Modelling the effect of season, sex and body size on the three-spined stickleback, Gasterosteus aculeatus, cellular innate immunomarkers: a proposition of laboratory reference ranges
Abstract
Due to their sensitivity to environmental contamination and their link with fish health status, innate immunomarkers are of great interest for environmental risk assessment studies. Nevertheless, the lack of knowledge about the effect of confounding factors can lead to data misinterpretation and false diagnoses. The aim of this study was to evaluate the impact of three confounding factors (season, sex and body size) on laboratory three-spined stickleback innate immunomarkers. Stickleback immunomarkers present a strong seasonality with higher immune capacities in late winter-early spring and a disturbance during the spawning period in late spring-summer. Sex and body size have seasonally-dependant effect on almost all tested immunomarkers. Laboratory reference ranges were designed using modelling tools and compared with data obtained from in vivo chemical expositions. The predictive power of the model was varying between immunomarkers, but the control data of the in vivo experiments were globally well-adjusted in the laboratory reference ranges. Moreover, some statistical effects of the in vivo exposures were correlated with an augmentation of data outside the reference ranges, indicating a possible harmful effect for the organisms. The reference ranges designed here for laboratory conditions seem to be attractive in biomonitoring studies and should be tested in field condition.