EGU21-6915, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Lake microbial communities are not resistant or resilient to repeated large-scale natural pulse disturbances 

Katie Brasell1,2, Jamie Howarth3, John Pearman1, Sean Fitzsimons4, Xavier Pochon1,2, Anastasija Zaiko1,2, Kevin Simon2, Marcus Vandergoes5, and Susanna Wood1
Katie Brasell et al.
  • 1Cawthron Institute, Nelson, New Zealand
  • 2University of Auckland, Auckland, New Zealand
  • 3Victoria University of Wellington, Wellington, New Zealand
  • 4University of Otago, Dunedin, New Zealand
  • 5GNS Science, Lower Hutt, New Zealand

Opportunities to study and understand community level responses to extreme natural pulse disturbances in unaltered ecosystems are rare. Lake sediment records that span thousands of years can contain well resolved sediment pulses, triggered by earthquakes. These paleo-records provide a means to study repeated pulse disturbance and the processes of resistance (insensitivity to disturbance) and ecological resilience (capacity to regain structure, function and process). In this study, DNA preserved in lake sediment layers was extracted from a sediment core from a lake in a near-natural catchment.  Metabarcoding and inferred functions were used to assess the lake microbial community over the past 1,100 years – a period that included four major earthquakes. Microbial community composition and function differed significantly between highly perturbed (postseismic, c. 50 yrs) phases directly after the earthquakes and more stable (interseismic, c. 260 yr) phases, indicating a lack of community resistance to natural pulse disturbances. A decoupling between community structure and function in successive postseismic phases suggest potential functional redundancy in the community. Significant differences in composition and function in successive interseismic phases demonstrates the communities are not resilient to large scale natural pulse disturbances. The clear difference in structure and function, and high number of indicator taxa in the fourth interseismic phase likely represents a regime shift, possibly due to the two-fold increase in sediment and terrestrial biospheric organic carbon fluxes recorded following the fourth earthquake. Large pulse disturbances that enhance sediment inputs into lake systems may produce an underappreciated mechanism that destabilises lake ecosystem processes. 

How to cite: Brasell, K., Howarth, J., Pearman, J., Fitzsimons, S., Pochon, X., Zaiko, A., Simon, K., Vandergoes, M., and Wood, S.: Lake microbial communities are not resistant or resilient to repeated large-scale natural pulse disturbances , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6915,, 2021.