Contrasting effects of solar UV radiation on dissolved organic sources forbacterial growth

Citation
Lj. Tranvik et S. Bertilsson, Contrasting effects of solar UV radiation on dissolved organic sources forbacterial growth, ECOL LETT, 4(5), 2001, pp. 458-463
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
ECOLOGY LETTERS
ISSN journal
1461-023X → ACNP
Volume
4
Issue
5
Year of publication
2001
Pages
458 - 463
Database
ISI
SICI code
1461-023X(200109)4:5<458:CEOSUR>2.0.ZU;2-F
Abstract
The photochemical transformation of dissolved organic matter (DOM) in lakes and oceans has been shown to either reduce or enhance bacterial utilizatio n. We compared the effects of UV radiation on the bacterial use of DOM in a wide range of lakes. Although complex DOM was converted in all irradiated samples into carboxylic acids that are readily utilized by bacteria, irradi ation in several lakes resulted in a decreased ability of DOM to support ba cterial growth. The effect of irradiation on the ability of DOM to promote bacterial growth was a positive function of the terrestrial humic matter, a nd a negative function of indigenous algal production. We suggest that the net effect of irradiation is a result of counteracting but concurrent proce sses rendering DOM either labile or recalcitrant. Humic DOM is predominantl y transformed into forms of increased lability, whereas photochemical trans formation into compounds of decreased bacterial substrate quality dominates in algal-derived DOM. Hence, solar-induced photochemical reactions interac t with microbial degraders in different ways, depending on the origin and n ature of the organic matter, affecting the transfer of energy within aquati c food webs, as well as the degradation and preservation of detrital organi c matter, in different directions.