A dynamic energy budget approach to understand and predict potential long-term effects of produced water on copepods in the Barents Sea

The ENERGYBAR project addressed the potential for effects of produced water (PW) on the dominating zooplankton species in the Barents Sea; the copepod Calanus finmarchicus. This species may in some areas reach densities of more than 3000 individuals per cubic meter of seawater. In order to make an assessment of PW effects on copepods in the Barents Sea, a combined approach between experimental studies and modelling was used. From exposure studies on copepods, uptake and elimination of polycyclic aromatic hydrocarbons (PAHs) have been studied in combination with toxicological effects in order to provide input to the development of a toxicokinetics model. In parallel a model dealing with mass and energy conservation in C. finmarchicus has been developed; a "Dynamic Energy Budget"-model (DEB). Using the unique SINTEF/NTNU Sealab culture of this species, basal data on copepod life cycle, life history and energy turnover has been obtained providing input to the DEB model. The project has established effect limits for PW toxicity as well as developed mechanistic model, which can be utilized to predict the potential for toxic effects on copepod populations given different PW emission scenarios. Our approach in combining a copepod culture, custom-made equipment for exposure experiments and model development was a prerequisite to increase the understanding of potential population-level effects of PW spills in the Barents Sea. The Research Council has provided this opportunity for our group over several years, and the delivery of predictive models provide added value of this project for academia, stake holders as well as industry.

The project addresses potential effects of produced water on the copepod Calanus finmarchicus, which has a key role in transferring energy from primary production to higher trophic levels in the North Atlantic and Barents Sea. The main approach is to meas ure changes energy allocation (growth and reproduction) during a normal life cycle in C. finmarchicus and record how these parameter changes during exposure to produced water under controlled laboratory conditions. Based on dynamic energy budget (DEB) the ory a modified DEB model for C. finmarchicus will be developed. Data on uptake and elimination of selected PW components and molecular changes in the copepods will be used to make a toxicokinetic model that will be linked to the DEB model. The aim of the work is to provide effect limits for potential long-term population effects of produced water that can be used in risk and impact modelling, and relate these data to molecular changes that can be used in environmental monitoring. The new models will be ad aptable for implementation as part of ecosystem model frameworks. The outcome of the project will thus benefit both the management and the industry in securing that the risk of environmental impacts from offshore petroleum activities are kept to a minimum .