Paper detail

Half-Saturation Constants in Functional Responses

Our aim is to provide an overview of half-saturation constants reported in literature and to explore their consistency with body size. In many ecological models, intake of nutrients by plants and consumption of food by animals is considered to be a hyperbolic function of the nutrient concentration and the food density, respectively. However, data on the concentration (or density) at which half of the maximum intake rate is reached are scarce, limiting the applicability of the computational models. The meta-analysis was conducted on literature published worldwide. Most studies focused on algae and invertebrates, whereas some included fish, birds and mammals. The half-saturation constants obtained were linked to body size using ordinary regression analysis. The observed trends were compared to those noted in reviews on other density parameters. Half-saturation constants for different clades range within one or two orders of magnitude. Although these constants are inherently variable, exploring allometric relationships across different taxa helps to improve consistent parameterization of ecological models.