Quantifying likely cetacean range shifts in response to global climatic change: implications for conservation strategies in a changing world

Abstract

As with many other taxa, climate change is expected to result in geographic range shifts of cetacean species as they track changes in temperature to remain within their ecological niches. Such changes in geographic range could have implications for the conservation and man- agement of cetaceans. Here, we propose a bioclimatic envelope modelling approach for providing quantitative predictions of how the ranges of cetacean species may respond to changing water temperatures. This combines predictions from habitat niche and 'thermal' niche models for an individual species to determine probable geographic range under specific climatic conditions. However, if this approach is to be used to inform conservation strategies, it is essential that the ability to predict responses to environmental change is validated beyond the period of data collec- tion used to construct the models. Therefore, in addition to validation of modelled current range, we included a step to validate the models' ability to predict previous changes in range over time in response to climatic changes using independent data. We demonstrate this approach using common dolphin Delphinus delphis data from the Northeast Atlantic. The combined model was constructed with data collected between 1980 and 2007, and validated using independent distrib- utional records collected between 1930 and 2006. The validated model was then applied to predict future range between 2010 and 2069, based on projected water temperatures. Thus, the modelling approach is shown to provide the type of information required to help ensure that conservation and management strategies remain effective in the face of a changing climate.