TAXONOMIC AND NONTAXONOMIC RESPONSES TO ECOLOGICAL CHANGES IN AN URBAN LOWLAND STREAM THROUGH THE USE OF CHIRONOMIDAE (DIPTERA) LARVAE

CORTELEZZI, A.; PAGGI, A. C.; RODRÍGUEZ, M.; RODRIGUES CAPÍTULO, A.

SCIENCE OF THE TOTAL ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Michigan; Año: 2011 vol. 409 p. 1344 - 1350

0048-9697

a b s t r a c t 6 Article history:7 Received 7 May 2010 8 Received in revised form 29 December 2010 9 Accepted 5 January 2011 10 Available online xxxx 11123 14 Keywords: 15 Chironomidae diversity 16 Chironomus calligraphus 17 Mentum deformities 18 Sublethal effects 19 Environmental degradation 20 Surveillance tool Biotic descriptors ? both taxonomic (diversity indices, species richness, and indicator species) and 21 nontaxonomic (biomass, oxygen consumption/production, and anatomical deformities) ? are useful tools 22 for measuring a stream´s ecological condition. Nontaxonomic parameters detect critical effects not reflected 23 taxonomically. We analyzed changes in Chironomidae populations as taxonomic parameters and mentum 24 deformities as a nontaxonomic parameter for evaluating a South-American-plains stream (Argentina). We 25 performed samplings seasonally (March, June, September, and December; 2005) and physical and chemical 26 measurements at three sampling sites of the stream (DC1 at river source, through DC3 downstream). The 27 specimens collected in sediment and vegetation were analyzed to investigate mouth deformities in 28 Chironomidae larvae. We identified a total of 9 taxa from Chironomidae and Orthocladiinae subfamilies. 29 Shannon´s diversity index for Chironomidae decreased from1.6 bits ind 30 −1 (DC1) to 0.3 bits ind−1 (DC3). The total density of the Chironomidae exhibited a great increase in abundance at site DC3, especially that of 31 Chironomus calligraphus. Chironomidae taxonomic composition also changed among the three sites despite 32 their spatial proximity: C. calligraphus, Goeldichironomus holoprasinus, Parachironomus longistilus, and 33 Polypedilum were present at all three; Corynoneura and Paratanytarsu at DC1 only; Cricotopus at DC1 and 34 DC3; Apedilum elachistus notably at DC2 and DC3; and Parametriocnemus only at DC2. C. calligraphus 35 individuals from DC1 showed no mentum deformities; only 2 from DC2 exhibited mouth-structure 36 alterations; while specimens from DC3 presented the most abnormalities, especially during autumn and late 37 winter. Type-II deformities (supernumerary teeth and gaps) were the most common. Anatomical deformities 38 are sublethal effects representing an early alert to chemically caused environmental degradation. Mentum 39 deformities in benthic-Chironomidae larvae constitute an effective biological-surveillance tool for detecting 40 adverse conditions in sediments and evaluating sediment-quality-criteria compliance. Taxonomic (commu- 41 nity composition) and nontaxonomic (condition of larval mouth parts) descriptors, used together, can 42 indicate a stream´s ecological state. 43 © 2011 Published by Elsevier B.V. 44