Population Consequences of Fipronil and Degradates to Copepods at Field Concentrations: An Integration of Life Cycle Testing with Leslie Matrix Population Modeling

Department of Environmental Health Sciences, Norman J Arnold School of Public Health, University of South Carolina, Columbia, South Carolina 29208, USA.
Environmental Science and Technology (Impact Factor: 5.33). 01/2005; 38(23):6407-14. DOI: 10.1021/es049654o
Source: PubMed


The predominant data used in ecological risk assessment today are individual-based rather than population-based; yet environmental policies are usually designed to protect populations of threatened species or communities. Most current methods in ecotoxicology are limited by largely logistic/ technology-driven requirements that yield data for a relatively small number of test species and end points that focus on acute lethality or sublethal nonproduction-based parameters (e.g., biomarkers, mutagenesis, genetic change, physiological condition). A contrasting example is presented here showing the predictive ability of meiobenthos-based full life cycle toxicity testing to extrapolate multi-generational effects of chemicals on variables of import to population growth and maintenance. Less than 24-h-old larvae of a meiobenthic copepod were reared individually in 96-well microplate exposures to parent and degradates of the phenylpyrazole insecticide fipronil. Survival, development rates, sex ratio change, fertility, fecundity, and hatching success were tracked daily for 32 d through mating and production of three broods in spiked seawater. These data were then inserted in a Leslie (Lefkovitch) matrix stage-based population growth model to predict relative rates of population increase (lambda) and changes in net population growth with time and toxicant concentration. Field-reported test concentrations produced strong reproductive (52-88%) and net production (40-80%) depressions for parent (at 0.25 and 0.5 microg/L), desthionyl (0.25 and 0.5 microg/L), and sulfide (0.15 microg/L) moieties as compared to controls. Spiked sediment exposures of 65-300 ng of fipronil/g of dry sediment yielded significantly reduced production rates per female that were 67-50% of control production. The consistent reproductively linked impacts of fipronil and its degradation products at the population maintenance levels suggest risks to sediment-dwelling crustaceans at concentrations well below noneffects for most aquatic test species based on risk assessment data from primarily acute and sub-life cycle toxicity tests.

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    • "ological relevancy compared to ap - proaches based on the organism level ( Forbes and Calow , 2002 ; Stark et al . , 2004 ; De Mott et al . , 2005 ; Raimondo et al . , 2006 ) . Matrix population models were recognised as particularly valuable tools to predict toxic effects on population dynamics ( Forbes et al . , 2009 ; Salice and Miller , 2003 ; Chandler et al . , 2004 ; Bin - Le and Yaobin , 2009 ; Charles et al . , 2009 ) . The method is promising under the condi - tion that detailed descriptions of life - histories and robust datasets on biological effects of ionising radiations are available for reliability of model predictions ( Klok and de Roos , 1996 ) . However , predictions may be put under q"
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    Full-text · Article · May 2012 · Science of The Total Environment
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    • "Our review showed that of the 90 model entries in the database, 81 (90%) could be used for extrapolating effects from the individual to the population level (Figure 1). The most commonly used method to estimate effects of chemicals on populations and their growth rates uses data on vital rates from life table response experiments or toxicity tests (Kuhn et al. 2000; Chandler et al. 2004). Vital parameters derived from stressed individuals as well as from the control group are then projected using a population model and compared with an unstressed situation (Klok and de Roos 1996; Salice and Miller 2003). "
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