Dive surveys of long spined sea urchin (Centrostephanus rodgersii) and barrens habitat, Tasmania

The spatial extent of the long spined sea urchin, Centrostephanus rodgersii, was estimated by divers using underwater visual census methods to survey rocky reef habitats at 13 regions along Tasmania's east coast (between Eddystone Point and Recherche Bay). Within each region 3 subsites were surveyed, and within each subsite 4 belt transects were surveyed.

Divers recorded depth, percent substrata type, percent C. rodgersii barrens habitat; abundance of urchins (C. rodgersii and H. erythrogramma), rock lobster (J. edwardsii) and abalone (H. rubra). Divers also recorded algal cover (estimated), C. rodgersii barrens and substratum type using set categories (see below).

研究人员借助潜水员开展水下视觉普查（underwater visual census），对塔斯马尼亚东海岸埃迪斯通角至雷切尔湾沿线的13个岩礁生境区域进行调查，以此估算长棘海胆（*Centrostephanus rodgersii*）的空间分布范围。每个区域内设置3个亚样地，每个亚样地内布设4条条带样带开展调查。

潜水员记录了调查点位的水深、底质类型占比、长棘海胆荒滩生境占比；同时记录了海胆（长棘海胆*C. rodgersii*与*H. erythrogramma*）、岩龙虾*J. edwardsii*以及鲍*H. rubra*的种群丰度。此外，潜水员还采用预设分类标准（详见下文）记录了藻覆盖度（估算值）、长棘海胆荒滩生境及底质类型。