Threat to mangroves

Title: Threat to mangroves Description: This indicator shows whether mapped mangrove habitats are within 20 km of the river mouth of a river modelled to emit more than 1 tonne of plastic/year into the ocean. It is based on modelled plastic emissions at river mouths by Lebreton et al. (2017) overlaid with polygon of habitat extents. The calculated plastic emissions are based on upstream activities, where plastic is transported along the rivers to the river mouth. The amount of plastic at the river mouth as well as the distance from the habitat to the river mouth are used to define this indicator. This indicator compares the location of mangrove habitats with modelled plastic emissions from rivers. The plastic emissions are based on Lebreton et al. (2017), which models plastic that is discharged at river mouths, considering plastic with sizes between 0.3 and 500 mm. This study uses annual averages from the 6th version of the point estimates. These points are overlaid with a polygon of habitat extents from UNEP-WCMC Ocean Data Viewer was used to define the habitats. It was dissolved into a 5 by 5 km grid and the habitat area in each cell was calculated. Using these two inputs, the study investigated which habitats were within 20 km of a river that was modelled to emit 1 tonne of plastic/year or more. These two numbers were arbitrarily selected as there are no defined thresholds for when habitats are affected by plastic pollution. The study finds that 54% of mangrove habitats are within 20 km of a river modelled to emit more than 1 tonne of plastic/year. The majority of exposed mangrove habitats are on tide-dominated coasts, and the exposed mangrove habitats are concentrated in southeast Asia, India, and West Africa. This indicator shows the mangrove habitats that are included in this study and whether they are within 20 km of a river modelled to emit more than 1 tonne of plastic/year. This layer is intended for informational, educational and research purposes only. More information about the data layer is available at: https://www.grida.no/publications/537 Source: GRID-Arendal Time period: 1954-2018 (data range for UNEP-WCMC reefs data on which this data layer is based). Original source: https://www.grida.no/publications/537 Partners: GRID-Arendal; University of Bergen; UNEP WCMC; The Modelling House标题：红树林威胁指标 描述：本指标用于展示已测绘的红树林栖息地是否位于某河口20公里范围内，且该河口所在河流经模型模拟后每年向海洋排放的塑料量超过1吨。本指标基于勒布雷顿等人（Lebreton et al., 2017）对河口塑料排放的模型结果，并与栖息地范围的多边形矢量图层叠加得到。 计算得到的塑料排放量基于上游人类活动，塑料经河流输送至河口。本指标通过河口的塑料排放量以及栖息地至河口的距离来定义，并将红树林栖息地的位置与模型模拟的河流塑料排放量进行对比。 此处的塑料排放数据源自勒布雷顿等人2017年的研究，该研究模拟了粒径介于0.3至500毫米的塑料在河口的排放情况。本研究采用了该研究第6版点估计值的年度平均值。将这些点数据与联合国环境规划署世界保护监测中心（UNEP-WCMC）海洋数据查看器提供的栖息地范围多边形图层叠加，随后将其聚合至5×5公里的网格中，并计算每个网格内的栖息地面积。 基于上述两项输入数据，本研究对满足以下条件的栖息地进行了排查：即该栖息地位于某条经模型模拟每年塑料排放量≥1吨的河流河口20公里范围内。选取20公里与1吨这两个参数属于任意设定，因目前尚无关于栖息地受塑料污染影响的明确阈值标准。 研究结果显示，54%的红树林栖息地位于每年塑料排放量超过1吨的河流河口20公里范围内。受影响的红树林栖息地大多分布在潮汐主导型海岸带，且集中于东南亚、印度与西非地区。 本指标展示了本研究纳入的红树林栖息地，以及这些栖息地是否位于每年塑料排放量超过1吨的河流河口20公里范围内。本数据图层仅用于信息展示、教育与研究用途。 如需了解该数据图层的更多信息，请访问：https://www.grida.no/publications/537 数据来源：GRID-Arendal 时间范围：1954-2018年（本数据图层所基于的UNEP-WCMC珊瑚礁数据的时间范围） 原始来源：https://www.grida.no/publications/537 合作机构：GRID-Arendal；卑尔根大学；UNEP-WCMC；The Modelling House