MaineDEP Seagrass Change Analysis

The Maine Department of Environmental Protection (MEDEP), Bureau of Water Quality, Division of Environmental Assessment, Marine Vegetation Mapping Program produces regional seagrass distribution maps on an annual basis, and both MEDEP and the Maine Department of Marine Resources have historically mapped seagrass distribution. The change in seagrass coverage was assessed for extent only (i.e. percent cover changes were not included in the analysis) by comparing all existing seagrass coverage maps to identify the four extent change type categories: 1) Persistent Extent: Areas of seagrass presence in all surveys, recent and historical; 2) New Extent: Areas of seagrass presence in the most recent survey, but absence in all historical surveys; 3) Lost Extent: Areas of seagrass absence in the most recent survey, but presence in any historical survey; and 4) Dynamic Extent: Areas of seagrass presence in the most recent survey, but absence in some historical survey(s) (e.g., beds that have recovered from a previous loss, and beds that have established semi-recently but before the most recent survey). In areas where no recent Maine DEP seagrass surveys are available, no analysis was conducted.缅因州环境保护局（Maine Department of Environmental Protection, MEDEP）下设水质局、环境评估司，其海洋植被制图项目每年都会编制区域海草分布地图；此前，MEDEP与缅因州海洋资源局均开展过海草分布制图工作。本次研究通过比对所有现有海草覆盖地图，仅针对海草覆盖范围的变化开展评估（即分析未纳入盖度百分比变化），并划分出四类覆盖范围变化类型： 1. 持续分布范围：所有历史与近期调查中均存在海草的区域； 2. 新增分布范围：仅在最新一轮调查中发现海草，而所有历史调查中均未出现的区域； 3. 消失分布范围：最新一轮调查中无海草分布，但曾在任意历史调查中存在海草的区域； 4. 动态分布范围：最新一轮调查中存在海草，但在部分历史调查中未出现的区域（例如此前受损后恢复的海草床，以及在近期调查前一段时期内形成但晚于最早历史调查的海草床）。 若某区域无缅因州环境保护局近期海草调查数据，则未开展相关分析评估。