“The goal of the expedition was to gather information about the condition of Lake Peipus as a whole, working on the basis of same initial data,” explained Ago Jaani, an adviser with the Water Department of the Ministry of the Environment. For most people, Peipus is associated with one thing: fish. However, a lot of the fish in the lake – such as bream, ruff and eels – feed on its muddy bed, which itself teems with life. The animal world of Lake Peipus is dominated by two large groups: midge (or chironomid) larvae and freshwater worms (or oligochaetes). In the shallow water on the lake’s shores you can also find the Gmelinoides fasciatus species of amphipod introduced from Lake Baikal in Russia, although the animal with the greatest biomass in Peipus is currently the wandering mussel, which purifies the water by filtering it. These and many other invertebrates who inhabit or live on the sediment of the lake bed represent the main fauna by which the ecological condition of the body of water can be evaluated. “Fauna samples were collected over the four days from Lakes Suurjärv, Lämmijärv and Pihkva,” Jaani explained. “96 samples were collected in total from 26 monitoring stations, and these will now be analysed in the laboratory of the Lake Võrtsjärv Centre for Limnology. It will take around a month before the scientists there know what’s happening on the bed of Lake Peipus.” The main hydrophysical indicators of the water from the lake were also measured during the expedition. The difference in water temperature between the northern and southern parts of the lake was seven degrees (ranging from 11.6 degrees near Alajõe to 18.5 degrees in Värska Bay). This is common during spring, when the water in different parts of the lake begins to heat up. Visibility also varied. In Lake Peipus it reached as much as 3.9 metres, but in Lakes Lämmijärv and Pihkva was only a metre or less – clearly due to the humus-rich water entering the lake from the surrounding marshes and bogs, giving the lakes their rusty brown colouring. The expedition took place on the Õnneleid, a ship belonging to the Institute of Agriculture and Environmental Science of the Estonian University of Life Sciences, led by Külli Kangur, senior scientist from the Lake Võrtsjärv Centre for Limnology. Russia was represented by long-time Peipus researcher Yevgeni Afanasyev, the senior scientist with the Pskov Department of the State Research Institute of Lake and River Fisheries (GosNIORH). The next Estonian-Russian expedition on the lake, which forms the border between the two countries, will take place in August, when a set of water chemistry, biota and sediment samples will be collected. A total of four expeditions on Lake Peipus and one on the Narva reservoir have been planned for 2007 by the joint committee for border waterways. For further information please contact: Külli Kangur Agnes Jürgens |
