Hydrological intermittency drives diversity decline and functional homogenization in benthic diatom communities
Articolo
Data di Pubblicazione:
2021
Abstract:
Over the last decades, the combined effects of global climate changes and severe land use modifications have
been exacerbating river hydrological alterations and habitat fragmentation in many Mediterranean rivers. This
trend is predicted to intensify,with expected significant impacts on taxonomic and functional diversity of benthic
communities in the next future.
By comparing perennial and intermittent reaches, the present research aims at investigating the role of flow intermittency,
driven by the combined effects of climatic variables and land use changes, on benthic diatom communities
in Mediterranean streams (NW Italy), by analysing data collected over 11 years. In order to avoid potential confounding
effects related to water quality, sites characterized by “poor” or “bad” water quality were excluded a priori.
We observed significant differences between permanent and intermittent sections in terms of both climatic variables
and land use: higher temperatures and lower precipitations, coupledwith an extensive anthropic land use,
intensify the natural flow intermittency in intermittent sites. This led to a significant decline in diatom species
diversity, at both local and regional scales, and to changes to life history traits. In particular, communities of intermittent
reacheswere taxonomically and functionally different and less heterogeneous than assemblages characterizing
perennial ones, showing higher percentages of small, mainly stalked and pioneer taxa belonging to the
low profile guild. Conversely taxa colonizing permanent reaches were bigger, belonging to the high profile guild
and able to produce colonies, thus indicating high environmental stability.
Our results highlighted how hydrological alterations are profoundly threatening Mediterranean streams and the
diatom communities inhabiting them, therefore representing an important benchmark in view of the improvement
of biological indices for the assessment of intermittent rivers.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
Bacillariophyceae
Diversity partitioning
Non-flow
Functional traits
Mediterranean rivers
Elenco autori:
Falasco E., Bona F., Risso A.M., Piano E.
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