Elevated aluminium concentration in acidified headwater streams lowers aquatic hyphomycete diversity and impairs leaf-litter breakdown.

Jean-Marc Baudoin (1) , François Guérold (1) , Vincent Felten (1) , Eric Chauvet (2) , Philippe Wagner (1) , Philippe Rousselle (1)

1 LIEBE - Laboratoire des Interactions Ecotoxicologie, Biodiversité, Ecosystèmes
2 LEFE - Laboratoire Ecologie Fonctionnelle et Environnement

Aquatic hyphomycetes play an essential role in the decomposition of allochthonous organic matter which is a fundamental process driving the functioning of forested headwater streams. We studied the effect of anthropogenic acidification on aquatic hyphomycetes associated with decaying leaves of Fagus sylvatica in six forested headwater streams (pH range, 4.3-7.1). Non-metric multidimensional scaling revealed marked differences in aquatic hyphomycete assemblages between acidified and reference streams. We found strong relationships between aquatic hyphomycete richness and mean Al concentration (r = -0.998, p < 0.0001) and mean pH (r = 0.962, p < 0.002), meaning that fungal diversity was severely depleted in acidified streams. By contrast, mean fungal biomass was not related to acidity. Leaf breakdown rate was drastically reduced under acidic conditions raising the issue of whether the functioning of headwater ecosystems could be impaired by a loss of aquatic hyphomycete species.

Mots clés: Aluminum; Decomposition; Biomass; Ecosystem impairment; Litter; Fungi

Domaines: Biodiversité et Ecologie

Jean-Marc Baudoin, François Guérold, Vincent Felten, Eric Chauvet, Philippe Wagner, et al.. Elevated aluminium concentration in acidified headwater streams lowers aquatic hyphomycete diversity and impairs leaf-litter breakdown.. Microbial ecology, 2008, vol. 56, pp. 260-269. ⟨10.1007/s00248-007-9344-9⟩. ⟨hal-00956836⟩