Predicting the impacts of climate change on grey seals (Halichoerus grypus) : implications for UK marine management

Abstract

Climate change impacts are particularly complex for animals at the interface between the marine and terrestrial environments, such as grey seals (Halichoerus grypus) which use these environments for survival and reproduction. For effective species conservation management, we need to consider the potential impacts of climate change. This thesis predicts where environment currently suitable for foraging will be in future, as well as assessing the potential impact of sea level rise (SLR) and future storm surges on grey seal breeding sites. This thesis utilises tracking data for 37 grey seals, in three regions of the North Sea and the Channel (south-east England, Scotland, and France). Chapter II: I demonstrate that there are differences in the habitat associations of foraging and travelling behaviours across regions using a random forest algorithm. Model performance AUC scores ranged from 0.58-0.74 across regions. Chapter III: I predict where currently suitable foraging habitat for grey seals will be in 2050. Predictions suggest that currently suitable foraging areas will decrease in the south-east England region by ~50% and increase for the Scotland and France regions by ~45% and ~65% respectively. There is uncertainty in future predictions due to extrapolation of environmental space from current conditions. Chapter IV: I present the first analysis of SLR and storm surge impacts on UK grey seal breeding sites. I show that a future 1-in-10-year storm will inundate more habitat than a current day 1-in-100-year storm at all breeding sites studied and may lead to increased pup mortality. This thesis highlights ecologically important areas for UK grey seals in the current day and in the future which will inform marine spatial planning and conservation management of UK grey seals. The methods will also be applicable for assessing future climate change impacts to other marine predator species.