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ISSN 0704-3716 CANADIAN TRANSLATION OF FISHERIES AND AQUATIC SCIENCES No. 4838 Oligochaetes of the Angara River and the Bratsk Reservoir by T.V. Akinshina and A.A. Tomilov Original Title: Oligokhety r. Angary i Bratskogo vodokhranilishcha From: Gidrobiol. Issled. Vodoyomov Sibiri p. 104-112, 1976. Translated by the Translation Bûreau (NDE) Multilingual Services Division Department of the Secretary of State of Canada Department of Fisheries and Oceans Institute of Ocean Sciences Sidney, B.C. 1982 13 pages typescript DEPARTMENT OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT TRANSLATION BUREAU BUREAU DES TRADUCTIONS MULTILINGUAL SERVICES DIVISION DES SERVICES CANADA DIVISION MULTILINGUES a 7-A:i./.5 TRANSLATED FROM - TRADUCTION DE INTO - EN Russian English AUTHOR - AUTEUR T.V. Akinshina and A.A. Tomilov TITLE IN ENGLISH - TITRE ANGLAIS Oligochaetes of the Angara River and the Bratsk Reservoir TITLE IN FOREIGN LANGUAGE (TRANSLITERATE FOREIGN CHARACTERS) TITRE EN LANGUE ÉTRANGÉRE (TRANSCRIRE EN CARACTÈRES ROMAINS) Oligokhety r. Angary i Bratskogo vodokhranilishcha REFERENCE IN FOREIGN LANGUAGE (NAME OF BOOK OR PUBLICATION) IN FULL. TRANSLITERATE FOREIGN CHARACTERS. RÉFÉRENCE EN LANGUE ÉTRANGÉRE (NOM DU LIVRE OU PUBLICATION), AU COMPLET, TRANSCRIRE EN CARACTÈRES ROMAINS. Gidrobiol. issled. vodoyomov Sibiri REFERENCE IN ENGLISH - RÉFÉRENCE EN ANGLAIS Hydrobiological Study of Siberian Water Bodies PUBLISHER - ÉDITEUR PAGE NUMBERS IN ORIGINAL DATE OF PUBLICATION NUMÉROS DES PAGES DANS not available DATE DE PUBLICATION L'ORI GINAL 104-112 YEAR ISSUE NO. VOLUME PLACE OF PUBLICATION ANNÉE N UM ÉRO NUMBER OF TYPED PAGES LIEU DE PUBLICATION NOMBRE DE PAGES DACTYLOGRAPHIÉES Irkutsk, USSR 1976 13 REQUESTING DEPARTMENT D F 0 TRANSLATION BLIREAU NO. MINISTÈRE-CLIENT NOTRE DOSSIER Nu 861173 BRANCH OR DIVISION S .I.P.B. TRANSLATOR (INITIA LS) N. De. DIRECTION OU DIVISION TRADUCTEUR (INITIALES) PERSON REQUESTING DEMANDÉ PAR Dr. R. Brinkhurst UNEDITED TRANSLATION YOUR NUMBER For information only VOTRE DOSSIER N 0 TRADUCTION NON REVISEE DATE OF REQUEST January 28, 1982 Information seulernent DATE DE LA DEMANDE zDA a 1982 SOS-200-1043 (REV. 2/68) 7830-21-029-5353 Ki& Secretary Secrétariat 19nr of State d'État MULTILINGUAL SERVICES DIVISION — DIVISION DES SERVICES MULTILINGUES TRANSLATION BUREAU BUREAU DES TRADUCTIONS Client's No.-1\1 0 du client Department — Ministère _ Division/Branch — Division/Direction City — Ville D F 0 S.I.P.B. Sidney, B.C. Bureau No.—No du bureau Language — Langue Translator (Initials) — Traducteur (Initiales) 861173 Russian N. De. "AM 1 3 1982 Gidrobiol. issled. vodoyomov Sibiri (Hydrobiological Study of Siberian Water Bodies), 1976, pp. 104-112 (104)* Oligochaetes of the Angara R. and the Bratsk Reservoir by T.V. Akinshina and A.A. Tomilov Oligochaetes are one of the leading groups of the zoobenthos in many of the artificially created water bodies, especially ponds and reservoirs. They are frequently superior to the other groups of invertebrates in numbers and biomass. Because of this, the ben- Z 0 42 thic laboratory of the Biological and Geographic Research Institute, .47 tIJ < g E 41) Reservoir from it 2 ••r, which has taken part in a joint study of the Bratsk Z 0 0 i; e the Ce (.12 the year it was filled (from 1964), has attempted to establish EZ g CI o0 I role of oligochaetes in the formation of the benthos, their quanti- Lu É CZ4 16 ‘12 among other invertebrates, and their horizontal Lu tative relations Z Ci »— D Ce and vertical distribution in the water body. We have studied the taxonomic composition in order to establish the dominant families, genera and species, and have attempted to establish the role of the Baikal endemic species (of those previously inhabiting the Angara R.) in the present-day bottom fauna of the reservoir. This paper is based on the material brought back by the 1967- 1968 expeditions conducted in the Angara sector of the reservoir, as well as on series of year-round collections of zoobenthos taken every ten days (1970-1971) and every week (1971-1972) at permanent *The numbers In the rïght-hand margIn are the pages of the Russîan text - translator SEC 5-25T (Rev. 6/78) 16, stations of the Balagansk section. Samples of the zoobenthos were taken three times at each station, with a Petersen bottom sampler, DCh-0.025. In 1967-1968, samples were taken at 293 stations along the lines of transverse sections for 10-20 km along the entire Angara sector of the reservoir, and at a large number of stations in the bays of Unga, Uda, Osa, Odissa, Yelovka, Kui, Balya, Zyaba and Kezhma- Kezhemskaya. The Balagansk section is found near the town of Balagansk, 107 km from where the backwater begins to peter out (Svirsk), in the middle of the reservoir. The stations are located on a transverse section through the Balagansk expansion of the reservoir from the left shore at depths of 1, 3, 5, 8, 12, 25 and 42 m in succession. The last station is found in the trough of the former Angara river bed. Oligochaetes comprised a large group of the benthos on the soft sandy-muddy and muddy substrates in the area:of the Angara now occu- pied by the Bratsk Reservoir even before its formation. According (10.5 to the data of N.V. Vershinin [1], they constituted an average 0.15- 6.4 g/m2 or from 16 to 80% of the biomass of the entire benthos in the upper half of this area which extends for 225 km between Malaya Buret' and Atalanka. In some places, e.g. near Konovalovo (in the part of the river adjacent to a sand bar along the shore), their 2 biomass reached 27 g/m . On 4 sections in the lower half of the area extending for 235 km between Atalanka and Bratsk,oligochaetés constituted an insignifi- cant part of the benthos 0.1-5.8% of the biomass or 0.03-1.2 g/m 2 . In comparison with the upper half of the area, here we observed a 6-fold decrease in the biomass of oligochaetes, which corresponded to the decrease in their population density. Above the Bratsk Reservoir, in the Angara R. below Irkutsk, R.A. Golyshkina [3] noted concentrations of oligochaetes with a bio- mass of up to 63 g/m2 on gray mud with detritus and sand, and 21.7 g/m2 on fine gray mud. In the lakes of the Angara floodplain, which are found on is- lands, the proportion of oligochaetes was extremely low with a high biomass of the benthos (from 6 to 81 g/m2) [1]. Thus, before the Bratsk Reservoir came into being, oligochaetes were an important group of the benthos in the Angara R., especially on silted sands and in the muds of the river bed, behind the islands and sand bars, in quiet channels and backwaters. An interesting peculiarity was nôted in the distribution of oligochaetes, i.e. they were more abundant in the part of the river from Irkutsk to Atalanka, than in its lower part from Atalanka to Bratsk. The same was observed during the years the reservoir was being filled. N.V. Vershinin and A.V. Sycheva [2] indicate that, iA July of 1963, the average biomass of oligochaetes in the former Angara river-bed in the upper and lower parts of the reservoir diminished from 4.0-2.5 to 0.5 g/m2 respectively, and the percentage of oligo- chaetes in the biomass of the entire benthos also decreased. By the time the reservoir had been filled (1967-1968), oligo- chaetes were distributed extensively, but nonuniformly. In the bays of the upper part of the rèservoir, where the conditions are the .eutro hic closest_to those of shallôw .,lpLkes, oligochaetes are of secondary importance and do not comprise more than an average 3-8% of the whole biomass of zoobenthos. In the deep bays of the middle and lower parts (Balya, Kezhma, Zyaba) which are found in the taiga zone, oligochaetes constitute 10-11% of the biomass, their numbers usually increasing with depth, toward the boundaries of the bays. The following changes in density, biomass and the quantitative significance of oligochaetes in the benthos are observed within the boundaries of the Angara stretch of water (without the bays), from the top of the reservoir (Svirsk) to the dam of the Bratsk Hydro- electric Power Plant. The upper part, which extends for 45 km, is (106 not very deep (up to 20 m) and has a slow, attenuated current. The littoral zone (0-5 m) occupies 1144 hectares, i.e. 7.6% of the en- • tire area of this sector which covers 15,022 hectares. Oligochaetes populate the entire bottom, and are characterized by a high density and biomass (table 1). They are scarce only in the near-shore strip (from 0 to 1 m). However, - às the bottom descends , the num- ber of oligochaetes on the profile of each of the 4 sections increases and reaches its maximum in the former Angara river bed. Because of this, the average biomass in the profundal zone is 4 times greater (16.1 g/m2 ) than in the littoral zone (4.1 g/m2 ). Oligochaetes dominate both in the profundal zone (88%) and in the littoral (65%), constituting 87.2% and 15.2 . g of the whole zoobenthic biomass in this area as a whole. Oligochaetes are equally scarce throughout the littoral zone in the middle and lower sectors (see table 1), their biomass averaging 0.32 g which is only 4.6% of the entire (107) benthos. However, the Oligochaeta sharply predominate over the other groups of animals in the profundal zone. The number of worms, their biomass and their percentage in the biomass of the entire benthos per square metre increase as we move farther from shore and as the depth increases (table 2).