Australian Institute of Marine Science, PMB No 3, Townsville, Queensland, 4810, Australia.
Department of Marine Science, University of Otago, 9016, Dunedin, New Zealand.
Sci Rep. 2018 Jan 12;8(1):642. doi: 10.1038/s41598-017-19132-w.
Coral-eating Crown-of-Thorns Sea stars (Acanthaster spp.) are major contributors to coral reef loss in the Indo-Pacific region. A release from food limitation of their planktotrophic larvae through enhanced pelagic productivity is one of the main hypothesis explaining population outbreaks ('nutrient limitation hypothesis'). To improve the understanding of these outbreaks we developed an automated flow- through larvae rearing system that maintained food (microalgae) at set levels over the course of four 15d experiments. This resulted in stable food concentrations in experimental tanks. Increased algae concentrations had a significant positive effect on larval development and size at 10 and 15 days post fertilization (dpf). Larvae densities had no effect at 10 dpf. At 15 dpf greater larvae densities were associated with declines in larvae size. Larval development was slowed under higher larvae densities. Thus, the effects of algae concentration and larvae density were additive at 15 dpf, with larvae under low densities at a given algae concentration being further developed than those under higher densities. The development of a flow-through system gives greater insight into the effect of algae and larvae concentrations on Acanthaster development, and the system can be applied to further test the nutrient-limitation hypothesis for present and future outbreaks.
食珊瑚的棘冠海星（Acanthaster spp.）是印度洋-太平洋地区珊瑚礁丧失的主要贡献者。通过提高浮游生物生产力来解除其浮游幼虫的食物限制，是解释种群爆发的主要假说之一（“营养限制假说”）。为了更好地理解这些爆发，我们开发了一种自动的浮游幼虫养殖系统，可以在四个为期 15 天的实验过程中将食物（微藻）维持在设定的水平。这导致实验水箱中的食物浓度保持稳定。在受精后 10 和 15 天，增加藻类浓度对幼虫发育和大小有显著的积极影响。幼虫密度在 10 天无影响。在 15 天，更高的幼虫密度与幼虫大小的下降有关。幼虫密度较高时，幼虫发育会减缓。因此，在 15 天，藻类浓度和幼虫密度的影响是相加的，在给定藻类浓度下，低密度的幼虫比高密度的幼虫发育得更好。该流动系统的发展使我们更深入地了解藻类和幼虫浓度对棘冠海星发育的影响，并且该系统可以进一步应用于测试当前和未来爆发的营养限制假说。
