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AE-407 UDC 593.1:
591.52
Zooplankton from Lake Magelungen,
Central Sweden 1960-63
E. Alrnquist
This report is intended for publication in a periodical. References may not be published prior to such publication without the consent of the author.
AKTIEBOLAGET ATOMENERGI
STUDSVIK, NYKOPING, SWEDEN 1970
AE-407
ZOOPLANKTON FROM LAKE MAGELUNGEN,
CENTRAL SWEDEN 1960-63
El isabeth Almquist
ABSTRACT
The investigation of the zooplankton of Lake Magelungen,
Central Sweden, was c a r r i e d out over a per iod of three y e a r s . The
aim of the investigation was to i l lus t ra te the qualitative and quantita
tive composition of the zooplankton before the re lease of waste water
from the Agesta Heat and Power Station began.
Ver t ica l sampling s e r i e s were collected once a month at three
different stations in the lake.
The highest volumes of zooplankton were obtained in the
s u m m e r . The ci l iates predominated when the conditions were un
favourable for other zooplankters , as in winter just below the ice.
The rot i fers dominated during and immediately after the spring
circulat ion. With one exception the crus taceans reached their peak
volume values in August or September .
The composition of the zooplankton indicates that Lake
Magelungen is highly eutrophic.
P r in ted and dis tr ibuted in November 1970.
LIST OF CONTENTS P a 8 e
Introduction
Methods
List of Species
Seasonal and Vert ical Distribution of the Zooplankton
Species Account
Compar ison Between the Three Stations In the Lake
The Trophic State of the Lake
Conclusions
References
Tables 1 - 5 .
Table 6.
Table 7.
Table 8.
Volume of zooplankton, Stations MA, MOB,
and MH (average values).
The phytoplankton - zooplankton rat io 1962.
Species regular ly occurring in plankton of
the three s ta t ions .
Most common zooplankton species found in
ea r l i e r investigations in Lake Magelungen.
F igure captions
F igures 1 - 47
3
3
7
11
1 3
21
22
24
25
27 - 30
30
31
32
33
34 - 61
- 3 -
INTRODUCTION
Lake Magelungen (map Fig. 1) is s i tuated on the boundary bet
ween Stockholm and the municipality of Huddinge, about 1 0 km S of
the centre of Stockholm. It has a length of about 6 km, its a r ea is 2
about 2. 4 km , and the maximum depth about 16 .4 m . A more thorough
descr ipt ion of the lake is given by Willen [21 J.
The investigation of the zooplankton of Magelungen was c a r r i e d
out as par t of a team job aiming to provide information about the l imno-
logical state of the lake with special r espec t to future changes due to
the outlet of waste water from the Agesta Heat and Power Station. The
r e s e a r c h work was planned and s ta r ted by Professor W. Rodhe of the
Institute of Limnology, Uppsala, and Dr. P - O . Agnedal and his staff
at Studsvik [1 ]. The phytoplankton was investigated by Dr. T. Willen
of the Institute of Limnology, Uppsala [21 ] .
The zooplankton collections began on March 28, I960, and went
on until May 28, 1963. To begin with, a l l sampling was done at the
main station MA (map Fig . 2) near the point of the future outlet of waste
water . F r o m 1961 on, additional collections were made at two other
s ta t ions , MH and MOB. During 1962 and 1963 a di rect compar ison of
the th ree stat ions was made .
METHODS
Sampling and preserv ing
The zooplankton samples were collected once a month at the main
locali ty, Station MA (Fig. 2), during the period March 28, I960, to
May 28, 1963. Samples were taken more frequently in spring and au
tumn. In order to check the plankton distr ibution of the lake, samples
were a lso taken, from 1961 on, at Stations MH and MOB.
- 4 -
Both qualitative and quantitative collections were made . A No.
25 Miiller gauze plankton net was used for the qualitative samplings
hauled up from bottom to surface. These samples were most ly ex
amined alive or , when this was not poss ible , immediately p r e se rved
with a portion of formalin to make a 4 per cent solution.
The determinat ion of ci l iates and rot i fers has most ly been p e r
formed on living m a t e r i a l . Some spec ies , such as the Synchaetae,
which a r e bes t studied when they a r e quite re laxed, were t rea ted with
a 2 per cent cocaine solution.
The quantitative plankton samples were collected s imul taneous
ly with a Ruttner 1 .51 sampler and a Rodhe 5 1 sampler [1 6 ] at the
following depths: at Station MA 0 . 2 , 1 , 3, 5, 8, and 10. 5 m; at Station
MH 0 .2 , 1 , 3, 5, 8, 10 .5 , and 12.5 m; and at Station MOB at 0 .2 , 1 ,
3, and 4. 5 m. During the f i rs t year of investigation al l organisms in
every sample were counted. F r o m the middle of 1961 the "Vollplankton"
samples collected with the Ruttner sampler were used for counting p r o
tozoans , ro t i f e r s , nauplii , and the smal les t c rus taceans . The fi l tered
5 1 Rodhe samples were used for counting al l c rus taceans but nauplii.
All samples were counted in Utermohl chambers with inverted
microscope [1 9 J.
Plankton volumes
The volume of each except the r a r e r zooplankton species in the
Magelungen m a t e r i a l has been calculated s t e reomet r i ca l ly or by weigh
ing (adult copepods and c ladocers) .
It is for many reasons difficult to determine the t rue volumes of
the zooplankters . Besides the seasonal and developmental s ize va r i a
tions there is a l so a variat ion in size from lake to lake !~9 ". A com-
- 5 -
par i son between my m a t e r i a l and the dimensions given, for ins tance ,
by Monti, Axelson, and Nauwerck [7, 3, 8 ] showed the r i sk of t r a n s
ferr ing the volume numbers of a species from one water to another
without checking and sampling a fair ly large m a t e r i a l . In this paper
I have applied the method introduced by Halme [5 ] to calculate the
zooplankton volumes on the basis of the biomass factor ("Biomasse
Fak to r " , BmF) for each spec ies . This may be a way of facilitating
compar isons between the standing crops of different w a t e r s .
Graphical presenta t ion
The "cake" d i ag rams , F igs . 3-6, show the distr ibution of the
zooplankton expressed as per cent of the total volume. These d iagrams
give no indication of the number of individuals; thus the sample col
lected from 3 m depth at station MOB on Apri l 8, 1961 , contained 208
smal l ci l iates and 1 copepodite of Diaptomus per l i t r e , whereas the
sample from the same depth and station collected on May 7, 1963, con
tained about 52 000 c i l ia tes of different s i zes , 200 ro t i f e r s , 0.2
c l adocer s , 3.6 copepods, and 25 nauplii per l i t r e .
The d i a g r a m s , F i g s . 7-35, a r e constructed according to Pe j le r
[l 1 , p. 226] . They show the frequencies of the most common species
at different depths and on different occasions over the sampling per iod.
Empty c i rc les indicate catches from which the species in question was
absent , black dots r ep re sen t samples containing the spec ies . The d iam
eter of each dot is proport ional to the third root of the number of in
dividuals per l i t r e . The i so therms for 6, 1 0, and 20 C as well as the
isopletes for 2 mg 0 ? per l i t re a r e drawn in the d i a g r a m s . The dia
g r a m s , F igs . 42-45, which show the distr ibution of the total zooplankton
volume, a r e drawn in the same manner , but for technical reasons the
- 6 -
black dots a r e replaced by c i r c l e s . In these d i ag rams , samples con
taining no zooplankters a r e represen ted by an x.
F igs . 39 and 40, showing some typical forms of Daphnia occur -
ing in Magelungen, a re drawn from the microscope with the aid of a
Treffenberg drawing apparatus constructed by Wild.
- 7 -
LIST OF S P E C I E S
Rhizopoda
A r c e l l a v u l g a r i s E h r b g
Difflugia h y d r o s t a t i c a Z a c h a r i a s
D. l i m n e t i c a L e v a n d e r
C i l i a t a
C o l e p s s p .
D id in ium n a s u t u m Mul l .
3 3 E p i s t y l i s r o t a n s Svec B m F 1 0 p,
E_. s p . , on D i a p t o m u s
L iono tus cf. fo l ium Duj .
4 3 Metopus es Mul l . B m F 1 0 p.
P a r a m a e c i u m a u r e l i a E h r b g
P . s p .
S p i r o s t o m u m cf. m i n u s Roux
S t e n t o r s p .
S t r o m b i l i d i u m g y r a n s (Stokes) Kahl
T i n t i n n i d i u m f luv ia t i l e (Stein) Kent B m F 1 0 |j>
5 3 T i n t m n o p s i s l a c u s t r i s En t z B m F 1 0 |X
3 3 V o r t i c e l l a s p . , on M i c r o c y s t i s B m F 1 0 [L
V_. s p . , on Daphnia
^V. s p . , on D i a p t o m u s
Z o o t h a m n i u m s p . , on D i a p t o m u s
5 3 C i l i a t a s p p . , l a r g e s p e c i m e n s B m F 1 0 |i
4 3 m e d i u m s i z e d B m F 10 (j,
3 3 s m a l l B m F 1 0 n
S u c t o r i a s p .
- 8 -
R o t a t o r i a
A n u r a e o p s i s f i s s a (Gosse) B m F 10 n
A s c o m o r p h a s a l t a n s B a r t s c h
h 3 A s p l a n c h n a p r i o d o n t a G o s s e B m F 10 ji,
5 3 B r a c h i o n u s a n g u l a r i s G o s s e B m F 10 |j,
ft 3 B . c a l y c i f l o r u s P a l l a s B m F 1 0 |i
B . q u a d r i d e n t a t u s H e r m a n n
5 3 B . u r c e o l a r i s Mul l . B m F 1 0 pi,
5 3 C o l l o t h e c a p e l a g i c a (Rousse l e t ) B m F 10 |i
C o l u r e l l a s p . i 3
C o n o c h i l o i d e s n a t a n s (Seligo) B m F 1 0 \i
C o n o c h i l u s h i p p o c r e p i s (Schrank)
5 3 C . u n i c o r n i s R o u s s e l e t B m F 1 0 |j[,
E u c h l a n i s d i l a t a t a (Ehrbg)
5 3 F i l i n i a l o n g i s e t a (Ehrbg) B m F 1 0 y,
5 3 Ke l l i co t t i a l ong i sp ina (Kel l icot t ) B m F 1 0 |a,
5 3 K e r a t e l l a c o c h l e a r i s (Gosse) B m F 10 \x
K. q u a d r a t a (Mul l . ) B m F 1 0 5 \i,3
L e c a n e luna (Mull . )
L . nana ( M u r r a y )
L e p a d e l l a p a t e l l a (Mul l . )
5 3 P o l y a r t h r a d o l i c h o p t e r a (Idelson) B m F 1 0 |j,
P . m a j o r ( B u r c k h a r d t )
5 3 P . r e m a t a (Skorikov) B m F 1 0 ^
5 3 P . v u l g a r i s C a r l i n B m F 1 0 |i
5 3 P o m p h o l y x s u l c a t a Hudson B m F 1 0 |i
5 3 S y n c h a e t a oblonga E h r b g B m F 1 0 |i
- 9 -
fi 3 S. p e c t i n a t a E h r b g B m F 1 0 [i,
5 3 S. t r u n c a t a von Hof s t en B m F 1 0 |i
T r i c h o c e r c a b i r o s t r i s (Minkiewicz) B m F 1
T. c a p u c i n a ( W i e r z e j s k i and Z a c h a r i a s )
T. c av i a (Gosse ) B m F 1 0 |i
T . p o r c e l l u s (Gosse)
5 3 T . pus i l ia ( Jenn ings ) B m F 1 0 |j,
5 3 T . r o u s s e l e t i (Voigt) B m F 1 0 |j,
C l a d o c e r a
Alona q u a d r a n g u l a r i s (Mull . )
A . r e c t a n g u l a S a r s
7 3 B o s m i n a c o r e g o n i B a i r d B m F 1 0 |i
B . l o n g i r o s t r i s (Mull. )
C e r i o d a p h n i a pu lche l l a S a r s
C . q u a d r a n g u l a (Mull . )
7 3 C h y d r o u s s p h a e r i c u s (Mull . ) B m F 1 0 fx
Daphnia c r i s t a t a S a r s s . s t r .
7 3 D. c u c u l l a t a S a r s s . s t r . B m F 10 |j,
7 8
D. long i sp ina Mul l , s . s t r . B m F 10 - 10
D i a p h a n o s o m a b r a c h y u r u m L i e v i n
G r a p t o l e b e r i s t e s t u d i n a r i a ( F i s c h e r )
L e p t o d o r a k ind t i (Focke) B m F 1 0 9 - 1 0 [i
P l e u r o x u s u n c i n a t u s B a i r d
Sida c r y s t a l l i n a (Mull . )
B r a n c h i u r a
A r g u l u s fo l i aceus (L . )
- 10 -
Copepoda
7 3 C y c l o p s ins ignis C laus B m F 1 0 |i
7 3 C . s t r e n u u s F i s c h e r s . 1 . B m F 10 |j,
7 3 D i a p t o m u s g r a c i l i s S a r s B m F 1 0 (i.
7 E u c y c l o p s s e r r u l a t u s ( F i s c h e r ) B m F 10 |j,
7 3 M e s o c y c l o p s l e u c k a r t i (Claus) B m F 1 0 [i
7 3 M. o i thono ides (Sars ) B m F 1 0 \i
P a r a c y c l o p s f i m b r i a t u s F i s c h e r
Ins e e ta
C h a o b o r u s s p . , l a r v a e
- 11 -
SEASONAL AND VERTICAL DISTRIBUTION OF THE
ZOOPLANKTON
Like the phytoplankton the zooplankters reached their highest
volumes in the s u m m e r . The occur rence of high values var ied a c c o r d
ing to the qualitative composit ion of the zooplankton (Figs. 3-6).
In I960 no marked peak values were observed; it i s , however ,
possible that high values occur red during in tervals when no sampling
was done. The peak in spr ing 1961 (Fig. 42) was due to Bosmina
coregoni , the peak in autumn 1962 (Fig. 43) mainly to Chydorus
sphaer icus and Daphnia cucullata, though at Station MH (Fig. 45) p r e
ceded by a heavy bloom of ro t i f e r s . In spring 1963 (Fig. 43), when the
investigation was concluded, the r is ing values were mainly due to
c r u s t a c e a n s , especial ly nauplii and copepodites of Cyclops.
C iliata
The ci l ia tes predominated at periods when the conditions were
unfavourable for other zooplankters , as in winter just below the ice .
In spring at about the t ime of the b reak -up of the ice they were m o r e
or l ess evenly dis t r ibuted throughout the whole water column, in s u m -
m a r they appeared in the deeper m o r e or less oxygen-depleted water
l aye r s .
Rotatoria
The ro t i fers formed the dominant group in all water layers du r
ing and immediate ly after the spring circulat ion. In July and August
1962 they were the mos t abundant group in the topmost water l a y e r s .
The ea r l i e s t of these large populations consis ted most ly of
Synchaetae followed by Polyathrae and Keratel la coch lea r i s . Highest
- 12 -
values in the peak of July 1962 were reached by Keratel la cochlear i s ,
in August 1962 by Tr ichocerca pusilla and Pompholyx sulcata .
Crus tacea
Among the c ladocers Bosmina coregoni reached a peak in June
1961 at Stations MOB and MA and in July 1961 at Station MOB. These
high values were never recorded again during this investigation nor
were Bosmina found in such large numbers at Station MH.
The most numerous c ladocers were Daphnia cucullata and
Chydorus sphaer i cus , the peaks of the la t te r being always coincident
with the bloom of the Cyanophytes [21 fig. 7 J. The occurrence of
Daphnia cucullata extended over a longer per iod of the year : often, as
in 1961 , Daphnia came ea r l i e r than Chydorus and was a l so found in
numbers right on to ear ly winter (December).
The Copepods were represen ted by Diaptomus graci l i s and some
species of the collective genus Cyclops. Diaptomus grac i l i s was present
prac t ica l ly al l the year round; it was volumetr ical ly dominant in many
autumn and winter samples . The Cyclops, of which the most important
was C. s t renuus , reached their highest values in the late spring when
their nauplii and copepodites dominated in a g rea t number of samples .
The seasonal and ver t ica l distr ibution of the total volumes or
"standing c rop" of zooplankton is shown in F igs . 42-45. The annual
cycle s t a r t s with very low values in ear ly spring in connection with
the b reak -up of the ice . The highest values were always recorded in
August or September (tables 1 -5) , with the exception of 1961 when the
ea r ly spring caused a high peak of Bosmina coregoni in June. This
peak was followed by a lower one in August.
- 13 -
SPECIES ACCOUNT
Rhizopoda
Arce l la vulgaris Ehrbg. Occasionally. Station MA.
Difflugia hydrosta t ica Zacha r i a s . Occasionally. Station MA.
D. l imnetica Levander . Single specimens in net samples from
Station MOB.
Ciliata
Coleps sp. Stations MA and MOB. They were most ly found just
under the ice before the b reak -up and near the bottom immediate ly
after the b r eak -up .
Didinium nasutum Mull. Mostly single spec iemens . The highest
numbers were found at Station MH on May 22, 1962 (1 m: 1 40 inds / l ;
8 m: 60 inds / l ) , and at Station M on May 7, 1963 (0. 5 m: 30 inds / l ;
1 m: 20 inds / l ) .
Epistyl is rotans Svec. Typical s u m m e r form found only May-
October, always at t empera tu re s above 10 C. The species seems to
avoid oxygen values lower than 2 m g / l . Most concentrated in the upper
water l a y e r s . Peak values in 1 961 at Station MOB on June 12 (0.5 m:
440 inds/ l ) and at Station MA on July 17 (0. 5 m: 1 00 inds / l ) , and in
1962 on August 6 Station MOB (0. 5 m: 440 inds / l ) , Station MA (3 m:
320 inds / l ) , and Station MH (0. 5 m: 250 inds / l ) .
E_. sp . Quite frequent on Diaptomus g rac i l i s .
Lionotus cf. folium Duj. Mostly found in late winter and ear ly
spring in connection with the b reak-up of the ice . In near -bot tom
samples a lso in summer at the oxygen-deficit per iod.
Metopus es Mull. Found only in the deepest water l ayers at Sta
tions MA and MH at the oxygen-deficit period. Mostly in grea t numbers
(> 12 000 inds / l ) .
- 14 -
P a r a m e c i u m aure l ia Ehrbg. In net samples from Station MOB.
P_. sp . was found during the winter most ly in 0. 5 m samples
(just below the ice cover) . Also in deep-water samples during sum
m e r . Most frequent at Station MOB.
Spiros tomum cf. minus Roux. In net samples from Station MOB.
Stentor sp . In net samples from Stations MA and MOB.
Strombil idium gyrans (Stokes) Kahl.
Tintinnidium fluviatile (Stein) Kent was found in fair ly grea t
numbers from Apri l to December at a l l th ree s ta t ions . Peak values
August 6, 1962, at Station MOB (1 m: 1 3 000 inds / l ) , at Station MA
(0. 5 m: 1 4 000 inds / l ) , and at Station MH (1 m: 3 000 inds / l ) . A g rea t
outburst occur red simultaneously at all th ree stations on May 7, 1963,
with peak values at Station MOB (3 m: 39 900 inds / l ) , Station MA (5 m:
3 200 inds / l ) , and Station MH (3 m: 3 200 inds/ l ) . Only once found below
the ice cover (April 16, 1962, Station MOB 0. 5 m: 2 inds/ l ) .
This species is by many authors found to be a cold-water form
[cf. 20, pp. 222, 228; 8, p. 40 ] . Halme [5 , p . 39, and Abb. 4, p. 38] ,
however , during his investigations in the Pojo bay, found the species
to behave as a dist inctly s tenotherm "mild-water o rgan i sm" reaching
its peak above 18 C. Also during the years of this investigation the
species appeared as a summer plankter , most abundant at a t e m p e r a
ture of about 18 C or m o r e .
Tintinnopsis l acus t r i s Entz (» Codonella c r a t e r a (Leidy)). Fig . 7.
Eury the rm. Found throughout the year at al l th ree s ta t ions . The species
seems to avoid periods of low oxygen va lues .
Vorticella spp. Anabaena, Microcyst is and other cyanophytes
were very often infested with sma l l vor t ice l lae . Other smal l vor t icel lae
were not infrequently found on Diaptomus and Daphnia.
- 15 -
Zoothamnium sp. The most commonly found epizootic ciliate on
Diaptomus g r a c i l i s .
Suctoria sp . A smal l Acineta- l ike suctor ian was somet imes
found on Diaptomus spp.
Ciliata spp. As mos t ci l iates were rendered more or less un
identifiable by the p re se rva t ive , they were all counted together except
Codonella c r a t e r a , Epistyl is ro tans , Metopus e s , and Tintinnidium
f luviati le.
Rotatoria
Anuraeopsis f issa (Gosse). Found only during the summer per iod
Apr i l -October . In quantit ies only Ju ly-September . The highest values
were found in the 1 -3 m water l ayers August 6, 1 962, Station MOB
(1 m: 6 200 inds / l ) , Station MA (3 m: 7900 inds / l ) , and Station MH
(1 and 3 m: 4 200 inds / l ) . This is quite in cont ras t to the findings of
Pe j le r [ 11 , p. 227] , who found pract ica l ly all the specimens of this
species in the deepest water l ayers of Osbysjon. Only on two occasions
did I find the Anuraeopsis population to be m o r e or less concentrated
to the deepest water l a y e r s : on October 1 1 , I960, at Station MA (1 0. 5 m:
2 700 inds / l ) and on October 1 , 1 962, at Station MH (12.5 m: 1 80 inds / l ) .
These two samples were taken just towards the end of the period of low
oxygen content.
Ascomorpha sal tans Bar t sch . Occasionally found at al l three
s ta t ions .
Asplanchna priodonta Gosse . Fig. 8. Males November 8, I960,
Station MA; eggs November 8, I960, Station MA, and May 1 5, 1961 ,
Stations MOB and MA.
- 16 -
Brachionus annular is Gosse . Fig . 9. Common but never in grea t
quant i t ies . Except during the winter 1961 this rotifer appeared as a
spring and autumn spec ies . Males Feb rua ry 1 3 and 28, 1961 .
B. calyciflorus Pa l l a s . F ig . 10.
B. quadridentatus Hermann. Single specimens at Station MA
July 5, 1960, and September 21 , I960.
B. u rceo la r i s Mull. Single specimens at al l th ree s ta t ions .
Collotheca pelagica (Rousselet) . In r a the r smal l numbers Station
MA July-November . Specimens with 1 -2 eggs found in the autumn
ca tches .
Colurel la sp.
Conochiloides natans (Seligo). Fig . 1 1 .
Conochilus hippocrepis (Schrank). Single spec imens , most ly from
Station MOB.
C. unicornis Roussele t . F ig . 12. No finds from s u m m e r I960.
Same distr ibutions at all th ree s ta t ions .
Euchlanis dilatata Ehrbg. In a net catch from Station MH.
Filinia longiseta (Ehrbg. ). F ig . 13. Throughout the year but
s c a r c e during the colder seasons . Same distr ibution at all three s t a
t ions . Females carry ing 1 -2 eggs each were found at a l l s easons . In
Apri l 1961 about 1 0 per cent of the females in the upper water l ayers
were found with 3 eggs each and at Station MOB about 3 per cent with
4 eggs.
Kellicottia longispina (Kellicott). F ig . 14. Absent in spring and
s u m m e r i960 , then common but never in g rea t quantities from Septem
ber 6, I960, to F e b r u a r y 26, 1962. Absent again during the summer
1962 until November 20.
- 17 -
Keratel la cochlear is (Gosse). F ig . 15. The most common rotifer
of the lake, miss ing only around the periods of g rea t oxygen deficit.
During the present investigation Keratel la cochlear is showed a p r o
nounced seasonal var ia t ion along the tecta s e r i e s l ine: f. macracantha
in winter , f. typica in spring and autumn, and ff. micracan tha and
tecta in s u m m e r , Fig. 36. Trans i t ional forms between macracantha
and typica and between typica and micracantha were abundant, between,
micracantha and tecta much r a r e r . According to Pe j le r [12, p. 6 ff. ]
this var ia t ional pa t te rn is well consistent with the physical and chemi
cal conditions of Magelungen.
K. quadrata (Mull. ) Fig . 1 6. Found throughout the yea r , only
avoiding the oxygen deficit pe r iods .
Lecane luna (Mull.) Single specimens Stations MOB and MA.
L. nana (Murray). Single specimens Station MA. On June 1 2,
1 962, 1 200 inds / l were found at 5 m and 200 inds / l at 1 0. 5 m . Here
we very likely encountered a l i t tora l outflow; other l i t tora l species as
well were found at Station MA on this occasion.
Lepadella patella (Mull.) Station MA June 12, 1962. The spec i
mens found belonged to the quadr icar ina ta type [1 3, p. 347 ff. ] .
Polyar thra dolichoptera (Idelson), Fig . 17, and P . vulgar is C a r -
l in, F ig . 18. P. dolichoptera was pract ica l ly absent during i960. In
1961 , however , it inc reased in numbers and in the samples of Apr i l 25
was the dominating rot ifer in the upper water l a y e r s . F i g s . 37 and 38
according to Pe j le r [9, p. 49; 10, p. 49; see a lso Amren 2, p. 239] .
P . dolichoptera, where they occur together , a r e most ly dr iven to the
less favourable water layers by P. vu lga r i s . Pe rhaps P . dolichoptera
got a be t ter s t a r t in spring 1 961 than P. vu lgar i s , which in s u m m e r i960
was ve ry often found infected with smal l globular bodies [11 ; p. 229-30 ] .
- 18 -
P. major (Burckhardt) was found only once, in September I960,
at Station MA.
P . r emata (Skorikov) was found at all three stations but never in
g rea t numbers .
Pompholyx sulcata Hudson. F ig . 19. Pej ler [~\ 4, p. 467 ] points
out that this species has a more or less pronounced preference for
wa te rs with low t r anspa rency va lues . In the present investigation the
peak values of P . sulcata occur at the per iod when the t r anspa rency is
lowest [ see a lso 21 j Fig . 4 ] .
Synchaeta oblonga Ehrbg. and S. t runcata von Hofsten. Fig . 20.
It was not possible to distinguish between these two species in the p r e
se rved m a t e r i a l . They have therefore been counted together and the
d iagram is made up of the values so obtained. The net ca tches , however,
showed that S. t runcata was by far the most common of the two, causing
the peaks in Apr i l and May. S. oblonga was most ly found in the autumn
to ear ly spring ca tches .
S. pectinata Ehrbg. Fig . 21 . Common in spring and autumn but
never in quant i t ies . Specimens carrying 1 -2 eggs were found in Apri l .
This species was often more numerous at Station MA, Station MH
showing the lowest va lues .
T r i choce rca b i ro s t r i s (Minkiewics). F ig . 22.
T. capucina (Wierzejski and Zachar ias ) . Occasional in September ,
Stations MOB and MA.
T. cavia (Gosse). This rot ifer was found regular ly at al l three
stations during July to September. Except at the shallow Station MOB
it was never found in the bottom layer of the wa te r .
T. porcel lus (Gosse). Station MA I960, September to November ,
and 1 961 , July 1 7 and September 4. Highest values found: 40 inds / l .
- 19 -
T. pus ilia (Jennings). F ig . 23. .Quantitatively insignificant during
1 960 and 1 961 , it reached a high peak on August 6, 1 962, and was on
that date both volumetr ical ly and numer ica l ly the dominant zooplankter
in the 0 .5 m layer .
T. rousse le t i (Voigt). Occasionally Ju ly-September , Stations
MOB and MA.
C la doc era
Alona quadrangular is (Mull . ) . Single specimens found at Station
MA August 2, i960, and in a net sample November 8, I960, the la t te r
with eggs.
A. rectangula S a r s . Single specimens Station MA September 4,
1 961 , and in a net sample November 1 3, 1 961 .
Bosmina coregoni Baird . F igs . 24 and 25.
B. long i ros t r i s (Mull. ). Occasionally at Stations MOB and MA.
Ceriodaphnia pulchella S a r s . Station MA on May 1 5, 1961.
C. quadrangula (Mull. ). Single specimens at Stations MOB and
MA August 2 - October 1 1 , 1 960, and August 1 4 - October 9, 1 961 . F e
males car ry ing ephippii were observed on October 1 1 , I960, at Station
MA and October 9, 1961 , at Station MOB. Two specimens of the var .
hamata were caught at Station MH on October 9, 1961 .
Chydorus sphaer icus (Mull.) . F i g s . 26 and 27.
Daphnia c r i s t a ta Sa r s . s. s t r . A few specimens were occasionally
found at Stations MA and MH. F ig . 39.
D. cucullata S a r s . s . s t r . F i g s . 28 and 29. This species seems
to be the mos t regular ly occurr ing cladocer of the lake. Males in August
and October -November . Females with ephippii were observed in July-
August and in November -December . D. cucullata showed a marked
seasonal var ia t ion. F ig . 40.
- 20 -
D. l ong i sp ina Mull . s . s t r . w a s found p r a c t i c a l l y t h roughou t the
y e a r but n e v e r in q u a n t i t i e s . In s u m m e r , h o w e v e r , it w a s found m o s t l y
in the d e e p e r w a t e r l a y e r s .
D i a p h a n o s o m a b r a c h y u r u m L iev in . S ingle s p e c i m e n s o c c a s i o n a l l y
a t S t a t ion MA in l a t e s u m m e r .
G r a p t o l e b e r i s t e s t u d i n a r i a ( F i s c h e r ) . One f e m a l e wi th eggs in a
ne t c a t c h , S ta t ion MA, S e p t e m b e r 2 1 , i 9 6 0 .
L e p t o d o r a k indt i (Focke ) . J u n e - O c t o b e r : S ta t ions MA a n d MH.
Mos t finds f r o m the u p p e r w a t e r l a y e r s . 1 -2 i n d s / l .
P l e u r o x u s unc ina tu s B a i r d . One s p e c i m e n , S ta t ion MA, S e p t e m b e r
4 , 1961 .
Sida c r y s t a l l i n a (Mull . ) . S ingle s p e c i m e n s , S ta t ion MA, June 12,
1 9 6 1 , and S ta t ion MOB, S e p t e m b e r 4 , 1962.
B r a n c h i u r a
A r g u l u s fo l i aceus (L . ) w a s found in a few ne t c a t c h e s a t S ta t ion
MH in s u m m e r .
Copepoda
C y c l o p s s p p . F i g s . 3 0 - 3 2 . C . s t r e n u u s w a s the m o s t i m p o r t a n t
of the C y c l o p s , found a l l the y e a r round a t S ta t ion MA. At S ta t ions MOB
a n d MH, h o w e v e r , it w a s not caugh t in s a m p l e s f r o m e a r l y s p r i n g . It
w a s a l w a y s the m o s t n u m e r o u s C y c l o p s in the s a m p l e s f r o m the d e e p e r
w a t e r l a y e r s , often s u c c e e d e d t o w a r d s the s u r f a c e by C. ins ign i s (C laus ) ,
M e s o c y c l o p s l e u o k a r t i (Claus) o r M. o i thonoides ( S a r s ) . F i g . 41 . E u c y -
c lops s e r r u l a t u s ( F i s c h e r ) w a s only found a t S ta t ion MA, often in s a m p l e s
wh ich c o n t a i n e d o the r m o r e o r l e s s l i t t o r a l s p e c i e s . P a r a c y c l o p s f i m b r i -
a tu s F i s c h e r w a s found in a few ne t s a m p l e s .
- 21 -
Diaptomus grac i l i s S a r s . F igs . 33-35. The females c a r r i e d
most ly about 1 2-1 6 eggs from s u m m e r to late winter . As a rule no
females with eggs were caught during March and Apr i l . In late spring
and ear ly s u m m e r , however, they were carrying about 20-30 eggs each.
The highest numbers of Diaptomus nauplii were found in late s u m m e r ,
and of copepodites in Apr i l .
Ins e eta
Chaoborus la rvae were found in near -bot tom water samples ,
most ly at Station MH, a few finds from Station MA.
COMPARISON BETWEEN THE THREE STATIONS IN THE LAKE
A m e r e glance at the map (Fig. 1) reveals a cer ta in difference
between the t r e e s ta t ions , MH, MA, and MOB. The roughly 1 3 m deep
stat ion MH is surrounded by s teep hi l ls ides which give the stat ion a
cer ta in shel ter from the winds. This condition, its re lat ive depth and
the fact that the station is si tuated off the main flow in the lake, con t r i
butes to the pronounced s u m m e r s trat i f icat ion of the water of this s tat ion.
Station MA, which is about 1 1 m deep, is si tuated within the main flow
of the lake. It is more openly si tuated and consequently more exposed
to the winds. Its summer strat if icat ion is usually somewhat less accen
tuated than that of Station MH. Station MOB is a l so si tuated within the
main flow; the influences of wind, flow and depth (about 5 m) , however ,
cause a more unstable summer stagnation: the strat if icat ion is s o m e
t imes broken down even in the middle of the s u m m e r . Station MOB is
further distinguished by the fact that it rece ives polluted waters from
^.ffluents to the NW par t of Magelungen and from Lake Agesta previous
to Station MA.
- 22 -
As mentioned above, the seasonal distr ibution of the standing
crop of zooplankton is about the same at al l three stations (Figs. 42-45
and tables 1 -5) .
F ig . 47 shows the situation during 1962 and 1963, when a di rect
compar ison between the three stat ions was made . In the d iagram the
average-va lue curves for the total volume of zooplankton a r e drawn for
the whole water column from surface to bottom.
The ciliate fauna of Station MOB, the most eutrophic (well
nourished) of the three s ta t ions , was more richly developed and var ied
than that of the other two s ta t ions . The rot i fers were the same at a l l
t h ree s ta t ions , with the exception of some accidental l i t tora l or rarely-
found spec ies . Also the c rus taceans a r e the same at al l th ree stations
with the exception of those indicating high oligotrophy. Daphnia c r i s ta ta
was very r a r e l y found at Stations MA and MH, and Leptodora kindti
was not found at al l at Station MOB. Chaoborus sp . was a lso miss ing
in samples from Station MOB.
THE TROPHIC STATE OF THE LAKE
The trophic degree (nutritional standard) of Lake Magelungen is
much higher than would be expected in view of its morphomet ry . Thus ,
of its about 36 species regular ly occurr ing in plankton (Table 7), no
less than 1 0 species (Station MA), or 28 per cent, a r e indicators of
eutrophy [l 4, p. 467 ff. ] : Coleps sp. , Anuraeopsis f issa , Brachionus an
gular is , Fil inia longiseta, Karatel la cochlear is f. t ec ta , Pompholyx
sulcata , Tr ichocerca b i r o s t r i s , T. pus i l ia , Chydorus sphaer icus , and
Daphnia cucullata, a fact which indicates a very high degree of eutrophy.
Also when scoring the lake according to some of the common point s y s
tems used in a s sess ing the t rophic degree of a lake, we obtain the same
- 23 -
resu l t : thus according to the sys tem of Thunmark [l 8, p. 45 ff. and
Tab. 1 ] Lake Magelungen is to be placed amongst the "sehr s t a r k
eutrophe Seen". The sco re sys tem of Pej ler [14, p. 468] gives for
Stations MH and MA 23, for Station MOB 25 points out of possible 2 7,
which marks the highest degree of eutrophy. The comparat ively low
score of Stations MH and MA is due to thei r depth, which gives only
2 points out of possible 5, which further emphasizes the fact that the
lake is more eutrophic than would be expected.
The p resen t high eutrophy of Lake Magelungen is undoubtedly
due to pollution, most ly from Lake Agesta and the Fage r s jo d i s t r i c t .
That the whole lake suffers from this pollution is i l lus t ra ted by a com
par ison with ea r l i e r investigations performed by the Stockholm City
Municipal Services Department [ 4 ] (Table 8). Among 1 5 zooplankton
species counted in 1 945 in samples from H a m m a r t o r p (Station MH in
the p resen t investigation) only 3 indicators of eutrophy were found. In
the yea r s 1954-1955 the indicators of eutrophy at Hammar to rp had in
c r ea sed to 6, which gives a percentage near ly as high as that for the
same yea r s at the sampling station Fagers jo at the NW end of the lake
[ 4 ] . During the p resen t investigation no less than 9 indicators of eutrophy
were regular ly found at Station MH (1 0 at each of Stations MA and MOB).
It is in teres t ing to notice how in Magelungen, in cont ras t to
Nauwerck ' s findings in Lake Erken [8 , p . 1 05 J, the zooplankton curve
(Fig. 47) follows that of the phytoplankton (Fig. 46), the zooplankton
maxima in genera l appearing somewhat la ter than the phytoplankton
maxima.
During the present investigation is was found that the average
volume of zooplankton is the same as that of phytoplankton (Station MOB)
- 24 -
or somewhat more (Stations MA and MH, Table 6). As a compar ison
it m a y b e mentioned that the average phytoplankton: zooplankton (P:Z)
ra t io of the mesot rophic Lake Erken is 0.18 [8 , p. 104] , i . e . about
5. 5 t imes more zooplankton than phytoplankton volume. Rawson [1 5,
p . 20 ] has found values up to 40 t imes more zooplankton than phyto
plankton volume in the oligotrophia Cree Lake in Northern Saskatchewan.
CONCLUSIONS
As a l r eady pointed out by Willen [21 , p. .28], further additions
of nutri t ional elements to the lake would augment the phytoplankton p r o
duction. At p resen t the average volume of zooplankton is about the same
as that of phytoplankton. It is not likely that an inc reased growth of
phytoplankton would a l te r this ra t io to the advantage of the zooplankton.
What could be expected is a continued decrease of the zooplankton in
proport ion to the phytoplankton and fouling of the shores and bottom as
a resu l t of water bloom.
The effect of the re lease of waste water is not easily anticipated.
The waste water may s t i r up mud and water containing hydrogen su l
phide during the winter and s u m m e r stagnation [cf. 6 ] , which would
de te r io ra te the conditions of animal life in the lake. It i s , however,
possible that , if the waste water contains a sufficiently high amount of
oxygen, the r e l ea se and the augmented flow might exer t a beneficial
effect upon the lake during the oxygen-depletion periods and a lso d i
minish the r i sks of an increased unbalance in the production of the lake.
An investigation of these problems might give resu l t s of vital in teres t
for other lakes which threa ten to become unbalanced.
- 25 -
REFERENCES
AGNEDAL, P - O . , (Personal communicat ion.)
AMREN, H. , Ecological and taxonomical studies on zooplankton from Spitzbergen. Zool. Bidr . Uppsala 36 (1964) p . 209.
AXELSON, J . , Zooplankton and impoundment of two lakes in Nor thern Sweden (Ransaren and Kultsj5n). Rep. Inst . F reshw. R e s . Drottningholm 42 (1961) p . 84.
CRONHOLM, M. , (Personal communicat ion.)
HALME, E . , Planktologische Untersuchungen in der Pojo-Bucht und angren-zenden Gewassern . IV. Zooplankton. Ann. Zool. Soc. "Vanamo" 1 9 (1 958):3.
KARLGREN, L. and LINDGREN, O. , Luftningsstudier i Trasks jon . Vattenhygien 19 (1963) p. 67.
MONTI, R . , Numer i , grandezze e volumi degli o rganismi pelagici viventi nelle aque Ital iane, in relat ione a l l 'economia l acus t re . Mem. 1st. Lombardo di Scienze e Le t te re 23-24 (1936) p. 83.
NAUWERCK, A. , Die Beziehungen zwischen Zooplankton und Phytoplankton im See Erken . Symbolae Botan. Upsal ienses 17 (1963):5.
PEJLER, B . , On var ia t ion and evolution in planktonic ro ta to r ia . Zool. Bidr . Uppsala 32 (1957) p. 1.
PEJLER, B . , Taxonomical and ecological studies on planktonic rota tor ia from Nor thern Swedish Lapland. Kgl. Sv. Vetenskapsakad. Handi. s e r . 4. 6 (1 957):5.
PEJLER, B . , The zooplankton of Osbysjon, Djursholm. I. Seasonal and ver t i ca l dis t r ibut ion of the spec ie s . Oikos 12 (1961) p. 225 .
- 26 -
PEJLER, B . , On the variat ion of the rotifer kera te l la cochlear is (Gosse). Zool. Bidr . Uppsala 35 (1962) p . 1.
PEJLER, B . , On the taxonomy and ecology of benthic and periphytic ro ta tor ia . Investigations in Northern Swedish Lapland. Ibid. 33 (1962) p . 327.
PEJLER, B . , Regional-ecological studies of Swedish f resh-water zooplankton. Ibid. 36 (1965) p . 407.
RAWSON, D.S . , Limnology and f isher ies of Cree and Wollaston Lakes in Nor thern Saskatchewan. 1959. F i she r i e s Report 4. Dept. of Natural Resources . Saskatchewan.
RODHE, W., Zur Verbesserung der quantitativen Plankton-Methodik. Zool. Bidr . Uppsala 20 (1941) p . 465.
RYLOV, W . M . , Das Zooplankton der Binnengewasser . Binnengewasser 15 (1935).
THUNMARK, S. , Zur Sociologie des Susswasserplanktons . Folia Limnol. Scand. 3 (1 945).
UTERMOHL, H . , . Zur Vervollkommung der quantitativen Phytoplankton-Methodik. Mitt. Int. Ver . fur Theor . und Angew. Limnologie, 1958:9.
VALIKANGAS, I . , Planktologische Untersuchungen im Hafengebiet von Helsingfors . I: l iber das Plankton, insbesondere das Netz-Zooplankton des Sommerha lb jahres . Acta Zool. Fennica 1 (1926) p. 1.
WILLEN, T . , Phytoplankton from Lake Magelungen, Centra l Sweden, 1960-1963. (AE-219) 1966.
- 27
Tab le 1
6 3 ; Volume of zoopl. inkton, St.ilion MA 1960 - 1963 ( ave rage va lues 0 .2 - 5 .0 m ; in 10 p /l)
1960 2 8 / 3 2 0 / 4 10/5 5 / 7 2 / 8 6 / 9 2 l / 9 l l / l 0
Ci l i a t a
R o t a t o r i a
C la doc e r a
Copepoda
Naupl i i
To ta l vo lume
8
27
29
16
5
28
75
13
35
92
748
47
74
345
380
1240
74
0
260
1490
490
97
46
101
128
433
63
11
75
128
315
31
27
75
220
305
44
80 121 922 21 13 2337 771 560 671
8/1 1 6/12 29 /12 1961
1/2 2 / 2 13 /2 2 8 / 2 14/3
C i l i a t a
R o t a t o r i a
C l a d o c e r a
Copepoda
Naupl i i
C i l i a t a
R o t a t o r i a
C l a d o c e r a
Copepoda
Naupl i i
C i l i a t a
R o t a t o r i a
C l a d o c e r a
Copepoda
Naupli i
To ta l volume
46
62
123
203
17
6
25
33
21
13
23
9
3
9
11
51
6
0
0
8
1 1
6
7
3
5
74
8
0
3
6
96
9
10
5
10
106
14
1 1
5
14
Total volume 451
10/4
98
25/4
55
15/5
65
12/6
32
17/7
91
14/8
130
4/9
150
9/10
258
65
0
140
27
38
1780
137
66
116
119
1215
820
399
249
9
74
13875
243
182
10
135
760
595
156
1
244
3350
1035
205
2
207
1850
131
107
8
64
898
455
223
Total volume 490
1961 13/11
2137
18/12
2802
1962 21/1
14383
26/2
1656
26/3
4835
16/4
2297
25/4
1648
22/5
5
21
283
388
14
711
1
3
1
133
13
141
2
1
7
77
4
91
12
102
4
2
29
148
2
185
30
0
1
4
0
35
175
1
0
25
2
203
27
513
26
140
107
813
C i l i a t a
R o t a t o r i a
C l a d o c e r a
Copepoda
Naupl i i
To ta l vo lume
12 /6 9 / 7 6 / 8 4 / 9 1/10 2 9 / 1 0 2 0 / 1 1
1029 1535 3973 8819 1959 656
1963 8 /1 12 /2 1 1 / 3 8 / 4 7 / 5 2 8 / 5
413
11 /12
2
215
141
238
433
119
832
383
159
42
192
1908
1425
309
140
143
463
7925
143
145
53
343
1278
227
58
23
17
296
300
20
28
15
161
188
21
61
10
56
120
31
278
Ci l i a t a
R o t a t o r i a
C l a d o c e r a
Copepoda
Naupli i
T o t a l volume
80
5
11
25
4
62
9
5
47
14
22
2
15
48
8
1
1
20
436
3
395
40
0
1 10
31
67
183
804
2045
995
125 137 95 461 576 4094
- 28 -
Table 2
6 3 , , Volume of zooplankton, Station MH 1961 - 1963 (average values 0 .2 - 5 . 0 ra; in 10 ^ /l).
1961 1/2 28/2 14/3
1962 21 /1 2 6 / 2 16/4 2 2 / 5 12/6
Cil ia ta
Rotator ia
C la doc e ra
Copepoda
Nauplii
Total volume
10
8
3
5
30
56
29
6
5
5
20
65
124
18
20
5
30
197
23
2
12
16
1
54
4
5
57
1 13
2
181
16
0
0
0
0
16
608
1
64
240
961
0
104
243
625
203
1 180
6 / 8 4 / 9 1/10 20 /11 1 1/12 1963 11/3 7/5 23 /5
Cil ia ta
Rota tor ia
C ladoce ra
Copepoda
Nauplii
Tota l volume
511
18728
1950
77
90
67
160
2825
95
1 1 1
145
39
228
59
30
21
10
66
87
10
65
10
68
25
18
17
3
rs 76
36
303
46
1
285
8
9
1 16
398
1705
805
21356 3258 501 194 186 147 643 3233
Table 3 6 3 , Volume of zooplankton, Station MOB 1961 - 1963 (average values 0 .2 - 5 .0 m; in 10 \j. /•£.)
1961 2 /2 2 8 / 2 14 /3 2 5 / 4 15/5 12/6 14/8 4 / 9
C i h a t a
Rotator ia
C ladocera
Copepoda
Nauphi
Total volume
64
9
5
0
2
360
2
0
0
1
137
31
0
40
9
130
1280
15
1 1
153
633
5050
106
178
370
19
138
1000
200
410
3
1 12
475
0
320
20
I ) I
395
0
178
80 363 217 1589 6337 1787 910 1224
9/10 13/1 1 18/12 1962 21 /1 26/2 26 /3 16/4 2 5 / 4
C il iata
Rotator ia
C ladoce ra
Copepoda
Xauplii
Tota l volume
37
175
1170
2180
365
3927
14
20
16
4
13
67
29
7
13
146
8
203
14
2
21
514
2
553
22
1
23
364
18
428
109
0
0
0
0
109
680
2
25
3
1 1
72f
840
0
108
15
964
22 /5 12/6 9 /7 6 /8 4 / 9 1/10 29 /10 1 1/12
Cil ia ta
Rota tor ia
C ladoce ra
Copepoda
Nauplii
C i l iata
Rota tor ia
C ladoce ra
Copepoda
Nauplii
Total volume
50
990
52
240
428
0
190
264
553
232
121
510
84
244
15
69
1890
2225
69
75
25
1260
8125
241
218
35
1030
983
360
74
22
58
136
47
50
5 7
15
15
34
29
Total volume 17S0
1963 8/1
1239
12/2
974
11/3
4328
8/4
9869
7/5
2482
28/5
313 150
57
8
9
65
15
3
0
3
5
0
0
0
1
0
0
0
1
0
39
0
390
49
54
38
39
10
325
580
1948
1115
254 11 40 570 3978
Table 4 29
6 3> Volume of zooplankton, Station MA 1960 - 1963 (average values 0.2 - 10.5 m; in 10 u /t)
1960 2 8 / 3 2 0 / 4 10/5 5/7 2 / 8 6/9 2 1 / 9 1 1 / 1 0
Ciliata
Rotatoria
Cladocera
Copepoda
Nauplii
Total volume
5
94
341
11
7
25
178
12
24
64
549
32
56
236
413
836
50
10
174
1025
340
65
50
72
1 12
376
63
8
69
82
252
33
1 17
60
179
315
39
451 222 669 1591 1614 673 444 710
8 /1 1 6 / 1 2 29/12 1961
1/2 2 / 2 13 /2 2 8 / 2 1 4 / 3
Ciliata
Rotatoria
Cladocera
Copepoda
Nauplii
Total volume
42
59
109
255
19
6
22
50
99
14
19
8
18
101
1 1
39
5
15
63
7
70
6
34
98
7
54
6
2
12
4
79
7
15
30
6
90
1 1
36
182
16
484 191 157 129 215 78 137 335
1 0 / 4 2 5 / 4 15 /5 12 /6 1 7 / 7 1 4 / 8 4 / 9 9 / 1 0
Ciliata Rotatoria Cladocera Copepoda Nauplii
Ciliata
Rotatoria
C ladocera
Copepoda
Nauplii
Ciliata
Rotatoria
Cladocera
Copepoda
Nauplii
Total volume
255
598
10
157
29
61
1232
92
60
89
91
825
558
326
201
12
61
10717
191
158
8
92
680
401
112
16
164
2525
810
166
30
1414
1773
104
81
8
51
773
388
162
Total volume 1049
1961 13/u
1584
18/12
2001
1962 21/1
11139
26/2
1293
26/3
3681
16/4
3402
25/4
1382
22/5
6
21
262
360
18
1
5
57
175
11
2
2
64
90
4
3
3
54
12
8
3
1
19
104
2
21
0
0
6
0
125
0
0
33
1
26
386
17
104
76
Total volume 667
12/6
249
9/7
162
6/8
80
4/9
129
1/10
27
29/10
159
20/11
609
1 1/12
4
150
94
217
437
88
556
257
111
28
187
1280
969
222
97
116
324
6207
134
107
126
237
1652
202
39
22
14
602
310
19
31
13
221
186
19
67
13
92
177
38
902 1040 2755 6888 2256 965 470 387
1963 8/1 12 /2 11 /3 8 / 4 7 /5 28/5
Ciliata Rotatoria Cladocera Copepoda Nauplii
Total volume
71
7
54
62
6
43
7
7
37
11
15
1
10
39
5
1
1
13
291
2
279
27
0
80
21
46
122
537
1415
698
200 105 70 308 407 2818
Table 5 - 30
6 3 , Volume of zooplankton, Sta t ion MH 1961 - 1963 ( ave rage va lues 0 .2 - 12.5 m ; in 10 u. /-t)
1961 1/2 2 8 / 2 1 4 / 3
1962 21/1 2 6 / 2 1 6 / 4 2 2 / 5 12 /6
Ci l i a t a
Ro ta to r i a
C l a d o c e r a
Copepoda
Xaupl i i
10
8
33
85
26
79
8
19
137
51
127
13
23
46
26
13
5
157
164
1
3
6
67
189
1
9
0
0
1
0
56
386
0
86
179
1
68
139
395
236
T o t a l v o l u m e 162
6 / 8
294
4 / 9
235
l / l O
340
2 0 / 1 1
266
11 /12
10
1963 11 /3
707
7 / 5
839
2 8 / 5
Ci l i a t a
R o t a t o r i a
C l a d o c e r a
Copepoda
Naupl i i
To ta l volume
292
1071 1
1115
45
51
12214
94
91
2199
75
68
2527
233
25
304
76 -
32
670
26
9
100
102
13
250
65
1 1
70
40
26
212
10
2
9
45
21
87
192
27
1
165
4
389
6
67
227
977
466
1743
Tab le 6
The Phytoplankton - Zooplankton r a t io 1962.
Date
2 1 / 1
2 6 / 2
2 6 / 3
1 6 / 4
2 5 / 4
2 1 / 5
12 /6
9 /7
6 / 8
4 / 9
1/10
2 0 / 1 1
1 1/12
M
P h y t o p l a n k t o n
i n t 0 6
M O B
224
45
102
329
1631
3250
1 1 187
9370
5066
1 152
3586
-540
3040
»>/<•
M A
256
68
58
164
341
3470
5350
4244
2376
728
1758
161
43
1463
v o l u m e s
M H
160
43
- ' 106
-6771
1 1230
-4910
828
468
174
66
2476
Z o o p l a n k t o n
i n
M O B
553
428
109
721
964
1760
1239
947
4328
9869
2482
-150
1963
iob n7<.
M A
91
102
185
35
203
813
1329
1553
3973
8819
1959
413
278
1496
v o l u m e s
M H
54
181
-16
-961
1 180
-21356
3258
501
194
186
2789
P h y t o p l a n k t o n : Zoo
M O B M A
0 .41 2 .81
0 .11 0 .67
0 . 9 4 0 .31
0 . 4 6 4 . 6 9
1.69 1.68
1.85 4 . 2 7
9 .03 5 . 2 0
9 . 8 9 2 . 7 3
1.17 0 . 6 0
0 . 1 2 0 . 0 8
1 .44 0 .90
0 . 3 9
3 .60 0 .15
1.04 0 . 9 8
p lank ton
M H
2 . 9 6
0 . 2 4
-6 . 6 3
-7.05
9 .52
-0 . 2 3
0 .25
0 . 9 3
0. 90
0. 35
0 . 8 9
(data on phytoplankton f rom Willen 1 966)
- 31 -
TabLe 7. Species regular ly occurr ing in plankton of the three s ta t ions.
CILIATA
Coleps sp . Epis ty l i s ro tans Tintinnidium fluviatile Tint innopsis l a cus t r i s
ROTATORIA
Anuraeops is f issa Asplanchna priodonta Brachionus angula r i s B . calycif lorus Conochiloides natans Conochilus unicornis Fi l inia longiseta Kell icott ia longispina Kera te l l a coch lea r i s K. coch l ea r i s , f. tec ta K. quadra ta Polyarthra dolichoptcra P . r ema ta P . vulgar is Pompholyx sulcata Synchaeta oblonga S. pect inata S. t runca ta T r i c h o c e r c a b i r o s t r i s T . cavia T . pusi l la
CLADOCERA
Bosmina coregoni Chydorus sphaer icus Daphnia cucullata D. longispina Leptodora kindti
COPEPODA
Cyclops insignis C . s t renuus Diaptomus g rac i l i s Mesocyclops leuckar t i M. oithonoides
INSECTA
Chaoborus sp . , l a rvae
Number of species Number of ind ica tors of eutrophy % of indica tors of eutrophy
MH
+ + +
+ + + + + + + + + + + + + + + + + + + + +
+ + + + +
+ + + + +
+
35
9
26
MA
+ + + +
+ + + + + + + + + + + + + + + + + + + + +
+ + + + +
+ + + + +
+
36
10
28
MOB
+ + + +
+ + + + + + + + + + + + + + + + + + + + +
+ + + +
+ + + + +
34
10
29
Indicator of eutrophy E
E
E
E
E
E E
E
E
E
E E
- 32 -
Table 8
Most common zooplankton species found in e a r l i e r invest igat ions of lake Magelungen.
RHIZOPODA
Difflugia l imnetic a
CILIATA
Coleps sp . E Epis ty l i s ro tans Tintinnidium fluviatile Tint innopsis l a cus t r i s
ROTATORIA
Anuraeops i s f issa E Asplanchna priodonta Brach ionus angular i s E B . calycif lorus Fi l inia longiseta E Kell icot t ia longispina Kera te l l a coch lea r i s K. quadra ta P o l y a r t h r a r e m a t a Pompholyx sulcata E Synchaeta pect inata T r i c h o c e r c a b i r o s t r i s E
CLADOCERA
Bosmina coregoni B . long i ros t r i s Chydorus sphaer icus E Daphnia c r i s t a t a D. cucul lata E Diaphanosoma brachyuum Leptodora kindti
Number of species
Number of ind ica tors of eutrophy (E)
% of indica tors of eutrophy
Hammar to rp 1945
+
+
+
+
+ + + + +
+
+ + + + +
15
3
20
Hammar to rp 1954 - 1955
+
+
+ +
+
+ + + + + + + 4-
+
+
+
16
6
37.5
F a g e r s j o 1954 - 1955
+ + +
+
+ + +
+ + + +
+
+
13
5
38.4
- 33 -
FIGURE CAPTIONS
Fig. 1 Map of Lake Magelungen.
Fig. 2 Map showing the sampling s ta t ions .
F i g s . 3-6 Diagrams showing the distr ibution of the zooplankton
expressed as per cent of the total volume:
Fig . 3 Station MA 1960-1961
Fig . 4 Station MA 1962-1963
Fig . 5 Station MOB 1962-1963
Fig . 6 Station MH 1962-1963
F igs . 7-35 Diagrams showing the frequencies of the most common
zooplankton species over the sampling period.
F ig . 36 Seasonal var ia t ion of Keratel la cochlear is in the upper
water l aye r s (0-5 m) of Stations MA and MOB.
F i g s . 37-38 Seasonal dis tr ibut ion of the Po lyar th ra spp. in the surface
water l ayers (0-5 m) of Stations MA and MOB.
Fig . 39 Some Daphnia c r i s t a ta from Station MA.
Fig . 40 Some seasonal forms of Daphnia cucullata from Lake
Magelungen.
Fig . 41 Seasonal dis tr ibut ion of the Cyclops spp. (average d i s t r i
bution for the period 1 960-1963).
F i g s . '42-43 The distr ibution of the total zooplankton volumes,
Station MA.
Fig . 44 The distr ibution of the total zooplankton volumes,
Station MOB.
Fig . 45 The distr ibution of the total zooplankton volumes,
Station MH.
Fig. 46 Total volume of phytoplankton, average values 0 . 2 - 0 . 5
m (from Willen 1966).
Fig . 47 Total volume of zooplankton.
- 34 -
- 35 -
Fagersjo +
LAKE MAGELUNGEN
From Lake Agesta-
MOB w
2 .5 12 s~\
MA
To Lake Drevviken
MH Hammartorp 0 500 1000m
1
Fig. 2
MAGELUNGEN Sta t ion MA 1960-1961
1960 Per Cent of Total Volume Zooplankton.
ON
Fig. 3
MAGELUNGEN Sta t ion MA 1962-1963
26.2 26.3 16.4 25.4 22.5 12.6 9.7 4.9 1.10 29.10 20.11
10.5 m
Fi".. J
MAGELUNGEN Station MOB 1961-1963
to 00
Per Cent of Total Volume Zooplankton.
F l j ; r>
- 39 -
MAGELUNGEN Station MH 1962-1963
1962
1 m
3 m
5 m
8 m
10.5 m
12,5 m
10,5 m
12,5 m
PerCent of Total Volume Zooplcmkton.
Ciliata
Rotatoria
Cladocera
= Ci J
= Ro
= Cl :
+ + + *• + + + + +
Hill : : : i
Copepoda = Co | j
Nauplii = N ^ ^ ^ |
F i g . 6
- 40 -
OtPTH rr. 1960 0 V,WWWIIIIII11WI»1»II>
TINTINNOPSIS LACUSTRIS
1961
STATION MA 1960 - 1963
10' i'
JANIIFCB. IMAR. lAPR. I HAY I JUN.I JUL. I AUGlSEP.I OCT I NOV I DEC I JAN ICES I MAR lAPP I MA/ I JUN I JUL 1 AUS.I3CP. I OCT.I NOV.I DEC.
Fig . 7
DEPTH T 1960*
A5PLANCHNA PRIODONTA
1961
STATION MA 1960-1983
6*
JMAR.IAPO. fwAWJUN.lJUL. I AUS.ISEP.I OCT.I NOV.I DEC.I JAN.IFCB I
Fig. 8
41 -
BRACHIONUS ANGULARIS STATION MA
1960 - 1963
Fig. 9
DZPTU
•» 1360 0 IVAJW
BRACHIONUS CALYCIFLORUS
(961
5TATI0N MA 1960 - 1963
I JAN.IPEB.lMAR. lAPR. I MAY I J U N . I J U L . I AUGlSEP. I OCT| NOV I DEC I JAN iFEB.lMAR. lAPR I MAY I JUN. I JUL. I AUG.ISEP. I OCT I NOV I DEC I
Fig . 10
- 42 -
CONOCHILOIDES NATAN5
1960
STATION MA 1960 -1963
JAN.lFEB. IMAR. I A P R . - I M A y l j U N . I JUL . I AUSI5EP I OCT. I NOV. I DEC.I J A N IFEB I M A R . I A P R [ MAy lJUN | j U L . I A U G T S E P . I OCT7I NOV.I DEC
F i g . 11
CONOCHILUS UNICORNIS OEPTH
m 1960 i'w 0 vjijtjj>/r//tsj/s///////u | |
STATION MA 1960-1963
10'
m 1962
lHAR. I A P B . I MAY I JUN. I JUL. I AU6.ISEP.I OCT. I NOV.I DEC.I JAN. lFEB. I MAR . I APR. I MAY IJUN I JUL . I AUG. ISEP . I OCT. I NOV.I DEC.
F i g . 12
- 43 -
FILINIA LONGISETA
1961
STATION MA
1960 -1963
mg/t imaA ama/e , ' m j / ' , . . . . lANTTra". I MAR. I APR. I MAy IjUN. IjUL. I AUC ISEP. I OCT. I MOV.TDEC.IJAH. IFEB.IMAR . I APR. I MAY IjUN. IjUL . I AUS.ISEP. I OCT. I NOV. I DEC.
F ig . 13
OEPTH "> 1960
KELLICOTTIA LONGISPINA STATION MA
1360-1963
;n»a/t i » s / t _ _lms_/*_ ,tm3'S __ _^_ JAN.IFEB. IMAR.IAPR. I MAYI JUN.IJUL. I AUS ISEPTI OCTTNOV.I OEC.I JAN.IFEB.IMAR.IAPRM MAV I JUK. I JUC . / *ue.tscr.l ocr fNOKI oec
F i g . 14
- 44 -
DEPTH m 1960 0 //s/t/tw>/'j//////////jn
KERATELLA COCHLEARIS
10- 6- 1961
STATION MA 1960-1963
•77777771-1 ^ 7 — —i 1 /}>/>>u/tt/t/rtrrr>
JAM.lFCB. IMAR, I APR .1 MAVl JUN.I J U L I AUG. I5EP. I OCT. I NOV.! OEC.I J A N . I F E 8 - I MAR. I APR. I HAY I J U N . | j U L . I AUC.ISEP. I OCT I NOV.I DEC.
Fig. 16
DCPTH m 1J60 0 Tj*r*rt>rmm
KERATELLA QUAORATA
u> v 1961 '• ,0-*
STATION MA 1960-1963
10'
OCT. I NOV.I DEC.I JAN. |FEB. |M»R. |AP». I MAY I JUN. I JUL . I AU S.I SEP . I OCT.I NOV. I DEC.
Fig . 16
- 45 -
POLyARTHRA DOLICHOPTERA STATION MA
1960-1963
JAN.lrEB.lMAB. lAPB.lMAyljUN.IJUL.I AU*.ljEP. I OCT.I NOV.I OEC.I JAN.lFEB.I MAP.. I AP». I MAV IjUN. IJUL .TAUSJSEP. I OCT.I MOV.l DEC.
F i g . 17
m 1960 0 fwrrwrr/?/////?.
POLYARTHRA VULGARIS
1361
STATION MA 19G0-1963
10.1
JAN.IFEB 2 "09 A 2ma7< 2m9/<
iMAB.lAPS. I MAVIjUN.IjUL. I AU&lsCP. I OCT.I NOV.I DEC.I JAN. IFEB. IMAB. I APB. I MAY IjUN. I JUL. I AUS.ISEP. I OCT.I NOV.I DEC.
F i g . 18
- 46 -
1960
POMPHOLyX SULCATA
,o- 6 . 1961
STATION MA 13GO-1963
6 '
JAN I F E 8 . I M A R . U P R . I MAy I JON. I JUL. I A U & l i E P . I OCT I NOV I DEC I JAN IFEB I MAP. I APR. I MAy IJUN. I JUL . I AUO.ISEP.1 OCT I NOV. I DEC
Fig. 19
SYNCHAETA spp. BmF 10 DCPTU
m 1960 0
1961
STATION MA 1960-1963
i c f
JAKl'IFEB. IMAB lAPR.I MAY I JUN. I JUL. I AUS. ISEP.IOCT. I NOV. I OEC I JAN. IFEB. I M A R . I A P R . I MAY | JUN. I JUL . I AU4 I SEP. I OCT I NOV.I DEC
Fig. 20
- 47 -
SyNCHAETA PEXTINATA
19G1
STATION
1 9 6 0 - 1
nq/t i»]/l iuq/l 2mq/t , ^ & ^ ^ _ ^ N.IFEB.IMAR. IAPB. I MAY I JUN IJUL I AUS.ISEP. I OCT. I NOV.I DEC I JAN IFEB.IMAR UPR MAY I JUN.IJUL. I AU&ISEP. I OCT.I NOV.I DEC.
Fig. 21
TRICHOCERCA BIROSTRIS DEPTH
m 1960 0
STATION MA
1960-1963 10* G"
2 m 3 / { JANIFEB.IHAQ IAPR I MAYIJUN.I JUL.I AUGISEP. I OCTI NOV ' DEC! JAI^FEB'MAR IAPR.1 MAY! JUN.IJUL. I AUC ISEP ' OCT.I NOVIDEC
Fig. 22
- 48
DEPTH m I960
TRICHOCERCA PUSILLA
10* c 1361
STATION MA
1960-1963
m 1962 0 \w//i»l/il/IIA)>/>//.
2""l/< 2ma/t JmsV* i - s / l OAN.IPEB.IMAR.IAPD. I MAY I JUH.I JUL.I AUSTISEP. t ocfF NOV! OECI JAN.IFEB.IMAR IAPR.I MAVIJUNJOUL.! AO«.I»EP.I OCT.I NO«I ote.
Fig . 23
DEPTH
0 9/////'/////J77TmsjJ//MJ/\ I
BOSMINA COREGONI
1961
STATION MA
1960-1963 6"
J A N I F E S . IMAR. I APR. I MAY I jUN . I j U L . I AUS.ISEP I OCT I NOV. I DEC. I JAN. IrEB. |MAR. lAPR. I MAY IJUN. I JUL. I AUS.ISEP.I OCT. I NOV. I DEC.
Fig . 24
- 49 -
DEPTH 2mg/« - 1361 0/j.
BOSMINA COREGONI
Id' 6' 1962 1' (• to' 15'
STATION MOB 1361 -1962
m 1361
2m 9 /« 2mg/«
1962
STATION MH 1961 -1962
J A N I P E B . I M A B . U P R I MAyljUN. I JUL. I AUS.ISEP. I OCT. I NOV I DEC I JAN. IrEB IMAO. lAPR. I MAY IjUN I JUL I AUGjSED.I OCT. I NOV. I DEC.
Fig . 25
CHYDORUS SPHAERICUS
IHO
STATION MA 1960 - 1963
JANICEB. IMAP IAPP. I MAVI J U N . I J U L . I AUS.ISEP. I OCT NOV I DECljAN.lFEB. iMAR.lAPR.' MAY I JUN. I JUL. FAUGISEP. I OCT I NOV.I DEC.
Fig. 26
50
DEPTH l m a / l m 1961 0." 0
CHyDORUS SPMAERICUS
1962 2* f 10' M'
STATION MOB 1961-1962
15' <0'
m 1961 0 y///>t>> />»//>»>>>>/
1962
STATION MH 1961 -1962
2mjA *mS/' ' m 9 / ' ' " ' A
JAN, lc tB . |HAP. lAPB. I MAV I j U N . I J U L . I AU6.|S£P, I OCT, I NOV.I DEC.I JAN IFEB. IMAR. I APP. I MAyl MH. I JUL. I AUC-ISEP, I OCT, I NOV.! OEC, I
Fig. 27
DAPHNIA CUCULLATA
DEPTH "> 1960
STATION MA 1960 - 1363
J A N I F E B MAP I APR. I MAY I J U N . I j U L . I AUGlSEP. I OCT.I NOvl DEC I JAN IFEB I M A R U P Q . I MAyl JUN. I JUL. I AUtt lSEP.I OCTl NOV.I OEC.
Fig . 28
- 51 -
DEPTH 2ms /« f" 1961 °, r 0 Y.V ••/}•? •-•[}•
DAPHNIA CUCULLATA
1962
STATION MOB 1961 -1962
1961
J fJ f l .
-»-<•-
STATION MH 1961-1962
1962
JAN I rEB I M A R . T A P R . I M A y l j U N . I JUL. I AUG IsEP I OCT ! NOV I DEC. I JAN I F E B . I MAR . I A P R ' MAvl JUN. I JUL . I AUG F3EP I OCT ! NOV i DEC
F i g . 29
CYCLOPS spp. ADULTS AND COPEPODITES
OEPTH m I960
STATION MA 1960 - 1963
JUL I AUGlSEP I OCT NOV DEC JAN.iPEB MAR IAPR I M A y l j U N i JUL I A U G . I S E P I OCT I NOV.I DEC
F i g . 30
52 -
eye LOPS spp.
ADULTS AND COPEPODITES STATION MOB
1961-1962 DEPTH 2mq *
m 1961 0, , . 1962 777777777 i///y]i/j>/j 1—r
- if—o-
2- f » • 15'
r >' » » • \ *•
I l
«*—o—
I
I I I I I I I I 1/
° "T° o — J — I \
2 m 3 / t
!-V .Ui
2mg/«
STATION MH 1961-1962
JAN. I CEB. I MAR . lAPR . I MAY I jUN. I JUL. I AUG ISEP. I OCT. I N O V T D E C T J A N . I F E B " IMAP.TIAPR I MAY I j U N . I j U L I AUS |3EP. I OCT. I NOV I DEC.
Fig. 31
OEPTH m 1360
cycLOPS spp. NAUPLII
1961
STATION MA 1360 - 1963
10' C
gmg/t 2mq/l lm$jl 2mg"/t
JAN V E S . I M A R . lAPR. I H A y l j U N I JUL. I AUGlSEP. I OCT I NOV I DEC I JAN lEEB.' MAR. I APR . I MAyl JUN. I JUL. I AUGlSEP. I OCT. I NOV. I DEC.
Fig. 32
- 53 -
1360
DIAPTOMUS GRACILIS NAUPLII
1361
STATION MA 1960 - 1963
in- t '
JANIFEB.IMAR
?™8/» 2m 9 7l i i " i / l I APR. I M*y I j U N . I JUL. I AUSlSEP. I OCT I NOV. I OEC I JAN | FEB.'MAR . I APB .1 MAy IjUN . I JUL . I AUS I SEP. I OCT.I NOV. I DEC.
Fig. 33
DIAPTOMUS GRACILIS ADULTS AND COPEPODITES
STATION MA 1960 - 1363
1360
AN |FEB. I M A R . I A P R . I MAYIJUN. I JUL I AUGlSEP I OCT I NOV I OEC I JAN lFE6.iMAR.lAPR I M A y l j U N . I JUL . I AUG.ISEP.I OCT I NOV. I DEC
Fig. 34
- 54 -
DIAPTOMUS GRACILIS ADULTS AND COPEPOD1TES
DZPTU !mj/< ™ 1961 "
STATION MOB 1961-1962
1962
— - W
4f-i r~i—7
~v~i
1961
1 > I
.4^ ra ItEt _ j — A .
2m3/t 2 m g / »
1962
STATION MH 1961-1962
10'6*
JAN 1 K B . I MAR. I APR. ! MAY I jUN. I JUL . I AUC 1SEP I OCT. I NOV i DEC I JAN IFCB. !HAR. iAPP. I MAY ,JUN. I J U L . 1 AUSlfiEP. i OCT. I NOV I DEC
F i g . 35
- 55 -
SEASONAL VARIATION OF KERATELLA COCHLEARIS IN THE UPPER WATER LAYERS (0-5m) OF STATIONS MA AND MOB.
STATION MA 1962 1963
^ f f MACRACANTHA AND TYPICA
f. MICRACANTWA
f TECTA
STATION MOB 1962 1963
f f MACRACANTHA AND TVPICA
f MICRACANTHA
f TECTA
THE DIAMETER OF THE CYLINOER CORRESPONDS TO THE CUBE ROOT OF THE MEAN VALUE OF I N O S / l .
I JAN. I FEB I MAR. I APR I MAy I JUN I JUL T A U G I SEP T O C T I N O V T D E X I JAN I F E T T M A R T A P R I MAY I JUN I j U L I AUG I SEP I O C T . I N O V . I DEC.I
Fig . 36
- 56 -
SEASONAL DISTRIBUTION OF THE POLYARTHRA spp IN THE SURFACE
WATER LAYERS ( 0 - 1 m) OF STATION MA
STATION MA 1960
P OOLICHOPTERA
P VULGARIS
P REMATA
1963
P DOLICWOPTERA
P VULGARIS
P REMATA
THE DIAMETER OF THE CYLINDER CORRESPONDS TO THE CUBE ROOT OF THE MEAN VALLE OF INDS/L_
I JAN 1 FEB I MAR I APR I MAY I JUN 1 JUL I AUG ISEP I OCT I NOV I DEC i JAN FFEB I MAR 1 APR] MAY I JUN ! J U t ' I A U G T S E P T O C T P N O V F O E C 1
Fig. 37
SEASONAL DISTRIBUTION OF THE POLYARTHRA spp. IN THE SURFACE
WATER LAYERS ( 0 - 1 m ) OF STATION MOB.
STATION MOB 1960 196-!
P DOLICWOPTERA
P VULGARIS
p RE:MATA
P DOLICHOPTERA
P VULGARIS
P REMATA
THE DIAMETER OF THE CYL1N0ER CORRESPONDS TO THE CUBE ROOT OF THE MEAN VALUE OF 1NDS/L
JAN I FEB I MAR I APR I MAV T JUN I JUL I AUG i SEP I OCT I NOV I DEC ] J A N T F E B MAR ' APR MAV I JUN JUL ' AUG I SEP I OCT ! NOV1 D£<P
Fig. 38
- 57 -
Some seasonal forms of Daphnia cucullata from Lake Magelungen
March-May. I960 May. 1962 May. 1962 Juv. June.19&1 July-August and August. 1961 Male. August and September. 1961 September, 1961 September-November November - December October November
A A / W / I A A ^ A A A A May.1961 Junt. 1961 July. 1961 July. 1961 Juv, July. 1961 July 1962 July 1962 July-August Sep I ember. 1961 July. 1962 July. 1962 November, 1961 November. 1961
Dorsa l view
Fig. 39
Som« Oaphnia crista la from Station MA
Fig. 40
- 58 -
SEASONAL DISTRIBUTION OF THE CYCLOPS spp (AVERAGE
DISTRIBUTION FOR THE PERIOD 1 9 6 0 - 1 9 6 3 )
V///X EGSBEARINS FEMALES
• • ADULTS
< X z o
v//////;//////////////;//////////A
m^mmmtm
^ ^ ^ ^ ^ ^
1 CyCLOPS INSICNIS
2 CYCLOPS STRENUUS
3 MESOCYCLOPS LEUCKARTI
A MESOCyCLOPS OITWONOIOES
5 EUCyCLOPS SERRULATUS
1 CYCLOPS INS1&NIS
2 CYCLOPS STRENUUS
3 MESOCYCLOPS LEUCKARTI
4 ME50CYCLOPS O1TH0N0IDES
( & EUCYCLOPS SERRULATUSj
V///////////////X
gg^^^
1 CYCLOPS INSIGNIS
2 CYCLOPS STRENUUS
3 MESOCVCLOPS LEUCKARTI
k HESOCVCLOPS OITHONOIDES
(5 EUCYCLOPS SERRULATUS)
I JAN. | FEeT MAR I APRl MAY | JUN I JUL I AUG I SEP f OCT I NOV I DEC I
F i g . 41
- 59 -
Station MA 5 3
Total zooplankton volumes 10 JJ /I
10*C 6'C 6'C^
F i g . 42
«5 3 , Station MA Total zooplankton volumes IO'JJ'/I
6'CIO'C ^ ^ ^ ^ 10*C 6'C 6*C10"CL.
F i g . 43
- 60 -
m 1961 02 2mg/l 6 « c
Station MOB 5 , Total zooplankton volume 10 JJ / I
022mg/l 2 0 . c | 0 . c 6 . c | g 6 2 6 . c ,0-c
r 0 2 2mg/ l 022
J ' F ' M l _ A r " M " ' J *~S A "^ S ' 6 ' N ' D ~ F l ' F r~M~ ~1 A ' M ' J ^ J ' A ' S ' 0 ' N ' 0~
Fig . 44
Station MH „5 3 ,
Total zooplankton volumes 10 JJ / I
6°C I0°C ^ B B B ^ _ 10°C 6°C
Fig . .45
- 61 -
U
to — to
22
20
1962
Fig. 46
A
V
fn
1963 Total volume (average values)
V=106,w3/l 0-105m MA 0-12 5m MH 0- 4.5 m MOB
12-
/ \ 10 r-
: \ (
Jan I Feb I Mar. TApr. TMay I Jun I Jul. I Aug I Sep I Oct I Nov I Dec i Jan I Feb I Mar I Apr TMay"]
Fig. 47
LIST OF PUBLISHED AE-REPORTS
1—340 (See back cover earlier reports.)
341. Nonlinear dynamic model of power plants with single-phase coolant reactors. By H. Vollmer. 1968. 26 p. Sw. cr. 10:-.
342. Report on the personnel dosimetry at AB Atomenergi during 1967. By J. Carlsson and T. Wahlberg. 1968. 10 p. Sw. cr. 10:- .
343. Friction factors in rough rod bundles estimated from experiments in partially rough annuli - effects of dissimilarities in the shear stress and turbulence distributions. By B. Kjellstrom. 1968. 22 p. Sw. cr. 10:- .
344. A study of the resonance interaction effect between i 3 ,U and u , Pu in the lower energy region. By H. Haggblom. 1968. 48 p. Sw. cr. 10:- .
345. Application of the microwave discharge modification of the Wilzbach technique for the tritium labelling of some organics of biological interest. By T. Gosztonyi. 1968. 12 p. Sw. cr. 10:- .
346. A comparison between effective cross section calculations using the intermediate resonance approximation and more exact methods. By H. Haggblom. 1969. 64 p. Sw. cr. 10:-.
347. A parameter study of large fast reactor nuclear explosion accidents. By J. R. Wiesel. 1969. 34 p. Sw. cr. 10:- .
348. Computer program for inelastic neutron scattering by an anharmonic crystal. By L. Bohlin, I. Ebbsjo and T. Hogberg. 1969. 52 p. Sw. cr. 10:- .
349. On low energy levels in 1 "W. By S. G. Malmskog, M. Hojeberg and V. Berg. 1969. 18 p. Sw. cr. 10:- .
350. Formation of negative metal ions in a field-free plasma. By E. Larsson. 1969. 32 p. Sw. cr. 10:-.
351. A determination of the 2 200 m/s absorption cross section and resonance integral of arsenic by pile oscillator technique. By E. K. Sokolowski andR. Bladh. 1969. 14 p. Sw. cr. 10:- .
352. The decay of 1 "Os. By S. G. Malmskog and A. Backlin. 1969. 24 p. Sw. cr. 10:- .
353. Diffusion from a ground level point source experiment with thermolumine-scence dosimeters and Kr 85 as tracer substance. By Ch. Gyllander, S. Hollman and U. Widemo. 1969. 23 p. Sw. cr. 10:- .
354. Progress report, FFN, October 1, - September 30, 1968. By T. Wied-ling. 1969. 35 p. Sw. cr. 10:-.
355. Thermodynamic analysis of a supercritical mercury power cycle. By A. S. Roberts, Jr. 1969. 25 p. Sw. cr. 10:- .
356. On the theory of compensation in lithium drifted semiconductor detectors. By A. Lauber. 1969. 45 p. Sw. cr. 10:-.
357. Half-life measurements of levels in "As. By M. Hojeberg and S. G. Malmskog. 1969. 14 p. Sw. cr. 10:- .
358. A non-linear digital computer model requiring short computation time for studies concerning the hydrodynamics of the BWR. By F. Reisch and G. Vayssier. 1969. 38 p. Sw. cr. 10:- .
359. Vanadium beta emission detectors for reactor in-core neutron monitoring. By I. O. Andersson and B. Soderlund. 1969. 26 p. Sw. cr. 10: - .
360. Progress report 1968. Nuclear chemistry. 1969. 38 p. Sw. cr. 10: - .
361. A half-life measurement of the 343.4 keV level in <"Lu. By M. Hojeberg and S. G. Malmskog. 1969. 10 p. Sw. cr. 10:- .
362. The application of thermoluminescence dosimeters to studies of released activity distributions. By B-l. Ruden. 1969. 36 p. Sw. cr. 10:- .
363. Transition rates in '"Dy. By V. Berg and S. G. Malmskog. 1969. 32 p. Sw. cr. 10:- .
364. Control rod reactivity measurements in the Agesta reactor with the pulsed neutron method. By K. Bjoreus. 1969. 44 p. Sw. cr. 10:—.
365. On phonons in simple metals I I . Calculated dispersion curves in aluminium. By R. Johnson and A. Westin. 1969. 124 p. Sw. cr. 10:- .
366. Neutron elastic scattering cross sections. Experimental data and optical model cross section calculations. A compilation of neutron data from the Studsvik neutron physics laboratory. By B. Holmqvist and T. Wiedling. 1969. 212 p. Sw. cr. 10:- .
367. Gamma radiation from fission fragments. Experimental apparatus - mass spectrum resolution. By J. Higbie. 1969. 50 p. Sw. cr. 10: - .
368. Scandinavian radiation chemistry meeting, Studsvik and Stockholm, September 17-19, 1969. By H. Christensen. 1969. 34.p. Sw. cr. 10: - .
369. Report on the personnel dosimetry at AB Atomenergi during 1968. By J. Carlsson and T. Wahlberg. 1969. 10 p. Sw. cr. 10:- .
370. Absolute transition rates in 1 u lr . By S. G. Malmskog and V. Berg. 1969. 16 p. Sw. cr. 10: - .
371. Transition probabilities in the 1/2+ (631) Band in ' " U . By M. Hojeberg and S. G. Malmskog. 1969. 18 p. Sw. cr. 10:-.
372. E2 and M1 transition probabilities in odd mass Hg nuclei. By V. Berg, A. Backlin, B. Fogelberg and S. G. Malmskog. 1969. 19 p. Sw. cr. 10: - .
373. An experimental study of the accuracy of compensation in lithium drifted germanium detectors. By A. Lauber and B. Malmsten. 1969. 25 p. Sw. cr. 10:- .
374. Gamma radiation from fission fragments. By J. Higbie. 1969. 22 p. Sw. er. 10: - .
375. Fast neutron elastic and inelastic scattering of vanadium. By B. Holmqvist, S. G. Johansson, G. Lodin and T. Wiedling. 1969. 48 p. Sw. cr. 10:- .
376. Experimental and theoretical dynamic study of the Agesta nucler power station. By P. A. Bliselius, H. Vollmer and F. AkerhieTm. 1969. 39 p Sw. cr. 10:-.
377. Studies of Redox equilibria at elevated temperatures 1. The estimation of equilibrium constants and standard potentials for aqueous systems up to 374°C. By D. Lewis. 1969. 47 p. Sw. cr. 10:- .
378. The whole body monitor HUGO II at Studsvik. Design and operation. By L. Devell, I. Nilsson and L. Venner. 1970. 26 p. Sw. cr. 10: - .
279. ATOMSPHERIC DIFFUSION. Investigations at Studsvik and Agesta 1960-1963. By L-E. Hasggblom, Ch. Gyllander and U. Widemo. 1969. 91 p. Sw. cr. 10:- .
380. An expansion method to unfold proton recoil spectra. By J. Kockum. 1970. 20 p. Sw. cr. 10:-.
381. The 93.54 keV lever "Sr, and evidence for 3-neutron states above N=50 . By S. G. Malmskog and J. McDonald. 1970. 24 p. Sw. cr. 10: - .
382. The low energy level structure of 2"ir. By S. G. Malmskog, V. Berg, A. Backlin and G. Hedin. 1970. 24 p. Sw. cr. 10:- .
383. The drinking rate of fish in the Skagerack and the Baltic. By J. E. Larsson. 1970. 16 p. Sw. cr. 10: - .
384. Lattice dynamics of Nacl, KCI , RbCl and RbF. By G. Raunio and S. Ro-landson. 1970. 26 p. Sw. cr. 10:- .
385. A neutron elastic scattering study of chromium, iron and nickel in the energy region 1.77 to 2.76 MeV. By B. Holmqvist, S. G. Johansson, G. Lodin, M Salama and T. Wiedling. 1970. 26 p. Sw. cr. 10:- .
386. The decay of bound isobaric analogue states in "S i and 3 !Si using (d. ny) reactions. By L. Nilsson, A. Nilsson and I. Bergqvist. 1970. 34 p. Sw. cr. 10 - .
387. Transition probabilities in "»Os. By S. G. Malmskog, V. Berg and A. Backlin. 1970. 40 p. Sw. cr. 10:- .
388. Cross sections for high-energy gamma transition from MeV neutron capture in "sPb. By I. Bergqvist, B. Lundberg and L. Nilsson. 1970. 16 p. Sw. cr. 10:-.
389. High-speed, automatic radiochemical separations for activation analysis in the biological and medical research laboratory. By K. Samsahl. 1970. 18 p. Sw. cr. 10:- .
390. Use of fission product Ru-106 gamma activity as a method for estimating the relative number of fission events in U-235 and Pu-239 in low-enriched fuel elements. By R. S. Forsyth and W. H. Blackadder. 1970. 26 p. Sw. cr. 10:- .
391. Half-life measurements in " * l . By V. Berg and A. Hoglund. 1970. 16 p. Sw. cr. 10:-.
392. Measurement of the neutron spectra in FRO cores 5, 9 and PuB-5 using resonance sandwich detectors. By T. L. Andersson and M. N. Qazi. 1970. 30 p. Sw. cr. 10:- .
393. A gamma scanner using a Ge(Li) semi-conductor detector with the possibility of operation in anti-coincidence mode. By R. S. Forsyth and W. H. Blackadder. 1970. 22 p. Sw. cr. 10:- .
394. A study of the 190 keV transition in " 'La. By B. Berg, A. Hoglund and B. Fogelberg. 1970. 22 p. Sw. cr. 10: - .
395. Magnetoacoustic waves and instabilities in a Hall-effect-dominiated plasma. By S. Palmgren. 1970. 20 p. Sw. cr. 10:- .
396. A new boron analysis method. By J. Weitman, N. Daverhog and S. Farvol-den. 1970. 26 p. Sw. cr. 10:- .
397. Progress report 1969. Nuclear chemistry. 1970. 39 p. Sw. cr. 10:—.
398. Prompt gamma radiation from fragments in the thermal fission of 33SU. By H. Albinsson and L. Lindow. 1970. 48 p. Sw. cr. 10:- .
399. Analysis of pulsed source experiments performed in copper-reflected fast assemblies. By J. Kockum. 1970. 32 p. Sw. cr. 10:- .
400. Table of half-lives for excited nuclear levels. By S. G. Malmskog. 1970. 33 p. Sw. cr. 10:- .
401. Needle type solid state detectors for in vivo measurement of tracer activity. By A. Lauber, M. Wolgast. 1970. 43 p. Sw. cr. 10: - .
402. Application of pseudo-random signals to the Agesta nuclear power station. By P-A. Bliselius. 1970. 30 p. Sw. cr. 10:- .
403. Studies of redox equilibria at elevated temperatures 2. An automatic divided-function autoclave and cell with flowing liquid junction for electrochemical measurements on aqueous systems. By. K. Johnsson, D. Lewis and M. de Pourbaix. 1970. 38 p. Sw. cr. 10:-.
404. Reduction of noise in closed loop servo systems. By K. Nygaard. 1970. 23 p. Sw. cr. 10: - .
405. Spectral parameters in water-moderated lattices. A survey of experimental data with the aid of two-group formulae. By E. K. Sokolowski. 1970. 22 p. Sw. cr. 10:- .
406. The decay of optically thick helium plasmas, taking into account ionizing collisions between metastable atoms or molecules. By J. Stevefelt. 1970. 18 p. Sw. cr. 10:- .
407. Zooplankton from Lake Magelungen, Central Sweden 1960-63. By E. Alm-quist. 1970. 62 p. Sw. cr. 10:- .
List of published AES-reports (In Swedish)
1. Analysis by means of gamma spectrometry. By D. Brune. 1961. 10 p. Sw. cr. 6:—.
2. Irradiation changes and neutron atmosphere in reactor pressure vessels-some points of view. By M. Grounes. 1962. 33 p. Sw. cr. 6:- .
3. Study of the elongation limit in mild steel. By G. Ostberg and R. Atter-mo. 1963. 17 p. Sw. cr. 6:- .
4. Technical purchasing in the reactor field. By Erik Jonson. 1963. 64 p. Sw. cr. 8 : - .
5. Agesta nuclear power station. Summary of technical data, descriptions, etc. for the reactor. By B. LilliehSok. 1964. 336 p. Sw. cr. 15:- .
6. Atom Day 1965. Summary of lectures and discussions. By S. Sandstrom. 1966. 321 p. Sw. cr. 15:-.
7. Building materials containing radium considered from the radiation protection point of view. By Stig O. W. Bergstrom and Tor Wahlberg. 1967. 26 p. Sw. cr. 10:- .
Additional copies available from the Library of AB Atomenergi, Fack, S-611 01 Nykoping 1 , Sweden.
EOS-tryckerierna, Stockholm 1970
