Effects of human impacts on diversity and distribution of chironomids (Diptera: Chironomidae) in prealpine springs

Effects of human impacts on chironomids in prealpine springs

  • Valeria Lencioni | valeria.lencioni@muse.it MUSE - Museo delle Scienze, Italy. http://orcid.org/0000-0002-4341-9923
  • Enrico Mezzanotte Museo Civico di Storia Naturale of Verona, Department of Zoology, Italy.
  • Camilla Spagnol Museo Civico di Storia Naturale of Verona, Department of Zoology, Italy.
  • Leonardo Latella Museo Civico di Storia Naturale of Verona, Department of Zoology, Italy.

Abstract

Diversity and distribution of chironomid fauna (Diptera: Chironomidae) in 36 springs in the Italian Prealps (Veneto and Trentino NE-Italy, 46°N, 10-11°E) was studied in relation to altitude, spring type and grade of disturbance. The springs were located between 62 and 1710 m asl of altitude, in three calcareous mountain areas (Mt. Baldo, Mts. Lessini and Mt. Pasubio). They differed in conservation status (natural, moderately and highly disturbed) and belonged to five hydromorphological types (rheocrene, limnocrene, rheohelocrene, rheolimnocrene, rheohygropetric). Each spring was surveyed once, between early summer and autumn, within 50 m of the spring’s source (eucrenal). A total of 4198 chironomid larvae and pupae were sorted from 111 macroinvertebrate samples collected, belonging to five subfamilies (Tanypodinae, Diamesinae, Prodiamesinae, Orthocladiinae and Chironominae), 41 genera and 60 species/groups of species, and three juveniles taxa. As expected, Orthocladiinae accounted for a large part of specimens (88%) and species (74%), with Tvetenia calvescens/bavarica as the most frequent and abundant taxon, shared by pristine and disturbed springs and by all spring types. Most taxa were found in few sites, and frequencies declined gradually for most wider distributed species. A high number (74%) of rare (= present in less than 10% of sites) taxa were found and from one to 23 taxa were identified per spring. Maximum richness occurred in moderately disturbed (Shannon-H = 1.29±0.60) springs, located at medium-high altitude (385-1266 m asl), according to the intermediate disturbance hypothesis. Even the evenness (Equitability-J) was higher as average in these springs. A Cluster Analysis run on Bray-Curtis similarity index highlighted a high similarity i) between the chironomid assemblages of moderately disturbed and natural springs (44 species in each spring group, with 29 species in common), and ii) between rheocrene and rheohelocrene types, thus the springs with the highest microhabitat heterogeneity. High individuality of springs was revealed, and new information about non-biting midges autecology provided. The utility of chironomids as bioindicators of water quality and ecological state of springs was confirmed, with some species e associated with high disturbance level (e.g., Polypedilum nubeculosum gr. to water intake works) and others with pristine conditions (e.g., Pseudodiamesa branickii).

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Author Biography

Valeria Lencioni, MUSE - Museo delle Scienze
Section of Invertebrate Zoology and Hydrobiology
Published
2018-05-28
Supporting Agencies
Authority of the Adige River, Speleological Commission of Verona
Keywords:
Orthocladiinae, eucrenal, mosaic, tapped springs, spring types, Italian Prealps.
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PDF: 208
Supplementary: 89
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How to Cite
1.
Lencioni V, Mezzanotte E, Spagnol C, Latella L. Effects of human impacts on diversity and distribution of chironomids (Diptera: Chironomidae) in prealpine springs. jlimnol [Internet]. 28May2018 [cited 23Jan.2020];77(1s). Available from: https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1804