MOSS LANDING, CA When it comes to food, most of the deep sea is a desert. Many seafloor animals feed on marine snowthe organic remnants of algae and animals that live in the sunlit surface waters, far above. However, marine snow only falls as a light dusting and doesn't have much nutritional value. Thus, any other sources of food that reach the deep sea provide a temporary feast. Even bits of dead wood, waterlogged enough to sink, can support thriving communities of specialized animals. A new paper by biologists at the National Evolutionary Synthesis Center and the Monterey Bay Aquarium Research Institute (MBARI) shows that wood-boring clams serve as "ecosystem engineers," making the organic matter in the wood available to other animals that colonize wood falls in the deep waters of Monterey Canyon.
In 2006, marine biologists Craig McClain and Jim Barry used MBARI's remotely operated vehicle Tiburon to place 36 bundles of acacia wood on the canyon floor, 3,200 meters below the sea surface. Five years later, they retrieved the bundles and McClain painstakingly picked out every animal that had colonized the logs.
McClain performed a variety of statistical analyses on the different types of animals found in each of the bundles, looking for differences and similarities. The results were surprising. Even though all of the bundles contained exactly the same type of wood and were placed on the seafloor at the same time, within a few tens of meters of each other, there were huge differences in the numbers and types of animals from one bundle to another.
Some of the bundles had been heavily colonized. The seafloor around and under these bundles was carpeted with tiny wood chips and fecal pellets from wood-boring clams, as well as bacteria and fungi that help decompose this organic matter. Other wood bundles had few, if any animals living in them, and lacked these "halos" of discolored sediment.
McClain's statistical analysis showed that as the wood g
|Contact: Kim Fulton-Bennett|
Monterey Bay Aquarium Research Institute