Ultraviolet radiation induces reversal of the bioavailability of DOM to marine bacterioplankton

Author(s)
Ingrid Obernosterer, Richard Sempéré, Gerhard J. Herndl
Abstract

The effect of solar radiation on the bioavailability of dissolved organic matter (DOM) was investigated during a cruise in the Southern Ocean (∼44.5°S, 63°E) in January and February 1999. Seawater was collected in the chlorophyll maximum layer (CML, 30 to 80 m depth) and in deep waters (DW, 200 to 5000 m depth), filtered through 0.2 μm pore-size filters, and exposed to surface solar irradiation for 8 h. The bioavailability of the irradiated DOM and of that in the corresponding dark treatment was subsequently tested in bioassay experiments performed in the dark. Seawater from the CML was also size-fractionated and the effect of solar radiation on the bioavailability of the <20 kDa DOM fraction was compared with that of the bulk DOM. Our results clearly demonstrate that the biological reactivity of DOM from both the CML and DW following exposure to solar radiation is inversely related to the initial bioavailability of the DOM prior to its exposure. The photochemically induced stimulation of the bacterial activity was ∼2-fold higher in the <20 kDa fraction than in the bulk DOM. These results clearly indicate that initially bioreactive DOM can be rendered biologically more recalcitrant by exposure to solar radiation, while DOM of initially low bioavailability can be, at least partly, photochemically transformed to compounds of higher biological reactivity.

Organisation(s)
Functional and Evolutionary Ecology
External organisation(s)
Royal Netherlands Institute for Sea Research
Journal
Aquatic Microbial Ecology
Volume
24
Pages
61-68
No. of pages
8
ISSN
0948-3055
DOI
https://doi.org/10.3354/ame024061
Publication date
03-2001
Peer reviewed
Yes
Austrian Fields of Science 2012
106021 Marine biology
Keywords
ASJC Scopus subject areas
Ecology, Evolution, Behavior and Systematics, Aquatic Science
Sustainable Development Goals
SDG 14 - Life Below Water
Portal url
https://ucris.univie.ac.at/portal/en/publications/ultraviolet-radiation-induces-reversal-of-the-bioavailability-of-dom-to-marine-bacterioplankton(9f11131d-b56f-4e75-97c8-4ebec72176a4).html