Colossal aggregations of giant alien freshwater fish as a potential biogeochemical hotspot

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...

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Veröffentlicht in:PloS one 2011-10, Vol.6 (10), p.e25732-e25732
Hauptverfasser: Boulêtreau, Stéphanie, Cucherousset, Julien, Villéger, Sébastien, Masson, Rémi, Santoul, Frédéric
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Sprache:eng
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Zusammenfassung: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.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0025732