Hydrological contingency: drying history affects aquatic microbial decomposition

Climate change, land use intensification, and water abstraction magnify the frequency and severity of droughts but also result in totally unnatural hydrological patterns. Longer and more severe droughts slow down organic matter decomposition, whereas the effect of drying history, i.e. the specific s...

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Bibliographic Details
Published in:Aquatic sciences 2018-07, Vol.80 (3), p.1-12, Article 31
Main Authors: Arroita, Maite, Flores, Lorea, Larrañaga, Aitor, Chauvet, Eric, Elosegi, Arturo
Format: Article
Language:English
Subjects:
Aeration
Biodiversity and Ecology
Biological activity
Biomass
Biomedical and Life Sciences
Climate change
Contingency
Decomposition
Disks
Drought
Drying
Ecology
Environmental impact
Environmental Sciences
Freshwater & Marine Ecology
Fungi
Hydrology
Land use
Leaf litter
Leaves
Life Sciences
Marine & Freshwater Sciences
Microbial activity
Microcosms
Microorganisms
Oceanography
Organic matter
Research Article
Sequencing
Sporulation
Stagnant water
Stagnation
Streams
Stress
Stresses
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Summary:Climate change, land use intensification, and water abstraction magnify the frequency and severity of droughts but also result in totally unnatural hydrological patterns. Longer and more severe droughts slow down organic matter decomposition, whereas the effect of drying history, i.e. the specific sequence of different conditions to which organic matter is exposed, has seldom been addressed. Drying history could have important consequences for microbial communities colonizing and decomposing leaf litter in streams given the rapid fluctuations in microbial composition and processes. We studied whether the effects of drought-related impacts (stagnation, drying and both) on microbial activity and leaf litter decomposition are affected by the timing when peak stress (stagnation or drying) occurs, and whether the effect of the drying history is consistent among the three different stress types. In laboratory microcosms, we recreated areas with flowing water (aerated water), isolated pools with stagnant water (non-aerated water) and dry beds (dry microcosms). Combining these conditions and their sequence, we created nine treatments (ten with the control) differing in stress type (stagnation, drying, both) and timing of peak stress (early, middle, late), and measured fungal biomass, sporulation, microbial respiration, and microbial decomposition of alder leaf disks. The effects of drought-related stress conditions were not consistent among response variables. However, disturbances were systematically more detrimental to decomposition in early stages, resulting in a lower fungal biomass and activity, and reduced microbial litter decomposition. These results suggest that the effects of stress on decomposition-associated variables depend not only on the intensity of the stress, but also on its timing, with early stress and its legacy effects having greatest impact on leaf litter decomposition.
ISSN:1015-1621
1420-9055
DOI:10.1007/s00027-018-0582-3