GBR - Coral mass bleaching extent in 1998 and 2002 by aerial surveys (MTSRF 1.1.5, AIMS)

The purpose of this study was to provide a large-scale documentation of the extent of bleaching, for comparison against SST and other bleaching events.

The data record the large-scale bleaching event on the GBR in 1998, mapped by aerial survey method. Surveys were conducted at a flying height of 160 m and covered a total of 654 reefs. Data are estimated bleaching status of whole reefs, conducted by one experienced observer (RB). The surveys were conducted soon after the hottest period was over, a compromise between ensuring that bleaching on reefs was as advanced as possible but before major mortality had set in. Approximately 42% of reefs bleached to some extent in 1998, with ~18% strongly bleached.

Aerial surveys of the 2002 large-scale (2,000 km) bleaching event on the GBR. Surveys were conducted at a flying height of 160 m over 11 days between 3 March and 20 March 2002 and covered a total of 641 reefs. Data are bleaching status of whole reefs. The surveys were conducted soon after the hottest period was over, a compromise between ensuring that bleaching on reefs was as advanced but before major mortality had set in.

The data allowed to compare GBR-wide spatial patterns of bleaching between 1998 and 2002. In both events, more inshore than offshore reefs bleached. In 2002, ~54% of reefs bleached to some extent with 18% strongly bleached (compared with ~42% of reefs bleached to some extent in 1998 with ~18% strongly bleached). These statistics and the fact that nearly twice as many offshore reefs bleached in 2002 compared to 1998 (41 vs. 21%, respectively) makes the 2002 event the worst bleaching event on record for the GBR.

The data is presented with five-point rating:
5 (60% bleached).

As part of the Reef Atlas project (now the eAtlas) the bleaching observations were interpolated over the whole GBR by Glenn De'ath using Generalized Additive Models with a Quasibinomial fit. This produced a gridded version of the dataset and is available as a KML.

Data format:

As part of the Reef Atlas project (now the eAtlas) the bleaching observations were interpolated over the whole GBR by Glenn De'ath using Generalized Additive Models with a Quasibinomial fit. This produced a gridded version of the dataset and is available as a KML.

Also available is the original bleaching observation data as a shapefile.

References:
- Berkelmans R, De’ath G, Kininmonth S, Skirving WJ (2004) A comparison of the 1998 and 2002 coral bleaching events on the Great Barrier Reef: spatial correlation, patterns, and predictions. Coral Reefs 23: 74–83

Data Location:

This dataset is filed in the eAtlas enduring data repository at: data\MTSRF\GBR_MTSRF-1-1-5_AIMS_Death-G_e-Atlas-maps-code\geomap\reef-data-eric\Coral_Bleaching

本研究旨在大规模记录珊瑚白化的发生程度，以用于与海表温度（Sea Surface Temperature, SST）及其他珊瑚白化事件开展对比分析。

本数据集记录了1998年大堡礁（Great Barrier Reef, GBR）的大规模珊瑚白化事件，通过航空勘测方法完成制图。勘测飞行高度为160米，共覆盖654座珊瑚礁。数据为单名资深观测者（RB）评估得到的整礁白化状态。本次勘测在最热时段结束后不久开展，兼顾了两个核心条件：一是确保珊瑚礁白化已充分显现，二是避免大规模珊瑚死亡已经发生。1998年约42%的珊瑚礁出现不同程度白化，其中约18%为重度白化。

本数据集同时包含2002年大堡礁2000公里尺度大规模珊瑚白化事件的航空勘测数据。本次勘测于2002年3月3日至3月20日的11天内完成，飞行高度仍为160米，共覆盖641座珊瑚礁，数据为整礁白化状态。勘测同样在最热时段结束后进行，以保证白化进程充分且未出现大规模死亡。

本数据集可用于对比1998年与2002年大堡礁全域的珊瑚白化空间格局。两次白化事件中，近岸珊瑚礁的白化比例均高于远岸珊瑚礁。2002年约54%的珊瑚礁出现不同程度白化，其中18%为重度白化；而1998年对应比例分别为约42%与18%。此外，2002年远岸珊瑚礁的白化比例（41%）约为1998年（21%）的两倍，这一统计结果表明2002年大堡礁白化事件为有记录以来最为严重的一次。

本数据集采用五分制评级标准：5级代表60%及以上珊瑚组织发生白化。

作为珊瑚礁图集项目（现更名为电子图集eAtlas）的一部分，Glenn De'ath使用准二项式拟合的广义可加模型（Generalized Additive Models）对所有白化观测数据进行了全大堡礁范围的空间插值，生成了网格化数据集，该数据集可通过KML格式获取。

原始白化观测数据以形状文件（shapefile）格式提供。

参考文献：
- Berkelmans R, De’ath G, Kininmonth S, Skirving WJ (2004) 大堡礁1998年与2002年珊瑚白化事件对比：空间相关性、格局与预测. 《珊瑚礁》(Coral Reefs) 23: 74–83

数据存储位置：
本数据集存储于电子图集（eAtlas）永久数据仓库中，具体路径为：dataMTSRFGBR_MTSRF-1-1-5_AIMS_Death-G_e-Atlas-maps-codegeomap
eef-data-ericCoral_Bleaching