| Title | Mechanisms underlying recovery of zooplankton in lake Orta after liming |
| Abstract | The goal of this study was to improve the understanding of the large-scale mechanisms underlying the recovery of the zooplankton of Lake Orta from historical contamination, following reduced input of ammonia and metals and the subsequent 1989/90 liming intervention. The industrial pollution had been severe and long-lasting (1929-1990). Zooplankton biodiversity has improved, but most of the new taxa appearing in our counts are rotifers, while many calanoids and the large cladoceran predators (Bythotrephes and Leptodora) that are common in the nearby Lake Maggiore, were still absent from Lake Orta 17 years after liming. To aid understanding of the large-scale mechanisms controlling changes in annual richness, we assessed the annual persistence (P) of Crustacea and Rotifera taxa as an estimator of whether propagules that survived introduction, as result of the natural recolonization process, also thrived. We found that the rate of introduction of zooplankton colonists and their persistence in the water column of Lake Orta changed from 1971 to 2007. New rotifer taxa appeared in the lake after the mid-1980s, when discharge of toxic substances decreased, but their annual persistence was low (P<0.5) until the turn of the century. The numerical values of rotifer and crustacean persistence in Lake Orta were unexpectedly high in 2001 and 2007 (0.55 and 0.72 for rotifers, 0.85 and 0.86 for crustacean, respectively), much higher than in limed lakes in Sudbury, Canada, and in adjacent Lake Maggiore. We hypothesize this could be related to the lack of Cladoceran predators and zooplanktivorous fish in the pelagic waters of Lake Orta. |
| Source | Journal of limnology (Testo stamp.) 75 (2S), pp. 15–21 |
| Keywords | Annual persistenceAnnual taxa richnessLake ortaPollutionZooplankton |
| Journal | Journal of limnology (Testo stamp.) |
| Editor | Istituto per lo Studio degli Ecosistemi., Verbania Pallanza, Italia |
| Year | 2016 |
| Type | Articolo in rivista |
| DOI | 10.4081/jlimnol.2016.1353 |
| Authors | Piscia R.; Yan N.D.; Manca M.M. |
| Text | 386293 2016 10.4081/jlimnol.2016.1353 Scopus 2 s2.0 84964824740 Annual persistence Annual taxa richness Lake orta Pollution Zooplankton Mechanisms underlying recovery of zooplankton in lake Orta after liming Piscia R.; Yan N.D.; Manca M.M. National Research Council, Institute of Ecosystem Study, Largo Tonolli 50, Verbania, 28922, , Italy; Biology Department, York University, Toronto, ON, , China; Dorset Environmental Science Centre, Box 39, Dorset, ON, P0A 1E0, , Canada The goal of this study was to improve the understanding of the large scale mechanisms underlying the recovery of the zooplankton of Lake Orta from historical contamination, following reduced input of ammonia and metals and the subsequent 1989/90 liming intervention. The industrial pollution had been severe and long lasting 1929 1990 . Zooplankton biodiversity has improved, but most of the new taxa appearing in our counts are rotifers, while many calanoids and the large cladoceran predators Bythotrephes and Leptodora that are common in the nearby Lake Maggiore, were still absent from Lake Orta 17 years after liming. To aid understanding of the large scale mechanisms controlling changes in annual richness, we assessed the annual persistence P of Crustacea and Rotifera taxa as an estimator of whether propagules that survived introduction, as result of the natural recolonization process, also thrived. We found that the rate of introduction of zooplankton colonists and their persistence in the water column of Lake Orta changed from 1971 to 2007. New rotifer taxa appeared in the lake after the mid 1980s, when discharge of toxic substances decreased, but their annual persistence was low P<0.5 until the turn of the century. The numerical values of rotifer and crustacean persistence in Lake Orta were unexpectedly high in 2001 and 2007 0.55 and 0.72 for rotifers, 0.85 and 0.86 for crustacean, respectively , much higher than in limed lakes in Sudbury, Canada, and in adjacent Lake Maggiore. We hypothesize this could be related to the lack of Cladoceran predators and zooplanktivorous fish in the pelagic waters of Lake Orta. 75 Published version http //www.scopus.com/inward/record.url eid=2 s2.0 84964824740 partnerID=q2rCbXpz Articolo 2016_Journal_of_Limnlogy_75_2s_15_21.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. roberta.piscia PISCIA ROBERTA marinamarcella.manca MANCA MARINA MARCELLA |
