f eRCHIVES

FISHERIES AND MARINE SERVICE

Translation Series No. 3741

Comparative characteristics of phyto- and bacterioplankton of the lake part of the Gorky

by G.M. Lavrent'eva, and A.P. Romanova

Original title: Sravniternaya kharakteristika fito- i bakerioplanktona ozernoi chasti Gor'hovskogo vodokhranilishcha

From: Izv. Gos. Nauchno-Issled. Inst. Ozern. Rechn. Rybn. Khoz. 95: 61-66, 1974

Translated by the Translation Bureau(jw ) Multilingual Services Division Department of the Secretary of State of Canada

Department of the Environment Fisheries and Marine Service Arctic Biological Station Ste. Anne de Bellevue, P.Q.

1976

12 cages typescript DEPARTMENT OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT

TRANSLATION BUREAU BUREAU DES TRADUCTIONS

MULTILINGUAL SERVICES ?f,Àem DIVISION DES SERVICES CANADA DIVISION MULTILINGUES

m -7q)

TRANSLATED FROM — TRADUCTION DE INTO EN Russian English

AUTHOR — AUTEUR G.M.Lavrent'eva and A.P.Romanova

TITLEINENGLISH—TITREANGLAIS Comparative characteristics of phyto- and bacterioplankton of the lake part of the Gorky reservoir

TITLE IN FOREIGN LANGUAGE (TRANSLITERATE FOREIGN CHARACTERS) TITRE EN LANGUE ÉTRANGÉRE (TRANSCRIRE EN CARACTÉRES ROMAINS) Sravnitel i naya kharakteristika fito- i bakterioplanktona ozernoi chasti Gorikovskogo 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 CARACTÉRES ROMAINS. lzvestiya gosudarstvennogo nauchno-issledovatel'skogo instituta ozernogo i rechnogo rybnogo khozyaistva

REFERENCE IN ENGLISH — RÉFÉRENCE EN ANGLAIS Proceedings of the State Scientific Research Institute of La ke and River Fisheries (GosNIORKh) PAGE NUMBERS IN ORIGINAL PUBLISHER ÉDITEUR DATE OF PUBLICATION NUMÉROS DES PAGES DANS Not given DATE DE PUBLICATION L'ORI.GINAL 61-66 YEAR ISSUE NO. VOLUME NUMÉRO PLACE OF PUBLICATION ANNÉE NUMBER OF TYPED PAGES NOMBRE DE PAGES LIEU DE PUBLICATION USSR DACTYLOGRAPHIÉES 'id Not 95 given 12

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505.200.10.0 (REV. 2/00) 7030-21-020-033 3 DEPARTMENT OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT TRANSLATION BUREAU BUREAU DES TRADUCTIONS

. MULTILINGUAL SERVICES DIVISION DES SERVICES DIVISION MULTILINGUES

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LMA From: Izv. gos. nauchno-issled. inst. ozern. i rechn. ryb. khoz (Proceedings of the State Scientific Research Institute of 0 Lake and River Fisheries (GosNIORKh)), vol. 95, pp. 61-66, F— " 0 -A 1974 (USSR) r 2; • 0 pe0 ICI r, n Comparative characteristics of phyto- and bacterioplankton E 2: g

of the lake part of the Gorky reservoir UJ .E Ë t, Z) by Lt4 L Cà

G.M. Lavrent'eva and A.P. Romanova Id*

UDC 581.526.325(47:282.4G) + 576.8(47;282.4G)

A study of the microflora of the river, in a section which now 61*

forms part of the Gorky reservoir, was begun before the dam at Gorodets was

built. The first study dealt with a description of the species composition

of phytoplankton (Esyreva, 1945). Intensive studies both of phytoplankton

(Priimachenko, 1959, 1960, 1961, 1966; Esyreva, 1967) and of bacterioplankton

(Kuznetsov, 1959; Rozanova, 1959; Romanova, 1965; Krasheninnikova, 1960)

were conducted in the years after the reservoir was filled. The studies of

that period established the most important indexes which determined the

productivity of the reservoir in its early stages: the abundance and biomass

of phyto- and bacterioplankton, their seasonal and annual dynamics. They

also established the main features of the vertical and lateral distribution

of the microflora.

* The numerals in the right-hand margin indicate page numbers of the original (Tr.).

SOS-200-10-31 2.

From 1960 to 1968 no systematic observations were conducted of the growth of the primary links in the food chain in the Gorky reservoir.

In 1968 the present authors commenced simultaneous studies of phyto- and bacterioplankton as part of a comprehensive fisheries project of Gos-

NIORKh which was undertaken for the purpose of compiling a commercial fishing map of the Gorky reservoir. These studies were continued in 1969-70 in the shallows of the reservoir (Lavrent t eva, 1974; Romanova, 1974), and in 1973 the main studies shifted again to the main channel area.

The Gorky reservoir, which is a valley-fluvial type of reservoir, has a distinctive lake portion as well. The effect of the backwater is quite noticeable in the area of Krasnyi-on-the-Volga, below Plës, where there is a marked reduction in the rate of current flow and hence reduced mixing of water. In the area of Elnat the reservoir clearly assumes the outlines of a "lake", reveals the beginnings of vertical biontic stratification and increased productivity (Priimachenko, 1966).

Yearly changes in the quantity of biomass of the primary links in

the food chain, varying with hydrometeorological conditions, are character-

istic of all water without exception. The amplitude of these

fluctuations in the reservoirs must obviously be larger than in natural water bodies, because in years with unfavorable water conditions water

consumption increases because of the use of water for irrigation purposes.

In years with unfavorable wind conditions the water can be quite agitated, especially in the open deep stretches in the vicinity of the dam, where

the waves exceed 2 m in height (Butorin, 1971).

In this paper we are comparing the results of phyto- and bacterio-

plankton studies which were conducted in the lower parts of the river and

lake section of the Gorky reservoir in 1968 and 1973-years with sharply

different hydrometeorological conditions. 3.

The studies were conducted in July 1968 and beginning of August

1973, which is the most productive period in the Middle Volga area.

At the beginning of the survey in 1968 (stations above the town of

Près to Yurevets) the water temperature in the reservoir was 19-200 and the water was not agitated, whereas at the mid-point and end of the survey 0 (stations between Yurevets and Gorodets) the temperature dropped 4 and the waves reached a height of 1.5 m.

The survey in 1973 was conducted under favorable weather conditions, with water temperature reading of 19 - 210 and practically no water agita- tion due to wind. The phyto- and bacterioplankton specimens were obtained with the aid of Rutner's bathometer on board a semer boat-type research vessel.

The water samples were taken at standard channel stations along the reser- voir (depth, 6 - 19 m) from the upper, middle and bottom layers. The final result was reduced to a quantity of the biomass which was expressed in g/m3 .

The algae biomass was calculated on the basis of sedimented samples by estimating the number of cells of each individual mass in a Nazhotta* chamber, and the bacterioplankton was determined with the use of membraned ultrafilters stained with erythrosin.

In July 1968, at a station above the town of Pl.és,we recorded an 3 algae biomass in the 0 level that was high (8.26 g/m ) in comparison with that of sections farther upstream (Lavrent'eva, 1972). This biomass was comprised of diatoms (Asterionella formosa) and of Pyrrophyta (Cryptomonas ovata). The algae distribution was vertically stratified, both quanti- tatively (see Table) and according to species, with the diatoms predomina- ting at the bottom. In a section below the town of Près the phytoplankton biomass was somewhat reduced and depended on the growth of other diatom species such as Melosira. As was already noted, the weather in the vicinity

*Transliterated from the Russian (Tr.). 4.

of Yurevets changed drastically; however, in protected bays the "flowering" of colonies of Microcystis was still visible. In the channel the "flowering" was already carried off by the agitation of the water, the algae biomass 3 was very low (0.79 g/m ) with over 50% being comprised of blue-green algae.

In the Sokol l sky section the phytoplankton biomass in the channel was even more reduced (see Table) and comprised mostly of Pyrrophyta. At

Puchezh and in the vicinity of the dam the biomass became reduced to 0.01 - 3 0.13 g/m and the samples contained only small forms of Protococcaceae.

In August 1973 the samples were taken at the same stations as in

1968 (see Table). Under the favorable weather conditions already noted, the picture of phytoplankton growth and distribution was complete47 different.

On the whole, the algae plankton biomass increased from a section above the town of Plës in the direction toward the dam. The exceptions were: a) samples taken from the upper level in a section above the town of Plës,where the phytoplankton biomass was greatest and 99.6% was comprised of Mycrocystis aeruginosa. This was due to the fact that our vessel had met up with a

"flowering" "batch" on the drift. The sample taken at this station near the bottom level, where the factors of drift are less marked, was relatively devoid of plankton; b) smaples taken at stations where the channel is strongly affected by the Yurevets shallows, which are the largest in the

Gorky reservoir (Lavrent t eva, 1974); c) samples taken near the dam at a depth of 4 m, where the phytoplankton biomass occurs in the largest quanti- 3 ties in the lake part, namely 217 g/m (of which 96% is comprised of

Mycrocystis aeruginosa). This is not indicated in the table.

At all stations the phytoplankton was vertically stratified, with a more or less sharply declining biomass and change in species composition toward the bottom. The blue-green or the blue-green and diatoms predominated Sctomacca cPlITO- H 6aKTepHonnamcrotta(a1A13 ) Ha pyczopwx cranuanx FopbKopcxoro BoAoxpaitHoHma .nerom 1968 It 1973 rr. Year 01- Above roa the Selow Pje. below Yprevets Sokol i skoe below 6 mleMle r.ccJeaosannii !Mile 11.1eca Hnwe rineca Hn>me Eznanz 10pbeoeu C01(0.1bCK0e linece lirtexa (-,c)Ivti _OF Elnat ës Level rOpH3OHT

0 5 0 5 0 5 0 5 0 5 0 5 1 0 1 5

0,39 0.47 0,37 0,49 0,15 0,17 0,14 0,08 • 0,06 0,18 0,18 0,48 1968 0,16 *- 8,26 3,67 17 1 0,67 0,31 637 0,79 0,18 (7,2•1: 0,01 0,02 0.13 -

Level rOPH3OHT

11 M 0 6,5 0 7 0 1 6,50 85 5 o

0,43 0,44 0,16 1973 0,32 0,32 0,30 0,38 0,35 0,48 0,30 0,35 0,30 0,67 0,33 21-67,03 -2,77- 70;bf 21,33- 2,07 -20,53 -5,33 leî 4,16. 11,29 1,54

fl pnme tt a n e. Hap, tteproil -6awrepHH, no ,p Iteproll - Popepocntt. .cpte: Above the line: bacteria; below the line: algae .

3 The biomass of phyto- and bacterioplankton( g/m ) at main-channel measuring stations of the Gorky reservoir in the summer of 1968 and in the summer of 1973.

Ui 6.

in the top level; diatoms or diatoms and Pyrrophyta predominated in the

intermediate level, and the diatoms were dominant at the bottom level.

The average algae biomass in the zero level in 1973 was 56 times

greater than that of 1968.

In July 1968 the distribution of bacterial biomass, as had been noted in previous studies (Romanova, 1972), was quite distinct between river

and lake parts of the reservoir. The average amount of biomass in the river 3 portion was more than double (0.34 - 0.40 g/m ), that of the lake portion 3 (0.14 - 0.18 g/m ). The largest amount of bacterioplankton biomass (0.44 - 3 0.47 g/m ) occurred, as a rule, in the 5 - 10 meter layer of the lower river portion, which was affected by the backwater conditions and where the rate

of current flow was significantly reduced. This suggests a definite verti-

cal stratification in the distribution of the bacterial biomass. The

increase in the bacterioplankton biomass is due largely to an enlargement

of the cells and is not accompanied by an increase in the number of bacteria.

This suggests that the 5 - 10 meter layer is rich in organic matter, which

is available to the bacteria but not in quantities sufficient for a burst

of massive reproduction. A marked decline in the bacterioplankton biomass 3 in the lake part of the reservoir (on average to 0.16 g/m ) left the upper 3 levels especially depleted (in some cases down to 0.06 g/m ). The maximum 3 biomass in the lake part (0.48 g/m ) occurred at a depth of 5 m in a section near the dam, which apparently was due to the fact that large masses of blue-green algae which had been destroyed during the storms had drifted into

this layer.

At the beginning of August 1973 consistently hot weather conditions had resulted in a completely different distribution of the bacterial biomass along the reservoir. The average biomass quantities in the river part 3 3 (0.31 - 0.37 g/m ) and in the lake part (0.3 - 0.5 g/m ) hardly differed. 7.

Moreover, at some measuring stations on the lake part of the reservoir the bacterial biomass exceeded the maximum biomass quantities noted for the 3 river portion, amounting to 0.67 and 0.43 g/m respectively.

As to the vertical distribution of the bacterial biomass, the readings obtained from the top and bottom layers in the lower portion of the river section coincided almost completely,and in the lake portion the baomass in the top layer was considerably larger (1.5 - 2 times; see Table) than in the bottom layer.

In years with varying hydrological conditions a steady correlation of the various morphological groups of bacterial plankton is maintained

(rod-shaped forms amount to 85 - 90%), but the size of their cells changes.

Thus in 1968, a year of extremely unfavorable hydrological conditions, the average size of bacterial cells varied within 0.19 - 0.23 cubic microns, whereas in 1973, when hydrological conditions were favorable, the amplitude of size fluctuation increased, with cell dimensions varying from 0.23 to

0.50 cubic microns.

In comparing the growth of phyto- and bacterioplankton in the summer months of these years, it should first be noted that their quantitative distribution in the reservoir is identical.

In 1968 the largest phyto- and bacterioplankton biomass occurred in a section with characteristics of river conditions (above P1ës and below

Elnat). Here the average biomass of phyto- and bacterioplankton at the 3 zero level amounted to 4.61 and 0.38 g/m respectively. The least amount of biomass was noted in the lake portion of the reservoir (Yurevets - dam), and the average amount was identical for phyto- and bacterioplankton, 3 amounting to 0.15 g/m . Hence deteriorating hydrometeorological conditions result in a declining phyto- and bacterioplankton biomass, but with a 8.

changing ratio. If this ratio amounted to 12 during favorable meteorological conditions, it equaled only 1 in poor meteorological conditions, that is to say, in favor of bacterioplankton.

In 1973, when both the phyto- and bacterioplankton biomass tended to increase in the reservoir in the direction toward the dam, their ratio amounted to 198, given the deviations referred to above.

In 1968, as well, the vertical distribution of the microflora revealed two distinct tendencies which were clearly linked to weather conditions. In a section below Pfès and below Elnat the phytoplankton distribution revealed direct stratification, with an average biomass correlation ratio of 2 for the zero- and the 5-meter levels. As to the bacterioplankton, it tended to be inversely stratified (multiple of 1.2 for the same levels).

In the section between Yurevets and the dam (under deteriorating weather conditions) the vertical distribution of the average pbytoplankton biomass assumed the outlines of inverse stratification, with a correlation ratio of about 2 for the zero- and 5-meter levels. The bacterioplankton distribution retained its former inverse stratification, though it was somewhat more marked (multiple of 1.4).

In 1973 the vertical phytoplankton distribution in the entire section under study revealed a clearly direct stratification, increasing an average of about 17 times from the zero level to a depth of 11 m. The bacterio- plankton distribution also revealed a tendency toward direct stratification, increasing about 1.5 times.

These data warrant certain conclusions with regard to the relation- ship in the growth of the autotrophic (algae) and heterotrophic (bacteria) microflora of the Gorky reservoir. 9.

Given deteriorating weather conditions in the summer in the lake part of the Gorky . reservoir, one should expect a marked reduction in the level of the phytoplankton biomass, which in this section is comprised of blue-green algae. The diatoms, which could occupy the freed ecological niche, are at a low ebb at this time - a condition that is characteristic of many lake-type reservoirs (Hutchinson, 1966). Thus unfavorable hydro- . meteorological conditions at the height of the summer season result in a sharp reduction of the synthesizing processes of organic matter (due to the dying off of the dominant blue-green algae) over wide areas of the reservoir, which are the most productive phytoplankton sections under normal conditions and, a little later, in a decline of related breakdown processes.

Along with the deletion of the leading forms of phytoplankton there is a decline in the level of bacterioplankton biomass, despite the fact that for a little the perished algae constitute an additional nutritive material for the microorganisms.

The simultaneous decline in the algae biomass and in the bacteria, which is linked to changing weather conditions, even though such decline proceeds at different rates, suggests that the phyto- and bacterioplankton are not antagonistic to each other.

This is confirmed by the fact that the. increase in the bacterio- plankton mass in the phytoplankton dissolution zone is far less than that of the maximum phytoplankton growth zone in years with favorable conditions.

Moreover, in such years both the algal and the bacterial biomass in the lake part of the reservoir gradually increase in the direction toward the dam.

Thus in the Gorky reservoir there is a definite positive relation- ship in the growth of these two links of the food chain. However, this 10.

interrelationship, even in the lake part of the reservoir, is most likely

a trend, while in closed water systems these correlations have a positive,

functional relationship (Lavrent l eva and Romanova, 1966).

References

1. Butorin, N.V. Hydrological processes in the water reservoirs of the Volga cascade. In the collection: "Studies in the rational utilization of biological water resources". Kuybyshev, 1971.

2. Esyreva, V.E. Volga algae between the cities of and Gorky. Proceedings of Leningrad State University, no. 82, 1945.

3. . Data on phytoplankton of the shallows of the Gorky reservoir. In the collection: "Plant morphology". Moscow, 1967.

4. Lavrent l eva, G.M. Phytoplankton of the Gorky reservoir. Proceedings of GosNIORKh, vol. 77, 1972.

5. . The phytoplankton of the shallows of three reservoirs of the Volga cascade. A fisheries study of inland reservoirs, no. 12. Publ. by GosNIORKh, 1974.

6. Lavrent'eva, G.M. and A.P. Romanova. Bacterio- and phytoplankton of fertilized lakes of Pskov °blast treated with polychlorpinene. Summary reports of the Interinstitutional Scientific Conference. Pskov, 1966.

7. Krasheninnikova, S.A. Microbiological characteristics of the Gorky reservoir in the second year of its existence. Proceedings of the Institute of Biology of Internal Water Reservoirs, issue 3(6), 1960.

8. Kuznetsov, S.I. Microbiological studies of the Gorky reservoir. Bulletin of the Inst. Biol. of Intern. Water Reserv., no. 3, 1959.

9. Priimachenko, A.D. Phytoplankton of the Volga between and Stalingrad in the period of reservoir construction. Proceedings of the Inst. Biol. of Intern. Water Reserv., issue 2(5), 1959.

10. . Composition and main distributional patterns of the phytoplankton biomass in the reservoirs of the plains rivers of the USSR. Proceedings: Inst. Biol. of Intern. Water Reserv.., issue 3(6), 1560.

11. Priimachenko, A.D. Phytoplankton of the Gorky reservoir in the first years of its existence. Proceedings: Inst. Biol. Of Intern. Water Reserv., issue 4(7), 1961.

12. . Phytoplankton of the Volga between Yaroslavl and in the first years after the Gorky and Kuybyshev dams were built. Proceedings: Inst. Biol. of Intern. Water Reserv., issue 11(4), 1966.

11.

13. Rozanova, E.P. Characteristics of the bacteria population of the Gorky reservoir in the first year of its existence. Bulletin of the Inst. Biol. of Intern. Water Reserv., no. 3, 1959.

14. Romanova, A.P. Abundance of bacterioplankton of the Gorky reservoir in the period from the third to the fifth years of its existence. Proceedings of GosNIORKh, vol. 59, 1965.

15. . Microbiological characteristics of the Gorky reservoir. Proceedings of GosNIORKh, vol. 77, 1972.

16. . Microbiological characteristics of the shallows of the Gorky reservoir in the area of Yurevets. Proceedings of GosNIORKh, vol. 89, 1974.

17. English entry.

M HTEPATYPA

ByT op it u II. B. 1971. FimponornnecKne riponeccbi B nonoxpainunintax noo:Kmoro xacna.u. B c6.: «I1p063embi 11.31.'1011151 n paulionaabitoro ItCIIO.1b3O1ihL1IH 6110.3orlitiecnitx pecypcon BOE.10CN1011». Nyii61,11.11CB. pena B. 11. 19-15. choopa no..3opocnell p. Boarn OT F. P1,16111ICKa ;40 r. Fopb- Koro. Yi. 3an. 131,111. 82. • -3. Ec i pen a 13. 11. 1967: MaTerniaam i 113r1C111110 (hirronaaliwroila me:worm:Inn FopbnoncNoro no,loxpaiinainna. B c6.: «,Mop(l)oaorlin pacTeunib>. M. 171. a npe ii rhena F. M. 1972. chnronaanwron Fopbnouclioro no,uoxpannanina. I13n. Foc1-1110PX, T. 77. JI anpenTben a F. M. 1974. (1)nroilaanwrolt is,teoKono.aiin Tpex. ncuoxpaillI,1111.11. 110.1i1:CI:OF0 hacKaaa. Phi6oxo3HficTnennoe 113ytieinie BIlyTp. no3.0emon, c5. ,. 12. 113. 1 . Foc11110PX. JI a npenrbena F. M. n Poma ii o n a A. Il. 1966. Banrepno- H (InrronaaliK- Ton yao6ps!embix 03ep FIcKoncKorr 06.3acTi1, 06pa6oTatilibix nomixaoptilinenom. TC3. noKa. Memoy3oncnoii Harmon noimPepeinuni. K p a at e ii n ii H 111: 0 11 a C. A. 1960. Min:po6no.aori1necnan xapawrepticTin:a ropb- 7. ROBCK0r0 noaoxpainimitua BO wropoil ro,3, ero cyntecTnonainin. Tp. nnyrp. Boa, ribui. 3(6). y 3 11C110B C. 14. 1959. .Min:p06no.loriitiecnile iicc.nenonainin FopbKoncKoro no- • 3,0x1)ainuni1na. Bio.i. 1111-Ta 6110.1011111 BlIVTO. BOA,.N.9 3. p u ù mane II K o A. ".1,. 1959. cbirromanwron BOM11 OT 5Ipocaan.1n io CTamui- 9- rpiula B IlCIlO.1 o6pa3onaillin no,u.oxpainuutiu. Tp. 6110.3orini nityrp. 110,R, nun. 2(5). /e p m a Ile ii K 0 A. 1960. Cocran ii ocitorinme aaKonomepilocTli paclipe.lene- 1111F1 6llomacci4 flurrormanKrolia n no,3oxpainunnuax panninnibix pex CCCP. Tp. 1411-Ta 6nonornit BlIyTp, 110,111, BbIn. 3(6). • /1. p u û m a ti en no A. 1961. (1)11Tormalinron FophKoncnoro no.aoxpaitilauma Blue ro.abi ero CyllICCT13011a111151. Tp. 1111-ra 6110:lorlin nityrp. 130:1„ BbIfl. 4(7). / • n p u i m a ti enzo A. ,111,. 1966. cDirron.natinron p. Bomn or 5Ipoc3anan ;to Boaro- rpaRa n nepuble FORM nocJie coopy)Keinin FopmwneKori H 1yil6bILLICBCKOil 11110T1111. 1111-Ta 6110.1011111 nilyrp. Bo, 131,111. 11(4). /3- Posanon a E. II. 1939. XapanTeplicTitKa 6awrepi1ainnioro nace.leinin ropbRois- cxoro noioxpaIu.mw.a iiepai ro. ero cymecTnonanini. bIO.JI. 4111-Ta 61t0.3ortiii nnyTp. 110..1, X9 3. &.• Poma it 0 B a A. n. 1965. lInciennocrb 6aKrepnormannTo1Ia l'OpbROBCK01.0 BO..10- ' . paiiii.iuiva }la 3-5-m roa,ax ero cytnecnionaillin. II3 13. 1-0C11110P.X, T. 59. /J Po manon a A. ri. 1972. Miii:po61(03orlitiecKan xapaKreplieTinia Fophnonckoro no,loxpaininnuta. 1130. Foc11110PN, T. 77. . Post a n on a A. 11. 1974. :■lin:p06iionoriinecnan NapawreplicritRa Fopbnoncuoro no;4oxpaiiii.inina n parione 10pbenna. 113n. FoelillOPX, T. 89. /7'• 11 utchinson G. E. 1966. A treatise on limnology. II Introdution to lake biology and litnnoplankton. Sidnay.

G. M. Lavrentyeva and A. P. Romanova 12.

'COMPARATIVE CHÀRACTERISTICS OF PHYTO- AND BACTERIOPLANKTON OF THE LAKE PART OF GORKY RESERVOIR SUMMARY Results are presented of both algal and bacteriological investiga- tions carried out in the enlarged part of Gorky reservoir in 1968 and 1973. years whose hydrometeorological conditions are sharply different. Positive correlation has been noted for the development of primary trophic chains in the reservoir.