Annual and seasonal bPAR index values for each NRM Region and Waterbody as reported in (NESP TWQ 5.3, AIMS and JCU)

This dataset contains annual and seasonal values of the benthic light (bPAR index) for water quality on the Great Barrier Reef as calculated for each NRM Region (Cape York, Wet Tropics, Dry Tropics, Fitzroy and Mary-Burnett) and waterbody (Closed Coastal, Open Coastal, Midshelf and Offshore) for each water year between 2003 and 2019, as reported in NESP TWQ Project 5.3. Code used to produce these values is also available through eAtlas, as is the daily bPAR data.

The amount of light available for photosynthesis (photosynthetically active radiation, or PAR) is an important determinant of ecosystem health. PAR reaching the bottom of the water column is known as benthic PAR (bPAR). Where there is sufficient light reaching the bottom, seagrasses and corals may thrive. bPAR varies seasonally as a function of surface PAR, but also varies function of both water depth and water quality.

This dataset contains the annual and seasonal values of the bPAR index developed through NESP TWQ Project 5.3.

Methods:
Daily benthic photosynthetically active radiation (bPAR) derived from remote sensing ocean colour observations is used to derive an index for water quality in the Great Barrier Reef (GBR). Daily bPAR observations at a nominal 1km2 resolution are used to calculate a cumulative seasonal and annual light stress experienced by benthic photosynthesising organisms at each pixel. This light stress is aggregated over each NRM region and waterbody of the GBR and scaled to produce an index with a value between 0 (no light penetration to benthic habitats) and 1 (excellent light penetration to benthic habitats).

Boundaries of NRM Regions and water bodies as used here are available as part of the “code” dataset also associated with NESP TWQ Project 5.3 in eAtlas. Spatial information (geographic outlines of GBR NRM regions and waterbodies) is provided as a SpatialPolygons variable “Polys” in the R data file Polys.rda

The full method used to calculate the index is described in the manuscript:
Canto, M. M., Fabricius, K. E., Logan, M., Lewis, S., McKinna, L. I. W., & Robson, B. J. (2021). A benthic light index of water quality in the Great Barrier Reef, Australia. Marine Pollution Bulletin, 169, 112539. https://doi.org/10.1016/j.marpolbul.2021.112539

Format:
This dataset consists of a comma separated variable (CSV) file containing the annual and seasonal values of the bPAR index for each water year from 2003 through 2019. Columns contain:
A) Water Year. Each water year is defined as the period from 1 October in the preceding calendar year through to 30 September of the year in question, so for example the 2003 water year runs from 1 October 2002 through to 30 September 2003, inclusive.
B) NRM Region. Name of NRM management region (Cape York, Wet Tropics, Dry Tropics, Fitzroy or Burnett-Mary).
C) Water Body. Name of water body (Closed Coastal, Open Coastal, Midshelf, or Offshore).
D) Annual bPAR index. Value of the bPAR index calculated over a full water year for the NRM region and waterbody in question. Values range between 0 (very poor light penetration to benthic habitats) to 1 (excellent light penetration to benthic habitats).
E) Wet season bPAR index. Value of the bPAR index calculated over the wet season of the water year in question (i.e. 1 October of the preceding calendar year to 30 April).
F) Dry season bPAR index. Value of the bPAR index calculated over the dry season of the water year in question (i.e. 1 May to 30 September).

References:
Canto, M. M., Fabricius, K. E., Logan, M., Lewis, S., McKinna, L. I. W., & Robson, B. J. (2021). A benthic light index of water quality in the Great Barrier Reef, Australia. Marine Pollution Bulletin, 169, 112539. https://doi.org/10.1016/j.marpolbul.2021.112539

Data Location:

This dataset is filed in the eAtlas enduring data repository at: data\nesp5\5.3_Benthic-light

本数据集包含大堡礁（Great Barrier Reef, GBR）水质相关的底栖光合有效辐射（benthic PAR, bPAR）指数的年度与季节值，该指数基于2003至2019年的每个水文年，按各自然资源管理（Natural Resource Management, NRM）区域（约克角、湿热带、干热带、菲茨罗伊与玛丽-伯内特）及水体类型（封闭近岸、开放近岸、陆架中部与远海）计算所得，相关成果源自NESP TWQ项目5.3。用于生成该数据集数值的代码，与每日bPAR数据一样，均可通过eAtlas平台获取。

可用于光合作用的光量（即光合有效辐射，photosynthetically active radiation, PAR）是决定生态系统健康状态的关键因素之一。抵达水柱底部的PAR被称为底栖光合有效辐射（benthic PAR, bPAR）。当有充足光线抵达海底时，海草与珊瑚可正常繁茂生长。bPAR既随表层PAR呈现季节性变化，同时也受水深与水质状况的影响而发生波动。

本数据集包含通过NESP TWQ项目5.3研发的bPAR指数的年度与季节统计值。

方法：本研究采用基于遥感海洋色观测得到的每日底栖光合有效辐射（bPAR），用于构建大堡礁水质评估指数。以标称分辨率为1平方千米的每日bPAR观测数据为基础，计算每个像素点处底栖光合生物所承受的累积季节性与年度光胁迫量。随后将该光胁迫数据在大堡礁的各NRM区域与水体范围内进行聚合，并通过缩放处理得到取值介于0（无光线抵达底栖生境）至1（光线可极佳抵达底栖生境）的指数。

本研究使用的NRM区域与水体边界，可作为关联至eAtlas平台上NESP TWQ项目5.3的"code"数据集的一部分获取。大堡礁NRM区域与水体的空间信息（地理轮廓）以空间多边形（SpatialPolygons）变量"Polys"的形式存储于R数据文件Polys.rda中。

该指数的完整计算方法详见以下学术论文：
Canto, M. M., Fabricius, K. E., Logan, M., Lewis, S., McKinna, L. I. W., & Robson, B. J. (2021). 澳大利亚大堡礁水质底栖光指数. 海洋污染通报, 169, 112539. https://doi.org/10.1016/j.marpolbul.2021.112539

数据格式：本数据集为逗号分隔值（comma separated variable, CSV）文件，包含2003至2019年每个水文年的bPAR指数年度与季节值。各列信息如下：
A) 水文年：每个水文年的定义为前一日历年10月1日至目标年份9月30日，例如2003水文年的时间范围为2002年10月1日至2003年9月30日（包含首尾两日）。
B) NRM区域：NRM管理区域名称（约克角、湿热带、干热带、菲茨罗伊或伯内特-玛丽）。
C) 水体类型：水体名称（封闭近岸、开放近岸、陆架中部或远海）。
D) 年度bPAR指数：针对对应NRM区域与水体类型，在完整水文年内计算得到的bPAR指数值，取值范围为0（底栖生境光线穿透状况极差）至1（底栖生境光线穿透状况极佳）。
E) 湿季bPAR指数：针对目标水文年湿季（即前一日历年10月1日至4月30日）计算得到的bPAR指数值。
F) 干季bPAR指数：针对目标水文年干季（即5月1日至9月30日）计算得到的bPAR指数值。

参考文献：
Canto, M. M., Fabricius, K. E., Logan, M., Lewis, S., McKinna, L. I. W., & Robson, B. J. (2021). 澳大利亚大堡礁水质底栖光指数. 海洋污染通报, 169, 112539. https://doi.org/10.1016/j.marpolbul.2021.112539

数据存储位置：本数据集存储于eAtlas永久数据存储库的data
esp55.3_Benthic-light路径下。