Benthic and substrate cover data derived from photo-transect surveys in Kubulau, Fiji, 2009-09-16 to 2009-09-21.

Underwater georeferenced photo-transect survey was conducted on September 16-21, 2009 at different sections of the reef flat, reef crest and reef slope in Kubulau, Fiji. For this survey a snorkeler or diver swam over the bottom while taking photos of the benthos at a set height using a standard digital camera and towing a surface float GPS which was logging its track every five seconds. A standard digital compact camera was placed in an underwater housing and fitted with a 16 mm lens which provided a 1.0 m x 1.0 m footprint, at 0.5 m height above the benthos. Horizontal distance between photos was estimated by three fin kicks of the survey diver/snorkeler, which corresponded to a surface distance of approximately 2.0 - 4.0 m. The GPS was placed in a dry-bag and logged its position as it floated at the surface while being towed by the photographer. A total of 9,646 benthic photos were taken. A floating GPS setup connected to the swimmer/diver by a line enabled recording of coordinates of each benthic.
Approximation of coordinates of each benthic photo was done based on the photo timestamp and GPS coordinate time stamp, using GPS Photo Link Software (http://www.geospatialexperts.com). Coordinates of each photo were interpolated by finding the gps coordinates that were logged at a set time before and after the photo was captured.
Dominant benthic or substrate cover type was assigned to each photo by placing 1 points over each image using the Coral Point Count excel program (Kohler and Gill, 2006). Each point was then assigned a dominant cover type, which represented the dominant benthic/substrate feature in the whole photo. Using a hierarchical benthic cover scheme containing four first-level categories (Coral, Algae, Seagrass, Non-living) and thirty second-level categories that was derived from Knudby et al. 2011.
Benthic cover composition summary of each photo scores was generated automatically using CPCE program. The resulting benthic cover data of each photo was linked to gps coordinates, saved as an ArcMap point shapefile, in Geographic Coordinate System WGS 1984.

2009年9月16日至21日，在斐济库布拉乌（Kubulau）的礁坪（reef flat）、礁脊（reef crest）与礁坡（reef slope）不同区段开展了水下地理参考照片样带调查。本次调查中，浮潜者或潜水员在海底上方游动，使用标准数码相机在固定高度拍摄底栖生物（benthos）照片，同时拖拽一台每5秒记录一次轨迹的水面浮标式全球定位系统（Global Positioning System, GPS）。该标准紧凑型数码相机被置于水下防水外壳中，搭配16毫米镜头，在距离底栖生物0.5米的高度拍摄时，可获得1.0米×1.0米的拍摄幅面。照片之间的水平距离通过调查潜水员/浮潜者的三次脚蹼划动估算得出，对应水面行进距离约为2.0至4.0米。GPS装置被装入防水干燥袋，随摄影师拖拽在水面漂浮的同时持续记录自身位置。本次调查共采集9646张底栖生物照片。通过绳索连接至游泳者/潜水员的浮式GPS装置，可记录每张底栖生物照片的拍摄位置坐标。

每张底栖生物照片的坐标近似工作基于照片拍摄时间戳与GPS坐标时间戳，通过GPS Photo Link软件（http://www.geospatialexperts.com）完成。具体通过查找照片拍摄前后设定时间内记录的GPS坐标，对每张照片的拍摄坐标进行插值计算。

采用Coral Point Count Excel程序（Kohler与Gill，2006）为每张图像分配优势底栖或底质覆盖类型：在每张图像上放置1个采样点，为每个采样点赋予优势覆盖类型，该类型代表整张照片中占主导的底栖/底质特征。本次研究采用源自Knudby等人2011年研究的分层底栖覆盖分类体系，包含4个一级类别（珊瑚、藻类、海草、非生物基质）以及30个二级类别。

使用CPCE程序自动生成每张照片的底栖覆盖组成评分汇总结果。将每张照片对应的底栖覆盖数据与GPS坐标进行关联，最终保存为采用世界大地测量系统1984（World Geodetic System 1984, WGS 1984）地理坐标系的ArcMap点形状文件（ArcMap point shapefile）。