Bleaching and Mortality Thresholds: How Much Is Too Much?
| Autor: | R. Berkelmans |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Ecological Studies ISBN: 9783319753928 Ecological Studies ISBN: 9783540697749 |
| Popis: | Time-integrated bleaching thresholds are one of a suite of locally specific bleaching indices that have been developed based on in situ measured temperature data. In recent years these have been adopted as an early warning system on the Great Barrier Reef (GBR), augmented by satellite-based early warning systems such as “HotSpots” and “ReefTemp”. The original bleaching thresholds were developed after the 1998 bleaching event, but how well have they performed since then, especially in predicting the 2002 GBR bleaching event? This study reviews the efficacy and accuracy of the time-integrated bleaching thresholds using statistical and empirical techniques. The results show that time-integrated bleaching thresholds accurately predicted bleaching (and non-bleaching) at most reefs in 2002. However, a number of reefs in the central GBR exceeded bleaching thresholds in 2004 and 2005 without bleaching. These anomalies are not explained by selective mortality or other meteorological factors, including global radiation and UV. They are also not explained by pre-season acclimatization. Long-term thermal acclimatization remains the most likely explanation. Mortality thresholds based on 50% mortality of thermally sensitive and locally abundant coral taxa were derived for six reefs that suffered high mortality during past bleaching events. An analysis of these curves in relation to their bleaching thresholds indicates that at most of these sites thermally sensitive taxa die |
| Databáze: | OpenAIRE |
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