Variance and rate-of-change as early warning signals for a critical transition in an aquatic ecosystem state: a test case from Tasmania, Australia

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dc.contributor.authorBeck, KKen_AU
dc.contributor.authorFletcher, MSen_AU
dc.contributor.authorGadd, PSen_AU
dc.contributor.authorHeijnis, Hen_AU
dc.contributor.authorSaunders, KMen_AU
dc.contributor.authorSimpson, GLen_AU
dc.contributor.authorZawadzki, AWen_AU
dc.date.accessioned2021-06-03T00:35:36Zen_AU
dc.date.available2021-06-03T00:35:36Zen_AU
dc.date.issued2018-02-21en_AU
dc.date.statistics2021-06-02en_AU
dc.description.abstractCritical transitions in ecosystem states are often sudden and unpredictable. Consequently, there is a concerted effort to identify measurable early warning signals (EWS) for these important events. Aquatic ecosystems provide an opportunity to observe critical transitions due to their high sensitivity and rapid response times. Using palaeoecological techniques, we can measure properties of time series data to determine if critical transitions are preceded by any measurable ecosystem metrics, that is, identify EWS. Using a suite of palaeoenvironmental data spanning the last 2,400 years (diatoms, pollen, geochemistry, and charcoal influx), we assess whether a critical transition in diatom community structure was preceded by measurable EWS. Lake Vera, in the temperate rain forest of western Tasmania, Australia, has a diatom community dominated by Discostella stelligera and undergoes an abrupt compositional shift at ca. 820 cal yr BP that is concomitant with increased fire disturbance of the local vegetation. This shift is manifest as a transition from less oligotrophic acidic diatom flora (Achnanthidium minutissimum, Brachysira styriaca, and Fragilaria capucina) to more oligotrophic acidic taxa (Frustulia elongatissima, Eunotia diodon, and Gomphonema multiforme). We observe a marked increase in compositional variance and rate-of-change prior to this critical transition, revealing these metrics are useful EWS in this system. Interestingly, vegetation remains complacent to fire disturbance until after the shift in the diatom community. Disturbance taxa invade and the vegetation system experiences an increase in both compositional variance and rate-of-change. These trends imply an approaching critical transition in the vegetation and the probable collapse of the local rain forest system. ©2018 American Geophysical Union - Open Accessen_AU
dc.identifier.citationBeck, K. K., Fletcher, M.-S., Gadd, P. S., Heijnis, H., Saunders, K. M., Simpson, G. L., & Zawadzki, A. (2018). Variance and rate‐of‐change as early warning signals for a critical transition in an aquatic ecosystem state: a test case from Tasmania, Australia. Journal of Geophysical Research: Biogeosciences, 123(2), 495-508. doi:10.1002/2017JG004135en_AU
dc.identifier.issn2169-8961en_AU
dc.identifier.issue2en_AU
dc.identifier.journaltitleJournal of Geophysical Research: Biogeosciencesen_AU
dc.identifier.pagination495-508en_AU
dc.identifier.urihttps://doi.org/10.1002/2017JG004135en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/10794en_AU
dc.identifier.volume123en_AU
dc.language.isoenen_AU
dc.publisherAmerican Geophysical Union (AGU)en_AU
dc.subjectDiatomsen_AU
dc.subjectPollenen_AU
dc.subjectCarbonen_AU
dc.subjectNitrogenen_AU
dc.subjectStable isotopesen_AU
dc.subjectTasmaniaen_AU
dc.subjectAustraliaen_AU
dc.subjectAquatic ecosystemsen_AU
dc.titleVariance and rate-of-change as early warning signals for a critical transition in an aquatic ecosystem state: a test case from Tasmania, Australiaen_AU
dc.typeJournal Articleen_AU
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