Barkley Canyon food web: Life in a cold seep community
A methane 'cold seep' supports bacterial mats (the white stuff), which transforms methane into energy through process called chemosynthesis, and supports a community of unique organisms.
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In the deep waters of the Barkley Canyon, part of the food web is powered by chemosynthesis and many extremophiles thrive here, similar to the Endeavour Ridge hydrothermal vent community.
However, unlike the Endeavour site, Barkley Canyon is a “cold seep” environment, where chemical rich fluids containing methane and sulfides seep into the surrounding seawater. |
 Chemosynthetic bacteria
(image courtesy of WHOI)
Bacteria grow in mats around the vents and near methane seeps. As in the hydrothermal vent communities, many Barkley Canyon organisms rely on chemosynthetic bacteria for energy. |
Also in Barkley Canyon are layers of gas hydrates. These are formed when carbon-dioxide, methane, and other hydrocarbon gases combine with water at low temperatures and high pressures - conditions found in the deep sea greater than 600 meters deep.
These gas hydrates look like ice - the methane gas interacts with water to form crystalline "cages" that enclose and trap the gas molecules.
Gas hydrates are a huge reservoir of methane, which is a fossil fuel and green-house gas. |
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Consumer organisms feed on mats of free-living, methane-consuming microbes found on hydrate outcrops. These bacterivores include snails, crabs and crawling worms. Strange clams, mussels and tubeworms live here too and benefit by “farming” sulfide-dependent microbes within their bodies. Symbiosis is a pretty good way to survive, as some clam and mussel species are so abundant that biologists refer to them as clam or mussel fields. These primary consumers provide food for other consumers such as fish, squid, octopus, and crabs. Detrivores include crabs and fish.
Barkley Canyon is also home to creatures that we usually associate with the deep sea. These animals exist on “marine snow”, a term that describes bits of food energy originally produced by photosynthesis that drift downward from the sun-lit waters above. The Canyon also receives sediments and organic material that has drifted along the sea floor from areas as near as Folger Passage! Corals, sponges, anemones, brittle stars, and so many other species obtain energy by filtering the water or muds for food morsels.
 FOOD WEB Lesson Plan
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