(y-2,

7 /'

'FISHERIES RESEARCH BOARD OF CANADA Translation Series No. 893

. Population dynamics and annual production of Acartia clausi Giesbr. and Centruagfs kreiyeri Giesbr,

in the neritic zone of the Black Sej-

By V.N. Greze and E.P. Baldina

Original title: Dinamika populyatsil ± godovaya produktsiya Acartia olausi Giesbr. ± Centropages

. kryeri Giesb17. V—neritich-eskoi zone Chernogo morya.;

From: Trudy Sevastopoltskoi Biologicheskoi Stantsii, Akademiya Nauk Ukrainskoi SSR, Vol. 17, pp. 249-261. 1964.

Translated by the Translation Bureau (AK) Foreign Languages Division

Department of the Secretary of State of Canada

Fisheries Research Board of Canada Atlantic Oceanographic Group

Dartmouth, N. S.,

1967

e■n“ '

■• • • • •

hdouncUon sulp, Incnt

,e,ea 44. Pe5

7682-7

• PepUlation .dynamics and,Annual/roduction of Acartla. _ dlausi Gicsbr. and Cenrog2ges'Myerl._Giesbr. in the I\Tritic

lone of the Black Sea ,

By V.N.Greze and E.P.Baldina.

/From: "Transactions of the Sevastopol Biological

Station. Volume XVII, 1964, published by the Ukranian

SSR Academy of Sciences, Kiev./

Beginning with May 1960, systematic observations were

carried out at the Sevastopol Biological Station of the dy-

namics of the numbers of the zooplankton within the ten-mile btoje

coastal zone of the Black Sea. Thesi§ask)of the research was

a study of the seasonal changes in the quantity of the mass

species of the plankton and of their various stages of deve- v

lopment, as well as a determination of the Evalues of tI an-

nual production.

In this article are shown the first,results obtained 1

as a result of the treatment of the annual cycle of collec-.

different ecology - . eurythermal Acartia clausi and themo-

phylic Centrepauls kr.±3yArl.

The collecrtions were carried out in the Sevastopol re-

gion at the traverse of the Kamysheva bay, at four stations

1/ocuee.f) tions in 1960-61, ac-c-Œrd-Ing-to two species of copepodslrlth

at a distance of 2.50 5: 7.5 and 10 miles from the coast,

on an average twice a month= more often during the summer

season. and. more rarely in winter. As catching equipment.

for the plankton . was used a r;rspAed-planktoxaoma ter which made

step-wise 15-minute catches covering hoY9 :• I-zons from 40 metors

in depth to the surface. This methodology ensured .mar-c3--c-a--

p_oi s and repre ser.itwt,3_ve samples of the pla.nktonP than those

obtained by means of nets (G.rezef 1962) and gav-e accurate,

quantity of water filt^r a-té.d by the apparatus. The towing

speed of the planktonometer was usually 0.5 -- 0.7 meters per

second; for its filtration cone was used mill gauze No. 64.

Since the diameter of the apertures in the gauze of this

_r.^.uml?er ta :?.nnroximstfr.ely 0,1 mi17_irnet.er; all the eggs of

2,kr8veni were eaug ht in the s,pparatusr their diameter being

approximately 0.12 millimeter with the spiness and a e.onsi.-

derable part of the eggs A.clausi, whose diameter is 0.06'-

-- 0;07 millimeter.

The treatment of the material consisted In counting.a

portion of the sample in the Bogorov chamber with considera-

tion of each development stage of the given species and with

a subsequent calculation of the average numbers of the stages

per one cubic meter,, To determine the production was used

a method su,^gested by V.N.Greze and V.S.Ten.

The general character of the seasonal changes in the

composition and abundance of the plankton was studied in the

J

•

30

L

Sevastopol region already by S.A.Îe .rnov ( 1904). However,

in this work the various species of the copepod.s wore not

differentiated and the evaluation of the abundance was given

visually. In subsequent studies, in various regions of the

Black Sea were obtained more detailed data on the seasonal

changes of the species in the plankton and of the changes

of their numbers and of the biomass (Dolgopolskaya, 1940;

Nikitin, 1939; K1yuGharev, 1952; Kusmorskaya, 1955; Brayko,

Goromosova, Pitsyk, Fedorina, 1960; Kova19 1961; niniov, ^g.2 0

1960; Marcus, 1957). However, it was not possible to uti-

lize these materials for a clarification of aetails in the'

life cycle and for .the determination of the. production of

ii:7ldivici.ual mass speèies of the plankton, because in these

works usually the data on the numbers of their larval stage,%

were lacking. It became only possible to carry out such

a task in respect to the copepods during recent years, as"

a result of detailed study of the larvae and of:.the--develop---l-, wu.L ,

ment r^-a-te..s^. ( Potemkina, 1940; Chays.nova, 1950; Sazhina, '11960,J

1961) o

Acartia çlausi Giesbr.

The annual cycle of the development of A. cla.usi may

be deciphered from table 1, where are shown figures of âver-,

age numbers or various stages of crustacèan. In each of

its horizontal graphs are shown values that are average for

the four stations. In summer the collections , were repeated

on 2-3 consecutive daya, and in such cases the results were

1263 943

1398 346 159 228

42 276 250 583 156

13 893

0 0

23 995 624 95

92 206 400 311

13 65 35 42

9 20 12

. 16 0

10 19 92 52

134 129

, 37 87 124 ! 306 323 702

-

4 .

united into one average figure related to the middle date

of the given series of collecttbons. A graph (fig. 1) was

set up according to table 1, in which the defects of the

material were somewhat corrected. These defect being con-

neeted with the irregularity of the intervals between the

collection dates caused by poor weather conditions or other

reasons. The course of the changes in the numbers of the

crustaceans according to the curves presented itself in a

smoother and more regular manner. .1

Table 1.

Seasonal dynamics of the numbers of A.clausi (in indiv./m3 )

nap-

sea

cope- podi- tes

fe- males males

total adults Date eGge

1960r. ; 25-29. V

8-13. VI 23-27. VI 9-12. VII

24--29. VII 17-19. VIII 1 5- 9. IX 21. IX 28. X 11. XI 7. XII

1961 r. • 4. I 2.11 1. III

18.111 • 3. IV 15.1v 13.V 24.V

1987 604

1372 763

1100 719

450 674

456 515

502 142

797 87

163. 16

105 ' 87

303 0

10') 6

133 101 737 134 730 82 375 177 ' 386 158 527 305

1364 274 1252 976

• 80 74

171 160

3 0 7 0 0

14 0

12 22 20 14 47 67

172 ' 280 571 ; 471

16 ' . 65

42 42

9 . 34

25 0

• 22 41

112 66

181 196

Annual average

5 .

Considering the fluctuations in the numbers of eggs ,

and nauplia\ stages of A.clausi, we may record that during

the course of the year seven increases take place, which

one may consider to correspond to the appearance of seven

generations of the crustaceans: - in the middle of May,,at

the end of June, in the beginning of August, in the begin- .

ning of September, in the middle of November, in the begin-

ning of February and in the beginning of April.

. The deVelopment length of the individual generations

thus turns out tà be different, fluctuating from one month

in stimmer to 2-3 months in winter. Obviously, these differences

.9r3P0

Elg27.. Seasonal changes in the numbers of A.clausi in the

Black Sea at Sevastopol.

1 - naupor, 2 - copepodites, 3 - adult crustaceans.

•

6.

are connected with the changes in the temperature conditions,

which in 1960-1961 in the surface layer of water in the. Se-

vastopol region were characterized according to the data

of the Hydrometeorological Observatory of the Azov and Black

Seas of the • HydroMeteorological Service, as the_following

average monthly figures:

Month: Temperature:

--- May 14.1 0

June 19.7

July . • • 22.1

August 23.5

September 20.3

October 17.5

November . 15.3

December 12.2

January . 9.5

. February 6.8

March • 7.8

April 11 0 0 .

Gw.,14,1 Comparing these data and the development deteme see

that ati the maximum wal„er temperature in August hç genera- vdk i

tion i*r_-_-ttrrritz--erve-1-oped—o-nl-Y.--a-bou-t 30 days, whaz't4iii,responds

also to the experimental data of L.A.Ohayanova (1950), "who

established the development period of A.clausi at a tempe- ,

rature of 17-2300 to•be 36 days. The mentioned author comes

7.

to the conclusion that the total number of A. clausi gene--,

rations in the Sukhumi bay should have been at least 9 per

year. This d&ffcrence from the results obtained by us, pro-

bably, 3.s likewiàe connected with the difference in the tem-

perature conditions of the sea in the region of Sevastopol^v C•°^ %^^ ^/i EL ^,j^r.

and of the Suklzumi. Sevastopol .I_E^^between the 1,ong-Lerm

February isoterms of 6 and 7°0 and <b^^;^.^^^lugust i soterms

of 22 and 23°C, while Sukhumi has February

water temperature above 8.500 and in August above 2500 (Ma-

rine Hydrometeorôlogical Monthly, 1961 ^ 1962).

Fig. 1 also shows that the most intensive reproduction

and the corresponding maximum indices of the numbers of all

the stages Of a^• clausi. are restricted to the spring-summer

period. Minimum numbers of the crustaceans are, however, 1p. 2 2

observed during-the months of hydrological autumn v 0cto-

ber - December. However, even in this period oocurs, although

not as sharply pronounced, a rise in the curve of the/numbers

of eggs and naupl.i4-e-a.. at the appearance of theNovember gene-

ration. Thus, the multiplication of A.clausi takes piaçe

in the Black Sea during the entire year round, a feature; dis-

tinguishing it from populations of certain other seas. Thus,

according to Conover's (1956) observations, in the Long-^sl.and,. .

Strait, A.elausi disappears almost comp7.et,i.-ly from the'

plankton from August to November-pecember, during the remain-

der of the year it produces four generations. Digby (1950)

;

I

!

8

5 10 20 30

1200i

1090

I 800 1 re)

400 1 1' II

70. .>

1 - 1

» - -"

',diurnal 'increase 103 milli -

gram 1.8

L1,4 •

-/,0 • 1. r -0.6

- Q2 40 50 50 7.0 vv-10173 ;

The numbers and the intensity àf the growth

of el-clausi.

believes that A.clausi, in the region of Plymouth, has fibe

and perhaps six generations (from the end of April to OCto-

ber) nor does it reproduce in winter months. although the

numbers curves set up .aGeord-Digby's data indicate

rather only four distinctly pronounced generations. It is myYmiw„,

natural to -did,m-l-t, that the decreade in the reproduction.period

of the crustaceans at Plymouth, as compared with theBlack

Sea, is connected with the temperature cônditions of these

regions. The maximum water temperature at Plymouth, accord-

in to Dlgby's data, did not exceed .18o 0 and the yearly total

of the monthly average teMperatures was approximately 150 °0 ..

compared to 1800 in the Sevastopol region. However, it

should be noted that the temperature of the fall-winte months

in both places is of similar magnitude. The entire annua.l^ S

cycle of the temperature curve in the Long-Island c^ts•ralt^ is

> _ _.. - • ;

Thus, we must assume that although .A.•clausi did, probably,

find in the Black Sea favourable temperature conditions that

also very close to the one at Sevastopol, however,6,^^: ` {C

the ana.log.ous -pa-th of the annual b3.ologi.-V`iG4^q frt J f^r^ % ^

i ,r<<i!cal cycle of A cl aust eczrz°e:^pond' i

permitted it to extend tits multiplication period to the entire

14year, the effect of these temperatures /i^--me,n1fle-e-tad) through

some other factoi^s, which we are unable to analyse. The main

feature of the seasonal cycle the restriction

of the period of the maximum intensity of reproduction to the

spoing-summer months)

romains constant in the Black. Sea A^cla-

usi• The main peak ôf, the curve showing the numbere . of^ adult11

crustaceans and the nauplih.i-s-e-s-,; takes place in May-June.

The hydrological seasons at Sevastopol may be charae-

terized by means of the following chart:

Duration Average(in days) . tempnra,t^re (oC),

summer JunedSeptember . 127 21

fall October-December 93 15

Wïnter January-March 92 8

Spring April-May 53 12

__..a__..___- _____- .._..__..__e- __- ..___d___o____- ....- ____..___- ..

The temperature conditions of the development of A.clausi

differ considerably from season to season, thus we must

10.

calculate the production for each of them separately. Since

the basis of the method for production determination is à

Curve of the oi'lganl_sm's growth rate, which is related to

the temperature, it-is necessary to determine, first of all, •

the development dateÂ3 of the crustaceans under the tempera-

turc conditions of the mentioned four seasons. For this pur-

pose are used L.A.0hayanova l s (1950) data on the develoP«;-

ment of A.clausi at an average temperature of 20 00, and the

coefficients calculated by G.G.Vinberg (1956) for changes

in the metabolisM in respect to the temperature ilccording

to Kroks curve. Results Of these calculations are shown

in table 2, where is shown the duration of various stages

at temperature conditions of individual seasons,

,

\AA- ,Le • •

. .The calculated deve1opment-,t1•ete-s of stages of A.clausi •

at various temperatures (in days). accord.to Sumer Fall Wiuter Spring Chayanova 21 0 15 0 8°C 12

(5 0 at 20 ° C

Table 2.

Stage

Nauplitiee-& 10

Copepod, s 20

Adulte

.Total 120

9.2

18.4 31.4 69.6 43.2 •

82.8 141.3 313.2 194.4

110.4 188.4 417.6 259.2

15.7 34.8 21.6

The average weight of the nauplluee-e, copepo4 and of

adult A.clausi obtained by T.S.Pet'ipa (1957) are 0.0008;

0.006 and 0.038 milligrams respectively. By using these

il.

figures and the data from.table 2, we may draw a series

of curves (a fig. 3) of the weight. growth of crusta-

ceans at temperature conditions of the four hydrological

seasons.

After the sexual maturity has been reached the growth

of the crustacean is almost ended, but the process of the

reproduction of live matter continues through egg formation.

Therefore, in fig. 3 the upper portions of the curves cor-

responding to the total amount of the biomass formation as

a result of growth through egg-laying, are shotian by dotted

lines. According to L.A.Chayanova's data (1950), a female

Ae clausi has 1- 5 1ay:Lngs of 16 eggs each time, this consti-

tutes, if an egg. welghs 0.00014 milligram° 0s033 milli-

gram per z-de^ female.

The diurnal growth in various sections of the curve

was. determined according to fig.. 3. For this purpose tan-

gents were drawn to a number of points of the curve, and the

diûrnal growth was determined as the tangent of the angle oC

between the tangent line and the horizontal axis of the graph

(see fig. 5).. On the basis of the above curv6 1 was drawn

(fig. 2) which charac te ri ze s the growth rate of one indiviM

dual of A. c i( in milligrams per 24 hours) in relation-to

its weight.

According to data in table 3,.for each season of the

year were drawn curves of the relation between the weight

12 ,

iip 3. Weight growth of Black Sea A.cla-usi according to 'seasons.

I . Weight of eggs pro- 1 duced by the females

: is shown by dotted -; linos.

Sec

WeiR2lt 101'.2 1073mil.,,

70

ligram 60 • /

0/

e •

51.'■-"A 50 à 200 300

(4 .c. :AAA

• 50

m

k\ 30 •

J.-, 20

• n « 10

I e et •

and the numbers similar to the curve 2 in fig. 2, whichi

characterizes the summer season. To set up these curves 2

upon the horizontal axis of the , graph, the maximum weight

of the naup11.4,e-s, copepods and adult crustaceanjeigere Plot-_

consideration-of - ttïe-ir- ega's determined by the irowtih,)

ye (fig. 3) -ifpon the vertical axis were plotted the - • ,

dumulative re.siats of the average numbers of the naupliese-a,

copepodeYand of adult individuals. Then, depending on the

course of.the curves 1 and 2, the graph in fig. 2 was diVided

into sections by a number of vertical lines. According /n.2521/

to each of them was determined the number of the indivi-

duals ni , n2 .....nn having a weight within the boundaries

*delineated by the neighbouring vertical lins. Thus, for .U.he

case shown in fig. 2, the numbers of the individuals weighing

less than 0.0025 milligrams was 850 individuals per cubic

' meter, in the second column the number of crustaceans weigUing

0.0025 - 0.01 milligram was 250 individuals per cubic meter

etc ,

,

13.

Table .3.

The total biomass (in milligram per cubic meter) and the

numbers of the stages of A.clausi (individuals per cubic

meter) according to seasons.

Stage s

Numbers:

naupliuses

copapodî.tes

adult

Summer Fall Winter Spring

730 141 571 916

406 . 36 130 316

l73 20 26 128

Total 1309 197 727 1360

Biomass 9.7 2.3 7.5

----------------------------------------------------

The n obtained by this manner were multiplied by the

average growth for the column in question, taken from the

curve 2 in the fig. 2. The calculation of the production

consisted in the summing up of the obtained results in all

the vertical sections of the graphs. The results of these

calculations by means of the graph in Fig. 2 were expressed

in particular in the fol.lowing manner (in 10-3 mïlligranj) :

Weight Number of Diurnal Diurnalgroup ind,/m3 growth of produc-

an i.ndiv.. tion

0-2,5 8502,5-10 25010-20 8720-30 3530-•50 4750-70 40

0,09 76,50,45• 108,01,20 104,41,68 58,81,20 56,40,47 18,8

.. _ .....+v^^• M

(t(^^^^ ^/ p ^ ^►.

I

I

PlÈ

Iv-

vi•

1,0y -/ 14.

vrt'a durauion of the/summer season of 127 days the r

total production was 9.423 x 127 - 'a 53.0 mil1igram/m3 . , -

The average biomass of A.clausi for the summer season was /n,a5.5./ !

9.6 milligram per cubic meter, thus total seasonalcoef-

ficient in the population was .53.0 - 5.5, and the diur- 9.6

poefficient - \43«ri • \

- 0.423 0.044. 6

Values of the diurnal production and the diurnal P/B .

coefficients calculated by the same manner, were:

i

Prluction 10- mg/m3

Fall 29.0

Winter

Spring

Summer

53.9

104.7

422.9

P/B

0.026

0.024

0.014

0.044

The obtained diurnal P/B coefficients differed.noticeably H &i,..,':.. 11, 'f• in'' Ceewle«.

from season to season. I46-4-s-ftatural, th-on the one hand, . // • / haele=m-p-e=wresed the effect of the temperature conditions •

/ of the given period of the year; on the other hand alsethe

-I-- age composition of the population, consequently also the

dimensional composition of the same, in which the slower

growing individuals were able to change considerably the re-

sult of the production-process. It was 'through these two CrC,e£,tm

ways that the eo,nne-c-tton between the production rate and the

intensity of the metabolism and the growth of the organisms

1 5.

waa manifested, as recorded by G.G.Vinberg (1962).

The total production result of the entire A.clausi pop-

ulation for a year was 66.8 milligram/cubic meter, to this '

corresponded a total annual P/B coefficient of 13.0 and an

average diurnal coefficient of, cypi5... to-t

In-ader-to-discussi"the relative intensity of the prod-

uction of the copepods in the Black Sea, it was of consider-

able interest to carry out similar calculations of the prod-

uction in other seas. This turned out to be possible for

the Atlantic population of A.clausi in the Plymouth region

utilizing the detailed data 9f Digby (1950). According to

figures in his table VI (page 422) were set up curves for

the numbers of stages according to which was calculated the

average density of nauplirls.es to be 1400, of copepods ,to be

. 550 and of adult A.clausi - 200 individuals per cubic

meter. The average temperature of the development of the

crustaceans was determined for the period from April to Oc-

tober to be according to the graph - (Digby, 1950, fig. 1,

page 397) - 13.2 ° C. From here was determined, according to

the data on the development dates of the Black Sea A.clausi

with utilization of the corresponding temperature coeffi-

cients, - the average duration of the stages of the Plymouth 1 A.clausi. For the nuup1is9. it was 17 days, for theibopepods

- 35 and for adult individuals - 150 days. Since the di-

mensions of A.clausi at the Plymouth presented by Digby in

, 16.

table XIV, have n_.o._.-ma.te,ri-al diffe-re'rcQS from the dimensions

of the same in the Black Sea (Kovalev, 1964), one could have--

utilized the weight characteristics of the developm^r^t sta^es^ f, "

of the Black Sea cr^lstaceans (Petipa, 1957) for

of the • ^^growth g.raph. A possible production of eggs during

the last stages of the life cycle tlas •taken into ooneidera-

tione

A graph of the growth rate in relation to the weight

was set up according to growth curve, and a graph of the

total numbers of,the, crustaceans in relation to the 1•rei Ight

according to the data on the numbers in the various stages.

A corresponding treatment of these curves gave the following

results (in 10-3 mill:igram):

weic^nt number diurnal diurnalgroup indiv/m3 growth of production

individual

0 2.5 1580 0.10 158,0

2.5 10 300 0.32 96.0

10 -- 20 '140 0.55 77.0

20 - 35 70 0.70 49.0

35 - 50 30 0.52 15.6

50 - 70 .. 30 0.25 7.5

/P..?YThe average diurnal production was 0.403 milligram

per cubic meter, the total production in 260 days was

104.8 milligrar.a/cubic meter. The average biomass per

season determined from the average weight and numbers of

14.9

5.1

66.8

13.0

,0.035

13.0

12.0

104.8

. 8.7

0.034

17.

the development stages of the crustaceans was 12.0 milli-

gram per cubic meter. From here the total P/B coefficient

for the season is 104.8 = 8<:7. Let Us compare these 12.0

results with those obtained in the Black Sea:

Black Sea Atlantic . population population of A.clausi of A.clausi

a

Length of the production season in days

Average temperatures during the season, ° O.

Average biomass, mg/m3

Annual production, mg/m3

Total P/B coefficient

Diurnal coefficient of growth

365 260

We see from this gompariSon that the same organism -

A.clausi develops a Smaller biomass in the Black Sea

because the life in plankton being drawn out over the entire

year gives a relatively higher production. The biomass of

A.clausi in the Black Sea turns out to be 2.3 times lesser

than in Plymouth, but the production created during the

course of the year is only 1.5 times lower.

2211trumes kr8yeri.

The course of the seasonal changes in the numbers of

C.kr8yeri and/individual stages of its development are shown

in table 4 and in fig. 4. In agreement with its thermophylic

18.

nature, this crustacean occurs in the sea from May to Oc-

tober, approximately during 150 days, as also noticed by

other authors. The numbers of 'the ^Iaupli^ée^ copepodites

and of adult individuals increase during this period until

the middle of August. The numbers of eggs was highest in

July. Fluctuations in their average numbers permit a record-

ing of four increases, which may be interpreted as appearance

of four subsequent generations of C.kr8yeri - in May, July,

•August and September. This agrees with observations of L.A.

Chayanovs, (1950)i who determines the development cycle of the

crustacean to be 26 - 30 days. It.should, however, be said

that as a result of the continuous multiplication of the in-

dividuals of the first generations, parallel with the multi--

pl ica ti on of the sube se quent one s, the numbers of the naup-

lial and copepodite stages, particularly in the second half

Of the summer, the individual maximums repre . senting a defi-

nitenite generation are not

_-_---------------_" --" ------------------------------_.

Tab.

Seasonal dynamics of the nurqbers of C.kr6yeri (in indiv/m3)

Date eggsInaup1 ^^ ^-1 copef feIll.

podite smale5 total of

adults

1960 r.25-29.V. 16 27 3 0 0 09-13.VI 9 ' 0 . + a:

'+

0

23-27.VI 0 47 21 + 0 -}-S-12.VII 54 14 20 8 5 1324--29.VII 90 403 44 28 6 34

17.VI1I 155 611 237 6 . 6 12.5-9.IX 10 151 27 20 0 2021.IX 79 54 29 , + .0 + •

tiF) Presence of crustaceans less than 1 indiv/m 3

-.,- - -- -T - ,-- -=^.-3^•^:^;-, . . .. -, ..^.,^-r,.-,n..^,-„,, ^ , . . • . ,..^^,_.. '^ r, ^.,^ ^•• ,-^

.50C1

400

300

/00

/\

À 30 -".7 30 15 39 15 30 15

IRkl iekt.SAVer

• • 19. ; •

/1) .?.51/ The temperature conditions <the . multiplication of

C.krzérl change very little during the five months of its •

presence in the plankton - frOm 15-16 °C in the second half

of May to 23° C iri August. But the development of its =1-

mum mass in July .- - September takes place within a still

narrower temperature Ilange - 23-18 °0. This permits us,

to ualculate the production of the crustacean

for the summer season, to avoid calculating it according to

the individual periods as we had to do for A.clausi. The

: 'mentioned temperatures (on an

average about 20 ° C) correspond . _

'.)•nd,ots. a9

to conditions in which

velopment of 0.kr8yeri

died by L.A,Chayanova.

we utilize her data concerning

the development stages of the

crIlistacean for the setting-up

of a growth curve (fig. 5) and .

accept the duration of the naup-

liar period to last 10 days, the

copepodic period - 27, and of the

adult stage - 58 days. According

to T.S.Petipa(1957) thecorrespond-

ing average weights of these :

when beginning

for

the

Fig. 4. Seasonal changes IF-USF numbei-s of C.kra-yeri:

1 - naupliuses, 2,- pope-'pods, 3 - adult crusta-ceans.

the de-

was stu-

Therefore,

20.

stages is0.0006; 0.008 and 0.05 milligram and of an egg

- 0.00016 milligram.

According to the growth cuve was obtained the charac- v-

teristics of the divrnal growth of the crustaceans by weight

(fig. 6,1)

Fig. 5. Weight growth of C.kr8yeri.

In order to obtain a curve for

to the weight (fig. 6, 2) the curves

with a planimetér and averages were

of various stages rof crustacean deve

They constituted 158 nauplitisee-i 53

viduals per cubic meter of adult C.krby

- When fig. 6 was treated by the

and

measured

numbers

season.

11 indi-

in -Lhe

the numbers in relation

In fig.4 were ÇoIr

obtainedçthe

lopment for the

copepodites

,.kr8yeri.

same method, as

21.

preceding case, we obtained the calculation of the average

diurnàl production of the population (in 10-3 milligram/m3)

(see page 258).

The productive period of C.kr8yeri in the ses, conti-

nued approximately 150 days. Consequent].y, the total prod-

uction for the season was 0.092 x 150 13.8 mi1.?,igram/m3

The average biomass for this period was 1.2 milligram/meter.

The total P/B coefficient is IM 11.5 and the average7..2

diurnal coefficient is 0^ 202 0.077.

02

•

55

10203050

Weight Number of Diurnal Diurnalgroup indjv/m3 growth of production

lndividual.

2.5 162 0.12 19.45 15 0.40 6.010 '16 0.83 13.320 16 1.80 28.830 5 2.27 11.350 5 2.00 10.0'T0 3 1.08 3.2

Thus, the production rate in the C.kr. 8yeri population

is twice as high, as the average annual production rate of

A. clausi and exceeds the latter 1.7 -times even when compa-

red with the summer period of the maximum intensity of prod-

uction. The cause of such a considerF_^ble difference .musti"e C'I 4 i C G^^ ^i e r c cn c ao ^, e (^

^_ rf5mari^y consist ^ ^in the .0-f erus-^

taceans, in which the^^Cwt-

{ , n^^growth ^s w^^a-ry fr•tg--^.ye-n^ ^ t-Y

and the life spans are different. If we - compare , the-'diurnal

22.

growths (with inclusion of the weight of the eggs) average

to the various weight groups of A. clausi and C. kr^yeri ^rr^r

pe.r'cen<<ua7^axpre_ss,^^^., then we will have for the summer

season at i.^entic^.l temperature cond^.tiona, the following

value s:

Weightgroup A.ciausi O.kr8yeri

o - 10 7.2 11.0

10 - . 20 B.Q. 11.7

20 - 30 6. 8,. 9.2

30 - 40 4.2. 6.3

40 - 50 2.0 3.9

.50 p 60 1. 0 2.5

50 - 70 0.. 6 1.8

Average 4.2 - 6.7

These figures.indicate sufficiently clearly that tlie

maln cause of the higher productivity in the C,krHyeri 'pop-

ulation consists mainly in a more intensive growth of the

individuals.

However, it should be taken into consideration that'

because of the change in the growth intensity with the âge,

the total results of the produotio of the entire population

may be materially affected by the ; haracter of the eliminati

tion, 1^hi ch changes in some manne r the age structure of the^

population.

!

23.

•

20 SO '

.-.-,

200-

I 17 150 i /

100 l i .

, i a • °: i.

i '

f: ; LI_ it)

CZ>

2, 0

0,5

oo 10 ,90 we" _

tu_ ,m1,Z

•

6. MmberS and 17ntensity of the , growth of C0kr8yeri.

/p.252/ • y

In particular, the more iiltensiVe-)i evoring,ef the .

0. kr8yeri. population . by the planktonophage-fish, proba4y,

contributes to a higher production rate in the latter. Be-

cause the main mass Of this species is distributed in the

upper strata of the « sea, where the main consumers of the co- ,

pepods are located (anchovy and juveniles of horsemackeel),

there are more fast-rowing juvenile stages in 2.1.1nL21-1., than in A.clausi. The major part of the population of t.,he

latter species living at depths exceeding 10 meters is

tively less destroyed by the fish, than the 2.1inqlurl (Cha- yanova, 1954), • . ,

Comparing the results obtained from ca1culation of the

. production of the two species in question, we may see a

24 .

considerable difference in the productivity of their pop-

ulations. Their main indices had the.fol7.owing values:

A.olausi " C.kr8yeri

Duration of the productionseason in days. . . . . , , . . , , 365 150

Average biomass per season, .milligram per cubic me ter- 5.1 1.2

Total produc :^ion per season,milligram per cubic meter 66.8 13.8

Diurnal P/B coefficient 0.035 0.077

To3bal P/B coefficient per season 13.0 11.5

Because of a higher diurnal growth, C.kr8yeri gives

during a relatively short season of its mass development

in the sea, aP/lB coefficient close to the one recorded

for Aç].s.usi, which develops in the plankton the entire

year round.

The average. diurnal geight growths differed in the

species in question more than twice, and per unit of bio-

mass the diurnal growth rate in Çfkr^yeri was approxima-

tely 8%, against 3.5% in A.clausi. Studies of the curves

of individual growth of the crustaceans during the period

of its maximum intensity at summer temperatures indicates,

that the maximum relative diurnal growths are recorded for

both crustacéans within the range of the weight grQup -

- 0.01 - 0.02 milligrams. This corresponds to the eope-

podite stages, and in A.clausi partly also to the first `t:na-go 1

25.

stages, when the growth in C.krlyArl.reaches up to 12-15%

of the body weight per 24 hours and in A.clausi - up to

8-.10%. On the basis of the aboire we must assume that—the

average production rate determined for the population of

2m.n1 to be approximately 8% must be close to the maxi-

mum possible production rate.

As a support of the above assumption may be quoted cer-

tain comparisons with the data taken from literature concern-

ing the intensity of the copepod feeding. The majority of

calculations and .observations in this field (Bogatova, 1951;

Delalo, 1961; Yanovskaya, 1956; Marshall, Nicholls, Orr,

1935; °large), Bonnet, 1939; Marshall, Orr e 1955; Conover,

1961; Corner, 1961; and others) indicate that the diurnal

rations usually constiture no more than 20-25% of the animal's

weight. In cases, however, of excessive feeding in periods

of the "flowering" of the phytoplankton, when its consump-

tion by the p .nytophages may reach higher value (Beklemishev,

1957; 1961) the assimilation of the consumed food turns out

to be low. According to Riley's calculations (1947) in the

Sargasso Sea, the assimilation of the carbon by the zooplank-

ton should not exceed under such conditions of excessive feed-

ing 8% of its content in the body of the animal per 24 hours.

Later (Riley, Gorgy, 1948) this value was determined to be

12%. Harvey and others (Harvey, Cooper, Lebour, Russel,

1935; Harvey, 1950) also accept the diurnal growth of the

zooplankton to be 10% of its biomass. According to the

26.

observations of T.S.Petipa (1963, in print) the Black Sea

Calanus hel .olandicus may have diurnal rations in the sea

of more than rO% of the weight 9f the crustaceans, this is

accompanied yell.: an intensive accumulation of fat, the reserve

of which, .however, is basically consumed during the very

same 24-hour period, because of-the teltea vertical mig-

rations of the crustaceans. Talus, also in similar rases it

is impossible to assume that there is an expenditure on

plastic metabâlism higherthan the portion of energy and to

assume a possibility of a growth ranging from 20-30% of the

weight of the body per 24 hours. Under such conditions, of f 1/ I .

almost the entire energy/should have been used for growth

even'at similar4high !diurnal rations exceeding the animall t s

weight.

CONCLUSIONLS

. 1. Concrete studies of the production rate in two

species of copepods of different ecological character have

. shown, that its intensity did not exceed, even in the summer

Beason, an average of 10% of the growth of the weight per

24 hours. In total the annual P/B coefficient constituted

11 - 13. Insofar as these species are mass and characteris-

tic elements àf the Black Sea zooplankton that multiply and

Cow at a rate not below the rate of the majority of other

. planktonic copepods, we may consider it to be very probable,

27.

that the average P/B coefficient. for the zoopl.ankton in

the Black Sea will be not more than 15-20. Therefore the

utilization in the çalcul.ations, of the zoopl.ankton produc-

tion of such a coefficient must give values close.r to the

actual, than the calculations of V.G.Datsko ( 1959), in which,

because of the absence of definite data this index was ori-

entatively accepted to b30.

2. Comparison of the production rate of the Black

Sea A. clausi with the production of the popu7.atIon of this

crustacean in the Atlantic Ocean at the English coast indi-

cates that regardless of the considerably higher biomass, the

total production in the region of Plymouth exceeds relatively

little the annual production in the Black Sea. Although the

intensity of the production process in both cases to be close

and approximately 3.5% of the weight per 24 hours, but owing

to the.._.&,,bbreviated production period at the temperate lati-

tudes of the Atlantic Ocean, the total annual P/B coefficient

of A.. c7.ausi is lower there, than in the Black Sea.

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_.1..... ,- .