Collective aggressiveness of an ecosystem engineer is associated with coral recovery

The ecological impacts of animal groups may be different and predictable depending on their collective behavior. Farmerfish (Stegastes nigricans) live in social groups and collectively defend gardens of palatable algae. These gardens also serve as settlement and nursery habitats for corals because farmerfish mob corallivores that attempt to forage on corals within their gardens. We detected large among-colony differences in farmerfish collective aggression towards intruder fish that persist across years. We further found that the territories of aggressive groups and territories containing larger farmerfish provided greater protection to corals than non-aggressive groups: territories of aggressive groups naturally harbored more branching corals than non-aggressive groups, and experimentally outplanted branching corals experienced 80% less skeletal loss and grew larger over 25 weeks in aggressive territories and in territories guarded by larger fish. These findings hint that factors that ...

动物群体的生态影响可能因其集体行为而呈现出差异，且具有可预测性。农民鱼（Stegastes nigricans）为群居生物，会集体捍卫其可食用藻类‘花园’。这些花园同时也是珊瑚的定居与育苗栖息地——因为农民鱼会围攻试图在其花园内珊瑚上觅食的珊瑚捕食者（corallivores）。我们发现，不同农民鱼群体对入侵鱼类的集体攻击性存在显著差异，且这种差异可多年持续。进一步研究表明，攻击性群体的领地及包含较大个体农民鱼的领地，相比非攻击性群体能为珊瑚提供更有效的保护：攻击性群体的领地自然拥有比非攻击性群体更多的分支珊瑚；在为期25周的实验中，移植至攻击性群体领地及较大个体农民鱼守卫领地的分支珊瑚，其骨骼损失减少了80%，且生长更为显著。这些发现暗示……