Correlation of dynamic internal waves with foraging activity of marine mammals in the South China Sea

Large-amplitude internal solitary waves and internal tides are common oceanographic features in the South China Sea, which are generated in the Luzon Strait and propagate westward cross the basin area to the continental shelf and hit the east wage of DongSha Atoll. These waves shoal near Dongsha plateau and force nutrients and plankton and potentially entraining fishes, squids, and nutrients into the upper ocean, potentially foraged by cetaceans. Several studies have indicated that dolphins and whales may exploit prey aggregations associated with predictable but ephemeral ocean features, such as upwellings, fronts, and eddies. Prey availability for dolphins in the South China Sea influenced by the aggregative properties of internal waves is speculated and once was reported by one photo in 2005 in a benign sea state. This study presents evidence that internal waves attract and aggregate dolphins by using integrative analysis of current data, pressure data, and passive acoustic monitoring data.