National Marine Science Centre, Southern Cross University, Charlesworth Bay, Coffs Harbour, New South Wales, Australia.
PLoS One. 2012;7(11):e49437. doi: 10.1371/journal.pone.0049437. Epub 2012 Nov 16.
Fish assemblages of unconsolidated sedimentary habitats on continental shelves are poorly described when compared to those of hard substrata. This lack of data restricts the objective management of these extensive benthic habitats. In the context of protecting representative areas of all community types, one important question is the nature of the transition from reefal to sedimentary fish assemblages. We addressed this question using Baited Remote Underwater Videos (BRUVs) to assess fish assemblages of sedimentary habitats at six distances from rocky reefs (0, 25, 50, 100, 200, and 400 m) at four sites in subtropical eastern Australia. Distance from reef was important in determining fish assemblage structure, and there was no overlap between reef sites and sedimentary sites 400 m from reef. While there was a gradient in assemblage structure at intermediate distances, this was not consistent across sites. All sites, however, supported a mixed 'halo' assemblage comprising both reef and sediment species at sampling stations close to reef. BRUVs used in conjunction with high-resolution bathymetric and backscatter spatial data can resolve differences in assemblage structure at small spatial scales (10s to 100s of metres), and has further application in unconsolidated habitats. Unless a 'reef halo' assemblage is being examined, a minimum of 200 m but preferably 400 m distance from any hard substrate is recommended when designing broader-scale assessments of fish assemblages of sedimentary habitats.
与硬底质栖息地相比，大陆架上未固结沉积物栖息地的鱼类组合描述较差。这种数据的缺乏限制了对这些广泛的底栖栖息地的客观管理。在保护所有群落类型的代表性区域的背景下，一个重要的问题是从珊瑚礁到沉积物鱼类组合的过渡性质。我们使用诱饵远程水下视频（BRUVs）来评估澳大利亚亚热带东部四个地点的从岩石礁（0、25、50、100、200 和 400 米）的六个距离处的沉积物栖息地的鱼类组合，以解决这个问题。与珊瑚礁的距离对鱼类组合结构的确定很重要，而在 400 米处的珊瑚礁和沉积物之间没有重叠。虽然在中等距离处存在组合结构的梯度，但在不同地点之间并不一致。然而，所有地点都在靠近珊瑚礁的采样站支持由珊瑚礁和沉积物物种组成的混合“晕圈”组合。与高分辨率水深和反向散射空间数据结合使用的 BRUVs 可以在小空间尺度（10 到 100 米）上解决组合结构的差异，并且在未固结栖息地中具有进一步的应用。除非正在检查“珊瑚礁晕圈”组合，否则建议在设计更大范围的沉积物栖息地鱼类组合评估时，从任何硬底质至少 200 米但最好 400 米的距离。
