| Title | A comparison of different biotic indices based on benthic macro-invertebrates in italian lakes |
| Abstract | Benthic macroinvertebrates samples were taken from Italian lakes with different geological, morphological and chemical characteristics. Thirty-two lowland small and large lakes sampled using a grab in soft substrate were selected to develop biotic indices. Diversity indices based on species numbers - abundances and indices using species sensitivity values were compared. The lakes selected were all situated in the Alpine Ecoregion below 800 m a.s.l. and had similar chemical composition but different levels of anthropogenic pressure. Lakes with data available in different years were included as separate lakes in the analysis; littoralsublittoral samples of large lakes were also separated from profundal samples yielding a total of 41 sites for analysis. Seven different biotic indices were compared: (1) Shannon diversity index (H), (2) weighted Shannon diversity index (Hw) including in the calculation a sensitivity value assigned to each species, (3) a benthic quality index based on means of three different environmental variables, measuring trophic status, weighted by species abundances (BQITS), (4) an index based on weighted means using a larger set of environmental variables (BQIENV), (5) a modified BQITS, which included both species numbers and total abundance of individuals (BQIES), (6) an index calculated according to a rarefaction method (ES), (7) an index considering indicator species based on experts judgment (BQIEJ). The indices were compared with a trophic status index (TSI) constructed by joining three environmental variables: O2% saturation in the hypolimnion during summer stratification, total phosphorous and transparency during full circulation. Comparisons were also made with another environmental stress index (ENI) constructed on a larger number of variables. All the biotic indices had significant correlations with both TSI and ENI. BQIES, WFD compliant and well correlated with TSI and ENI, was selected to tentatively assign the investigated lakes into 5 quality classes: high (H), good (G), moderate (M), poor (P) and bad (B). The statistical power of the classification was estimated. Assuming tentatively equal intervals for each of the five quality classes, 2 lakes were classified at high status, 7 lakes were classified as good, 13 were classified as moderate, 13 were classified as poor and 4 were classified as bad. Fifteen lakes were classified with a power less than 80%. Some of the lakes resampled in different periods displayed a shift of class in the different years. Future work should focus on extending the database to test the indices in other lake types subjected to different pressures. |
| Source | Journal of limnology (Testo stamp.) 70, pp. 109–122 |
| Keywords | ChironomidaeOligochaetaDiversityEutrophicationWFD 60/2000 |
| Journal | Journal of limnology (Testo stamp.) |
| Editor | Istituto per lo Studio degli Ecosistemi., Verbania Pallanza, Italia |
| Year | 2011 |
| Type | Articolo in rivista |
| DOI | 10.3274/JL11-70-1-13 |
| Authors | Bruno Rossaro; Angela Boggero; Brigitte Lods Crozet; Gary Free; Valeria Lencioni; Laura Marziali |
| Text | 42442 2011 10.3274/JL11 70 1 13 Chironomidae Oligochaeta Diversity Eutrophication WFD 60/2000 A comparison of different biotic indices based on benthic macro invertebrates in italian lakes Bruno Rossaro; Angela Boggero; Brigitte Lods Crozet; Gary Free; Valeria Lencioni; Laura Marziali Bruno Rossaro Dipartimento di Biologia, Universita degli Studi di Milano CNR IRSA; Angela Boggero CNR ISE; Brigitte Lods Crozet Service des Eaux, Sols et Assainissement, Chemin des Boveresses 155, CH 1066 Epalinges, Switzerland; Gary Free Scientific Officer, Aquatic Environment, Environmental Protection Agency, Mc Cumiskey House Richview Clonskeagh Road, Dublin 14, Ireland; Valeria Lencioni Museo Tridentino di Scienze Naturali, Trento ; Laura Marziali CNR IRSA Benthic macroinvertebrates samples were taken from Italian lakes with different geological, morphological and chemical characteristics. Thirty two lowland small and large lakes sampled using a grab in soft substrate were selected to develop biotic indices. Diversity indices based on species numbers abundances and indices using species sensitivity values were compared. The lakes selected were all situated in the Alpine Ecoregion below 800 m a.s.l. and had similar chemical composition but different levels of anthropogenic pressure. Lakes with data available in different years were included as separate lakes in the analysis; littoralsublittoral samples of large lakes were also separated from profundal samples yielding a total of 41 sites for analysis. Seven different biotic indices were compared 1 Shannon diversity index H , 2 weighted Shannon diversity index Hw including in the calculation a sensitivity value assigned to each species, 3 a benthic quality index based on means of three different environmental variables, measuring trophic status, weighted by species abundances BQITS , 4 an index based on weighted means using a larger set of environmental variables BQIENV , 5 a modified BQITS, which included both species numbers and total abundance of individuals BQIES , 6 an index calculated according to a rarefaction method ES , 7 an index considering indicator species based on experts judgment BQIEJ . The indices were compared with a trophic status index TSI constructed by joining three environmental variables O2% saturation in the hypolimnion during summer stratification, total phosphorous and transparency during full circulation. Comparisons were also made with another environmental stress index ENI constructed on a larger number of variables. All the biotic indices had significant correlations with both TSI and ENI. BQIES, WFD compliant and well correlated with TSI and ENI, was selected to tentatively assign the investigated lakes into 5 quality classes high H , good G , moderate M , poor P and bad B . The statistical power of the classification was estimated. Assuming tentatively equal intervals for each of the five quality classes, 2 lakes were classified at high status, 7 lakes were classified as good, 13 were classified as moderate, 13 were classified as poor and 4 were classified as bad. Fifteen lakes were classified with a power less than 80%. Some of the lakes resampled in different periods displayed a shift of class in the different years. Future work should focus on extending the database to test the indices in other lake types subjected to different pressures. 70 Articolo 2011_Journal_of_Limnology_n_70_1_109_122.pdf Articolo in rivista Istituto per lo Studio degli Ecosistemi. 1129 5767 Journal of limnology Testo stamp. Journal of limnology Testo stamp. J. limnol. Testo stamp. Journal of limnology. Testo stamp. laura.marziali MARZIALI LAURA bruno.rossaro ROSSARO BRUNO angela.boggero BOGGERO ANGELA TA.P04.016.004 Ecologia teorica e applicata degli ecosistemi acquatici TA.P04.032.003 La risposta delle comunita acquatiche bioindicatori e WFD |
