Effects of sea-level rise and storm surge on Pacific harbor seal habitat : a comparison of haul-out changes at the Russian and Eel River estuaries

Patterns and changes in the distribution of marine mammals can serve as indicators of environmental change. These indicators fill critical information gaps in coastal and marine environments. Coastal habitats are particularly vulnerable to the effects of near- term sea-level rise. In California, Pacific harbor seals (Phoca vitulina richardii) are a natural indicator species of coastal change due to their abundance, wide distribution, and site fidelity. Pinnipeds are marine top predators, and relatively easily observed on land at terrestrial habitats, called haul-outs, essential for resting, pupping, and molting. Increasing inundation from sea-level rise and storm driven flooding have already changed the California coastline. However, little is known about how sea-level rise and increases in storms will alter harbor seal haul-out availability and quality in California. We modeled harbor seal habitat at two typical sand bar-built estuaries under a series of likely sea-level rise and storm scenarios. The primary findings of these scenarios reveal that, over time, habitat at both estuaries decreased with increasing sea-level, and storm enhanced water levels contributed significantly to habitat flooding.