Impact of pressure on bacterial activity in water columns situated at the European continental margin

• Published in: Netherlands journal of sea research 1994, Vol.33 (1), p.29-35
• Main Author: Poremba, Knut
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; bacterial activity; baroadaption; Biological and medical sciences; correlation; deep-sea; Fundamental and applied biological sciences. Psychology; Marine; Microbial ecology; Offshore water column; Various environments (extraatmospheric space, air, water)
• ISSN: 0077-7579
• DOI: 10.1016/0077-7579(94)90048-5

The vertical profiles of bacterial abundance and activity were measured in water columns situated at the European continental margin of the Celtic Sea in July 1993 and January 1994. The stations lay in the middle of a submarine canyon (depth: 3713 m) and at the base of the continental slope (depth: 4480 m). The bacterial numbers were counted using epifluorescence microscopy, the cell multiplication was determined as 3H-thymidine uptake, the accumulation of proteinaceous biomass was measured as 3H-leucine uptake, and the impact of pressure on bacterial activity was studied in experiments under pressure conditions between 1 and 450 atm. In upper water layers or in July, the ratio of leucine uptake compared to thymidine uptake was generally higher than in deep layers or in January. The populations of all water layers generally preferred their in situ pressure, especially in July, while in January the barotolerance of the upper communities in 10 to 150 m water depth increased. A comparison of per-cell activity under in situ pressure showed that cells close to the bottom occasionally possessed higher specific activities than in the euphotic water layer. These findings indicate that the performance of experiments under elevated pressure is highly recommended, if the detection of phenomena such as those shown here in the deep sea is wanted.