TY - JOUR
T1 - Warming and organic matter sources impact the proportion of dissolved to total activities in marine extracellular enzymatic rates
AU - Baltar, Federico
AU - Moran, Xose Anxelu G.
AU - Lønborg, Christian
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors would like to thank the SeaSim team at AIMS for the help with setting up the experiments. The study was co-financed by the AIMS visiting fellowship program as part of the capability development fund (CDF). F. Baltar was supported by a University of Otago Research Grant.
PY - 2017/4/19
Y1 - 2017/4/19
N2 - 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.
AB - 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.
UR - http://hdl.handle.net/10754/623442
UR - http://link.springer.com/article/10.1007/s10533-017-0334-9
UR - http://www.scopus.com/inward/record.url?scp=85017715364&partnerID=8YFLogxK
U2 - 10.1007/s10533-017-0334-9
DO - 10.1007/s10533-017-0334-9
M3 - Article
VL - 133
SP - 307
EP - 316
JO - Biogeochemistry
JF - Biogeochemistry
SN - 0168-2563
IS - 3
ER -