Coral mortality induced by the 2015–2016 El-Niño in Indonesia: the effect of rapid sea level fall
The 2015–2016 El-Niño and related ocean warming has generated significant coral bleaching and mortality worldwide. In Indonesia, the first signs of bleaching were reported in April 2016. However, this El Niño has impacted Indonesian coral reefs since 2015 through a different process than temperature...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-02-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/14/817/2017/bg-14-817-2017.pdf |
| Summary: | The 2015–2016 El-Niño and related ocean
warming has generated significant coral bleaching and mortality worldwide.
In Indonesia, the first signs of bleaching were reported in April 2016. However,
this El Niño has impacted Indonesian coral reefs since 2015 through a
different process than temperature-induced bleaching. In September 2015,
altimetry data show that sea level was at its lowest in the past 12 years,
affecting corals living in the bathymetric range exposed to unusual
emersion. In March 2016, Bunaken Island (North Sulawesi) displayed up to
85 % mortality on reef flats dominated by <i>Porites, Heliopora</i>
and <i>Goniastrea</i> corals with differential mortality rates by coral
genus. Almost all reef flats showed evidence of mortality, representing
30 % of Bunaken reefs. For reef flat communities which were living at a
depth close to the pre-El Niño mean low sea level, the fall induced
substantial mortality likely by higher daily aerial exposure, at least during
low tide periods. Altimetry data were used to map sea level fall throughout
Indonesia, suggesting that similar mortality could be widespread for shallow
reef flat communities, which accounts for a vast percent of the total extent
of coral reefs in Indonesia. The altimetry historical records also suggest
that such an event was not unique in the past two decades, therefore rapid sea
level fall could be more important in the dynamics and resilience of
Indonesian reef flat communities than previously thought. The clear link
between mortality and sea level fall also calls for a refinement of the
hierarchy of El Niño impacts and their consequences on coral reefs. |
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| ISSN: | 1726-4170 1726-4189 |