The ubiquity and fascinating nature of animal aggregations are widely recognised. We report here consistent and previously undocumented occurences of aggregations of a giant alien freshwater fish, the Wels catfish (Silurus glanis). Aggregative groups were on average composed of 25 (±10 SD, ranging from 15 to 44) adults with estimated average total biomass of 651 kg (386 – 1132) and biomass density of 23 kg m−2 (14 – 40). Aggregations always occurred within the same location. No foraging, reproductive or anti-predator behaviour were observed during the aggregations. A mass-balance model estimated that these colossal aggregations of an alien species can locally release, through excretion only, up to 70 mg P m−2 h−1 and 400 mg N m−2 h−1, potentially representing the highest biogeochemical hotspots reported in freshwater ecosystems and another unexpected ecological effect of alien species
展开▼
机译：动物聚集体的普遍性和令人着迷的性质得到了广泛认可。我们在此报告了巨型外星淡水鱼Wels fish鱼（Silurus glanis）聚集体的一致发生和以前未记录的发生。聚集组平均由25个成年人组成（±10 SD，范围从15到44），估计平均总生物量为651 kg（386 – 1132），生物量密度为23 kg m-2（14 – 40）。聚集总是发生在同一位置。在聚集过程中未观察到觅食，繁殖或反捕食行为。质量平衡模型估计，这些外来物种的巨大聚集仅通过排泄就可以局部释放高达70 mg P m-2 h-1和400 mg N m-2 h-1，这可能是最高的生物地球化学热点报告在淡水生态系统和外来物种的另一意外生态影响
展开▼
