Williams Dana E, Miller Margaret W, Bright Allan J, Cameron Caitlin M
Cooperative Institute for Marine and Atmospheric Studies, Rosenstiel School of Marine and Atmospheric Science, University of Miami , Miami, FL , USA ; Southeast Fisheries Science Center, NOAA-National Marine Fisheries Service , Miami, FL , USA.
Southeast Fisheries Science Center, NOAA-National Marine Fisheries Service , Miami, FL , USA.
PeerJ. 2014 Nov 27;2:e680. doi: 10.7717/peerj.680. eCollection 2014.
Corallivorous snail feeding is a common source of tissue loss for the threatened coral, Acropora palmata, accounting for roughly one-quarter of tissue loss in monitored study plots over seven years. In contrast with larger threats such as bleaching, disease, or storms, corallivory by Coralliophila abbreviata is one of the few direct sources of partial mortality that may be locally managed. We conducted a field experiment to explore the effectiveness and feasibility of snail removal. Long-term monitoring plots on six reefs in the upper Florida Keys were assigned to one of three removal treatments: (1) removal from A. palmata only, (2) removal from all host coral species, or (3) no-removal controls. During the initial removal in June 2011, 436 snails were removed from twelve 150 m(2) plots. Snails were removed three additional times during a seven month "removal phase", then counted at five surveys over the next 19 months to track recolonization. At the conclusion, snails were collected, measured and sexed. Before-After-Control-Impact analysis revealed that both snail abundance and feeding scar prevalence were reduced in removal treatments compared to the control, but there was no difference between removal treatments. Recolonization by snails to baseline abundance is estimated to be 3.7 years and did not differ between removal treatments. Recolonization rate was significantly correlated with baseline snail abundance. Maximum snail size decreased from 47.0 mm to 34.6 mm in the removal treatments. The effort required to remove snails from A. palmata was 30 diver minutes per 150 m(2) plot, compared with 51 min to remove snails from all host corals. Since there was no additional benefit observed with removing snails from all host species, removals can be more efficiently focused on only A. palmata colonies and in areas where C. abbreviata abundance is high, to effectively conserve A. palmata in targeted areas.
食珊瑚蜗牛的啃食是受威胁的鹿角珊瑚组织损失的常见原因，在七年的监测研究区域中，约占组织损失的四分之一。与诸如白化、疾病或风暴等更大的威胁不同，短缩珊瑚嗜食螺的珊瑚捕食行为是少数可在当地进行管理的部分死亡直接原因之一。我们进行了一项野外实验，以探究清除蜗牛的有效性和可行性。佛罗里达群岛上游六个珊瑚礁上的长期监测区域被分配到三种清除处理之一：（1）仅从鹿角珊瑚上清除，（2）从所有宿主珊瑚物种上清除，或（3）不清除作为对照。在2011年6月的首次清除中，从12个150平方米的区域中清除了436只蜗牛。在为期七个月的“清除阶段”又进行了三次蜗牛清除，然后在接下来的19个月内进行了五次调查以计数重新定殖情况。实验结束时，收集、测量并鉴定了蜗牛的性别。前后对照影响分析表明，与对照相比，清除处理中的蜗牛数量和啃食疤痕发生率均有所降低，但清除处理之间没有差异。蜗牛重新定殖到基线数量估计需要3.7年，清除处理之间没有差异。重新定殖率与基线蜗牛数量显著相关。在清除处理中，蜗牛的最大尺寸从47.0毫米降至34.6毫米。从鹿角珊瑚上清除蜗牛所需的工作量为每150平方米区域30潜水员分钟，而从所有宿主珊瑚上清除蜗牛则需要51分钟。由于从所有宿主物种上清除蜗牛没有观察到额外的益处，因此清除工作可以更有效地仅集中在鹿角珊瑚群落以及短缩珊瑚嗜食螺数量较多的区域，以有效地保护目标区域内的鹿角珊瑚。
