Feeding biology of the crown-of-thorns starfish, Acanthaster planci (Linnaeus)
Feeding biology of the crown-of-thorns starfish, Acanthaster planci (Linnaeus)
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发表时间：
1990-03
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通讯作者：
J. Keesing
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作者：
J. Keesing
我们进行了实地和实验室研究，以研究大堡礁中部地区棘蛉（Linnaeus）的摄食生物学。进行昼夜调查以检查摄食周期，并通过监测标记的动物来测量摄食和运动速率。我们在现场评估了饮食和喂养偏好，并进行了实验室研究，以评估食物营养质量在控制喂养偏好方面的重要性。小海星在夜间进食，白天保持神秘。大型海星主要是昼夜进食者，很少隐藏。海星在黎明和黄昏时最活跃。有人提出，观察到的行为模式已经演变为一种躲避捕食者的策略，大型海星在尺寸上达到了避难所。这些依赖于体型大小的行为模式，以及种群规模结构的变化，对于评估在 A. planci 调查和控制计划中未被发现的海星数量具有重要意义。 A. planci 的移动速度取决于食物的供应情况。在珊瑚覆盖率较高的地区，这一数字约为 1 m.day ́；在珊瑚覆盖率较低的地区，这一数字约为 4 m.day ́。海星在大片珊瑚覆盖枯竭的区域中以大约 10 m.day 的速度移动。海星的摄食率取决于海星的大小和季节，在夏季产卵季节之前摄食率最高。夏季，戴维斯礁的海星平均每天进食 1.5 次，每天杀死约 300 平方厘米的珊瑚覆盖层或 15 克 DW（干重）的软珊瑚组织。生物质利用率约为每天 4 g DW 或 90 kJ。冬季的饲喂量约为夏季的一半。饲喂速率测量应用于 A. planci 的生态和生理考虑。在 A. planci 爆发期间被杀死的珊瑚面积和生物量方面，珊瑚群落发生了巨大的变化。爆发的种群数量（每个珊瑚礁约 100000 只海星）将杀死数千平方米的珊瑚；相当于每天数百公斤软组织的干重。摄食率测量用于预测每平方公里约 1000 只海星的阈值种群水平，这将对大堡礁的珊瑚群落造成最小的损害。显然，A. planci 种群的大规模波动可能会发生，但不会导致珊瑚大量死亡。生理需求与摄食率的比较证实，尽管大型成虫的摄食率有所增加，但生长是决定性的，并且可以预期大型蜈蚣的衰老。正如之前的研究表明，出现这种情况是因为随着海星的生长，其进食能力无法满足代谢组织的需求。 A. planci 的饮食几乎全部是石珊瑚 (90 - 95 %)。在珊瑚稀少的地区，非珊瑚猎物的数量不断增加。 A. planci 在现场和实验室中都表现出强烈的摄食偏好。石珊瑚科 Acroporidae 和 Pocilloporidae 是最受欢迎的。在偏好物种耗尽的地区，非偏好猎物的数量不断增加。评估了不同种类珊瑚猎物的营养价值，并将其与观察到的摄食偏好相关联。有几个属性可能会影响珊瑚物种作为食物的适宜性；这些是表面积复杂性、生物量、营养价值和丰富度。猎物偏好与食物适宜性的一般评估关系比与最佳饮食理论的绝对预测关系更密切。有人提出，更有效地捕食某些猎物类型的能力是引起观察到和公布的猎物选择模式的最重要因素。
Field and laboratory studies were undertaken to examine aspects of the feeding biology of Acanthaster planci (Linnaeus) in the central region of the Great Barrier Reef. Day and night surveys were carried out to examine feeding periodicity, and measurements of feeding and movement rates were made by monitoring tagged animals. Diet and feeding preferences were assessed in the field and laboratory studies were undertaken to assess the importance of nutritional quality of food in governing feeding preferences. Small starfish feed nocturnally and remain cryptic during the day. Large starfish are primarily diurnal feeders and are rarely cryptic. Starfish are most mobile around dawn and dusk. It is proposed that the observed behaviour patterns have evolved as a predator avoidance strategy with large starfish achieving a refuge in size. These size dependent behavioural patterns, together with changes in population size structure, have important implications for assessing the numbers of starfish remaining undetected in A. planci survey and control programs. Rates of movement in A. planci are dependent on food availability. These are about 1 m.day¯¹ in areas of high coral cover and about 4 m.day¯¹ in patches of low coral cover. Starfish in extensive areas of depleted coral cover move at rates of about 10 m.day¯¹. Feeding rates in A. planci are dependent on starfish size and season, being greatest prior to the summer spawning season. Starfish at Davies Reef in summer averaged 1.5 feeds per day, killing about 300 cm² of coral cover or 15 g DW (dry weight) of soft coral tissues per day. Biomass utilization is about 4 g DW or 90 kJ per day. Feeding rates in winter are about half those of summer. Feeding rate measurements were applied to ecological and physiological considerations in A. planci. The magnitude of changes to coral communities in terms of area and biomass of coral killed during A. planci outbreaks is substantial. Outbreaking populations (ca. 100000 starfish per reef) will kill thousands of square metres of coral; equivalent to hundreds of kilograms dry weight of soft tissues per day. Feeding rate measurements were used to predict a threshold population level of about 1000 starfish per km² which would cause minimal damage to coral communities on the Great Barrier Reef. It is evident that large scale fluctuations in A. planci populations can occur without causing extensive coral mortality. Comparison of physiological requirements with feeding rates confirms that, despite increased feeding rates in large adults, growth is determinant and senility of large A. planci can be expected. As suggested in previous studies, this occurs because as the starfish grows its capacity to feed cannot meet the demands of metabolising tissue. The diet of A. planci is almost exclusively scleractinian corals (90 - 95 %). Non-coral prey are taken in increasing abundance in areas of low coral availability. A. planci exhibits strong feeding preferences in both the field and the laboratory. The scleractinian families Acroporidae and Pocilloporidae are most favoured. Non-preferred prey are taken in increasing abundance in areas depleted of favoured species. The nutritional value of different species of coral prey was assessed and related to the observed feeding preferences. Several attributes may affect a coral species suitability as food; these are surface area complexity, biomass, nutritional value and abundance. Prey preference was more closely related to a general assessment of food suitability than to the absolute predictions of optimal diet theory. It is proposed that the ability to feed more efficiently on certain prey types is the most important factor giving rise to observed and published patterns of prey selection.