Potential climate change effects on mussel larvae dispersal in a Danish estuary based on sensitivity analysis of a biophysical model

Larval dispersal is dependent on multiple physical and biotic factors and is a key driver of population connectivity. Connectivity is believed to be important in determining how species will cope in a changing climate by allowing species’ ranges to expand or constrict in response to environmental shifts. In the following study, we couple a 3D physical model system with an individual-based model to answer whether climate change effects on mussel larvae will affect the dispersal and the structure of the demographic connectivity in the Limfjorden. The Limfjorden in Denmark supports a large mussel fishery of the species Mytilus edulis and extensive mussel farming, which may be impacted by changes in larval supply under climate change. We produced scenarios changing the pelagic larval duration, spawning time, and presence of spawning mussels after events of hypoxia, and analysed the changes in potential larval recruitment. The results showed that only the 6-day and 36-day pelagic larval duration scenarios are significantly different from the reference scenario. There was no significant event on changes in spawning time. We described the hydrography of the basins to explain the connectivity results and concluded that severe events of hypoxia could potentially lead to the isolation of the fjord. Overall, this well-connected system is very stable to the changes addressed in this study. It is important to continue the research in this area since the adaptation and evolution of species in a changing ocean will bring discoveries that will be useful for future management and conservation decisions.