Warming and organic matter sources impact the proportion of dissolved to total activities in marine extracellular enzymatic rates

Author(s)
Federico Baltar, Xose Anxelu G. Moran, Christian Lonborg
Abstract

Extracellular enzymatic activities (EEAs) are the rate-limiting step in the degradation of organic matter. Extracellular enzymes can be found associated to cells or dissolved in the surrounding water. The proportion of cell-free EEA constitutes in many marine environments more than half of the total activity. This high proportion causes an uncoupling between hydrolysis rates and the actual bacterial activity. However, we do not know what factors control the proportion of dissolved relative to total EEA, nor how this may change in the future ocean. To resolve this, we performed laboratory experiments with water from the Great Barrier Reef (Australia) to study the effects of temperature and dissolved organic matter sources on EEA and the proportion of dissolved EEA. We found that warming increases the rates of organic matter hydrolysis and reduces the proportion of dissolved relative to total EEA. This suggests a potential increase of the coupling between organic matter hydrolysis and heterotrophic activities with increasing ocean temperatures, although strongly dependent on the organic matter substrates available. Our study suggests that local differences in the organic matter composition in tropical coastal ecosystems will strongly affect the proportion of dissolved EEA in response to ocean warming.

Organisation(s)
Functional and Evolutionary Ecology
External organisation(s)
University of Otago, King Abdullah University for Science and Technology, University of Queensland
Journal
Biogeochemistry: an international journal
Volume
133
Pages
307-316
No. of pages
10
ISSN
0168-2563
DOI
https://doi.org/10.1007/s10533-017-0334-9
Publication date
05-2017
Peer reviewed
Yes
Austrian Fields of Science 2012
Microbiology
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/warming-and-organic-matter-sources-impact-the-proportion-of-dissolved-to-total-activities-in-marine-extracellular-enzymatic-rates(df19dc9f-1b8f-444c-ae06-dc6a2c711abd).html