestion and elimination rates. However, equilibrium concentrations of the radionuclide in the wild population were predictable from negative exponential models based on average annual temperature and its effects on intake and elimination rates, also suggesting that predicting ectotherm responses to long-lived contaminants (such as 137Cs) may be possible without complex ecophysiological modeling.

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The vision for Ecological Monographs is that it should be the place for publishing integrative, synthetic papers that elaborate new directions for the field of ecology. In this world of rapid scientific advancement and never-ending environmental change, there needs to be room for the thoughtful integration of scientific ideas, data, and concepts that feeds the mind and guides the development of the maturing science of ecology. Ecological Monographs provides that room, with an expansive view to a sustainable future.

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Wiley is a global provider of content and content-enabled workflow solutions in areas of scientific, technical, medical, and scholarly research; professional development; and education. Our core businesses produce scientific, technical, medical, and scholarly journals, reference works, books, database services, and advertising; professional books, subscription products, certification and training services and online applications; and education content and services including integrated online teaching and learning resources for undergraduate and graduate students and lifelong learners. Founded in 1807, John Wiley & Sons, Inc. has been a valued source of information and understanding for more than 200 years, helping people around the world meet their needs and fulfill their aspirations. Wiley has published the works of more than 450 Nobel laureates in all categories: Literature, Economics, Physiology or Medicine, Physics, Chemistry, and Peace. Wiley has partnerships with many of the world’s leading societies and publishes over 1,500 peer-reviewed journals and 1,500+ new books annually in print and online, as well as databases, major reference works and laboratory protocols in STMS subjects. With a growing open access offering, Wiley is committed to the widest possible dissemination of and access to the content we publish and supports all sustainable models of access. Our online platform, Wiley Online Library (wileyonlinelibrary.com) is one of the world’s most extensive multidisciplinary collections of online resources, covering life, health, social and physical sciences, and humanities.

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Ecological Monographs © 1996 Wiley
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