Recent findings regarding non-native or poorly known diatom taxa in north-western Italian rivers
Autor: | Francesca Bona, Elisa Falasco |
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Jazyk: | angličtina |
Rok vydání: | 2013 |
Předmět: |
non-indigenous taxa
River ecosystem Range (biology) Cymbella Aquatic Science Biology diatoms NW Italy Relative species abundance lcsh:Physical geography lcsh:Environmental sciences Water Science and Technology lcsh:GE1-350 river ecosystem Ecology lcsh:Geography. Anthropology. Recreation Didymosphenia geminata diatoms NW Italy Didymosphenia geminata non-indigenous taxa river ecosystem biology.organism_classification Diatom lcsh:G Benthic zone Water quality lcsh:GB3-5030 |
Zdroj: | Journal of Limnology, Vol 72, Iss 1, Pp e4-e4 (2013) |
ISSN: | 1723-8633 1129-5767 |
Popis: | Diatoms of the major rivers of North-Western Italy were investigated to highlight the presence of species of particular ecological interest but not as yet recorded. The survey area included streams belonging to seven different hydroecoregions (HERs) with a wide range of physical characteristics. Between 2008 and 2010, 200 samples were taken for the study of the diatom community composition, while a larger set of samples was examined to determine the presence or absence of the nuisance diatom species Didymosphenia geminata (Lyngbye) Schmidt. A specific field study was performed in two rivers characterized by persistent blooms of this species to evaluate the effects of its proliferation on the benthic communities. D. geminata was present in almost 20% of the samples. From a comparison with published data, we can confirm that D. geminata has recently been expanding its ecological range, as it has been found also in mesotrophic lowlands water. In some instances the formation of massive proliferation has been recorded. The calculation of autecological values confirmed its preference for oligotrophic waters with low mineral content and organic loading, although with a wider ecological amplitude than recorded in the first studies on this species. Another four taxa of particular interest were detected: Achnanthidium subhudsonis (Hustedt) Kobayasi (in 15 sites), Cymbella tropica Krammer (11 sites), Mayamaea cahabaensis Morales and Manoylov (2 sites) and Reimeria uniseriata Sala, Guerrero and Ferrario (18 sites). The first three species must be considered new records for Northern Italy. A. subhudsonis and C. tropica reached up to 20% relative abundance. From the analysis of their distribution and autecological values, we can assert that A. subhudsonis and M. cahabaensis show a preference for high values of nitrogen, this latter preferring also quite high values of total phosphorus. C. tropica prefers intermediate values of nitrogen nutrients and R. uniseriata is the least demanding species in terms of water quality. All the taxa studied have a wide ecological range, confirming their potential invasive behaviour. Finally, considerations are provided with respect to Italian and European historical data in order to understand whether these species can be considered non-indigenous and/or bloom forming, in the study area. The results may help improve the process of ecological classification of water bodies in the seven HERs, and the water protection actions introduced by the Water Framework Directive (2000/60). |
Databáze: | OpenAIRE |
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