A Life‐Table‐Response Experiment lasting 78 d was performed to investigate the toxic effects of sediment‐associated 4‐n‐nonylphenol (NP) on growth, reproduction, and survivorship of isolated hermaphrodites of the infaunal polychaete Capitella sp. I. Demographic effects were evaluated using both a fully age‐classified and a simple two‐stage model to estimate population growth rates (λ). Decomposition analysis was performed to explore the contributions of each of the affected life‐history traits to the effects observed on λ. Elasticity analysis was applied to examine the relative sensitivity of λ to changes in each of the different life‐history traits under different exposure levels. In the lowest NP treatment (14 μg NP/g dry mass of sediment) significant stimulatory effects were observed for both asymptotic body volume and average brood size, but these did not result in a significant effect on λ. Negative effects on brood size, volume‐specific fecundity, time to first reproduction, and individual growth rate were significant in the highest NP treatment (174 μg/g dry mass), and these effects resulted in a significant reduction in λ. Decomposition of the two‐stage model indicated that the effect of NP on time to first reproduction was a major cause of changes in population growth rate. Although time to first reproduction increased by only ∼20% in the highest NP treatment relative to the control, it was responsible for more than half (55%) of the effect on λ. In contrast, per‐individual fecundity decreased by 75% but only explained 44% of the effect on λ. Elasticity analysis of the two‐stage model showed that λ became less sensitive to changes in fecundity and time to maturity, but not to changes in juvenile and adult survival probabilities, with increasing NP exposure. In this study, population growth rate was not significantly affected by NP concentrations lower than those affecting the individual life‐history traits. However, since the population‐level consequences of changes in each trait depend on the starting value of λ, on the extent to which the other traits are impacted by the toxicant, and on the life‐history characteristics of the species under consideration, the application of demographic analyses to chronic toxicity test results is required to link individual‐level responses to population‐level impacts of toxicant exposure.

The LOFT mission concept is one of four candidates selected by ESA for the M3 launch opportunity as Medium Size missions of the Cosmic Vision programme. The launch window is currently planned for between 2022 and 2024. LOFT is designed to exploit the diagnostics of rapid X-ray flux and spectral variability that directly probe the motion of matter down to distances very close to black holes and neutron stars, as well as the physical state of ultradense matter. These primary science goals will be addressed by a payload composed of a Large Area Detector (LAD) and a Wide Field Monitor (WFM). The LAD is a collimated (<1 degree field of view) experiment operating in the energy range 2-50 keV, with a 10 m2 peak effective area and an energy resolution of 260 eV at 6 keV. The WFM will operate in the same energy range as the LAD, enabling simultaneous monitoring of a few-steradian wide field of view, with an angular resolution of <5 arcmin. The LAD and WFM experiments will allow us to investigate variability from submillisecond QPO's to yearlong transient outbursts. In this paper we report the current status of the project

2000. Confidence intervals for population growth rate of organisms with two-stage life histories. -Oikos 88: 335-340.Although life histories can be modelled with great generality using projection matrices, for organisms with life histories that can be accurately described by a simplified set of parameters, e.g. when adult fecundity and mortality are independent of age, more accurate estimates of life table parameters and of population growth rate and its standard error can be readily obtained. Here an analytic method for calculating approximate confidence intervals for population growth rate is given for two-stage life histories that can be described by four variables representing age at first breeding, fecundity per unit time, and juvenile and adult survivorships per unit time. The method is applied to experimental data on Capitella sp. I obtained by Hansen et al., and quite good agreement is found between the analytic and bootstrap estimates of the standard error of l. The analytic estimates were a little conservative, probably because of the way the action of mortality was modelled. Alternative life-history models are briefly discussed, and the desirability of formulating life-history models so that the variables involved are independent of each other is stressed. Analytic estimates of l may be biassed if an inappropriate model is chosen or if variables are not independent and the correlations between them are not measured. To allow for these possibilities, where necessary a conservative approach should be taken to significance testing using the analytic method. R. M. Sibly, Di6. of Zoology, School of Animal & Microbial Sciences, Uni6. of Reading, PO Box 228, Reading, UK RG6 6AJ (r.m.sibly@reading.ac.uk). -F. T.

Abstract. A Life-Table-Response Experiment lasting 78 d was performed to investigate the toxic effects of sediment-associated 4-n-nonylphenol (NP) on growth, reproduction, and survivorship of isolated hermaphrodites of the infaunal polychaete Capitella sp. I. Demographic effects were evaluated using both a fully age-classified and a simple twostage model to estimate population growth rates (). Decomposition analysis was performed to explore the contributions of each of the affected life-history traits to the effects observed on . Elasticity analysis was applied to examine the relative sensitivity of to changes in each of the different life-history traits under different exposure levels.In the lowest NP treatment (14 g NP/g dry mass of sediment) significant stimulatory effects were observed for both asymptotic body volume and average brood size, but these did not result in a significant effect on . Negative effects on brood size, volume-specific fecundity, time to first reproduction, and individual growth rate were significant in the highest NP treatment (174 g/g dry mass), and these effects resulted in a significant reduction in . Decomposition of the two-stage model indicated that the effect of NP on time to first reproduction was a major cause of changes in population growth rate. Although time to first reproduction increased by only ϳ20% in the highest NP treatment relative to the control, it was responsible for more than half (55%) of the effect on . In contrast, perindividual fecundity decreased by 75% but only explained 44% of the effect on . Elasticity analysis of the two-stage model showed that became less sensitive to changes in fecundity and time to maturity, but not to changes in juvenile and adult survival probabilities, with increasing NP exposure.In this study, population growth rate was not significantly affected by NP concentrations lower than those affecting the individual life-history traits. However, since the populationlevel consequences of changes in each trait depend on the starting value of , on the extent to which the other traits are impacted by the toxicant, and on the life-history characteristics of the species under consideration, the application of demographic analyses to chronic toxicity test results is required to link individual-level responses to population-level impacts of toxicant exposure.

Summary 1.A simple two-stage population model was applied to data from a previously published life-table response experiment (LTRE), which examined the toxicity of 4-n-nonylphenol to life-history traits of the polychaete Capitella sp. I. Population growth rates (λ) and the relative sensitivities (= elasticities) of λ to changes in each of the individual life-history traits were calculated. 2. In the present study, the life-history parameters measured in laboratory-reared individuals were manipulated to simulate potential effects of competition and predation on fecundity, time to reproductive maturity and juvenile survival to explore how such factors might influence the sensitivity of population growth rate to toxicant-caused changes in individual life-history traits. 3. Dramatic changes in elasticity patterns among simulations indicate that population growth rates may respond very differently to toxicant exposure depending on the extent to which other demographically limiting factors (e.g. competitors and/or predators) are operating on the population. 4. Effectively predicting the population-level consequences arising from toxicant effects measured on individuals can be improved by exploring the elasticity pattern of λ for the population over a range of realistic ecological situations.