Department of Environmental Conservation and Intercampus Marine Science Graduate Program, University of Massachusetts Amherst, 160 Holdsworth Way, Amherst, MA, 01003, USA.
Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
Oecologia. 2023 Jun;202(2):353-368. doi: 10.1007/s00442-023-05390-1. Epub 2023 Jun 8.
Research from terrestrial communities shows that diminished predation risk is a principal driver of heterospecific grouping behavior, with foraging ecology predicting the roles that species play in groups, as more vulnerable foragers preferentially join more vigilant ones from whom they can benefit. Meanwhile, field studies examining the adaptive significance of heterospecific shoaling among marine fish have focused disproportionately on feeding advantages such as scrounging or prey-flushing. Juvenile bonefish (Albula vulpes) occur almost exclusively among mojarras (Eucinostomus spp.) and even elect to join them over conspecifics, suggesting they benefit from doing so. We evaluated the roles of risk-related and food-related factors in motivating this pattern of affiliation, estimating: (1) the relative levels of risk associated with each species' search and prey capture activities, via behavioral vulnerability traits discerned from in situ video of heterospecific shoals, and (2) resource use redundancy, using stable isotopes (δC, δN, and δS) to quantify niche overlap. Across four distinct metrics, bonefish behaviors implied a markedly greater level of risk than those of mojarras, typified by higher activity levels and a reduced capacity for overt vigilance; consistent with expectations if their association conformed to patterns of joining observed in terrestrial habitats. Resource use overlap inferred from stable isotopes was low, indicating that the two species partitioned resources and making it unlikely that bonefish derived substantive food-related benefits. Collectively, these findings suggest that the attraction of juvenile bonefish to mojarras is motivated primarily by antipredator advantages, which may include the exploitation of risk-related social cues.
陆地群落的研究表明，被捕食风险降低是异种种群聚集行为的主要驱动因素，觅食生态学预测了物种在群体中所扮演的角色，因为更脆弱的觅食者更倾向于加入更警惕的觅食者，从而从后者那里受益。与此同时，考察海洋鱼类异种种群聚集的适应性意义的实地研究，过多地关注了觅食优势，如觅食或驱赶猎物。幼年骨鱼（Albula vulpes）几乎只出现在莫加拉鱼（Eucinostomus spp.）中，甚至选择与它们一起而不是与同种鱼一起，这表明它们这样做会受益。我们评估了与风险相关的因素和与食物相关的因素在促使这种关联模式形成中的作用，通过对异种种群聚集的现场视频中识别出的行为易损性特征，估计了：(1) 每种鱼类搜索和捕食活动相关的风险水平，(2) 使用稳定同位素（δC、δN 和 δS）来量化生态位重叠的资源利用冗余度。通过四个不同的指标，骨鱼的行为暗示着比莫加拉鱼更高的风险水平，表现为更高的活动水平和减少的公开警戒能力；如果它们的关联符合在陆地栖息地观察到的加入模式，这是符合预期的。稳定同位素推断出的资源利用重叠度较低，表明两种鱼类对资源进行了划分，这使得骨鱼不太可能获得实质性的食物相关益处。总的来说，这些发现表明，幼年骨鱼对莫加拉鱼的吸引力主要是由捕食者回避优势驱动的，这可能包括利用与风险相关的社会线索。
