Effects of Sea-Level Rise on Northern Elephant Seals in Point Reyes Peninsula

Abstract

 

Northern elephant seals (Mirounga angustirostris) historically experienced a significant decrease in population to the brink of extinction, but have since recovered and re-colonized in former breeding/haul-out sites. The coast of Point Reyes Peninsula is one location where the recent increase in population has resulted in the expansion of colonies and breeding sites. This study used Maxent to build species distribution models by using occurrence data and environmental predictor variables. Maxent models identified suitable breeding habitats and suggested that human disturbance, geomorphology, mean wave height, and slope were important explanatory variables. Thus, protection from disturbance and safety from the effects of storms were critical factors for the seals to select breeding sites.

Sea level rise (SLR) models were also built for three scenarios (0.5, 1.0, 1.4m in 2050, 2081, and 2099, respectively). These SLR scenarios indicated that current habitats and high suitability areas would mostly be inundated by 2050. As rising sea levels would undoubtedly affect the Point Reyes coast that possesses limited space for the seals to colonize, conservation measures in a response to SLR should be taken in the near future. The resulting analyses can be used for a better understanding of the species and contribute to effective protection and management of the species within Point Reyes National Seashore.