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(74-01) Using a Leslie matrix model for translating bioassay results with Corophium volutator to population effects. Smit, Mathijs*,1, Jak, Robbert1, 1 TNO-MEP, Den Helder, Netherlands ABSTRACT- For the assessment of sediment contamination bioassays are widely used. It is however impossible to predict directly from the response measured in bioassays the impact on the population of the test species used. In order to evaluate the consequences of contamination on the populations, results from bioassays could be incorporated in population models. For Corophium volutator, a marine species used in sediment bioassays, a population model based on a Leslie matrix model has been developed. Based on growth, reproduction, predation and mortality this model describes the population development of Corophium volutator by the number of individuals in different length classes. The size-structure of the Corophium population, having 2-3 generations per year, varies strongly during the season. This implies for the model that the elements, which describe the biological processes in the matrix, are not constant in time. In the model, it is assumed that the variability of the elements can be described as a function of water temperature. Using the results of a year lasting monitoring study (1995) of the population in the Oesterput, a location in the Dutch Oosterschelde area, the population model is calibrated, resulting in a r-square value of 0.75. The results of another year lasting monitoring study (2000) were used for validation of the model. Effects of contaminated sediments, normally expressed as a certain mortality percentage measured in bioassays, were introduced in the population model as an additional mortality to natural mortality and mortality caused by predation. Effects on the different stages of Corophium in the population and effects on the total population can be visualised. Key words: population model, bioassays, sediment, effects |
