Data from: Extremely long-distance seed dispersal by an overfished Amazonian frugivore

Throughout Amazonia, overfishing has decimated populations of fruit-eating fishes, especially the largebodied characid, Colossoma macropomum. During lengthy annual floods, frugivorous fishes enter vast Amazonian floodplains, consume massive quantities of fallen fruits and egest viable seeds. Many tree and liana species are clearly specialized for icthyochory, and seed dispersal by fish may be crucial for the maintenance of Amazonian wetland forests. Unlike frugivorous mammals and birds, little is known about seed dispersal effectiveness of fishes. Extensive mobility of frugivorous fish could result in extremely effective, multi-directional, long-distance seed dispersal. Over three annual flood seasons, we tracked fine-scale movement patterns and habitat use of wild Colossoma, and seed retention in the digestive tracts of captive individuals. Our mechanistic model predicts that Colossoma disperses seeds extremely long distances to favourable habitats. Modelled mean dispersal distances of 337–552 m and maximum of 5495 m are among the longest ever reported. At least 5 per cent of seeds are predicted to disperse 1700–2110 m, farther than dispersal by almost all other frugivores reported in the literature. Additionally, seed dispersal distances increased with fish size, but overfishing has biased Colossoma populations to smaller individuals. Thus, overexploitation probably disrupts an ancient coevolutionary relationship between Colossoma and Amazonian plants.

在整个亚马孙流域，过度捕捞已导致食果鱼类种群大幅衰减，其中尤以大型脂鲤科鱼类巨脂鲤（Colossoma macropomum）为甚。在一年一度的漫长洪水期内，食果鱼类会进入广袤的亚马孙泛滥平原，摄取大量坠落的果实并排出具有生活力的种子。许多乔木与藤本植物显然特化于依赖鱼媒传播（icthyochory），而鱼类介导的种子传播或许是维持亚马孙湿地森林生态系统的关键环节。与食果哺乳动物和鸟类不同，学界对鱼类介导的种子传播效能的了解仍十分有限。食果鱼类极强的移动能力，可能促成极为高效、多向性的长距离种子传播。在连续三个年度洪水周期中，我们追踪了野生巨脂鲤的精细运动模式与栖息地利用情况，并测定了圈养个体消化道内的种子留存时长。我们构建的机制模型预测，巨脂鲤可将种子长距离传播至适宜生境中。模型预测的平均传播距离为337~552米，最大传播距离达5495米，属于迄今已有记录的最长传播距离之一。据模型预测，至少5%的种子传播距离可达1700~2110米，远超文献中记录的几乎所有其他食果动物的种子传播距离。此外，种子传播距离会随鱼类体型增大而增加，但过度捕捞已使巨脂鲤种群偏向小型个体。因此，过度捕捞或已破坏了巨脂鲤与亚马孙植物之间延续已久的协同进化关系。