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Consecutive earthquakes temporarily restructured the zooplankton community in an Alpine Lake
Brancelj, A.; Zibrat, U.; Mezek, T.; Brancelj, I.R.; Dumont, H.J. (2012). Consecutive earthquakes temporarily restructured the zooplankton community in an Alpine Lake. Ann. Limnol. 48(1): 113-123. hdl.handle.net/10.1051/limn/2012001
In: Annales de Limnologie = International Journal of Limnology. Masson et Cie/EDP Sciences: Paris. ISSN 0003-4088, more
Peer reviewed article  

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Author keywords
    Competition / earthquake / high-mountain lake / invasion / zooplankton community

Authors  Top 
  • Brancelj, A.
  • Zibrat, U.
  • Mezek, T.
  • Brancelj, I.R.
  • Dumont, H.J., more

Abstract
    Two consecutive earthquakes temporary changed a zooplankton community in a high-mountain Lake Krn (altitude 1383 m a.s.l.). It was dominated by the eurytherm copepod, Cyclops vicinus, until 1998, when the first earthquake hit the lake (EMS=5.6). After the earthquake, the population of C. vicinus collapsed and the thermophilic cladoceran, Ceriodaphnia quadrangula, took over. After the second earthquake in 2004 (EMS=4.0), C. vicinus became untraceable. In 2008, few copepods reappeared and by 2010 they became the sole dominant again. Only Secchi-disc depth showed a statistically significant increase over time, while Ntot, Ptot and temperature showed an increasing trend, yet the relationship was insignificant. To compare multi-parameter properties of the water column, the studied period was divided into Period 1 (before the first earthquake), Period 2 (between earthquakes) and Period 3 (after the second earthquake). A Hotteling T2 test confirmed a statistically significant difference between Periods 1 and 2 & 3 (P<0.01), but not between Periods 2 and 3 (P>0.1). During simple laboratory experiment, specimens of C. vicinus were covered with a thin layer of sediment, to mimic the earthquake's effect on their survival. A hypothesis was that the timing of both earthquakes had been crucial for decimation of C. vicinus population as they re-suspended sediment with hibernating copepodites. As these became subsequently buried they were deprived of a re-activation signal and exposed prolonged anoxic conditions there. C. quadrangula temporary filled the void left by the copepod, which needed 6 years to regain its dominance.

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