Macroalgal coverage from video surveys of long spined sea urchin (Centrostephanus rodgersii) barrens habitat, eastern Tasmania, Australia (2001-2002)

The macroalgal cover was recorded from video surveys of the spatial extent of C. rodgersii "barrens" on rocky reef habitats using a towed underwater video system. Sampling took place at 13 regions along the east coast of Tasmania, each comprising 3 subsites. Thus, at each site, ca. 6-7 km of inshore rocky reef was surveyed for barren habitat using this method, with the entire survey covering > 80 km of reef. Substratum types were resolved as either "unclassified reef" if the substratum type was unclear (usually where macroalgal cover prevented a clear view of the substratum) or, where the substratum could be discerned, "flat rock" with little apparent relief, "boulder reef", "cobble", "gravel", "pebble", or "sand". Habitat types denoted either C. rodgersii barrens, or habitat dominated by particular canopy-forming species. Absence records are recorded. Macroalagal cover per taxa is measured as percent cover in 3 categories of 'Dominant algal species, >80% of canopy','Common algal species, 40-80% of canopy' and 'Rare algal species,

本研究采用拖曳式水下视频系统（towed underwater video system），通过视频调查塔斯马尼亚东海岸岩礁生境中C. rodgersii荒礁生境的空间分布范围，记录大型藻类盖度情况。采样工作在塔斯马尼亚东海岸的13个区域开展，每个区域包含3个亚站点。以此方法，每个站点约调查6~7千米的近岸岩礁荒礁生境，整体调查覆盖岩礁长度超过80千米。底质类型可分为两类：若底质无法识别（通常因大型藻类覆盖导致视野受阻），则记为‘未分类岩礁’；若可清晰辨别底质，则分为‘低起伏平整岩礁’‘巨砾礁’‘圆石’‘砾石’‘细砾’‘沙质底’。生境类型分为C. rodgersii荒礁生境，或以特定冠层形成物种为主的生境，同时记录无该类生境的缺席数据。各分类群的大型藻类盖度以百分比盖度划分为三类：‘优势藻类（冠层占比>80%）’‘常见藻类（冠层占比40%~80%）’以及‘稀有藻类，’