Ecological Release and Resistance at Sea: Invasion of Atlantic Coral Reefs by Pacific Lionfish

“这项奖励是根据2009年美国复苏和再投资法案（公法111-5）资助的。”人类活动越来越多地将入侵物种引入世界上以前从未存在过的新地区。在本土没有天敌（捕食者、竞争者和疾病）的情况下，入侵物种可能对入侵生态系统，特别是物种较少的系统（“生态释放”）产生强烈的负面影响，甚至可能导致本地物种灭绝。然而，如果本土的天敌能够以某种方式控制入侵者（“生态抵抗”），那么生态破坏就可以被防止或至少是缓和。海洋中的许多入侵物种大多是海藻和无脊椎动物，少数有记录的入侵海洋鱼类并没有造成重大问题。然而，这种情况最近发生了令人震惊和不祥的变化。在20世纪90年代早期，来自太平洋的狮子鱼（Pterois volitans）被意外或故意地从水族馆释放到佛罗里达州附近的海洋中。狮子鱼被形状和颜色所伪装，被有毒的刺所保护，贪婪地吃掉当地的珊瑚礁鱼类，并迅速繁殖，随后经历了种群爆炸。它们现在的分布范围从美国大西洋中部海岸到加勒比海，包括巴哈马群岛。本土的大西洋鱼类以前从未遇到过这种多刺、隐蔽、高效的捕食者，很少采取躲避行动。事实上，研究人员已经记录了一条狮子鱼能够在短短5周内将一小块珊瑚礁上的小鱼数量减少近80%。人们非常担心，入侵的狮子鱼可能会严重减少作为人类重要食物的本地珊瑚礁鱼类的丰度（例如，幼年阶段的石斑鱼和鲷鱼），以及通常维持珊瑚礁完整性的物种（例如，可以防止海藻窒息珊瑚的食草鹦嘴鱼）。太平洋的珊瑚礁鱼类种类远多于大西洋，因此这次入侵可能代表了一种极端生态释放与轻微生态抵抗的情况。Hixon博士和他的同事们将研究狮子鱼的生态释放机制，以及在严重入侵的巴哈马群岛检查生态抗性的潜在来源。由于人们对狮子鱼在太平洋原生栖息地的生态和行为知之甚少，他还将在两个海洋进行比较研究，这可能会为这次入侵的巨大成功提供线索。在巴哈马，调查人员将记录狮子鱼作为捕食者和竞争对手对生态释放对本地物种的直接和间接影响。这些研究将在不同的时间和空间尺度上进行，从小型斑块珊瑚礁的短期实验到大型珊瑚礁的长期实验和观察。虽然直接影响主要涉及本地物种丰度的变化，但间接影响可能是高度可变的。例如，狮子鱼实际上可能通过消耗或超越这些本地物种的竞争对手，间接地使一些本地物种受益。该项目将通过确定是否有任何巴哈马本土物种是狮子鱼的有效天敌，包括掠食者、寄生虫和幼狮鱼和成年狮子鱼的竞争对手，来探索可能的生态抵抗力。对大西洋和太平洋的天敌以及狮子鱼的生态和行为进行比较研究，可能会为狮子鱼在大西洋的爆炸性传播提供线索。就更广泛的影响而言，这项基础研究将为珊瑚礁和渔业管理者提供有价值的信息，以对抗美国、巴哈马群岛和大加勒比海的狮子鱼入侵，特别是如果确定了本地生态抗性的来源。该研究将资助美国研究生的博士研究，并涉及各种本科生和珊瑚礁/渔业管理人员的协助和参与，包括妇女、少数民族、巴哈马土著和太平洋土著岛民。参与这个项目将通过Hixon博士和研究生的教学和推广活动直接促进海洋生态学和保护生物学的教育，通过本科生实地助理和各种同事的经验间接促进海洋生态学和保护生物学的教育。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."Invasive species are increasingly introduced by human activities to new regions of the world where those species have never existed previously. In the absence of natural enemies (predators, competitors, and diseases) from their homeland, invasives may have strong negative effects on invaded ecosystems, especially systems with fewer species ("ecological release"), and may even drive native species extinct. However, if native natural enemies can somehow control the invaders ("ecological resistance"), then ecological disruption can be prevented or at least moderated. Most of the many invasive species in the sea have been seaweeds and invertebrates, and the few documented invasive marine fishes have not caused major problems. However, this situation has recently changed in a stunning and ominous way. In the early 1990s, lionfish (Pterois volitans) from the Pacific Ocean were accidentally or intentionally released from aquaria to the ocean in the vicinity of Florida. Camouflaged by shape and color, protected by venomous spines, consuming native coral-reef fishes voraciously, and reproducing rapidly, lionfish have subsequently undergone a population explosion. They now range from the mid-Atlantic coast of the US to the Caribbean, including the Bahamas. Native Atlantic fishes have never before encountered this spiny, stealthy, efficient predator and seldom take evasive action. In fact, the investigator has documented that a single lionfish is capable of reducing the abundance of small fish on a small coral patch reef by nearly 80% in just 5 weeks. There is great concern that invasive lionfish may severely reduce the abundance of native coral-reef fishes important as food for humans (e.g., grouper and snapper in their juvenile stages) as well as species that normally maintain the integrity of coral reefs (e.g., grazing parrotfishes that can prevent seaweeds from smothering corals). There are far more species of coral-reef fish in the Pacific than the Atlantic, so this invasion may represent a case of extreme ecological release with minor ecological resistance. Dr. Hixon and colleagues will study the mechanisms of ecological release in lionfish, as well as examine potential sources of ecological resistance in the heavily invaded Bahamas. Because very little is known about the ecology and behavior of lionfish in their native Pacific range, he will also conduct comparative studies in both oceans, which may provide clues regarding the extreme success of this invasion. In the Bahamas, the investigator will document the direct and indirect effects on native species of the ecological release of lionfish, both as a predator and as a competitor. These studies will be conducted at various scales of time and space, from short-term experiments on small patch reefs, to long-term experiments and observations on large reefs. Whereas direct effects involve mostly changes in the abundance of native species, indirect effects can be highly variable. For example, lionfish may actually indirectly benefit some native species by either consuming or outcompeting the competitors of those natives. The project will explore possible ecological resistance to the invasion by determining whether any native Bahamian species are effective natural enemies of lionfish, including predators, parasites, and competitors of both juvenile and adult lionfish. Comparative studies of natural enemies, as well as lionfish ecology and behavior, in both the Atlantic and the Pacific may provide clues regarding the explosive spread of lionfish in the Atlantic.Regarding broader impacts, this basic research will provide information valuable to coral-reef and fisheries managers fighting the lionfish invasion in the US, the Bahamas, and the greater Caribbean, especially if sources of native ecological resistance are identified. The study will fund the PhD research of U.S. graduate students, as well as involve assistance and participation by a broad variety of undergraduates and reef/fisheries managers, including women, minorities, native Bahamians, and native Pacific islanders. Participation in this project will promote education in marine ecology and conservation biology directly via the Dr. Hixon's and graduate students' teaching and outreach activities, and indirectly via the experiences of undergraduate field assistants and various associates.