Lago di Orta - Italy
Lago di Orta
Parent Site Name
Lake Orta is a deep subalpine lake, located in Northern Italy, at a mean altitude of 290 m a.s.l. Its perimeter is 33,8 km, surface area 18,14 km2, volume 1,29 km3. Lake Orta has a maximum depth of 143 m and a mean depth of 71 m. Lake Orta is well known for being polluted by industrial discharges (copper sulphate and ammonia) since the late 1920: as a consequence, the pH of the lake water dropped down till 4 and the food web was almost completely destroyed, except for some few, strongly adapted species. The pollution stopped around mid 1980s and a liming intervention was carried out in 1989-1990, to neutralize the acidic waters of the lake. The recovery was very fast, new species started to colonise the lake just after the liming. The lake, however, is still at risk, due to the large amount of heavy metals stored in the sediments.
General Characteristics, Purpose, History
Long-term changes of temperature, heat content and of mixing depth of the lake water. Seasonal monitoring of hydrochemistry and phytoplankton. Analyses of sediment cores: algal and bacterial pigments, fossil remains of thecamoebians, diatoms, and cladocerans, pollen, metals (particularly mercury and copper). Analysis of perifiton during the lake evolution. Other research topics: Laboratory testing on adaptation and clonal selection of zooplanktonic organisms in different stages of lake pollution and recovery. Comparison of the response of organisms obtained from resting eggs preserved in sediment cores compared to that of present-day zooplanktonic organisms (resurrection ecology and biology). Estimation of changes in the size and composition, and of the genetic fingerprint, of the bank of resting stages during the lake evolution through analysis of lake sediment cores. Comparison of periphyton and phytoplankton communities in relation to trophic and chemical evolution. Functional analysis of phyto-and zooplankton communities 20 years after the liming. Monitoring of fish community according to the Water Framework Directive (2000/60 / EC) and restocking of pelagic fish species (Alosa agone and Coregonus lavaretus). Restoration of the ecological connections with Lake Maggiore. Ecotoxicological and sclerochronological researches on bivalves molluscs and monitoring of their population.
Affiliation and Network Specific Information