Discovery of a whale fall in the deep sea

Published 2019-11-04

Photo: E/V Nautilus

Recently, the Exploration Vessel Nautilus, operated by the Ocean Explorer Trust, discovered a community of organisms consuming a baleen whale carcass on the Davidson Seamount in the Monterey Bay National Marine Sanctuary at a depth of 3,240 m. Unlike many other discoveries of whale falls in the ocean, crew on the Nautilus found this relatively recent fall in a mid-stage of ecological succession, providing an exciting look into life in the deep sea.

Whale falls are importance influxes of nutrients and energy to the deep sea. This pulse in food availability becomes the foundation of a new ecosystem, which undergoes stages of community succession and provides evolutionary and ecological stepping stones across the ocean. Progression through these stages of succession can last for decades, providing habitat and nutrition from organisms ranging from sharks and octopus to worms and microbes. The concentration of these organisms on the whale fall provides a prime opportunity to scientists to observe and describe new species. There are three general stages of succession and colonization of a whale fall: 1) mobile scavenger stage, 2) enrichment-opportunist stage, and 3) sulfophilic stage. First, a new whale fall community is dominated by large, mobile organisms scavenging the sea floor for food. These scavengers, including sleeper sharks, large amphipods, rattails, and hagfish, strip the flesh from the bones of the whale. After a few months, populations of polychaete worms, crustaceans, and molluscs move in to feed on the remaining biological material and enriched sediments surrounding the fall. For the decades to follow, sulfur-reducing bacteria digest fats in the bones of the whale, releasing hydrogen sulfide. This environment supports a food web of organisms resembling those found at hydrothermal vents. Bacterial mats, mussels, bone-eating worms, and tube worms can all be found on mid- to late-stage whale falls.



Watch the amazing discovery of this whale fall by the Nautilus here: https://www.youtube.com/watch?time_continue=2&v=CZzQhiNQXxU and learn more about the expedition here: https://nautiluslive.org/video/2019/10/17/baleen-whale-fall-becomes-deep-sea-banquet-davidson-seamount.