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/' 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“ ' ,e,ea 44. Pe5 ■• • • • •
7682-7 hdouncUon sulp,Incnt
• 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- 1/ocuee.f) tions in 1960-61, ac-c-Œrd-Ing-to two species of copepodslrlth 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 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 •
L
J 30
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, i t 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
-
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- cope- fe- males total Date eGge podi- males adults sea tes
1960r. ; 25-29. V 1263 1987 604 92 • 80 172 ' 8-13. VI 943 1372 763 206 74 280 23-27. VI 1398 1100 719 400 171 571 ; 9-12. VII 346 450 674 311 160 471 24--29. VII 159 456 515 13 3 16 ' 17-19. VIII 228 502 142 65 0 . 65 1 5- 9. IX 42 797 87 35 7 42 21. IX 276 163. 16 42 0 42 28. X 250 105 ' 87 9 0 9 11. XI 583 303 0 20 14 . 34 7. XII 156 10') 6 12 0 1961 r. • 4. I 13 133 101 . 16 25 2.11 893 737 134 0 0 1. III 0 730 82 10 12 • 22 18.111 0 375 177 ' 19 22 41 • 3. IV 23 386 158 92 20 112 15.1v 995 527 305 52 14 66 13.V 624 1364 274 134 47 181 24.V 95 1252 976 129 67 196
124 Annual average 323 702 306 87 , 37 ! 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- vdki 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 17-230 0 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 of 22 and 23°C, while Sukhumi has February I 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) ! 8 1200i » - 3 -" ',diurnal 'increase 10 milli - 1090 gram 1.8 800 I 1 re) L1,4 • -/,0 • 1. r 400 1 1' II -0.6 70. - Q2 .> 5 10 20 30 40 50 50 70. vv-10173 ; 1-1 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- o in to Dlgby's data, did not exceed .18 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 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< 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, , • Table 2. \AA- ,Le • . .The calculated deve1opment-,t1•ete-s of stages of A.clausi • at various temperatures (in days). accord.to Sumer Fall Wiuter Spring(5 Stage Chayanova 21 0 15 0 8 ° C 12 0 at 20 ° C Nauplitiee-& 10 9.2 15.7 34.8 21.6 Copepod, s 20 18.4 31.4 69.6 43.2 • Adulte 82.8 141.3 313.2 194.4 .Total 120 110.4 188.4 417.6 259.2 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 , and the numbers similar to the curve 2 in fig. 2, whichi the summer season. To set characterizes 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 I e etc , et • Sec WeiR2lt 101'.2 70 iip 3. Weight growth 1073mil.,, of Black Sea A.cla- ligram 60 e • usi according to • / • 50 'seasons. 0/ m I . Weight of eggs pro- 1 duced by the females k\ 30 : is shown by dotted • -; linos. J.-, 20 • n « 10 15 .'■-"A 50 à 200 300 (4 .c. :AAA 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 Summer Fall Winter Spring Numbers: naupliuses 730 141 571 916 copapodî.tes 406 . 36 130 316 adult 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 Diurnal group ind,/m3 growth of produc- an i.ndiv.. tion I 0-2,5 850 0,09 76,5 2,5-10 250 0,45• 108,0 10-20 87 1,20 104,4 20-30 35 1,68 58,8 30-•50 47 1,20 56,4 50-70 40 0,47 18,8 .. _ .....+v^^• M I (t(^^^^ ^/ p ^ ^►. Pl È 1,0y Iv- -/ 14. vi• 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 - - 0.423 0.044. \43«ri\ • 6 Values of the diurnal production and the diurnal P/B . coefficients calculated by the same manner, were: i Prluction 10- mg/m3 P/B Fall 29.0 0.026 Winter 53.9 0.024 Spring 104.7 0.014 Summer 422.9 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 diurnal group 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..?Y The 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 a 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 Length of the production season in days 365 260 Average temperatures during the season, ° O. 14.9 13.0 Average biomass, mg/m3 5.1 12.0 Annual production, mg/m3 66.8 104.8 Total P/B coefficient 13.0 . 8.7 Diurnal coefficient of growth ,0.035 0.034 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- nite generation are not _-_------_" --" ------_. Tab. Seasonal dynamics of the nurqbers of C.kr6yeri (in indiv/m3) Date eggsInaup copef feIll. male5 total of 1 ^^ ^-1 podite s adults 1960 r. 25-29.V. 16 27 3 0 0 0 + a: 0 9-13.VI 9 ' 0 . + 23-27.VI 0 47 1'2 + 0 -}- S-12.VII 54 14 20 8 5 13 24--29.VII 90 403 44 28 6 34 17.VI1I 155 611 237 6 . 6 12. 5-9.IX 10 151 27 20 0 20 21.IX 79 54 29 , + .0 + • tiF) Presence of crustaceans less than 1 indiv/m 3 -.,- - -- -T - ,-- ,..^^,_..- '^ r, ^.,^ ^•• ,-^ =^.-3^•^:^;-, . . .. -, ..^.,^-r,.-,n..^,-„,, ^ , . . • . • • 19. ; • /1).?.51/ The temperature conditions 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, when beginning to ualculate the production of the crustacean forfor 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,otsa9 . to conditions in which the de- .50C1 /\ velopment of 0.kr8yeri was stu- died by L.A,Chayanova. Therefore, 400 we utilize her data concerning 300 the development stages of the crIlistacean for the setting-up of a growth curve (fig. 5) and . /00 À accept the duration of the naup- liar period to last 10 days, the 30 -".7 30 15 39 15 30 15 IRkl iekt.SAVer copepodic period - 27, and of the Fig. 4. Seasonal changes adult stage - 58 days. According IF-USF numbei-s of C.kra- yeri: to T.S.Petipa(1957) thecorrespond- 1 - naupliuses, 2,- pope- ing average weights of these : 'pods, 3 - adult crusta- ceans. 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 the numbers in relation to the weight (fig. 6, 2) the curves In fig.4 were measured ÇoIr with a planimetér and averages were obtainedçthe numbers of various stages rof crustacean deve lopment for the season. They constituted 158 nauplitisee-i 53 copepodites and 11 indi- viduals per cubic meter of adult C.krby,.kr8yeri. - When fig. 6 was treated by the same method, as in -Lhe 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 average 7..2 diurnal coefficient is 0^ 022 0.077. Weight Number of Diurnal Diurnal group indjv/m3 growth of production lndividual. 0 2.5 162 0.12 19.4 2 5 5 15 0.40 6.0 5 • 10 '16 0.83 10 13.3 20 16 1.80 28.8 20 30 5 2.27 11.3 30 50 5 2.00 10.0 50 '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 .must i"e C'I 4 i C G^^ ^i e r c cn c ao ^, e (^ ^_ rf5mari^y consist in the ^ .0-f ^ erus- ^^Cwt- ^ taceans, in which the growth ^s w^^a-ry fr•tg--^.ye-n^{, ^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< season at i.^entic^.l temperature cond^.tiona, the following value s: Weight group 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. CZ> tu_ ,m1,Z .-.-, • • 200- 2,0 I 150 i 17 100 li /. ,i a • 0,5 °:i. i ' LI_f: ; oo 10 ,90 we" it) 20 SO ' _ 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 production season 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 animal 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. BIBLSOGRAPIiY: ..------..--..--.. Beklemishev K.V. 1957. "Izbytochnoye pitaniye zooplanktona. i vopros ob istochnikakh pishchi donnykh zhivotnykh."0 /Excessive feeding of the zooplankton and the problem of the food sources ofthe bottom animals/. Transactions of the All-Union Hydrobiological Society, -' Vol. VIII. 28. BomIova I.B. 1951. 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I 31. k'e tipa TeS., 1959. 1°Fitaniye venlonogogo rachka Acartila çlauai Giesbr. 11 /Feeding of the copepod ^kcart:ta c'1a- usi.Giesbr./ Transactions, of the Sevastopol Biologi- cal Station, Volume X3:. ^ Pesipa T.S. 1964. P6Sutochny ritm v pitanii i eutochnyye ratsiony Calanus helgo landicus (Claus) v Chernom more." /The diurnal rhyth in the feeding and the diurnal ra- tions of Calanus hel^o landicus (Claus) in the Black Sea/. Transactions of the 'Sevaetopol Biological Station, Volume XVI. • gotemkina L1.oQ, 194Q. "Vozrastnyye etadi3, nekotorykh Copepoda Chernogo morya. ". /Age stages of certain Copepoda in the Black Sea/, Zoological Journal, volume XIX. Sazhina L.I., 1960. °tRazvitiye chernomorekikh Copepoda. I. Nauplialnyye stadii Acartia clauai Giesbro, Cen.txopagee krE3yeri Gieebr., Oithona minuta Kritc7.'0 / Development of the Black Sea Copepoda. 1. Naupliar stages Acartia clauei Gie sbr. , Çent•roa. 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