THRESHOLDS: How does climate affect baby herring in the North Sea?

Approach

North Sea herring represents a perfect case study, as increased larval mortality in the last decade has been related to changes in temperature and prey abundance/composition, but the mechanisms behind these changes remain unknown. THRESHOLDS will contribute to close these knowledge gaps by 1) measuring physiological indicators of the performance of laboratory-reared and field-caught larvae, 2) resolving prey fields experienced by larvae during their first months of life, and 3) integrating these laboratory and field data to a model to examine bottom-up drivers of larval mortality. We will combine results from the laboratory experiments, field surveys and model simulations in order to determine the impact of prey type, size and abundance on larval herring physiology under controlled laboratory conditions and estimate the energetic cost of feeding at suboptimal prey fields in herring larvae. Furthermore, we will estimate and analyses zooplankton dynamics in the North Sea during fall- and wintertime and explore bottom-up regulation impacting larval herring growth under different climatic conditions. Individual-based simulations will help us to quantify the importance of suboptimal feeding for the overall larval survival