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，尤以大型脂鲤科鱼类巨脂鲤（Colossoma macropomum）为甚。在漫长的年度洪水期内，食果鱼类会进入广袤的亚马孙泛滥平原，取食大量坠落的果实并排出具有活力的种子。诸多乔木与藤本物种显然特化依赖鱼媒传播（icthyochory），而鱼类介导的种子扩散或许对亚马孙湿地森林的存续至关重要。与食果哺乳动物和鸟类不同，学界对鱼类的种子扩散效能尚知之甚少。食果鱼类极强的移动能力，或可促成极为高效、多向性的长距离种子扩散。在三个年度洪水季中，我们追踪了野生巨脂鲤（Colossoma macropomum）的精细运动模式与栖息地利用情况，并监测了圈养个体消化道内的种子留存时长。我们的机制模型预测，巨脂鲤可将种子长距离扩散至适宜生境。模型得出的平均扩散距离为337–552米，最大扩散距离达5495米，属于迄今已报道的最长扩散距离之一。据模型预测，至少5%的种子扩散距离可达1700–2110米，远高于文献中已报道的绝大多数其他食果动物的种子扩散距离。此外，种子扩散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，过度捕捞或已破坏巨脂鲤与亚马孙植物之间古老的协同进化关系。