Sediment patch selectivity in tropical sea cucumbers on the Great Barrier Reef

Five species of aspidochirotide holothurians, (Holothuria atra, Holothuria edulis, Holothuria nobilis [now whitmaei], Stichopus chloronotus and Stichopus variegatus) were subjected to multiple choice feeding preference experiments in aquaria, to investigate selectivity of sediment patches. Experiments on Holothuria atra, Holothuria edulis and Stichopus chloronotus were conducted at AIMS using specimens collected from Great Palm Island. Experiments on Holothuria nobilis and Stichopus variegatus were carried out at Lizard Island on specimens collected from the local reefs. Sediment was collected from the natural habitat of each species, for the culture of sediment microalgae. Samples of sediments were subjected to one of four treatments (which were designed to create sediments with differing amounts of microalgal biomass) for a period of 8-12 days: TR1=dark, TR2=nutrient reduced, TR3= normal, TR4= nutrient enhanced. Only TR1 and TR3 were prepared at Lizard Island.Five replicate sediment samples per treatment and experiment were analysed for chlorophyll a and phaeophytin prior to commencement of each experiment. Duplicate water samples from all treatments used in 2 experiments with Holothuria atra, 1 experiment with Holothuria edulis and 3 experiments with Stichopus chloronotus were analysed for dissolved inorganic nitrogen (ammonium, nitrate, nitrite) and phosphate.Experiments were conducted with Holothuria atra, Holothuria edulis and Stichopus chloronotus by placing individuals in aquaria with one pre-weighed sediment dish from each of the four treatments placed randomly in the corners of the aquaria. After 48 hours, the sediment dishes were removed and re-weighed. Experiments with Holothuria nobilis and Stichopus variegatus were conducted in a similar manner except that two dishes of each of the two treatments prepared for these species were placed randomly at each corner of the container.Field sediment samples for analysis of chlorophyll a and phaeophytin were collected from underneath the feeding tentacles of holothurians (15 samples for each species) and also haphazardly collected from the surrounding sediment (15 samples). Sediment was collected at Great Palm Island from a shallow area where Holothuria atra and Stichopus chloronotus occur and from a deeper area where Holothuria edulis occurs. Samples were collected from the reef flat at John Brewer Reef for Holothuria nobilis and from the reef slope at Britomart Reef for Stichopus variegatus. To investigate whether holothurian species are patch selective in their feeding behaviour.本数据集针对5种盾手目海参（Aspidochirotide Holothurians），分别为黑海参（Holothuria atra）、红斑海参（Holothuria edulis）、高贵海参（现更名为惠特迈海参，Holothuria nobilis [now whitmaei]）、绿刺参（Stichopus chloronotus）与杂色刺参（Stichopus variegatus）。研究团队在受控水族箱中开展多选式摄食偏好实验，以探究其对沉积物斑块的摄食选择偏好。针对黑海参、红斑海参与绿刺参的实验由澳大利亚海洋科学研究所（AIMS）开展，实验个体采自大棕榈岛（Great Palm Island）采集的野生海参样本。针对高贵海参与杂色刺参的实验则在蜥蜴岛（Lizard Island）开展，实验个体采自当地礁区的野生海参样本。沉积物样本取自各物种的自然栖息生境，用于培养沉积物微藻（sediment microalgae）。实验设置4种处理方案，以构建具有差异化微藻生物量的沉积物基质，培养周期为8至12天：TR1=遮光组，TR2=营养盐削减组，TR3=正常对照组，TR4=营养盐强化组。其中仅TR1与TR3两种处理组的沉积物在蜥蜴岛完成制备。每项实验正式启动前，均需对每个处理组的5份平行沉积物样本进行叶绿素a（chlorophyll a）与脱镁叶绿素（phaeophytin）含量检测。针对黑海参的2组实验、红斑海参的1组实验以及绿刺参的3组实验，所有处理组的平行水样均需检测溶解态无机氮（dissolved inorganic nitrogen，包括铵态氮、硝态氮、亚硝态氮）与磷酸盐（phosphate）含量。实验流程如下：对于黑海参、红斑海参与绿刺参的实验，将单只海参个体置于水族箱内，将4种处理组各取1份预称重的沉积物培养皿，随机放置于水族箱的四个角落。48小时后取出培养皿并重新称重。针对高贵海参与杂色刺参的实验流程与之类似，仅需将该实验所用的2种处理组各取2份沉积物培养皿，随机放置于实验容器的四角。用于叶绿素a与脱镁叶绿素检测的野外沉积物样本，分别采集自海参摄食触手下方区域（每个物种采集15份样本）以及周边沉积物中（每个物种随机采集15份样本）。沉积物的具体野外采集地点如下：大棕榈岛的浅水区为黑海参与绿刺参的自然栖息区域，深水区为红斑海参的自然栖息区域；约翰布鲁尔礁（John Brewer Reef）的礁坪为高贵海参的采样点，布里托马雷夫礁（Britomart Reef）的礁坡为杂色刺参的采样点。本研究的核心目的为探究海参物种是否存在摄食行为的斑块选择性。