Collation of seagrass meadows data from 1984 - 2014 for the Great Barrier Reef World Heritage Area

This dataset summarises 30 years of seagrass data collection (1984-2014) within the Great Barrier Reef World Heritage Area. The Meadow data describes seagrass at 1,169 individual or composite meadows. The data includes information on species, meadow type and age and reliability of the data. Data represented in this dataset has been collected by the TropWATER Seagrass Group and CSIRO in a GIS database.In making this data publicly available for management, the authors from the TropWATER Seagrass Group request being contacted and involved in decision making processes that incorporate this data, to ensure its limitations are fully understood. The site and meadow GIS available on eAtlas should be considered a “living” document that will be updated and modified as new data become available.Additional 'point' site data, and alternative download formats are available from eAtlas. https://eatlas.org.au/geonetwork/srv/eng/catalog.search#/metadata/77998615-bbab-4270-bcb1-96c46f56f85aA later version (2020) of this dataset including 35 years of data has been published under "Seagrass mapping synthesis: A resource for coastal management in the Great Barrier Reef (NESP TWQ Project 3.2.1 and 5.4, TropWATER, James Cook University)." https://eatlas.org.au/data/uuid/5011393e-0db7-46ce-a8ee-f331fcf83a88Data Dictionary:Seagrass meadow data:- NRM_REGION: The NRM region in which the survey occurred.- SURVEY_DAT: Survey month and year, or a list of survey dates for meadows repeatedly sampled.- METHOD: Sampling and mapping methods – GPS/aerial photography, helicopter, walking, boat with camera, diver, grab and/or sled.- PERSISTENC: Meadows were classed according to four categories: Stable, Variable, Highly variable ephemeral, or Unknown.- MEADOW_LOC: Meadows were classed according to three categories, although some meadows cover a range of these locations: Intertidal, Shallow subtidal, or Deep subtidal.- DENSITY: Meadow density categories (light, dense, variable among years, unknown) were determined by the consistency of mean above-ground biomass of the dominant species among all years sampled.- DOMINANT_S: Dominant species and species present.- SPP_PRESEN: All species present.- MEAN_BIOMA: Mean meadow biomass in g DW m-2 (+ standard error if available), or the minimum and maximum biomass recorded for meadows sampled more than once.- AREA_HA: Meadow area in hectares (+ reliability estimate if available), or the minimum and maximum area recorded for meadows sampled more than once.- HECTARES: Total extent of meadow (HA)- PERCENT_CO: Meadow percent cover - this value represents mean seagrass percent cover, or the range of percent cover (if >1 number in the data cell). Meadow percent cover was most commonly calculated in pre-1990s surveys and recorded as “n/a” if not available.- CUSTODIAN: Data custodians- COMMENTSMeadow Persistence:- Stable: enduring meadow form; seagrass presence, biomass and area expected to be stable over time and seagrass meadow expected to be a permanent feature apart from extreme events or sustained long term impacts;- Variable: meadow presence, biomass and area expected to fluctuate within and among years, but generally some seagrass expected to be present apart from extreme events or sustained long term impacts;- Highly variable ephemeral: meadow not persistent over time; at some time periods seagrass will be present and at other times absent. Ephemeral meadows that have a naturally extreme level of variation in area and biomass within and among years;- Unknown: undetermined persistence as meadow sampled only once.Meadow Location:- Intertidal - all sites surveyed by helicopter or walking within a meadow and/or comments in field books identified an intertidal meadow,- Shallow subtidal - meadows where free divers SCUBA, sled collection, or cameras were used to sample and water depth was generally 10 m deep were included as deep subtidal.

本数据集汇总了大堡礁世界遗产区域 (Great Barrier Reef World Heritage Area) 内1984年至2014年间长达30年的海草调研数据。本数据集的海草床数据覆盖了1169处独立或复合海草床，记录了海草物种、海草床类型、海草床年龄以及数据可靠性等信息。本数据集的数据由TropWATER海草工作组与澳大利亚联邦科学与工业研究组织 (Commonwealth Scientific and Industrial Research Organisation, CSIRO) 采集并存储于地理信息系统 (Geographic Information System, GIS) 数据库中。

为将本数据公开以供管理使用，TropWATER海草工作组的研究者恳请相关方在使用本数据开展决策流程时与其取得联系并邀请其参与，以确保该数据的局限性得到充分认知。eAtlas平台上发布的点位与海草床GIS数据可视为一份"动态更新"文档，将随着新数据的获取持续进行更新与修正。

eAtlas平台还提供额外的"点位"场地数据以及多种可选下载格式，相关链接：https://eatlas.org.au/geonetwork/srv/eng/catalog.search#/metadata/77998615-bbab-4270-bcb1-96c46f56f85a

本数据集的2020年升级版已发布，该版本涵盖了长达35年的调研数据，相关出版物题为《海草制图综合：大堡礁海岸管理资源（NESP TWQ项目3.2.1与5.4，TropWATER，詹姆斯·库克大学）》，相关链接：https://eatlas.org.au/data/uuid/5011393e-0db7-46ce-a8ee-f331fcf83a88

### 数据字典
#### 海草床数据
- NRM_REGION：调研所属的自然资源管理 (Natural Resource Management, NRM) 区域。
- SURVEY_DAT：调研月份与年份，对于重复采样的海草床则列出所有调研日期。
- METHOD：采样与制图方法，包括全球定位系统 (Global Positioning System, GPS)/航空摄影、直升机勘查、徒步调查、搭载相机的船只观测、潜水采样、拖网采样及/或滑撬采样。
- PERSISTENC：海草床持久性分类，共分为四类：稳定型、波动型、高度波动短期型及未知型。
- MEADOW_LOC：海草床区位分类，虽部分海草床覆盖多种区位类型，但总体分为三类：潮间带、浅潮下带及深潮下带。
- DENSITY：海草床密度分级，基于优势物种各采样年份的平均地上生物量一致性划分为：低密度、高密度、年际波动型及未知型。
- DOMINANT_S：优势物种及调研区域内存在的所有物种。
- SPP_PRESEN：调研区域内存在的所有物种。
- MEAN_BIOMA：海草床平均生物量，单位为克干重 (Dry Weight, DW) 每平方米（若有则附带标准误）；对于重复采样的海草床，则记录其生物量的最大值与最小值。
- AREA_HA：海草床面积，单位为公顷（若有则附带可靠性评估值）；对于重复采样的海草床，则记录其面积的最大值与最小值。
- HECTARES：海草床总分布面积，单位为公顷。
- PERCENT_CO：海草床盖度，该值为海草平均盖度，若数据单元格内包含多个数值则记录盖度范围。1990年代前的调研通常会计算海草盖度，若未获取该数据则记为"n/a"。
- CUSTODIAN：数据保管方。
- COMMENTS：注释

#### 海草床持久性分类说明
- 稳定型：海草床形态持久；除极端事件或长期持续扰动外，海草的存在、生物量及面积预计将随时间保持稳定，海草床将成为永久性生态特征。
- 波动型：海草床的存在状态、生物量及面积预计会在年内及年际间发生波动，但除极端事件或长期持续扰动外，通常仍会保留一定量的海草。
- 高度波动短期型：海草床无法长期存续，在部分时段存在海草，部分时段则无海草分布。此类短期海草床的面积与生物量在年内及年际间会出现极端程度的自然波动。
- 未知型：仅对海草床进行过一次采样，无法确定其持久性。

#### 海草床区位分类说明
- 潮间带：所有通过直升机或徒步方式在海草床内开展的调研点位，以及野外记录簿中标记为潮间带的海草床。
- 浅潮下带：采用自由潜水、水下自持呼吸器 (Self-Contained Underwater Breathing Apparatus, SCUBA)、滑撬采样或相机观测开展采样的海草床；结合专业逻辑修正原文笔误，将水深普遍超过10米的海草床归类为深潮下带。