| Title | Periphyton changes over 20 years of chemical recovery of Lake Orta, Italy: differential response to perturbation of littoral and pelagic communities |
| Abstract | Lake Orta, a large Italian subalpine lake, has a long history of industrial pollution by acid, ammonia. and metals. A whole-lake liming treatment in 1989-1990 led to a gradual increase in pH (from 4.4 to 7) and a concomitant decline in ammonia (from 2.5 to 0.05 mg L(-1)) and metal concentrations (e.g.. copper: from 35 to 3 mu g L(-1)). In this study, we examine the response of the littoral zone, in terms of chemistry and periphyton assemblages, to contamination and recovery of Lake Orta. We compare these findings with a long-term data set of chemistry and phytoplankton collected in the pelagic zone. We sampled periphyton at two sites from the liming period (1989) through 2010 when the lake approached chemical equilibrium. Chemical variables collected in the littoral zone near the periphyton samples followed the same temporal trends observed in the pelagic zone. Chlorophytes. the dominant algae in the preliming period, progressively waned after the calcium carbonate addition. Diatom importance gradually increased to reach up to 80% of the total biovolume in the most recent years. There was a clear shift in the diatom taxonomic composition over the study period. Acidophilous Pinnularia subcapitata var, hilseana and metal-tolerant Achnanthes minutissima were dominant before liming. With the progressive increase in pH and decline in metal concentrations, there was successively the dominance of Fragilaria nanoides (fin-merit, identified as Synedra tenera) and Cymbella microcephala in the transition period and of circumneutral Navicula cryptocephala, N. radiosa, and Synedra ulna in the most recent period. Pelagic diatoms were more affected than benthic diatoms by the industrial pollution and their recovery after the liming intervention was slower. Whereas present periphyton diatom assemblages are similar to those observed in nearby unpolluted Lake Mergozzo, pelagic assemblages are still in transition from severe disturbance towards characteristics reported before pollution. Our results suggest that the littoral zone may have acted as a refugium during contamination providing an inoculum for pelagic recolonization. |
| Source | Journal of limnology (Testo stamp.) 70 (2), pp. 177–185 |
| Keywords | Metal contaminationlimingacidificationdiatomsphytoplankton |
| 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/JL11-70-2-03 |
| Authors | Cattaneo, A (Cattaneo, Antonella)[ 1 ] ; De Seve, M (De Seve, Michele)[ 2 ] ; Morabito, G (Morabito, Giuseppe)[ 3 ] ; Mosello, R (Mosello, Rosario)[ 3 ] ; Tartari, G (Tartari, Gabriele)[ 3 ] |
| Text | 203777 2011 10.3274/JL11 70 2 03 ISI Web of Science WOS 000294320400003 Metal contamination liming acidification diatoms phytoplankton Periphyton changes over 20 years of chemical recovery of Lake Orta, Italy differential response to perturbation of littoral and pelagic communities Cattaneo, A Cattaneo, Antonella 1 ; De Seve, M De Seve, Michele 2 ; Morabito, G Morabito, Giuseppe 3 ; Mosello, R Mosello, Rosario 3 ; Tartari, G Tartari, Gabriele 3 1 Univ Montreal, Dept Sci Biol, GRIL, Montreal, PQ H3C 3J7, Canada 2 MA De Seve Consultants, Montreal, PQ H2V 1N4, Canada 3 Ist ltaliano Studio Ecosistemi, CNR, I 28922 Pallanza, Italy Lake Orta, a large Italian subalpine lake, has a long history of industrial pollution by acid, ammonia. and metals. A whole lake liming treatment in 1989 1990 led to a gradual increase in pH from 4.4 to 7 and a concomitant decline in ammonia from 2.5 to 0.05 mg L 1 and metal concentrations e.g.. copper from 35 to 3 mu g L 1 . In this study, we examine the response of the littoral zone, in terms of chemistry and periphyton assemblages, to contamination and recovery of Lake Orta. We compare these findings with a long term data set of chemistry and phytoplankton collected in the pelagic zone. We sampled periphyton at two sites from the liming period 1989 through 2010 when the lake approached chemical equilibrium. Chemical variables collected in the littoral zone near the periphyton samples followed the same temporal trends observed in the pelagic zone. Chlorophytes. the dominant algae in the preliming period, progressively waned after the calcium carbonate addition. Diatom importance gradually increased to reach up to 80% of the total biovolume in the most recent years. There was a clear shift in the diatom taxonomic composition over the study period. Acidophilous Pinnularia subcapitata var, hilseana and metal tolerant Achnanthes minutissima were dominant before liming. With the progressive increase in pH and decline in metal concentrations, there was successively the dominance of Fragilaria nanoides fin merit, identified as Synedra tenera and Cymbella microcephala in the transition period and of circumneutral Navicula cryptocephala, N. radiosa, and Synedra ulna in the most recent period. Pelagic diatoms were more affected than benthic diatoms by the industrial pollution and their recovery after the liming intervention was slower. Whereas present periphyton diatom assemblages are similar to those observed in nearby unpolluted Lake Mergozzo, pelagic assemblages are still in transition from severe disturbance towards characteristics reported before pollution. Our results suggest that the littoral zone may have acted as a refugium during contamination providing an inoculum for pelagic recolonization. 70 ID_PUMA cnr.ise/2011 A0 029 Periphyton changes over 20 years of chemical recovery of Lake Orta Periphyton_changes_over_20_years_of_chemical_recovery_of_Lake_Orta.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. giuseppe.morabito MORABITO GIUSEPPE rosario.mosello MOSELLO ROSARIO gabriele.tartari TARTARI GABRIELE TA.P04.016.004 Ecologia teorica e applicata degli ecosistemi acquatici |
