Patterns in the distribution of the crinoid community at Davies Reef, central Great Barrier Reef

Surveys of the diversity and distribution of crinoids were conducted on Davies Reef between 1981 and 1983.A total of 25 fives sites were sampled within 5 habitat types. The habitats sampled were the reef slope, reef crest, moat, lagoon and back reef. The reef slope was further divided into three depth habitats (5m, 10m and 15m). The reef crest was sampled at 0m and the moat, lagoon and back reef were sampled at 5m.A sampling site consisted of 25 adjacent 1m² quadrats along a depth contour on the reef. Four replicate sampling sites were examined in each habitat, except for the 15m reef slope habitat. Within each quadrat, all crinoids on the surface and those occurring within the substrate, to a depth of about 50cm, were recorded. The position of each crinoid within the quadrat was recorded and crinoids collected for later preservation and identification in the laboratory.Habitats were also ranked with respect to the following external factors: current, energy, depth, sediment and coral cover. This research was undertaken to determine the structure of the crinoid community at Davies Reef by investigating species diversity and distribution across a variety of reef habitats. This allowed comparisons with other reef communities, such as coral, fish and sponges from the same reef.This survey was also used to establish suitable field and analytical techniques to enable more intensive local distributional studies and more extensive between-reef studies. Extensive taxonomic revisions of some of the comasterid genera were published in: "Rowe FWE, Hogget AK, Birtles RA and Vail LL (1986) Revision of some comasterid genera from Australia (Echinodermata: Crinoidea), with descriptions of two new genera and nine new species. Zool J Linn Soc 86:197-277." New species names from this publication are included in the following list of crinoids identified.Crinoid species identified from within quadrats: Comasteridae:Comanthus parvicirrusComanthus samoanus = Comanthus sp. cf. C. wahlbergii (J. Muller)Comanthus sp. AComasterinae n. gen. n. sp. A = Oxycomanthus mirusComasterinae n. gen. n. sp. B = Oxycomanthus exilisComanthina schlegeliComantheria alternansComantheria briareus: to be included with Comantheria alternansComanthus luteofuscum = Clarkcomanthus luteofuscumComanthus timorensis = Clarkcomanthus littoralisComaster multifidusComaster gracilisComatella nigraComatella stelligeraComatella maculataComatula purpureaComissia pectiniferaColobometridae:Cenometra bella Petasometra claraeMariametridae:Stephanometra oxyacantha Tropiometridae:Tropiometra afraAdditional species collected outside quadrats:Comasteridae:Comanthus bennetti = Oxycomanthus bennettiComanthina sp. A = Comanthina nobilisComantheria n. sp. A = Comanthus mirabilisCapillaster multiradiatusColobometridae:Colobometra perspinosaOligimetra serripinna

1981年至1983年间，研究者于戴维斯礁（Davies Reef）开展了海百合（Crinoid）多样性与分布格局的系统调查。本次调查共在5类生境中设置了总计25个采样位点。所调查的生境包括礁坡（reef slope）、礁脊（reef crest）、礁沟（moat）、泻湖（lagoon）以及礁后区（back reef）。其中礁坡进一步被划分为3个深度亚生境（5m、10m与15m）；礁脊的采样位点设置于0m水深处，礁沟、泻湖与礁后区的采样位点则设置于5m水深处。

每个采样位点由沿礁体等深线分布的25个相邻1m²样方（quadrat）组成。除15m水深的礁坡亚生境外，每类生境均设置了4个重复采样位点（replicate sampling site）。在每个样方内，研究者记录了附着于表面以及埋藏于基质中、深度约50cm范围内的所有海百合；同时记录了每只海百合在样方内的具体位置，并采集海百合样本用于后续实验室保存与分类鉴定。

研究者还针对流速、水动力能量、水深、沉积物以及珊瑚覆盖度等外部环境因素对各生境进行了排序分级。本研究旨在通过调查不同礁体生境中海百合的物种多样性与分布格局，阐明戴维斯礁海域海百合群落的结构特征，同时可与该礁体上的珊瑚、鱼类、海绵等其他礁栖群落进行对比分析。

本次调查同时还用于建立标准化的野外采样与实验室分析技术，以支持后续更精细化的局部分布格局研究以及更大范围的跨礁体分布研究。部分羽星科（Comasteridae）类群的分类学修订（taxonomic revision）成果已发表于文献："Rowe FWE, Hogget AK, Birtles RA 及 Vail LL (1986) 澳大利亚部分羽星科类群的分类学修订（棘皮动物门：海百合纲）—— 两新属与九新种的描述. 林奈学会动物学杂志（Zoological Journal of the Linnean Society）86:197-277"。该文献中记载的新物种名称已纳入本次调查鉴定得到的海百合物种名录中。

本次样方内鉴定得到的海百合物种如下：
羽星科（Comasteridae）：
Comanthus parvicirrus
Comanthus samoanus = Comanthus sp. cf. C. wahlbergii (J. Muller)
Comanthus sp. A
Comasterinae n. gen. n. sp. A = Oxycomanthus mirus
Comasterinae n. gen. n. sp. B = Oxycomanthus exilis
Comanthina schlegeli
Comantheria alternans
Comantheria briareus：归入Comantheria alternans
Comanthus luteofuscum = Clarkcomanthus luteofuscum
Comanthus timorensis = Clarkcomanthus littoralis
Comaster multifidus
Comaster gracilis
Comatella nigra
Comatella stelligera
Comatella maculata
Comatula purpurea
Comissia pectinifera
美羽星科（Colobometridae）：
Cenometra bella
Petasometra clarae
马里亚羽星科（Mariametridae）：
Stephanometra oxyacantha
热带羽星科（Tropiometridae）：
Tropiometra afra

本次样方外采集得到的额外物种如下：
羽星科（Comasteridae）：
Comanthus bennetti = Oxycomanthus bennetti
Comanthina sp. A = Comanthina nobilis
Comantheria n. sp. A = Comanthus mirabilis
Capillaster multiradiatus
美羽星科（Colobometridae）：
Colobometra perspinosa
Oligimetra serripinna