Recovery from the 2004 Coral Bleaching Event in the Gilbert Islands, Kiribati

Donner, Simon D.; Kirata, Taratau; Vieux, Caroline

doi:10.5479/si.00775630.587.

Cited by 7 publications

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“…In each of these 18 years, indicator kriging expanded the historical representation of the area that likely experienced bleaching. This is demonstrated in maps ( Fig 4 ) for 2005 in northeastern Caribbean, where coral reef monitoring is common and reporting was relatively dense [ 23 ], and for 2004 in the central equatorial Pacific around Kiribati and Tuvalu, where coral reef monitoring is rare and reporting was opportunistic [ 24 ]. The spatial relationship between the raw observations in these two examples is characterized by their semi-variograms ( Fig 4e and 4f ), which describe the dissimilarity between values as a function of distance.…”

Section: Resultsmentioning

confidence: 99%

A new, high-resolution global mass coral bleaching database

2017

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Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50%) or likely (>66%) probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures.

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Section: Resultsmentioning

confidence: 99%

A new, high-resolution global mass coral bleaching database

2017

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“…Butaritari experiences lower year-to-year variability in SST than Abaiang and Tarawa, which are more directly influenced by current and wind reversals during ENSO events [16] , [47] . Although heat stress in 2004 was lower at Butaritari than at Abaiang and North Tarawa, massive Porites sp.…”

Section: Discussionmentioning

confidence: 99%

“…DHW >4°C·week) may not accurately describe the likelihood of bleaching in locations with high inter-annual temperature variability like the Gilbert Islands; a method using the past inter-annual temperature variability to estimate the bleaching threshold may be more appropriate in these locations [16] . The evidence that bleaching resistance depends on thermal history, from the coral cores and from coral community surveys [47] , suggests that the climatic variability of the Gilbert Islands, particularly those atolls closest to the equator (Abaiang and Tarawa), may have caused the corals to acclimatize to the observed level of heat stress.…”

Section: Discussionmentioning

confidence: 99%

“…Corals in South Tarawa experience similar year-to-year temperature variability to those at Abaiang and North Tarawa, but are subject to greater local human-induced stress due to the proximity to the population and administrative centre of Kiribati [47] . Previous studies have found that local stress reduces bleaching resistance with a given amount of heat stress [11] , [18] .…”

Section: Discussionmentioning

confidence: 99%

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Historical Temperature Variability Affects Coral Response to Heat Stress

2012

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Coral bleaching is the breakdown of symbiosis between coral animal hosts and their dinoflagellate algae symbionts in response to environmental stress. On large spatial scales, heat stress is the most common factor causing bleaching, which is predicted to increase in frequency and severity as the climate warms. There is evidence that the temperature threshold at which bleaching occurs varies with local environmental conditions and background climate conditions. We investigated the influence of past temperature variability on coral susceptibility to bleaching, using the natural gradient in peak temperature variability in the Gilbert Islands, Republic of Kiribati. The spatial pattern in skeletal growth rates and partial mortality scars found in massive Porites sp. across the central and northern islands suggests that corals subject to larger year-to-year fluctuations in maximum ocean temperature were more resistant to a 2004 warm-water event. In addition, a subsequent 2009 warm event had a disproportionately larger impact on those corals from the island with lower historical heat stress, as indicated by lower concentrations of triacylglycerol, a lipid utilized for energy, as well as thinner tissue in those corals. This study indicates that coral reefs in locations with more frequent warm events may be more resilient to future warming, and protection measures may be more effective in these regions.

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“…Despite their small individual sizes and the fact that none actually intersect the equator, nine of the major atolls together block 55% of the total north-south distance between 2 ∘ S and 2 ∘ N -a potentially formidable obstacle to the westward-flowing SEC that also lies within the corridor through which the EUC flows. The Gilbert Islands have been included in several recent assessments of historical and future climate impacts on tropical island ecosystems and civilizations (Donner et al, 2011;Karnauskas and Cohen, 2012;Karnauskas et al, 2016a;Karnauskas et al, 2016b;personal communication). In this paper, we reverse their questions and ask whether the Gilberts, such as the Galápagos, can have a significant influence on the ocean and climate system at scales beyond that of an individual island or archipelago.…”

Section: Introductionmentioning

confidence: 99%

On the climate impacts of atolls in the central equatorial Pacific

2016

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Contrary to the above title, a more typical question might be ‘How does climate variability and change impact atolls (and associated ecosystems and civilizations)?’ While several studies have focused on the effects of island topography on local circulation, equatorial currents and their dynamics play a vital role in the tropical heat balance and therefore global climate through atmospheric teleconnections. The Gilbert Islands, which straddle the equator in the western Pacific, block 55% of the corridor between 2°S and 2°N. Here we explore the potential role of relatively small open‐ocean topographic features, in particular equatorial atolls such as the Gilbert Islands, on the large‐scale climate system. Observations and high‐resolution ocean model simulations spanning the full width of the Pacific basin indicate that, whereas the Gilbert Islands have only a local impact on the Equatorial Undercurrent (EUC), the South Equatorial Current (SEC) is substantially reduced downstream of the islands, resulting in a surface warming and freshening over a ∼1000‐km wide region along the sharp temperature and salinity front defining the eastern edge of the Indo‐Pacific warm pool (IPWP), the heat engine that is a critical player in global climate processes. The simulated mean thermohaline structure in the central and western Pacific, which has previously been shown to be crucial for El Nino‐Southern Oscillation (ENSO) dynamics, is improved by including the Gilbert Islands. Implications for coupled model biases, ENSO simulation and paleoclimate are discussed.

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Recovery from the 2004 Coral Bleaching Event in the Gilbert Islands, Kiribati

Cited by 7 publications

References 0 publications

A new, high-resolution global mass coral bleaching database

A new, high-resolution global mass coral bleaching database

Historical Temperature Variability Affects Coral Response to Heat Stress

On the climate impacts of atolls in the central equatorial Pacific

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