High-resolution ocean sea ice model outputs to predict species distribution: case study of crabeater seal Lobodon carcinophagus in East Antarctica

Species distribution models (SDMs) quantify the relationship between species presence and environmental factors. They are often used to guide conservation management plans, but limited availability of environmental and biological data in undersampled regions, such as the Southern Ocean, represent an important challenge preventing us from accurately estimating species distributions. We used a weighted ensemble of 4 SDMs to predict crabeater seal Lobodon carcinophagus distribution in East Antarctica. We combined georeferenced occurrence records from multiple open-source databases to fit an SDM ensemble. Environmental data from satellites and a high-resolution sea ice–ocean model were used to fit SDMs. Outputs were compared to evaluate if predicted crabeater seal distributions were similar. Sea-ice-related variables and the distribution of Antarctic krill, the main prey of crabeater seals, were identified as key drivers of crabeater seal distribution. The inclusion of prey in our SDMs improved their performance, highlighting the importance of predator–prey relationships. We emphasise the importance of including a comprehensive suite of ecologically relevant environmental predictors in SDMs, as a reduced set may not capture key drivers of distribution. We reiterate that prior to estimating habitat distribution for any species, an evaluation of the ability of an ocean model to realistically reproduce observed past environmental conditions within the area of interest is necessary. These steps add rigour to SDM development and build confidence when using high-resolution coupled ocean models to predict the fate of top-level predators and inevitably the ecosystem as a whole.