Galasso Nicola M, Bonaviri Chiara, Di Trapani Francesco, Picciotto Mariagrazia, Gianguzza Paola, Agnetta Davide, Badalamenti Fabio
CNR-IAMC, via Giovanni da Verrazzano 17, 91014 Castellammare del Golfo, Italy.
Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Via Archirafi 22, I-90123 Palermo, Italy.
Sci Rep. 2015 Jul 22;5:12409. doi: 10.1038/srep12409.
Although protected areas can lead to recovery of overharvested species, it is much less clear whether the return of certain predator species or a diversity of predator species can lead to re-establishment of important top-down forces that regulate whole ecosystems. Here we report that the algal recovery in a Mediterranean Marine Protected Area did not derive from the increase in the traditional strong predators, but rather from the establishment of a previously unknown interaction between the thermophilic fish Thalassoma pavo and the seastar Marthasterias glacialis. The interaction resulted in elevated predation rates on sea urchins responsible for algal overgrazing. Manipulative experiments and field observations revealed that the proximity of the seastars triggered an escape response in sea urchins, extending their tube feet. Fishes exploited this behavior by feeding on the exposed tube feet, thus impairing urchin movement, and making them vulnerable to predation by the seastars. These findings suggest that predator diversity generated by MPA establishment can activate positive interactions among predators, with subsequent restoration of the ecosystem structure and function through cascading consumer impacts.
尽管保护区能够促使过度捕捞的物种数量恢复，但某些捕食者物种的回归或捕食者物种的多样性是否能导致调节整个生态系统的重要自上而下的力量重新建立，却远没有那么明确。在此我们报告，地中海一个海洋保护区内藻类的恢复并非源于传统强势捕食者数量的增加，而是源于一种此前未知的、嗜热鱼类孔雀锦鱼（Thalassoma pavo）与海星冰川棘冠海星（Marthasterias glacialis）之间相互作用的建立。这种相互作用导致对造成藻类过度啃食的海胆的捕食率升高。操控实验和实地观察表明，海星的靠近引发了海胆的逃避反应，使其管足伸展。鱼类利用这一行为，以暴露在外的管足为食，从而削弱海胆的移动能力，使其更容易被海星捕食。这些发现表明，建立海洋保护区所产生的捕食者多样性能够激活捕食者之间的积极相互作用，随后通过消费者的连锁影响恢复生态系统的结构和功能。
