Durham, NC Surplus food can be a double-edged sword for bottom-feeders in the ocean deep, according to a new study in the April issue of Ecology. While extra nutrients give a boost to large animals on the deep sea floor, the feeding frenzy that results wreaks havoc on smaller animals in the seafloor sediment, researchers say.
Descend thousands of feet under the ocean to the deep sea floor, and you'll find a blue-black world of cold and darkness, blanketed in muddy ooze. In this world without sunlight, food is often in short supply.
Animals in the deep sea survive on dead and decaying matter drifting down from above, said marine biologist Craig McClain of the National Evolutionary Synthesis Center. Only about 3-5% of the remains of microscopic plants and animals that feed life at shallower depths actually makes it to the deep sea floor, he explained. "If the ocean's primary production were a 5-pound bag of sugar, that would be the equivalent of a sugar packet."
Collaborating with James Barry of the Monterey Bay Aquarium Research Institute (MBARI), McClain traveled to the deep waters off the coast of California to an area of the ocean floor that receives an additional source of food. In a steep, winding, underwater gorge known as Monterey Canyon similar in size to the Grand Canyon bottom-feeders get a boost from nutrient-rich sediments that slough off the canyon walls and collect on the canyon floor.
"There's typically more food available in the canyon than you would see outside the canyon," Barry explained. "The stuff that rains down from above and accumulates at the base of the cliffs isn't just mud it's food," McClain added. "There are tiny food particles and bacteria in the sediment."
The researchers wanted to understand how the surplus food affected deep sea life on the canyon floor. Buried in the sediment and hidden from view, a diverse world of tiny marine animals snails, worms, crustaceans, clam
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National Evolutionary Synthesis Center (NESCent)