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AN INDIVIDUAL-BASED MODELING APPROACH FOR EVALUATION OF ENDPOINT SENSITIVITY IN HARPACTICOID COPEPOD LIFE-CYCLE TESTS AND OPTIMIZATION OF TEST DESIGN
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
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2011 (English)In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 30, no 10, 2353-2362 p.Article in journal (Refereed) Published
Abstract [en]

In the present study, an individual-based model for Nitocra spinipes was developed and used to optimize the test design of a proposed Organisation for Economic Co-operation and Development test guideline for harpacticoid copepods. The variability between individuals was taken into account, based on measured data, leading to stochastic model output. Virtual experiments were performed with the model to analyze the endpoint sensitivity and the effect of number of replicates and inspection intervals on statistical power. The impact of mortality was evaluated; most sublethal effects could not be determined if the mortality was >= 70%. Most sensitive to mortality was the determination of effects on brood size, for which the statistical power was reduced at 10% mortality. Our simulations show that increasing the number of replicates from 72 to 96 or 144 has little impact on the statistical power, whereas 25 replicates disallow relevant endpoint detection. Furthermore, it was demonstrated that the proposed ID inspection interval can be shifted to a 3D interval, without losing statistical power. It was demonstrated that developmental endpoints have a higher statistical power than reproductive endpoints in the current test design. The present study highlights the usefulness of individual-based models for optimizing the experimental design. The use of such models in the development of standard test guidelines will lead to a faster and less resource-demanding process.

Place, publisher, year, edition, pages
2011. Vol. 30, no 10, 2353-2362 p.
Keyword [en]
Virtual ecology, Test design, Biotests, Sublethal effects
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:su:diva-66527DOI: 10.1002/etc.614ISI: 000295309400023OAI: oai:DiVA.org:su-66527DiVA: diva2:469830
Note
authorCount :5Available from: 2011-12-27 Created: 2011-12-20 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Population modeling using harpacticoid copepods: Bridging the gap between individual-level effects and protection goals of environmental risk assessment
Open this publication in new window or tab >>Population modeling using harpacticoid copepods: Bridging the gap between individual-level effects and protection goals of environmental risk assessment
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

To protect the environment from contaminants, environmental risk assessment (ERA) evaluates the risk of adverse effects to populations, communities and ecosystems. Environmental management decisions rely on ERAs, which commonly are based on a few endpoints at the individual organism level. To bridge the gap between what is measured and what is intended for protection, individual-level effects can be integrated in population models, and translated to the population level. The general aim of this doctoral thesis was to extrapolate individual-level effects of harpacticoid copepods to the population level by developing and using population models. Matrix models and individual based models were developed and applied to life-history data of Nitocra spinipes and Amphiascus tenuiremis, and demographic equations were used to calculate population-level effects in low- and high-density populations. As a basis for the population models, individual-level processes were studied. Development was found to be more sensitive compared to reproduction in standard ecotoxicity tests measuring life-history data. Additional experimental animals would improve statistical power for reproductive endpoints, but at high labor and cost. Therefore, a new test-design was developed in this thesis. Exposing animals in groups included a higher number of animals without increased workload. The number of reproducing females was increased, and the statistical power of reproduction was improved. Individual-level effects were more or equally sensitive compared to population-level effects, and individual-level effects were translated to the population level to various degrees by population models of different complexities. More complex models showed stronger effects at the population level compared to the simpler models. Density dependence affected N. spinipes populations negatively so that toxicant effects were stronger at higher population densities. The tools presented here can be used to assess the toxicity of environmental contaminants at the individual and population level, improve ERA, and thereby the basis for environmental management.

Place, publisher, year, edition, pages
Stockholm: Department of Applied Environmental Science (ITM), Stockholm University, 2014. 36 p.
Keyword
Population modeling, (Eco)toxicity tests, Environmental risk assessment, Harpacticoid copepods
National Category
Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-102541 (URN)978-91-7447-894-5 (ISBN)
Public defence
2014-05-23, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 09:30 (English)
Opponent
Supervisors
Funder
Mistra - The Swedish Foundation for Strategic Environmental Research, 1323907
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.

Available from: 2014-04-30 Created: 2014-04-08 Last updated: 2014-05-29Bibliographically approved

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