25 research outputs found
Stimulation of leaf litter decomposition and associated fungi and invertebrates by moderate eutrophication: implications for stream assessment
1. We investigated the effect of moderate eutrophication on leaf litter decomposition and
associated invertebrates in five reference and five eutrophied streams in central Portugal.
Fungal parameters and litter N and P dynamics were followed in one pair of streams.
Benthic invertebrate parameters that are considered useful in bioassessment were
estimated in all streams. Finally, we evaluated the utility of decomposition as a tool to
assess stream ecosystem functional integrity.
2. Decomposition of alder and oak leaves in coarse mesh bags was on average 2.3–2.7·
faster in eutrophied than in reference streams. This was attributed to stimulation of fungal
activity (fungal biomass accrual and sporulation of aquatic hyphomycetes) by dissolved
nutrients. These effects were more pronounced for oak litter (lower quality substrate) than
alder. N content of leaf litter did not differ between stream types, while P accrual was
higher in the eutrophied than in the reference stream. Total invertebrate abundances and
richness associated with oak litter, but not with alder, were higher in eutrophied streams.
3. We found only positive correlations between stream nutrients (DIN and SRP) and leaf
litter decomposition rates in both fine and coarse mesh bags, associated sporulation rates
of aquatic hyphomycetes and, in some cases, total invertebrate abundances and richness.
4. Some metrics based on benthic invertebrate community data (e.g. % shredders, %
shredder taxa) were significantly lower in eutrophied than in reference streams, whereas the IBMWP index that is specifically designed for the Iberian peninsula classified all 10
streams in the highest possible class as having ‘very good’ ecological conditions.
5. Leaf litter decomposition was sufficiently sensitive to respond to low levels of
eutrophication and could be a useful functional measure to complement assessment
programmes based on structural parameters.3F10-AC72-52D0 | VerĂ³nica Ferreirainfo:eu-repo/semantics/publishedVersio