The impact of temperature change on the activity and community composition of sulfate-reducing bacteria in arctic versus temperate marine sediments

• Published in: Environmental Microbiology
• Main Authors: Robador, Alberto, Brüchert, Volker, Jørgensen, Bo Barker
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2009
• Subjects: Arctic; Arctic Ocean; Svalbard
• Online Access: https://pure.au.dk/portal/da/publications/the-impact-of-temperature-change-on-the-activity-and-community-composition-of-sulfatereducing-bacteria-in-arctic-versus-temperate-marine-sediments(934ec270-d2a6-11de-a30a-000ea68e967b).html; https://doi.org/10.1111/j.1462-2920.2009.01896.x

Arctic regions may be particularly sensitive to climate warming and, consequently, rates of carbon mineralization in warming marine sediment may also be affected. Using long-term (24 months) incubation experiments at 0°C, 10°C and 20°C, the temperature response of metabolic activity and community composition of sulfate-reducing bacteria were studied in the permanently cold sediment of north-western Svalbard (Arctic Ocean) and compared with a temperate habitat with seasonally varying temperature (German Bight, North Sea). Short-term 35 S-sulfate tracer incubations in a temperature-gradient block (between -3.5°C and +40°C) were used to assess variations in sulfate reduction rates during the course of the experiment. Warming of arctic sediment resulted in a gradual increase of the temperature optima (T opt ) for sulfate reduction suggesting a positive selection of psychrotolerant/mesophilic sulfate-reducing bacteria (SRB). However, high rates at in situ temperatures compared with maximum rates showed the predominance of psychrophilic SRB even at high incubation temperatures. Changing apparent activation energies (E a ) showed that increasing temperatures had an initial negative impact on sulfate reduction that was weaker after prolonged incubations, which could imply an acclimatization response rather than a selection process of the SRB community. The microbial community composition was analysed by targeting the 16S ribosomal RNA using catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH). The results showed the decline of specific groups of SRB and confirmed a strong impact of increasing temperatures on the microbial community composition of arctic sediment. Conversely, in seasonally changing sediment sulfate reduction rates and sulfate-reducing bacterial abundance changed little in response to changing temperature.