Microbial food webs under severe nutrient limitations: life in the deep sea

• Main Authors: Lochte, K., Boetius, A., Petry, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2000
• Subjects: Arctic; Arctic Ocean; Indian; Laptev Sea; laptev
• Online Access: http://hdl.handle.net/21.11116/0000-0004-6550-0; http://hdl.handle.net/21.11116/0000-0004-6552-E

Particulate organic matter (POM) settling to the floor of the deep-sea is the nutritional basis for benthic life. This material loses most of its labile organic fraction during descent in the water column. Therefore, survival of bacteria in the deep-sea environment depends to a large extent on the production and regulation of extracellular enzymes. The amount of active extracellular enzymes, as well as the relative proportions of enzymes, changes as POM changes in relation to water depth. Studies carried out from shelf to deep sea in the Laptev Sea (Arctic Ocean) and in the Arabian Sea (Indian Ocean) have shown that different levels of food supply are reflected by different concentrations of hydrolytic enzymes. In deep-sea sediment samples, experimental additions of specific substrates induce the production of glucosidases and chitobiases, or repress the activity and production of peptidases. These differences in regulation imply different functional roles of these enzymes in the environment. Enzyme activities in the sediment show significant correlations with parameters related to organic carbon input and may potentially be used as indicators of organic matter turnover in the sediment.