Coral juvenile belt transects

Belt surveys were conducted to determine coral juvenile densities and size frequencies within each EcoRRAP monitoring plot. Methods followed AIMS LTMP survey protocols (SOP10: AIMS_LTMP_SOP10v2_Benthic-surveys-photography_2020_DOI.pdf). Briefly:Methods: Run tape in straight line between plot star pickets. Really big bommies that need to be circumnavigated to pass on the more shallow side on reef slope, others crossed Survey slate-width belt of 0.34 x 5.00 m along the transect line on the upward side of the tape (=up the reef slope). Skip >1 m patches of sand (ie extend the transect beyond 5 m by the length of the sand patch). Record all living HC juveniles ≤ 5 cm, to whatever taxonomic resolution possible - at least family, or genus. Estimate size of each to nearest cm. Avoid remnant patches of corals Record ‘% available substratum’ = estimate % cover of TA+CCA+MA (I also include large rubble as habitable space). This follows LTMP protocol: “proportion of substrate occupied by algae. We used total algal cover as corals do not only settle on coralline algae and we wished to preserve the possible negative effects of macroalgae.” Record turf algal height (in mm with calliper) at a single point each meter for the first 3 m of the transect. Find nearest turf to each meter mark. Estimate amount of sediments on surface: 0, none; 1, thin layer; 2, considerable amount of sediment but still removable by fanning, and 3, thick deep layer of sediment. Estimate the slope of the reef as either 0, 30, 60 or 90 degrees Photograph unknown juveniles, record time of pic so we can attribute it to plot, and its size. Transect length 4m in deep, 5m in shallows.

本研究通过样带调查法，测定各EcoRRAP监测样地内珊瑚幼体的密度与尺寸频率分布。调查方法遵循澳大利亚海洋科学研究所（Australian Institute of Marine Science, AIMS）长期监测项目（Long-Term Monitoring Program, LTMP）的标准操作流程SOP10（对应文档：AIMS_LTMP_SOP10v2_Benthic-surveys-photography_2020_DOI.pdf）。简要流程如下：
1. 基线布设：在样地的桩柱之间沿直线布设测绳。若遇到巨型礁丘，需绕行至礁坡较浅一侧通过；其余区域则直接横穿。
2. 样带布设：沿测绳朝向礁坡上方一侧，布设宽度为0.34m、长度为5.00m的样带（宽度与调查记录板一致）。若遇到长度超过1m的沙斑，则跳过该区域，并将样带延长沙斑的长度以补足原5m的样带总长。
3. 幼体记录：记录所有体长≤5cm的活硬珊瑚（Hard Coral, HC）幼体，尽可能提升分类鉴定精度，至少需达到科或属水平。将每只幼体的体长估算至最接近的厘米数，注意避开珊瑚残体斑块。
4. 有效基底占比记录：估算可供珊瑚附着的基底占比，即藻席藻类（Turf Algae, TA）、结壳珊瑚藻（Crustose Coralline Algae, CCA）与大型藻类（Macroalgae, MA）的总盖度，同时将大型碎石视为可栖息空间。该方法遵循LTMP的标准规程："基底被藻类占据的比例。我们采用总藻类盖度作为指标，因为珊瑚不仅可在结壳珊瑚藻上附着，同时我们希望保留大型藻类可能带来的负面影响"。
5. 藻席高度测量：在样带前3m区段内，于每米标记点处选取距标记最近的藻席群落，使用游标卡尺测量其高度（单位：mm）。
6. 沉积物覆盖度估算：对基底表面的沉积物量进行分级估算：0代表无沉积物；1代表仅存在薄层沉积物；2代表沉积物量较多但仍可通过拂扫去除；3代表存在厚层且深厚的沉积物堆积。
7. 礁坡坡度估算：将礁坡坡度分为0°、30°、60°、90°四个等级进行估算。
8. 未知幼体拍摄：对无法鉴定的珊瑚幼体进行拍照，并记录拍摄时间，以便关联至对应样地及幼体尺寸信息。
9. 样带长度调整：深水区样带长度为4m，浅水区样带长度为5m。