Benthic decomposition of organic matter at a deep-water site in the Panama Basin

Deep-sea sediments are linked to processes in surface waters by the sinking of participate matter^1-3. These particles represent the supply of energy for the biota of most of the deep sea⁴. The particulate matter that sinks through the water column to a deep-water site (3,856 m deep) in the Panama Basin (North Malpelo Flat; 5°21' N, 81°53' W) consists largely of coccolithophorids and associated macroaggregates⁵. The surface sediments at the same site were extremely depleted in these biogenic materials, suggesting rapid rates of mineralization in a narrow transition layer near the sediment/water interface. Here we present evidence suggesting that 50-85% of the organic carbon that reaches these deep-sea sediments is remineralized within one year. The decomposition of these recently surface-derived particles may account for essentially all of benthic decomposition at this site.