"Simulation of the impact of 4-nonylphenol on the population dynamics of Japanese medaka (Oryzias latipes) in the wild using full life-cycle toxicity data" 

Meng Yaobin, Lin Bin-Le, Akihiro Tokai, Mamoru Tominaga, Junko Nakanishi

National Institute of Advanced Industrial Science and Technology

SETAC 24th Annual Meeting in North America (Austin, Texas, USA 2003/11/11)

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Abstract

Based on the experimental full life-cycle toxicity data of 4-nonylphenol (4-NP) on Japanese medaka (Oryzias latipes), the population-level impact of this compound was investigated by incorporating dose-response relationships into a stochastic population model for wild medaka. 

Experimental survival and fecundity rates for different 4-NP concentrations were resampled with a bootstrap method to calculate responses which were further regressed by Weibull, Logit and Probit dose-response models. A stochastic population matrix model depicting a typical life-cycle of wild medaka was simulated according to three scenarios to probe the population-level impacts.

 The scenarios were based respectively on a stochastic finite population growth rate, , under optimal conditions,  under annual periodic environmental variations, and population dynamics when density-dependence was considered. A 4-NP concentration corresponding to a  of unity in the first scenario was clearly higher than that in the second scenario, while  for a deterministic model from our previous work was situated between them.

 Based on the population dynamics scenario, reductions in adult abundance and interval quasi-extinction risks were employed as assessment endpoints. From a standpoint of elucidating the effect of 4-NP, adult abundance reduction was a potent endpoint in that changes in density-dependence strength had a minimal effect on it.

Keywords

Full life-cycle toxicity data, Nonylphenol, Population growth rate, Simulation, Wild medaka population