Endocrine disruption: From a whole-lake experiment to a calibrated ecosystem model

An Extended Ecosystem Model for Understanding EE2 Indirect Effects on a Freshwater Food Web and its Ecosystem Function Resilience

“…The epilimnion is defined as the surface layer of water with uniform temperature (ignoring any shallow temporary stratification phenomena), while the hypolimnion is defined as the bottom layer of water, also with uniform temperature. More information about the physico-chemical data used for the model, such as temperature, oxygen, light, organic matter and nutrients, can be found in [12].…”

“…A dynamic ecosystem model was previously built and calibrated in an object-oriented framework using simplified AQUATOX equations and the software package WEST (DHI Water Environment Health, Hörsholm, Denmark) [12,23]. The model consists of a set of objects, each describing the growth of a model population in terms of its biomass concentration using differential equations including biological processes such as assimilation, photosynthesis, respiration, consumption or mortality, and additional processes such as migration, diffusion or loading.…”

“…After an initial phase in water, adult insects "emerge" to the terrestrial environment. The mass balance used for Chaoborus was adapted from the one used for fish in reference [12], with the active respiration (when fish swim) and gamete loss (only a small fraction of gametes results in viable fish) removed. Below only the equations that were changed are presented.…”

“…During this experimental study, a collapse of fathead minnow was measured after one year of exposure to EE2. A mix of reduced gamete production, increased gamete mortality and an increase of both adults and juvenile mortality was hypothesized to explain the collapse of both adult and juvenile fathead minnow due to EE2 addition in reference [12].…”

“…According to Barnes et al [22], integrating trophic complexity is key to understanding how biodiversity affects whole-ecosystem functioning. Therefore, this study takes up the challenge to improve an ecosystem model that was previously developed and successfully calibrated [12], with the addition of Chaoborus, an omnivorous insect that is an important food source for higher trophic levels and preys on lower trophic levels. This extended ecosystem model will be used to confirm and take further the hypotheses on EE2 indirect effects on a freshwater food web [13].…”