Mass falls of crustacean carcasses link surface waters and the deep seafloor

Massive swarms of the red crab, Pleuroncodes planipes (Stimpson 1860), a species of squat lobster, are a dominant functional component of the upwelling ecosystem in the eastern Pacific Ocean (Boyd 1967, Smith et al. 1975). These swarms can wash ashore on the coast creating mass depositions of crustacean carcasses, a striking phenomenon that has been long documented in Baja California and California (Boyd 1967, Aurioles-Gamboa et al. 1994). However, little is known about the fate of crab swarms transported offshore by oceanic currents. In May 2015, using an autonomous deep-sea robot, we discovered an unexpectedly large fall of red crab carcasses (> 1000 carcasses ha-1 ) at 4050 m depth on the abyssal Pacific seafloor (Fig. 1), almost 1500 km away from their spawning areas off the NW American coast. Several questions arise from this novel finding that may help unveil additional close linkages in nutritional transport between processes at the sea surface and the remote abyssal seafloor.