Influence of the 2015-2016 El Niño on the record-breaking mangrove dieback along northern Australia coast

S Abhik; Pandora Hope; Harry H Hendon; Lindsay B Hutley; Stephanie Johnson; Wasyl Drosdowsky; Josephine R Brown; Norman C Duke

doi:10.1038/s41598-021-99313-w

Influence of the 2015-2016 El Niño on the record-breaking mangrove dieback along northern Australia coast

Sci Rep. 2021 Oct 14;11(1):20411. doi: 10.1038/s41598-021-99313-w.

Authors

S Abhik¹, Pandora Hope², Harry H Hendon^{2

3}, Lindsay B Hutley⁴, Stephanie Johnson⁵, Wasyl Drosdowsky², Josephine R Brown^{6

7}, Norman C Duke⁸

Affiliations

¹ Bureau of Meteorology, Melbourne, Australia. abhik.climate@gmail.com.
² Bureau of Meteorology, Melbourne, Australia.
³ School of Earth, Atmosphere and Environment, Monash University, Clayton, Australia.
⁴ Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Australia.
⁵ Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, Australia.
⁶ School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Melbourne, Australia.
⁷ ARC Centre of Excellence for Climate Extremes, University of Melbourne, Melbourne, Australia.
⁸ Centre for Tropical Water and Aquatic Ecosystem Research, James Cook University, Townsville, Australia.

Abstract

This study investigates the underlying climate processes behind the largest recorded mangrove dieback event along the Gulf of Carpentaria coast in northern Australia in late 2015. Using satellite-derived fractional canopy cover (FCC), variation of the mangrove canopies during recent decades are studied, including a severe dieback during 2015-2016. The relationship between mangrove FCC and climate conditions is examined with a focus on the possible role of the 2015-2016 El Niño in altering favorable conditions sustaining the mangroves. The mangrove FCC is shown to be coherent with the low-frequency component of sea level height (SLH) variation related to the El Niño Southern Oscillation (ENSO) cycle in the equatorial Pacific. The SLH drop associated with the 2015-2016 El Niño is identified to be the crucial factor leading to the dieback event. A stronger SLH drop occurred during austral autumn and winter, when the SLH anomalies were about 12% stronger than the previous very strong El Niño events. The persistent SLH drop occurred in the dry season of the year when SLH was seasonally at its lowest, so potentially exposed the mangroves to unprecedented hostile conditions. The influence of other key climate factors is also discussed, and a multiple linear regression model is developed to understand the combined role of the important climate variables on the mangrove FCC variation.

Publication types

Research Support, Non-U.S. Gov't