Russ Garry R, Payne Cody S, Bergseth Brock J, Rizzari Justin R, Abesamis Rene A, Alcala Angel C
College of Science and Engineering, James Cook University, Townsville, Australia.
Australian Research Council Centre of Excellence for Coral Reef Studies, Townsville, Australia.
J Fish Biol. 2018 Nov;93(5):887-900. doi: 10.1111/jfb.13809.
No-take marine reserves (NTMR) are increasingly being implemented to mitigate the effects of fishing on coral reefs, yet determining the efficacy of NTMRs depends largely on partitioning the effects of fishing from the effect of benthic habitat. Species of coral-reef fishes typically decline in density when subjected to fishing or benthic disturbances, but this is not always the case. This study documents the long-term (8-31 years) response of six species of detritivorous surgeonfishes (family Acanthuridae) to NTMR protection and benthic habitat change at four islands (Apo, Sumilon, Mantigue, Selinog) in the central Philippines, each island with a NTMR and a monitored fished site. Despite being subject to moderate fishing pressure, these species did not increase in density with NTMR protection. However, density of these surgeonfishes had a strong negative relationship with cover of live hard coral and a strong positive relationship with cover of dead substratum (sand, rubble, hard dead substratum). These surgeonfishes typically feed over dead substrata and thus probably increase in density following large environmental disturbances that substantially reduce live hard coral cover. Here, we describe effects of environmental disturbance events (e.g., use of explosives, typhoons) that reduced live hard-coral cover and subsequent large increases (up to 25 fold) in surgeonfish densities, which then slowly (over 5-15 years) decreased in density as live hard coral recovered. Density of these functionally important surgeonfish species was influenced more by changes to benthic cover than by NTMR protection. Thus, we highlight the greater importance of bottom-up controls (i.e., benthic changes to food availability) than top-down control (i.e., fishing) on a functionally important group of coral-reef fishes.
为减轻捕捞对珊瑚礁的影响，禁捕海洋保护区（NTMR）的实施越来越普遍。然而，确定NTMR的成效很大程度上取决于区分捕捞影响和底栖生境影响。珊瑚礁鱼类在遭受捕捞或底栖干扰时，其密度通常会下降，但情况并非总是如此。本研究记录了菲律宾中部四个岛屿（阿波岛、苏米龙岛、曼蒂格岛、塞利诺格岛）上六种食碎屑刺尾鱼（刺尾鱼科）对NTMR保护和底栖生境变化的长期（8至31年）响应，每个岛屿都有一个NTMR和一个受监测的捕捞区域。尽管受到适度捕捞压力，但这些物种的密度并未因NTMR保护而增加。然而，这些刺尾鱼的密度与活硬珊瑚覆盖率呈强烈负相关，与死基质（沙子、碎石、硬死基质）覆盖率呈强烈正相关。这些刺尾鱼通常在死基质上觅食，因此在大幅减少活硬珊瑚覆盖率的大型环境干扰之后，其密度可能会增加。在此，我们描述了环境干扰事件（如使用炸药、台风）的影响，这些事件减少了活硬珊瑚覆盖率，随后刺尾鱼密度大幅增加（高达25倍），然后随着活硬珊瑚的恢复，密度在缓慢（5至15年）下降。这些功能上重要的刺尾鱼物种的密度受底栖覆盖率变化的影响大于NTMR保护。因此，我们强调对于功能上重要的珊瑚礁鱼类群体，自下而上的控制（即底栖食物可利用性的变化）比自上而下的控制（即捕捞）更为重要。
