hRc» f Vr 5

FISHERIES RESEARCH BOARD OF CANADA

Translation Series No. 2787

Formation of plankton in the Lielupe river

by N. A. Sloka

Original title : Formirovanie zooplanktona reki Lielupe

From: Trudy Karel'skogo Otdeleniya GosNIORKh (Proceedings of the Karelian Section of.GosNIORKh), 5(1) : 177-182, 1967.

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

Department of the Environment Fisheries Research Board of Canada Freshwater Institute Winnipeg, Man.

1973

9 pages typescript*

f DEPXRTMEt4T OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT TRANSLATION BUREAU BUREAU DES TRADUCTIONS

MULTILINGUAL SERVICES DIVISION DES SERVICES DiVISION CANADA MULTILINGUES

CLIENTS NO. DEPARTMENT DI VISION/BRANCH CI TY N° toe CLIENT MINISTERE DIVISION/DIRECTION VI LLE Environment Fisheries Service Ottawa

BUREAU NO. LANGUAGE TRANSLATOR (INITIALS) N° DU BUREAU LANGUE TRADUCTEUR (INITIALES) Russian JW 143986 i\e-N - 1 1973

From: Trudy Karel'skogo Otdeleniya GosNIORKh. Vol. 5, No. 1, 1967 (USSR).

Formation of zooplankton in the Lielupe river • TRANSLATION by LII1EDTi.D irdorm.n.ion RWISEE N.A. Sloka l'IDjCTICS NON Inlormeion seulemiet The Lielupe river basin is in the central part of the Latvian

SSR, in the Zemgal' lowland. The Lielupe river has its source in the

southern part of the Republic, at the confluence of the Memel and Musa

rivers near the town of . The river is 119 km long and its basin 2 comprises an area of 17,814 km .

The Lielupe river flows into the Gulf of . Its average annual /p.179 3 run-6ff amounts to 3.64 km and its average rate of water flow is 115.2 3 m /sec.

Thermally, the Lielupe river is one of the warmest in . The

hydrothermal indez of the large Latvian rivers is shown in Fig. 1.

The Lielupe is a typical plains river with a very low gradient.

Its rate of flow is greatest over the first 20 km in its upper reaches,

where its gradient is from 1 to 0.3 m per km. Farther downstream the

gradient amounts to an average of no more than 0.005 m per km. Salt water

from the can penetrate far up the Lielupe river due to the

SOS-200-10-31

7530.21-02g-5332 2

latter's Slow rate of flow (Table 1)'.

AS'efe Gauya river. ...etseexne Lielupe river eeeece# paugava river es 23 - 1 Il de 111 MOO MUM 'Wm. mm m /7 m mum mm mmeammmummumm mm m e m mum IMMOMMUMM 113111111 WU II MIll MI MOW 1 .\. II 1. , • 0113 IIIIII MI1111 çi4.1 • f Ftia a) • () • V, ra 1 7 L 6 • 1. a I . • tb 4 .\\, 1— V \‘,.. 2 ., [ 9 q : 1,1Y • ‘\\ ,-,'- J H I1 i i 11. i . l'. • I 2 _7 Z.e.

- .Pile. 1. FliapoTepmliKa 6o.lbtuilx peK TiaTedicmon CCP the large Latvian rivers .1.) Fig.'. Hydrothermal index of

The hydrobiological and hydrochemical regime of the Lielupe river is also affected by the industrial and domestic waste waters that are being discharged into it. It is particularly strongly affect- ed by the waste waters of the city of Elgava, by those of the Sloka

Pulp and Paper Combine and by those of the population centers in the 3

Gulf area. These waste waters strongly reduce the oxygen content in individual sections of the river. A reduction in oxygen is especially noticeable below the point where the waste waters from the Sloka Pulp and Paper Combine are being discharged into the river (Table 1).

The reactivity of the water is generally satisfactory and.its pH factor fluctuates within the limits of a weak alkaline reaction.

Only when increased amounts of waste water are being discharged at the

Sloka Pulp and Paper Combine is there an acid reaction (pH 4.5) that suggests a possible deterioration of the conditions of life for organisms.

Water compos ition of the L i e I upe river rLl^bûr^â il (data fr^?ôCTaâyàdAbbpexE^7ls,ényné ^âH b,éJ1Ù57 roqa -P. H. Kowiaw)

Aata oT6opa I Ha 5 x.u Hn;r.e i BMwe Bbiwe Y cnycxa Ha 5 x.u Oico.io Oicoao npo6w U... r. E.ira- Fa.In- C.^oicn 1(6K rnuhe CT. 1y- M ^ïne- n Enra©w ocI 1111eaia cnycica 6ynrw nyne o b c e 9 CF)^ 11-12/VI - 7,2 6,72 6,80 6,0 2,24 3,26 7,6 p^i117 2-3/V11 8,88 5,76 7,36 7,12 4,16 1,92 5,36 9.04 ^,^ â 6-7/VIII 8,24 5,92 7.20 7,52 5.68 5,28 5,36 6,56 ? ^° 3-4/IX 8,8 8,9 8,1 7,8 4,8 4,4 5,7 7,2 0n 23-24/X 10,16 I 9,76 8,96 9,12 9,04 9,04 8,56 8,24

M N 11-12/VI - 20,0 10,0 11.0 22,0 14,0 121,0 720,0 2-3/V11 18,0 17,0 21,0 30,0 147,0 430,0 780,0 1610,0 L. CY) 6-7/VIII 16,0 15,0 16,0 15,0 530,0 320,0 1120,0 1500,0 0 E ô 3-4/1X - - - - 54,0 390,0 550,0 920,0 Va ^ 23-24/X 1110 14,0 15,0 17,0 12,0 19,0 19,0 22,0

a-date of samp I i ng; b-.3 km above EI gava; c-be ( owE I gava; d-above F.a I nts i ema; e-above 61 oI<,a; F-at the. pu I p-and-Pap Combine; y-3 krn be l ow Pu ! p-an d-paper Comb. h-near the Du bu 1 ta stat'i.on ^;--i--near L i e I upe station,, . 4

^uï^cd^b^!coastÎa M a

^ ^ `sr e c. ^ ^ G

^

3 ^ - • -^ ..^ --- ro U 4- M Puc: 2. KonNVecTao 3oottnaKKToxa e p. 1litenyrrte 3Q; VI-12/VII 1961 r. Fig.2. Uuantity of zooplankton in the river Lielupe ..

Fig. 2. a-Lielupe river below Bauska; i-Spun'upe river; b- " if ". Mezhotnoe; j-Lielupe river at Pumpuri; it if c- it " if Emburga; k- " . Maiori; it if d- " " above Engava; 1- It the mouth. e- " " below Engava; f- at Kniva; g- " " below Kalitsiema; h- tr " at Sloka;

5

- 'In -ihousanc4 of /feer spec tmérts/nr)• - • / f.§'ser.a. /'/.11 Zi° -,16 21f- A -- e - -* •

-3e /7[le —30 - de - /31- 7- 36 - 31 /21:

to - 3o /d G71- 7I- 61-

I I- d 'bee I 18

.•

Pue. 3. KOJIWIeCTBeHliblf cocras 3oonnauKroHa B aa- BlICIINIOCTII or remneparypb; (p. Ylite.nyne y Kum- nitema)

Fig. 3. Quantitative composition of zooplankton in relation to the temperature (the Lielupe river at Kalitsiema).

The Musa and Memel rivers feed only small quantities of rotifers

into the Lielupe river, and this situation remains unchanged for the

first 20--30 km (Fig. 4) due to the fast water flow in this section. The

qualitative composition of the zooplankton is variegated and sporadic

and it consists mainly of random benthic and phytophilous forms.

As the rate of water flow slackens,the composition and quantity

of zooplankton gradually change. The zooplankton increases in abundance

and, along with an increase in rotifers, there is a gradual increase in

the proportion of lower crustaceans. Below the city of Elgava copepods

constitute the main plankton group (Fig. 2). As was already noted, the 6

.formation of zooplankton is strongly affected by the water current. A

reduction in the rate of the current, on the one hand, has a favorable

effect on the conditions of life of all zooplankton forms, especially on

the crustaceans, and on the.other, salt water from the Gulf of Riga pen- /p.181

etrates far up the river and alters its hydrochemical regime.

The upstream movement of water from the Gulf of Riga also includes

elements of zooplankton, especially larvae of crustaceans and rotifers.

Penetrating farther than any other brackish group from the Gulf of Riga

are Eurytemora hirundoides, whose larvae and adult forms can be found as

far upstream as the city of Sloka. Several other forms of zooplankton

from the Gulf of Riga occur in the mouth of the river as well: Keratella

quadrata platei, of the protozoans Tintinnopsis tubulosa, and of the

crustaceans, Acartia, Podon polyphemoides and others. In examining a

longitudinal section of the lower reaches of the Lielupe river, it is

evident that the level containing the.greatest abundance of plankton is

the 2 and 4-meter level, and that the section containing the most abundant

quantities of planktôn is the mouth of the river, where the zooplankton

from fresh and salt water accumulate.

The zooplankton in the Lielupe river is also favorably affected

by Lake Babite--a shallow eutrophic basin with an abundance of zooplankton.

Two short streams connect Lake Babite with thé river Lielupe. These

streams are Spun'upe and Gate, through which the water exchange between

the river and the lake occurs. The sharp increase in the abundance of

plankton in the Lielupe river at Pumpuri (Fig. 2) is due not only to the

slow rate of flow and ^he effect of the sea but also to the influence of

7

?0000 -.._ rec. ›ttlid Gauy rlv r 7._ _ re „91 0 "0 o 7 i final 200 km L eke Aar/mew...ea/74A, _ _ e _ do to 11 so ,00 so ef0 la so A* om aimre/e0 my oloe. ow .iJ kW am seirtie from 12 9/1 9" 41 471 efrynea•weep,twq , riverbed gradient,

river over the entire course of th 4,Yeehmecee,teweffld4, eoff / ,ffi

- mWPer from mouth of river egeŒ g/e'eqee/ee/eeA,PepYege riverbed gradien foc,o00.0 7"tvc._exVer 3 1 II1 I I ..; • „1„4,1. eLy 1 ! Dau aye river forteee I i I . 1 a 1 efelaje I I I I faavo I 1_ . _ Final 200 kril I1 . I I I nocneciwc..€ Peocokw. 1 iw r , , - 30 ei 1r0e." 1 I ,r00. i ,., ■ I .. ,From mouth of riîlr 1 I i• , fe 8, Of el le der ,7d ,,,Jei.fs:/..../..f . ,...., ..,,ye7,4-0, /,14.: 1..w.4.0.f f.it0,.0.1 Lyn Yeerts;\ ee/;* lie , • ce mierfe4,0..ftyenegrad(ent Puc. 4. 300flitaliKT011 El Hemoropbtx peKax J arrmücKoll' CCP 11 1961 C. F 19.40 Zooplankton of several Latvian rivers, 1961. 8

Lake Babite. This is also suggested by a comparison of the qualitative composition of zooplankton of Lake Babite; Spun'upe and of the Lielupe river.

Of the factors affecting the formation of zooplankton in, the

Lielupe river, one should.note temperature and flood waters. In differ- ent years the temperature of the water changes drastically. One can speak of cold and of warm years. During warm years (1961, 1963) the zoo- plankton biomass is significantly larger than during cold years (1958,

1962).

Fig. 3 shows the water temperature and quantity of zooplankton for two different years, for 1963, when it was warm, and for 1958 which was a cold year. The water temperatûre is indicated by the curves and

the monthly quantity of zooplankton by the columns. In the warm year the

zooplankton is much more abundant than in the cold year. When widespread

floods inundate large areas of cultivated land in the Lielupe river basin, much mineral and organic matter is transported into the river. Extensive

floods in 1960 and 1961 had a favorable effect on the development of zoo-

plankton. But when unfavorable thermal conditions combine with high

floods, as in 1958, the zooplankton develops only poorly.

Finally, the Lielupe river is distinct in that its zooplankton

population is greater than that of any river in the Latvian Republic,

significantly exceeding the plankton reserves of the Gauya, Salatsa and

Venta rivers and by lesser amounts those of the Daugavu river (Fig. 4).

This is due mainly to the slow.water flow and to the favorable

thermal regime of the Lielupe river. 9

The Lielupe may be considered the warmest river with the slowest rate of flow in the Latvian Republic, and that is why, in contrast to most rivers, its zooplankton consists predominantly of lower crustaceans.

The Lielupe river can be characterized as containing a good food supply for fishes, but, unfortunately, the normal rhythm of life of the fishes is adversely affected by the waste waters from the Sloka Pulp and

Paper Combine.

References

1. Zhadin, V.I. Rivers, lakes and water reservoirs of the USSR, their fauna and flora. Moscow, 1961.

2. Kochish, B.I. Pollution of the Lielupe river by domestic and industrial waste waters. The Latvian Inland Fishing Industry, 3. Riga, 1959.

3. Matisone, M.N. The hydrological regime of a section of the mouth of the Lielupe river and of the coastal area of the Gulf of Riga. Gidrokhimicheskie materialy, vol. 19. Moscow, 1957.

4. Sloka, N.A. Zooplankton of the large rivers of the Latvian SSR. The Hydrobiology and Ichthyology of Inland Water Basins of the Baltic. Riga, 1963.

5. Zarins, E. and J. Ozolins. The effects of effluents from the Baltic cellulose factory on the quality of water of the Lielupe river, related to development of hydrogen sulfide in water and the dying of fishes. Riga, 1939.

J1 141 EPATYPA

)1( a no B. H. Pm!, o3epa u Boa,oxpauu.nuna C:CCP, lixcp ayiia u (1).lopa. M., 1961. 1(o tIll LU B. 14. 3arpu3neune 6WT011611%10 0 upomsnu.neunumn c-routibuun uogamn. Pb16110e X0351ACTBO Burpenunx uo,a,onion JlaTa. CCP, 3, Pura, 1959. Mar ucone M. H. ruapommuniecuuii peatum npuyc -rbeaoro yuacTua p. ,Threayne npu6peazuoil nacTu Pluucsoro swim:tn. piRpoxiimiptecttlie btaTepita,rtt,t, XIX, M., 1957. C o I< a H. A. 3oonaarucTou 6oamunx peu Tlarunricuoft CCP. Fn1Lpo6noaorun nxTuo- aorun aurpeintux Hoxoemou Ilpu6aannal, Pura, 1963. Zarinà E. un 0 z 0 1i n J. Baltijas celulozes fabrikas notekudenu ietekine uz Lielupes tidens sastà-Vu un ispa'St-b-am sakar-a ar zivju mirsiTbu un s-eiudenraia atti-st-tganos. Rig-a, 1939.