The impact of eucalypt on the leaf-associated aquatic hyphomycetes in Spanish streams

Abstract

Aquatic hyphomycete assemblages on decomposing leaf litter of the exotic species Eucalyptus globulus Labill. were compared with those on the native riparian species Alnus glutinosa (L.) Gaertn. in three low-order streams of the Agüera watershed (Basque Country – Cantabria, Spain). These streams contrast by the importance of eucalypt in the riparian vegetation and by the nutrient contents in the water. Neither the total conidial production nor the number of fungal species differed between the two leaf species in any of the streams. Fungal colonization of eucalypt leaves appeared to be delayed by about 2 weeks, probably owing to their high content in inhibitory constituents. While Flagellospora curvula Ingold largely dominated pioneer assemblages on both leaf species, the second most important species, Lunulospora curvula Ingold, exhibited a preference for eucalypt. In the stream surrounded by eucalypt, the fungal diversity was surprisingly lower on eucalypt than on alder. In the stream with higher orthophosphate concentrations, the conidial production was similarly increased on both leaf species. The present data together with recent results from a similar investigation in Portugal suggest a minor impact of eucalypt on the activity and diversity of aquatic hyphomycete leaf-associated assemblages in southern European streams. Key words: aquatic hyphomycetes, eucalypt, alder, leaf litter, stream.

The influence of water quality and macroinvertebrate colonization on the breakdown process of native and exotic leaf types in sub-alpine stream

“…Moreover, the establishment of exotic riparian plants can alter the exchange of organic material between terrestrial and lotic ecosystems, both changing the quantity (Mineau et al 2011(Mineau et al , 2012 or the quality (B€ arlocher & Graça 2002) of terrestrial litter inputs, leading to alterations in the composition (Serra et al 2013) and density (Lester et al 1994) of benthic assemblages. Many studies have shown that, for instance, the introduction and spread of Eucalyptus globulus plantations in Spain had a strong effect on in-stream terrestrial detritus colonization and degradation (Chauvet et al 1997;Pozo et al 1998;Ferreira et al 2006), while other studies have shown weak influence of exotic species on streams (Braatne et al 2007). Our study gave evidence that mass loss of leaf bags was generally higher in the unpolluted site A rather than in the polluted site B.…”

Aquatic Hyphomycete Communities Associated with Decomposing Alder Leaf Litter in Reference Headwater Streams of the Basque Country (northern Spain)

“…There are few studies examining particular components of the community (individual taxa) or relative abundance distributions such as evenness or dominance degrees [11,50]. The natural variability of these communities is often overlooked, and most studies only compare a given reference situation with others supposedly impaired.…”

Yeast and Macroinvertebrate Communities Associated with Leaf Litter Decomposition in a Second Order Stream

“…Eucalyptus leaves attained the maximum ergosterol content reached by alder on day 28, on day 56. BÄRLOCHER et al (1995), andCHAUVET et al (1997) also noticed a delay between fungal colonisation of alder and eucalypt leaves. The latter reached a higher value than alder (day 171, approximately 400 µg ergosterol/g dry mass), probably because it can support higher fungal biomass (eucalypt leaves are thicker than alder leaves).…”

“…Succession studies during litter decay in aquatic systems have been confined to single biological groups such as macroinvertebrates (e.g., BASAGUREN and POZO, 1994;ROBINSON et al, 1998;COLLIER and HALLIDAY, 2000), and aquatic hyphomycetes (e.g., CHAUVET et al, 1997). These asexual and filamentous fungi are often found on decomposing leaves, wood and twigs in wellaerated water bodies.…”