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Communication Dans Un Congrès Année : 2018

Combining multi-variate palaeoecological indicators and mining closed gradual patterns for refining past lake dynamics and the induced ecological legacies

Résumé

The overloading of water bodies with nutrients is a widespread ecological alteration. A recent synthesis (CNRS, IFREMER, INRA, IRSTEA) shows that lake ecosystems are partic- ularly concerned by the eutrophication process which results in: (1) ecological disturbances (e.g. invasive species, loss of biodiversity, algal and cyanobacterial blooms), and (2) pub- lic health problems (e.g. water quality degradation due to cyanotoxin production). This makes the restoration of eutrophic freshwaters an environmental top-priority and a key-issue for scienti c research. Accurate assessments of the present-day lake ecosystems state are thus needed. Moreover, long-term retrospective models of lake dynamics must be developed concomitantly to the analysis of natural and anthropogenic modi cations of the catchment,which enhance the external input of sediment and nutrients. Palaeoecological researches are therefore required because they characterize through time the lake’s responses to cumula- tive changes caused by natural (e.g. climate) and anthropogenic impacts (e.g. vegetation clearance, agriculture). They furnish thus fresh insights into a good understanding of the ecological legacies which also determine current lake structure and function, and which must be considered for sustainable lake management. A palaeoecological research was conducted in the hyper-eutrophic Lake Aydat (837 m a.s.l.), located in the Chaˆıne des Puys (French Massif Central). The high resolution and multi-proxy analysis (pollen, non-pollen paly- nomophs, diatoms, sedimentology) was combined to an approach of data mining (extraction of frequent (closed) gradual patterns of multi-variate indicators under temporal constraint) and allow to address the: (1) reference conditions of the lake (prior to extensive human impact) and its natural vari- ability; (2) aquatic changes phases: timing, intensity, frequency, delay; (3) reversibility or directions in which the lake is driven by the long-term cumulative impact (e.g. loss of resilience, ratchet effect); (4) potential drivers: climate vs the diverse range of land uses; (5) degree of resistance/sensitivity and vulnerability of present-day lake ecosytems.
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Dates et versions

hal-02176551 , version 1 (08-07-2019)

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  • HAL Id : hal-02176551 , version 1

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Yannick Miras, Beauger Aude, Jerry Lonlac, Benjamin Legrand, Delphine Latour, et al.. Combining multi-variate palaeoecological indicators and mining closed gradual patterns for refining past lake dynamics and the induced ecological legacies. International Conference on Ecological Sciences, SFEcologie 2018, Oct 2018, Rennes, France. ⟨hal-02176551⟩
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