Cold Seep

A cold seep is an area of the ocean floor where fluids rich in hydrogen sulfide, methane and other hydrocarbons escape from the seabed, sometimes pooling into dense brine pools; the seepage is called cold only in a relative sense, since it is somewhat warmer than the surrounding seawater but far cooler than a hydrothermal vent, which reaches temperatures of at least 60 degrees Celsius. Cold seeps support their own specialized communities of species found nowhere else, and over time the chemical reaction between escaping methane and seawater, often driven by bacteria, builds up carbonate rock and reef structures at the seep, including minerals such as ikaite that form as the methane oxidizes. The first cold seep was found in 1983 on the Florida Escarpment in the Gulf of Mexico at a depth of about 3,200 meters, and similar seep ecosystems have since been documented in every major ocean basin, from shallow intertidal waters down to hadal depths beyond 7,000 meters in the Japan Trench.