Data from: 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 increase farmerfish group aggressiveness (e.g., higher temperatures) could enhance the protective value of their territories for the replenishment of coral populations.

动物集群的生态影响可因群体行为模式的差异而存在不同，且该差异具备可预测性。农场鱼（Farmerfish，Stegastes nigricans）以社群群体为单位栖息，会集体管护适口藻类形成的藻园。这些藻园同时也是珊瑚的定居与育苗栖息地，因为农场鱼会围攻试图在其藻园内觅食的食珊瑚动物（corallivores）。我们观测到，农场鱼种群间对入侵鱼类的集体攻击性存在显著差异，且这种差异可延续多年。我们进一步发现，相较于非攻击性群体的领地，攻击性群体的领地以及栖息有更大体型农场鱼的领地能为珊瑚提供更优的保护：攻击性群体的领地自然存续的分枝珊瑚（branching corals）数量更多；且在25周的观测周期内，实验移植至攻击性领地或大型农场鱼守护领地的分枝珊瑚，其骨骼损耗量减少80%，生长规模也更为可观。上述研究结果显示，能够提升农场鱼群体攻击性的因素（例如水温升高），可增强其领地对珊瑚种群补充的保护价值。