Diatom flora in Mediterranean streams: flow intermittency threatens endangered species
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- 作者：Elisa Falasco ; Elena Piano ; Francesca Bona
- 关键词：Red list ; Bacillariophyceae ; Hydrological instability ; Pools
- 刊名：Biodiversity & Conservation
- 出版年：2016
- 出版时间：December 2016
- 年：2016
- 卷：25
- 期：14
- 页码：2965-2986
- 全文大小：871 KB
- 刊物类别：Biomedical and Life Sciences
- 刊物主题：Life Sciences
Evolutionary Biology
Plant Sciences
Tree Biology - 出版者：Springer Netherlands
- ISSN：1572-9710
- 卷排序：25
文摘
In the context of global environmental changes, Mediterranean rivers are considered highly endangered. Temporal and spatial increases of the dry stretches during the summer lead to the loss of river tridimensional connectivity, which represents a major threat for freshwater biodiversity. In this study, we aimed at exploring the response of diatom communities to summer droughts by analyzing taxonomical composition, specific ecological requirements, ecological guilds and percentages of endangered species. The evolution of diatom communities was monitored under both intermediate and intermittent flows, with traditional and innovative sampling procedures, i.e. collecting diatoms from transects and microhabitats, respectively. Microhabitats differed in terms of water velocity, substrate, isolation and presence of macrophytes. Diatom flora was mainly composed of β-mesasoprobous taxa. We highlighted an increase of species considered as aerophilous and planktonic in sites characterized by intermittent flow. In general, ecological guilds did not respond to hydrological disturbance as expected. Statistical models identified the maintenance of a minimum of 0.20 m/s flow velocity as the main factor influencing the abundance of endangered species. Conversely, flow instability, lentification and habitat fragmentation represented the major threats for endangered species. In conclusion, diatoms can provide useful information to improve river management practices when faced with an increasing water scarcity scenario. Water stability and river habitat heterogeneity strongly favor the presence of endangered diatom species. In the absence of these conditions, isolated pools surrounded by dry riverbed are very important habitats to be preserved, representing the only refugia for benthic diatom communities during summer.