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Medientyp:
E-Artikel
Titel:
Depth-related patterns in microbial community responses to complex organic matter in the western North Atlantic Ocean
Beteiligte:
Brown, Sarah A.;
Balmonte, John Paul;
Hoarfrost, Adrienne;
Ghobrial, Sherif;
Arnosti, Carol
Erschienen:
Copernicus GmbH, 2022
Erschienen in:
Biogeosciences, 19 (2022) 24, Seite 5617-5631
Sprache:
Englisch
DOI:
10.5194/bg-19-5617-2022
ISSN:
1726-4189
Entstehung:
Anmerkungen:
Beschreibung:
Abstract. Oceanic bacterial communities process a major fraction of marine organiccarbon. A substantial portion of this carbon transformation occurs in themesopelagic zone, and a further fraction fuels bacteria in the bathypelagiczone. However, the capabilities and limitations of the diverse microbialcommunities at these depths to degrade high-molecular-weight (HMW) organicmatter are not well constrained. Here, we compared the responses of distinctmicrobial communities from North Atlantic epipelagic (0–200 m), mesopelagic(200–1000 m), and bathypelagic (1000–4000 m) waters at two open-oceanstations to the same input of diatom-derived HMW particulate and dissolvedorganic matter. Microbial community composition and functional responses tothe input of HMW organic matter – as measured by polysaccharide hydrolase,glucosidase, and peptidase activities – were very similar between thestations, which were separated by 1370 km but showed distinct patterns withdepth. Changes in microbial community composition coincided with changes inenzymatic activities: as bacterial community composition changed in responseto the addition of HMW organic matter, the rate and spectrum of enzymaticactivities increased. In epipelagic mesocosms, the spectrum of peptidaseactivities became especially broad and glucosidase activities were veryhigh, a pattern not seen at other depths, which, in contrast, were dominatedby leucine aminopeptidase and had much lower peptidase and glucosidase ratesin general. The spectrum of polysaccharide hydrolase activities was enhancedparticularly in epipelagic and mesopelagic mesocosms, with fewerenhancements in rates or spectrum in bathypelagic waters. The timing andmagnitude of these distinct functional responses to the same HMW organicmatter varied with depth. Our results highlight the importance of residencetimes at specific depths in determining the nature and quantity of organicmatter reaching the deep sea.