| Summary: | When assessing population level effects of oil spills, data are required onboth the life history parameters of species and toxicity end-points. Weconstructed age-structured matrix models for Arctic copepods to predictthe impact of potential oil spills at the population level. Two matrix modelswere defined, representing the Arctic shelf species Calanus glacialis,spawning in waters all around the Arctic shelf and C. hyperboreus, theArctic oceanic species connected to deep-sea, with a 2x2 and a 4x4 matrixmodel, respectively, which refer to a 2-year and a 4-year life-cycle. Thepost-breeding models included egg production and mortality rates as lifehistoryparameters. Relevant Arctic conditions were taken into account bydefining a winter diapause period, where no mortality is assumed to takeplace. Toxicity information on exposure to oil and oil-components wascollected for Calanus species. It appeared that the life-history parameterwith the highest elasticity in the model was the adult survival, meaning thatchanges therein have most impact on the output, i.e. population size. Thisis because the adult class produces offspring. Published data on mortalityrates in field and laboratory studies appeared too high to maintain viablepopulations. Therefore, we modified these parameter values such that modeledpopulations became viable. Adequate toxicity information on oil andoil components for Calanus species appeared to be scarce, and we thereforeselected pyrene as a model compound. However, reported end points forpyrene were not directly applicable in the matrix model, and we developednew approaches to derive a dose-response relationship from the availabledata. Based on the generic matrix models, simulation models using day-todaycalculation steps were developed to test the effects of various oil spillscenarios at the population level, taking into account a range of exposureconcentrations and exposure durations. The results show that the calculatedpopulation effects are very different, when based on different typesof effect ...
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