Coral bleaching following wintry weather

Abstract

Extensive coral bleaching occurred intertidally in early August 2003 in the Capricorn Bunker group (Wistari Reef, Heron and One Tree Islands; southern Great Barrier Reef). The affected intertidal coral had been exposed to unusually cold (minimum ϭ 13.3ЊC; wet bulb temperature ϭ 9ЊC) and dry winds (44% relative humidity) for 2 d during predawn low tides. Coral bleached in the upper 10 cm of their branches and had less than 0.2 ϫ 10 6 cell cm Ϫ2 as compared with over 2.5 ϫ 10 6 cell cm Ϫ2 in nonbleached areas. Dark-adapted quantum yields did not differ between symbionts in bleached and nonbleached areas. Exposing symbionts to light, however, led to greater quenching of Photosystem II in symbionts in the bleached coral. Bleached areas of the affected colonies had died by September 2003, with areas that were essentially covered by more than 80% living coral decreasing to less than 10% visible living coral cover. By January 2004, coral began to recover, principally from areas of colonies that were not exposed during low tide (i.e., from below dead, upper regions). These data highlight the importance of understanding local weather patterns as well as the effects of longer term trends in global climate.

The use of remote sensing to scale up measures of carbonate production on reef systems: a comparison of hydrochemical and census-based estimation methods

“…Despite the occurrence of bleaching eipsodes in the intervening period that may have reduced live coral cover (Hoegh-Guldberg et al 2005) and observed reductions in net calcification at a long term monitoring site (Silverman et al 2012), these differences arise because of the increased spectral detail available from the multiple image wavebands of the satellite image. While this detail enables a notable improvement on historical reef maps derived from air photos, which were unavoidably generalised, it highlights the methodological differences in the upscaling component of the procedure for estimating carbonate production of entire reef systems.…”

Host–symbiont recombination versus natural selection in the response of coral–dinoflagellate symbioses to environmental disturbance

“…Severe or prolonged exposure to abnormally high or low temperatures may cause physiological stress that disrupts the intracellular symbiosis between photosynthetic dinoflagellates in the genus Symbiodinium (symbiont) and reef-building corals Hoegh-Guldberg et al 2005). For example, increases of a few degrees above normal sea surface temperatures (SSTs) have induced large numbers of symbiotic corals to perish around the world after losing their symbionts (mass bleaching ;Glynn 1993;Hoegh-Guldberg 1999).…”

Remote Sensing of Coral Bleaching Using Temperature and Light: Progress towards an Operational Algorithm

“…This occurs when the symbiosis breaks down under any stressful condition that pushes the symbiosis beyond its limits of stability. The causes or "stressors" can include but are not restricted to: anomalous temperature (both hot and cold), anomalous increasing levels of light, anomalous levels of salinity (both high and low), reduction in water quality (e.g., heavy metals) and diseases [1][2][3][4][5][6][7]. Additionally, partial loss of coral pigmentation can occur during acclimation to high-light conditions [8][9][10] or too low nutrient availability [11].…”