title: Large-amplitude internal waves benefit corals during thermal stress.
abstract: Tropical scleractinian corals are particularly vulnerable to global warming as elevated sea surface temperatures (SSTs) disrupt the delicate balance between the coral host and their algal endosymbionts, leading to symbiont expulsion, mass bleaching and mortality. While satellite sensing of SST has proved a reliable predictor of coral bleaching at the regional scale, there are large deviations in bleaching severity and mortality on the local scale that are poorly understood. Here, we show that internal waves play a major role in explaining local coral bleaching and mortality patterns in the Andaman Sea. Despite a severe region-wide SST anomaly in May 2010, frequent upslope intrusions of cold sub-pycnocline waters due to breaking large-amplitude internal waves (LAIW) mitigated coral bleaching and mortality in shallow waters. In LAIW-sheltered waters, by contrast, bleaching-susceptible species suffered severe bleaching and total mortality. These findings suggest that LAIW benefit coral reefs during thermal stress and provide local refugia for bleaching-susceptible corals. LAIW are ubiquitous in tropical stratified waters and their swash zones may thus be important conservation areas for the maintenance of coral diversity in a warming climate. Taking LAIW into account can significantly improve coral bleaching predictions and provide a valuable tool for coral reef conservation and management.
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany GEOMAR, Helmholtz Center for Ocean Research, Marine Geosystems, Wischhofstraße 1-3, 24148 Kiel, Germany mwall@geomar.de.
authors.forename: M
authors.initials: M
authors.lastname: Wall
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany Phuket Marine Biological Center, 51 Sakdidet Road, 83000 Phuket, Thailand.
authors.forename: L
authors.initials: L
authors.lastname: Putchim
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: G M
authors.initials: GM
authors.lastname: Schmidt
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Jantzen
authors.affiliation: Phuket Marine Biological Center, 51 Sakdidet Road, 83000 Phuket, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Khokiattiwong
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Richter
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D003247:Conservation of Natural Resources; D057894:Coral Reefs; D004777:Environment; D016014:Linear Models; D012623:Seawater; D013312:Stress, Physiological; D013696:Temperature; D014329:Tropical Climate; D014872:Water Movements
keywords: cooling; coral bleaching; global warming; large-amplitude internal waves; solitons