142
Куликова и др., 1997; Кутикова, Николаева, 2002). Best studied is
zooplankton in the lake’s largest tributaries (Suna – 266 taxa, Shuja – 183,
Kumsa – 149), lakes within their watersheds, especially Shuja watershed
(Syamozero – 232, Pertozero – 140, Konchezero – 117), as well as in small
rivers within Petrozavodsk City (Lososinka – 184 and Neglinka – 156).
Special focus in the study of these water-bodies has been on the species
composition of rotifers. Large and small lakes on the eastern and south-eastern
coasts of Lake Onego still remain insufficiently studies, largely due to their
remoteness.
Water-bodies in the Lake Onego catchment belong to a variety of bionomic
types differing considerably in a number of morphometric, hydrological,
hydrochemical parameters determining the diversity of the plankton fauna and
its quantitative characteristics: from oligotrophic (rarer) to eutrophied
(mesoeutrophic and eutrophic) types, as well as humification-related
dystrophic ones. On the other hand, there are quite a few common features
characteristic of south Karelian lakes as regards zooplankton taxonomic
composition and development level. Studies have shown that the majority of
species constituting the basic zooplankton background in water-bodies of the
catchment are typical of lakes of the European North of Russia. They are
widespread in Karelian water-bodies and widely eurybiotic. Zooplankton
taxonomic composition and abundance depend on the type of the river and are
closely related to the hydrographic characteristics of its watershed. Plankton
species diversity is the greatest in rivers with the largest drainage area and a
high percent cover of lakes, such as Shuja, Suna, Lizhma, Kumsa. The planktic
complex in rivers is formed chiefly of lacustrine plankton elements coming
from source and drainage lakes, whereas typical riverine species are difficult to
identify. Abundant forms of the crustacean complex in both large and small
lakes, as well as in rivers, are Daphnia cristata Sars and bosmina – Bosmina
obt. lacustris Sars, B. coregoni Baird, B. longirostris (O. F. Müller) among
cladocerans. A significant proportion of copepods is constituted by
Eudiaptomus gracilis (Sars), Thermocyclops oithonoides (Sars) and
Mesocyclops leuskarti (Claus), of rotifers – by Kellicottia longispina
(Kellicott), Keratella cochlearis (Gosse), Asplanchna priodonta Gosse,
Conochilus unicornis (Rousselet), Bipalpus hudsoni (Imhof), Polyarthra major
(Burckhardt), P. dolichoptera Idelson, P. euryptera Wierzejski, Synchaeta
grandis Zacharias, S. stylata Wierzejski, S. pectinata Ehrenberg, S. kitina
Rousselet, Euchlanis dilatata Ehrenberg, E. lyra Hudson, E. deflexa Gosse.
Lake and river sites overgrown with macrophytes (horsetail, water-lilies,
pondweeds, reeds, etc.) and featuring low flow rate are usually noted for a
more species-rich and abundant plankton. It includes a specific complex of
phytophilous and littoral/bank-side forms (Sida, Eurycercus, Acroperus,