GREAT-BARRIER-REEF
; LORD HOWE ISLAND
; CLIMATE-CHANGE
; GLOBAL BIODIVERSITY
; TAXONOMIC CLASSIFICATION
; TEMPERATURE-VARIATION
; COMMUNITY STRUCTURE
; MAXIMUM-LIKELIHOOD
; RANGE SHIFTS
; IN-SITU
Environmental anomalies that trigger adverse physiological responses and mortality are occurring with increasing frequency due to climate change. At species' range peripheries, environmental anomalies are particularly concerning because species often exist at their environmental tolerance limits and may not be able to migrate to escape unfavourable conditions. Here, we investigated the bleaching response and mortality of 14 coral genera across high-latitude eastern Australia during a global heat stress event in 2016. We evaluated whether the severity of assemblage-scale and genus-level bleaching responses was associated with cumulative heat stress and/or local environmental history, including long-term mean temperatures during the hottest month of each year (SSTLTMAX), and annual fluctuations in water temperature (SSTVAR) and solar irradiance (PARZ(VAR)). The most severely-bleached genera included species that were either endemic to the region (Pocillopora aliciae) or rare in the tropics (e.g. Porites heronensis). Pocillopora spp., in particular, showed high rates of immediate mortality. Bleaching severity of Pocillopora was high where SSTLTMAX was low or PARZ(VAR) was high, whereas bleaching severity of Porites was directly associated with cumulative heat stress. While many tropical Acropora species are extremely vulnerable to bleaching, the Acropora species common at high latitudes, such as A. glauca and A. solitaryensis, showed little incidence of bleaching and immediate mortality. Two other regionally-abundant genera, Goniastrea and Turbinaria, were also largely unaffected by the thermal anomaly. The severity of assemblage-scale bleaching responses was poorly explained by the environmental parameters we examined. Instead, the severity of assemblage-scale bleaching was associated with local differences in species abundance and taxon-specific bleaching responses. The marked taxonomic disparity in bleaching severity, coupled with high mortality of high-latitude endemics, point to climate-driven simplification of assemblage structures and progressive homogenisation of reef functions at these high-latitude locations.
1.Univ Queensland, Sch Biol Sci, Australian Res Council Ctr Excellence Coral Reef, St Lucia, Qld 4072, Australia 2.Univ Sydney, Sch Life & Environm Sci, Sydney, NSW, Australia 3.Univ Leeds, Fac Biol Sci, Sch Biol, Leeds, W Yorkshire, England 4.Univ Queensland, Ctr Biodivers & Conservat Sci, Sch Biol Sci, St Lucia, Qld, Australia 5.New South Wales Dept Primary Ind, Fisheries Res, Coffs Harbour, NSW, Australia 6.Australian Inst Marine Sci, Townsville, Qld, Australia 7.Solitary Isl Underwater Res Grp, Coffs Harbour, NSW, Australia 8.Southern Cross Univ, Natl Marine Sci Ctr, Coffs Harbour, NSW, Australia 9.James Cook Univ, Coll Sci & Engn, Phys Dept, Marine Geophys Lab, Townsville, Qld, Australia 10.US Natl Ocean & Atmospher Adm, Coral Reef Watch, College Pk, MD USA 11.James Cook Univ, Australian Res Council Ctr Excellence Coral Reef, Townsville, Qld, Australia 12.Univ Sydney, Bosch Inst, Anat & Histol, Sydney, NSW, Australia 13.Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA 14.Univ Technol Sydney, Sch Life Sci, Broadway, NSW, Australia
Recommended Citation:
Kim, Sun W.,Sampayo, Eugenia M.,Sommer, Brigitte,et al. Refugia under threat: Mass bleaching of coral assemblages in high-latitude eastern Australia[J]. GLOBAL CHANGE BIOLOGY,2019-01-01