Riccardo Cabrini - XXI Congresso SITE - 2011

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Riccardo Cabrini - XXI Congresso SITE - 2011

  1. 1. Breakdown and macroinvertebrate colonization patterns of leaf packs in impaired streams Cabrini R. 1 , Canobbio S. 1 , Sartori L. 1 , and Mezzanotte V. 1 XXI Congresso della Società Italiana di Ecologia Palermo, 5 ottobre 2011 1 Dipartimento di Scienze dell’Ambiente e del Territorio, Università degli Studi di Milano-Bicocca, Piazza della Scienza 1, 20126 Milano, Italia, email: [email_address]
  2. 2. Introduction Water Directive 2000/60/CE  “ good ” ecological status Macroinvertebrates prefer leaf litter of some species over others (Graça, 2001) Reintroduction of native vegetation  river restoration tool
  3. 3. Why leaf packs? T he contribution of shed leaves by riparian vegetation is the most important source of organic matter (Wallace et al ., 1997; Power & Dietrich, 2002) and forming leaf packs are then degraded by a combination of physical and biological processes Degradation of leaf packs Microbial activity (fungi and bacteria) Physico-chemical alteration (water flow, abrasion) Macroinvertebrate colonization (food and refuge) CPOM  FPOM Introduction
  4. 4. <ul><li>Aim of the work </li></ul><ul><li>We want to determine: </li></ul><ul><li>the effects of wastewater on composition and functional organization of colonizing macroinvertebrate assemblages; </li></ul><ul><li>if leaf packs formed by native leaves can improve diversity of macroinvertebrate community structure in control and impaired sites . </li></ul>Aim of the work Limido Comasco – Impaired group Vertemate– Control group
  5. 5. <ul><li>Material and methods </li></ul><ul><li>Study site </li></ul><ul><li>Seveso, Lura and Bozzente streams, located in the piedmont area of Lombardy region in Italy. </li></ul><ul><li>S ix sites  the six sites were morphologically similar, but different for physico-chemical water characteristics. </li></ul><ul><li>Two groups of sites </li></ul><ul><li>Impaired group  characterized by the presence of untreated sewage spill ; </li></ul><ul><li>Control group  characterized by the absence of untreated sewage spill. </li></ul><ul><li>The presence of pollution due to treated effluent was not considered as impaired condition as suggested by Spanhoff et al. (2007). </li></ul>Material and methods
  6. 6. Material and methods Material and methods Three kind of leaves Native mix leaves: alder, oak and white hornbean Naturalized leaves: locust-tree Alien “ urban ” leaves: laurel Leaves was dried for 24 hours at 105° C to obtain standardized moisture contents.
  7. 7. The greatest differences between control and impaired sites were observed for total phosphorous and nitrogen, ammonia nitrogen, COD and E. coli Results Water Chemistry
  8. 8. Results Leaf breakdown Control group Impaired group ANOVA split-plot – Weight loss
  9. 9. ANOVA split-plot – Taxa Richness Results ANOVA split-plot – Shannon Index Macroinvertebrate assemblages Taxa richness and Shannon index shows values ​​significantly different between site gr ou p division ( variable: Quality ). Taxa richness is ​significantly different among substrate .
  10. 10. Results Macroinvertebrate assemblages Control group Impaired group Laurel Locust-tree Native mix Taxa richness
  11. 11. Results Macroinvertebrate assemblages Laurel Locust-tree Native mix Taxa richness Control group Impaired group
  12. 12. Results Macroinvertebrate assemblages Tukey HSD Test P<0,001 Laurel Locust-tree Native mix Taxa richness Control group Impaired group
  13. 13. Results Macroinvertebrate assemblages Control group Impaired group Shannon Index Laurel Locust-tree Native mix Laurel Locust-tree Native mix Taxa richness
  14. 14. Results Macroinvertebrate assemblages Control group Impaired group Laurel Locust-tree Native mix D-Shredders ANOVA split-plot – FFG-FHG
  15. 15. Results Macroinvertebrate assemblages Tukey HSD test P<0,05 Control group Impaired group Laurel Locust-tree Native mix D-Shredders ANOVA split-plot – FFG-FHG
  16. 16. Results <ul><li>Results in brief… </li></ul><ul><li>Breakdown rates of leaf packs did not differ significantly between the site groups and among different substrates. </li></ul><ul><li>Composition of macroinvertebrate assemblages differs among site group and substrate, but the interaction between sites and substrate do not shown any significance, except for taxa richness and d-shredders in native mix leaves . </li></ul>
  17. 17. Results <ul><li>Conclusions </li></ul><ul><li>Macroinvertebrate colonization of leaf packs seems to be influenced principally by water quality and not by leaf types, as shown by all biological metrics and functional traits. </li></ul><ul><li>Use of native leaves improves microhabitat quality and, thus, macroinvertebrate biodiversity. </li></ul><ul><li>Work in progress </li></ul><ul><li>Three collections of leaf packs: after 21, 42, 63 laying days  comparison of communities and leaf breakdown over time </li></ul><ul><li>Over time: </li></ul><ul><li>number of taxa increases; </li></ul><ul><li>After 21 laying days all feeding and habit groups are present in leaf packs. </li></ul>
  18. 18. Thanks for your attention!

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