ACTA PHYTOGEOGRAPHICA SUECICA
EDIDIT
SVENSKA V .lXTGEOGRAFISKA SA.LLSKAPET 37
PLANKTON
OF
FRESH AND BRACKISH WATERS
IN THE
- S()DERTALJE AREA
_ BY
MAJ-BRITT FLORI�
UPPSALA 1957
ALMQVIST &-WIKSELLS BOKTRYCKERI AB
S V EN S K A V A X T G E 0 G RAF I S K A SAL L S K APE· T
(SOCIETAS PHYTOGEOGRAPHICA SUECANA)
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ACTA PH.YTOGEOGRAPHICA SUECICA
37PLANKTON
OF
FRESH AND BRACKISH WATERS
IN THE
SODERTALJE AREA
BY
MAJ-BRITT FLORIN
UPPSALA 1957
Almqvist & Wiksells Boktryckeri AB
Flygjotografierna (planscherna 2, 3, 4A och 4B) aro publicerade med tillstdnd av Forsvarsstaben.
Kartorna (fig. 1 och plansch 1) aro publicerade med tillstand av Rikets allmanna kartverk.
Printed in Sweden
C ONTENT S
PREFACE • . • • . . • • . • • . . "'- . . • • • • • • • • • • • • • • • • • • • • • • • • • • • 5
The Sodertalje Area . Grouping of Lakes Methods . . .
I. Physical and Chemical Analyses 2. Biological Analyses .
Bedrock . . . .
I. Upland Lakes . . . Langa Acksjon (67 m) . Lilla Acksjon (59 m).
Fagelsjon (58 m) Barsjon (54 m) . Malmsjon (51 m) Concluding Notes
I. Lake Malaren (0.3 m) Sundsorsviken . Sodertalj evik en Snackviken . . .
INTRODUCTION
7 Notes on Post-glacial History.
7 Physical and Chemical Survey 9 Adjacent Areas . . . . . . 9 I. Sodertorn . . . . . .
9 2. The Katrineholm Area ll
INLAND LAKES
28 2. Lowland Lakes . 29 Miaren (28 m) . . 30 Masnaren (27.5 m) 33 Getasjon (26 m) 34 Tullan (20.5 m) . . 35 Lill-Turingen (5.9 m) 42 Djupviken (3.2 m)
Concluding Notes . .
MXLAREN-BALTIC FJARDS
2. The Baltic 68 Maren . . . . 72 Sodertalje Canal 76
12 19 24 24 27
44 44 46 53 54 60 66 66
80 85
PLANKTON CoMMUNITIES oF MXLAREN-BALTIC FJARDS
I. Diatoms . . . . General Remarks . . . . Malaren Diatoms in the Baltic Baltic Diatoms in Malaren Euryhaline Diatoms. . . . .
Diatoms restricted to the Baltic Concluding N ote.'l . . . . . . .
88 II. Other Phytoplankters . . . 96 88 Ill. Seasonal Distribution of the dominant Spe-
92 cies . . . . . 97
93 IV. Zooplankters I03
94 95 96
A cta Phytogeogr. Suec. 37
SUMMARY
TAXONOMICAL NOTES REFERENCES • • . •
Special Plankton Tables:
Malmsjon, p. 40; Masnaren, p. 51; Tullan, p. 58;
Lill-Turingen, p. 64; Sundsorsviken, p. 70; Soder- General Tables .
Acta Phytogeogt·. Suec. 37
118 . 121 . 139
taljeviken, p. 74; Snackviken, p. 78; Maren, p. 82;
Sodertalje Canal, p. 86.
. . · . . . . . . . . . . . . . . . . . . . . . . 104
A
LAKE is the landscape's m.ost beautij�ll and ex]JTes8ive featu1·e.l t is earth's eye; look'ing into which the beholde1· measu1·es the depth of his oun natw·e. 'Phe jlu�·iatile tr-ees next the sho1·e are the slende1· eyelashes which fringe it, and the wooded hills and cliffs a1'0und a1·e its overhanging bTows.
THOREAU
PREFACE
The present limnological investigation has been carried out in the eastern part of the province of Sodermanland in the watershed region between Lake Malaren and the Baltic. The town of Soder
talje is situated in the centre of the area investi
gated, therefore it has been called the "Sodertalje area".
A rift valley, the northern part of which is occu
pied by inlets of Lake Malaren and the southern by an inlet of the Baltic, divides the Sodertalje area into two parts. The investigation is mainly carried out west of Sodertalj e rift valley.
During the summers of 1947 and 1948, on the suggestion of Professor Sven Thunmark, plankton samples were collected in the Sodertalje area from three lakes (Malmsjon, Masnaren, and Lill-Tu
ringen) west of the rift valley, and from one lake (Tullan), located on the Sodertorn peninsula, east of the valley, further from three inlets of Lake Malaren, and from two inlets of the Baltic, adjacent to Sodertalje. The majority of the plankton ana
lyses were made in 1947 and 1948 in the labora
tories of the Limnological Institute of the Uni
versity of Lund, situated in Aneboda and Lund.
In connection with these investigations my thanks are due to Professor Sven Thunmark for working facilities, and for his valuable suggestions.
The plankton samples from 1947 and 1948 have been re-analysed at the Institute of Plant Ecology (Vaxtbiologiska Institutionen) of the University of Uppsala; in this instance, special attention has been paid to the desmids.
New samples were collected from six lakes during 1955 and 1956, and they have been examined at
Colour plate. Shore vegetation of Langa Acksjon, MaJmsjo plateau . •July 21, 1 956.
the same Institute. Finally the present paper has been prepared there for publication.
I wish to express my most sincere gratitude to Professor G. Einar Du Rietz who has read and criticized my manuscript, and put the resources of the Institute at my disposal.
My thanks are due to Dr. Einar Teiling for his great assistance in identifying desmids, his inesti
mable help and stimulating interest for this work, to Professor Astrid Cleve-Euler for inspirating dis
cussions on problems of diatoms, to Mr. Bruno Berzins for his identifications of Microzoa.
To my husband, Dr. Sten Florin, Head of the Institute of Quaternary Geology of the University of Uppsala, I am indebted for working facilities and good advice concerning quaternary problems.
Oxygen determinations for July 1947 were made by Prof. S. Thunmark. Specific conductivities and pH values (electrometric method) for July 1956 were determined by Dr. L. Karlgren, Uppsala. The specific conductivities, pH values ( electrometric method), contents of calcium and chloride, and alkalinity values for August 1956 were performed at the Analytical Laboratory of the University of Uppsala. All other analyses and determinations were made by the author, partly at the Laboratory of Stockholm Water-Works at Norsborg, partly at the Central Laboratory of Astra Ltd., partly in my home in Sodertalje.
The late Mr. Uno Laren, Chief Chemist at the Laboratory of Stockholm Water-Works at Nors
borg, has contributed to this paper a number of beautiful microphotographs, and also placed at my disposal working facilities during 1947 and 1948, for which, after his untimely death, I now render my sincerest thanks.
Furthermore, my thanks are due to Dr. Hakan Winberg for his extraordinary assistance during Acta Phytogebgr. Suec. 37
6 Preface field work, and.to Dr. Bertil Sjogren, of the Central Laboratory of Astra Ltd., Sodertalje, for working facilities during 1947 and.1948.
To my colleagues at the Vaxtbiologiska Institu
tionen, Bengt Pettersson, Nils Quennerstedt, Kuno Thomasson, and Mats W rern, and to Frank E. Round at the University of Bristol I extend my thanks for many helpful discussions on limnological prob
lems. In particular my special thanks are due to Kuno Thomasson whose extensive knowledge of planktic species has always been at my disposal and who has also given up much of his time in discussing this work with me. Mr. Thomasson kindly placed at my disposal plankton samples from a site of the Baltic S of Sodertalje, and sup
plied me with lists of plankton from a site in Malaren S of Uppsala, and from two lakes east of the Soder
talje area.
My sincere thanks are due to Professor Otto Zdansky, who revised a great part of the manu
script, and to Mr. John C. Richmond, who revised the remaining portions.
A cta Phytogeogr. Suec. 37
The final drawings of illustrations, diagrams and maps have been excellently carried out by Mrs.
Inga Thomasson.
The printing blocks used to illustrate this paper have been excellently prepared at the photo-engrav
ing works of Grohmann & Eichelberg, Stockholm.
Also, may I thank Mr. Per S. Fjrestad, head of Grohmann & Eichel berg, for his generosity in pre
senting me with the plates for the printing of the colour picture featured at the beginning of this book.
The Faculty of Science at the Royal University of Uppsala has rendered financial assistance for the field work during 1956. For the publication of this paper a grant has been received from the Swed
ish Natural Research Council. For the assistance I have enjoyed from both bodies I wish to express my sincerest thanks.
Vaxtbiologiska Institutionen, Royal University of Uppsala, April 4, 1957.
Maj-Britt Florin.
INT R ODUC T I ON
J 'The SoderUilje Area
GROUP I N G O F THE LA K E S The waters investigated are, as mentioned in the
Preface, situated in the neighbourhood of the town of Sodertalje (Lat. 59°12'0" N, Long. 17°37'50" E;
Fig. 1 ) .
The Sodertalje area we�:�twards borders upon a part within the Malaren region characterized by a climate rather .similar to that of western Oland, and represents one of the most arid parts of south
ern and Central Sweden. At the same time, the situation of the area between Lake Malaren and the Baltic accounts for the maritime character of its climate. The precipitation is less than 500 mm a year, mostly from July to October. The average temperature for. the coldest months, January and February, is between -2 and - 3°C, and for the warmest month, July, it is 16°C.
Studies of the local climate of the individual lakes would certainly have been of importance for this investigation. However, material has not been available. (For general data, see Atlas of Sweden, Nos. 25-26, Temperature; 29-30, Precipitation; and 3 1-32, Annual Precipitation and Temperature; fur
ther, Angstrom, 1932 . )
1 All heights are expressed i n metres above sea-level.
The lakes of the Sodertalje area have been grouped as follows:
( 1 ) The Inland lakes:
(a) Upland lakes, comprising Langa Acksjon (67 m),1 Lilla Acksjon (59 m), Fagelsjon (58 m), Barsjon (54 m), ·and Malmsjon (51 m);
(b) Lowland lakes, comprising Miaren (28 m), Masnaren (27.5 m), Getasjon (26 m), Tullan (20.5 m), Lill-Turingen (5.9 m), and Djup
viken (3.2 m);
(2) The Malaren-Baltic fjards, comprising (a) in Malaren: Sundsorsviken, Sodertalje
viken, and Snackviken (0-:-0.3 m);
(b) in the Baltic: Maren and Sodertalje Canal.
From E to W the maximum distance between the lakes examined by the author is 17 km, and from N to S 6 km,_ thus the rectangular Sodertalje area occupies only about 102 sq.km. Nevertheless, great contrasts are observed, both as regards vegeta
tion and the physical and chemical properties of the waters. Differences have also been noted between individual lakes, and also between these and Lake Malaren and the Baltic.
Acta Phytogeogr. Stwc. 37
FIG. I . The Sodertalje area and its surroundings. Parishes of Turinge, Ytterenhorna, and Sodertalje.
Waters investigated: Llmga Acksjon, 67 m, Lilla Acksjon, 59 m, Fagelsjon, 58 m, Barsjon, 54 m, Malmsjon, 51 m, Miaren, 28 m, Masnaren, 27.5 m, Getasjon, 26 m, Tullan, 20.5 m, Lill-Turingen, 5.9 m, Djupviken, 3.2 m (the lake east of Sundsorsviken). Lake Malaren, 0-0.3 m (Sundsorsviken, Sodertaljeviken, and Snackviken), and the Baltic (Maren and Sodertalje Canal). Watershed between Lake Malaren and the Baltic indicated by short dashes.
Acta Phytogeogr. Suec. 37
PLATE 1
Land-forms of the Sodertalje area and its surroundings.
Raised parts of the bedrock blocks shaded. Lakes in solid black. Shore-line of the Limnaea Sea (middle
neolithic period, about 1 600-1 800 B.o.) at 23-24 m above present sea level. Brackish bays and inlets horisontally striated. Eskers with heavy diagonal striation.
The raised bedrock blocks, e.g. the Malmsj6 block, are bounded by faultlines in east-west and north-west
south-eastern direction. The most impressive precipices are formed by the north-western edges of the blocks.
The rift valley west of Malmsj6 plateau is filled up by a large inlet of the Limnaea Sea. Today it is occupied by the twin lakes Turingen and Lill-Turingen (5.9 m). The rift valley east of Malmsj6 plateau is filled up by the brackish water of the Limnaea Sea. Due to isostatic rise this waterway was closed about 500 B.O., and Malaren was formed. Today an excavated canal through the Sodertalje esker interconnects the Baltic with Lake Malaren.
The Sodertalje esker continues northwards and divides the Malmsj6 plateau into two parts. The lakes investigated of this plateau are situated west of the esker. (After S. Florin, 19,43.)
Acta Phytogeogr. Suec. 37
::::..
("";
IS �
�
c� C1l
� c
;'!
V.<
r:::
C1l � c.s '<
Upland lakes of Malmsjo plateau; air photograph. To the east of Malmsjon is the Sodertalje esker on which the road is running since old days. Boggy areas are distinguished by greyish tint in the picture. No cultivated soil occurs on the Malmsj 6 plateau.
Shallow lowland lake Masnaren, air photograph of its northern part. Note the great amount of cultivated fields around the lake-i.e. the Masnaren plain composed of clayey deposits.
Acta Phytogeogr. Sllec. 37
PLATE 3
PLATE 4
A
Lowland lakes Tullan and Getasjon, air photograph.
The character of the lakes as tectonically determined is clearly visible. Very little cultivated soil adjacent to the lakes which are mostly surrounded by morainic areas covered by pine forest.
Acta Phytogeogr. s�wc. 37
B
Lowland lakes Lill-Turingen, Djupviken, and Sundsorsviken, air photograph. Rift valley lakes. West of Lill-Turingen are clayey deposits whilst east of the lake rises Malmsjo plateau.
PLATE
5Langa Acksjon, 67 m. Small and shallow upland lake with brown water. View from the eastern shore facing north. In the lake a sparse growth of Sci1·pus lacustris, Equisetum fluviatile, and Nymphaea cf. candida. On the edge of the mire, bordering the northern shore, are low shrubs of Nlyrica gale and Ledum palustre. In the background pine forest, intermingled with birch, growing on the bog which also bears shrubs of Ledum palustre intermingled with Rubus chamaemorus. -,July 21, 1 9 56.
Acta Phytogeogr. Suec. 37
PLATE 6
Upland lake Lilla Acksjon, 59 m. Rather large tuft of Clad?·um mariscus in a sheltered bay in the southern part of the lake. The bottom layer is lake dy. - July 21, 1956.
Acta Phytogeogr. Suec. 37
PLATE 7
Lilla Acksjon, 59 m. Small and shallow upland lake with clear and slightly yellow water. At the edge of the ice-polished rock a few specimens of Cladium mariscus. Besides, there is a belt of Myrica gale along the shore. On the muddy bottom outside the rock Lobelia dortmanna. -July 21, 1956.
Acta Phytogeogr. S11e0. 37
PLATE 8
Malmsjon, 51 m. Among the upland lakes, Malmsjon is the largest. Maximum depth of water 6 m. View towards the eastern sandy beach and the gradual slope of the Sodertalje esker which dams up the lake in the east. Here the esker is covered by a tall-grown pine forest. The sandy bottom of the lake adjacent to the shore line is covered by compact swards of Litorella uniflom.-Sept. 16, 1955.
Acta l'hytogeogr. Suec. 37
PLATE 9
Malmsjon, 51 m. \Vater level very low during Sept., 1955.
The eastern shore is partly composed of gravel and rubble-stones bearing shrubs of Alnus glutinosa. Emerging from the lake are flower-stalks of Lobelia dortmanna, growing on the muddy bottom further offshore. No dense reedswamps of Phmgmites communis occur in this lake.- Sept. 16, 1955.
Acta Phytogeogr. Suec. 3'1
PLATE 10
Upland lake Malmsjon, 51 m. Along the shora, apart from the region of sandy beaches, a belt of J.11.y'rica gale is growing. Here and there ice-polished rocks occur. No dense reedswamps occur in this lake.- Sept.
16, 1955.
Acta Phytogeogr. Suec. 37
PLATE 11
Masnaren, 27.5 m. Shallow lowland lake of the clay plain. Facing the south-eastern shore. The lake is practi
cally fringed by dense reedswamps composed of Phragmites communis, Typha a ngustifolia , and Scirpus lacustris.
Outside the reedswamps grow abundant Nympha ea cf. ca ndida and Pota mogeton na ta ns.-Oct. 7, 1955.
Acta Phytogeogr. S'Uec. 37
PLATE 12
Lake Tullan, 20.5 m. R.ift valley lake. Facing north. In the background a field sloping towards the lake.
To the right ice-polished rock abruptly descending to great depth in the lake (according to fishermen isolated
<.leptbs of 60 m are known from Tullan). Outside the rock a pure growth of Typha a ngustifolia. Near this growth
.a sparse population of Lobelia dortma nna was noted. - Sept. 16, 1 955.
Acta Pltytogeogr. Suec. 37
PLATE
13Lowland lake Tullan. R.ift valley lake. Facing a rocky part of the north-eastern shore. Typha ang'Ustifolia to the left. The shore forest is here composed of Pin'Us silvestr'is, Aln'Us gl'Utinosa, and J'Uniper'Us comm'Unis •.
The water level very low.-Sept. 16, 1955.
Acta Phytogeogr. Suec. 37
PLATE 14
Lowland lake Tullan. Facing north. Pure growth of Typha angu stifolia.- Sept. 16, 1955.
Acta Phytogeogr. Suec. 37
PLATE 15
Lake Tullan. Rift valley lake. The northern inlet. Facing the northern shore which is composed of a steeply rising bedrock block covered by moraine. Pine forest intermingled with birch grows on the morainic soil, and near the shore is A lnus gluti,nosa. The pictured part of Tullan leads to the outflow, and is rather shallow. Only in such shallow parts of the lake exist dense reedswamps of Phragmites communis, Scirpus lacustris, Typha an
gustijolia, and T. atifo lia.-Sept. 1 6, 1 955.
Acta Phytogeogr. S1wc. 37
� c:,
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'-'=l �
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:::::
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-..---.:-� �
" . ,,��l!
,.-:·J�::-
·-, �=:=·· , ,_ .. ;;c�·-".;� � � ; � 1
L;:
. ·;�-�- �
Lake Lill-Turingen, 5. 9 m. Rift valley lake. Facing south towards the narrow channel to Lake Turingen, leading through dense reedswamps composed of Phragmites communis, Scir·pus lacustris, and Typha angustijolia. To the left and right of the channel are shrubs of Salix, Alnus gluti
nosa, and Pinus silvestris, growing on the deposits of alluvial sediments. In the background rises the Malmsj6 plateau to altitudes of about 70-90 m.
-Sept. 16, 1955.
�
>-8 i::'j
i-'
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9
METH O D S
1. Physical and Chemical Analyses Water samples were collected between 0 and 0.5 m water depth on Aug. 4, and Sept. 27, 1947, and on June 3, July 7, Aug.
22,
and Sept. 1 8, 1948.One-litre glass-bottles with cork stoppers were used.
Samples were also collected on July
21
(Lilla Acksjon and Langa Acksjon), Aug.
23
(Lilla Acksjon, Langa Acksjon, Fagelsjon, Barsjon, and Malmsjon), and Aug. 24 (Miaren, Djupviken, and Getasjon) in 1956, when polythene bottles were used. Samples for oxygen determination were collected in bottles with ground glass stoppers. The physical and chemical investigations comprise the following: tempe
rature, transparency, colour, pH values, specific conductivity (u18 x 106), KMn04 consumption, cal
cium, total hardness, dissolved oxygen saturation per cent, total alkalinity, chlorides, and silicon dioxide.
·CoLOUR. The colour of the water was determined on unfiltered samples by the platinum-cobalt stan
dard method (see Ohlmiiller-Spitta, 1931, p. 7 ) . The colour of the water was also estimated i n field as observed against a Secchi disk and recorded as e.g. yellow, green, etc.
pH. For determination of the hydrogen ion con
centration a Hellige comparator was used, with the following indicators: brom-thY:'mol blue (pH range 6.0-7 .6), and phenol red (pH range 6.8-8 .4).
SPECIFIC CONDUCTIVITY was measured at the Central Laboratory of Astra Ltd., ·using a "Philo
scop GM 4140" with an oscillator GM 4260 and a measuring cell GM 4221. The conductivity is ex
pressed in reciprocal ohms at l8°C (u18 x 106) . KMn04 CONSUMPTION. Unfiltered samples were used after thorough shaking. According to the method employed·, 10 ml 0.1 N potassium perman
ganate solution and l ml concentrated sulphuric acid were added to lOO ml sample. After exactly 10 minutes' ·gentle boiling 10 ml 0.1 N sodium
1 The samples collected in 1 94 7 were also examined for ammonia, iron, and hydrogen sulphide content. As the results were practically negative further search was dis
continued. Unfortunately no analyses were made of soluble phosphorus content of the water.
thiosulphate solution was added. Finally, titration was carried out with the 0.1 N standard perman
ganate solution. KMn04 consumption is expressed in mg of KMn04 per litre.
ToTAL HARDNESS was measured by titration with a palmitate solution (cf. "Anvisningar", 1942) . The results are given in mg of Ca per litre. To convert to German degrees ( dH) multiply by the factor 0.14.
DISSOLVED OXYGEN. For the determination of dissolved oxygen the Winkler method was em
ployed, modified with the bromine treatment ad rnodum Alsterberg. The result is expressed in mg of 02 per litre.
ToTAL .ALKALINITY was measured by titration with 0.2 N hydrochloric acid and with brom-cresol green as indicator. The result is expressed in ml of 1 N HCl per litre.
CHLORIDES. The chloride content was determined with silver nitrate using potassium chromate as indicator. The result is expressed in mg of Cl ion per litre.
SILICON DIOXIDE was determined by titration with potassium chromate solution as indicator. l g ammonium molybdate and 5 ml 10% HCl were added to a lOO ml water sample. The result is expressed in mg of Si02 per litre.l
2. Biological Analyses
The vascular plants have been only superficially examined. Investigations were restricted principally to the shore vegetation and to the aquatic vegeta
tion, the latter being zoned according to the scheme given by Raunkirer ( 1 907) and Du Rietz ( 1 92 1 ).
Taxonomy and nomenclature ace. Hylander (1955).
The main object has been to study the composi
tion of the plankton communities, The material for the plankton investigation was collected once every month between May and September in 1947 and 1948, and at some occasions in 1955 and 1956.
A plankton net of Miiller gauze No. 25 was used.
Thus, this material does not include the nanno
plankton. One part of each sample was fixed in the A cta Phytogeogr. S�tec. 37
1 0 Methods field with formalin. A preliminary examination was then carried out in the laboratory. Living and dead organisms were carefully distinguished.
Attempts were made to identify the diatoms without embedding them in a mounting medium.
As this proved to be impossible with small diatoms, the following treatment was tried: a few drops of the sample were dried on the cover glass at room temperature, and mounted in Hyrax (R.I. 1.65).
This method permitted satisfactory preservation of the chromatophores, and dead taxa (abioseston), could still be distinguished. The diatoms were then investigated under higher magnification (oil im
mersion
1ft6
ap. 1.32, ocular x 10) . However, this method is only applicable to plankton, since benthos samples require treatment with 30 % hydrogen peroxide in order to remove organic material. More
over, with planktic diatoms it is necessary to incin
erate organic material, and then to boil a few drops of xylol on the cover glass in order to expel air bubbles which would probably prevent the Hyrax from permeating the diatoms. Several tycho
planktic species were found amongst the euplanktic species.
A short description of the different plankton communities is given in the following pages, whilst their composition appears in the special Tables and Tables 34--35 provide a more detailed analysis of all the plankton communities found in the region.
The plants which are recorded in Table 34 but not in special Tables have been observed for the first time in 1955 and 1956.
For biocoenotic purposes (see Thunmark, 1945b;
Nygaard , 1949; Lillieroth, 1950; A. Lundh, 1951;
and K. Thomasson, 1953) these qualitative lists must, however, be supplemented with quantitative data. Consequently, I have tried to distinguish between dominant species, subdominant species, and other constituents, both in plant and animal communities. As a criterion for dominant and sub
dominant species, relative volumes have been used, determined by estimation at lOO x magnification, according to the method proposed by Thunmark (1945b, pp. 16-26). Nygaard has already pointed out (1949) that the reliability of the method is only approximate and very dependent on the personal factor. It can hardly give completely satisfactory A cta Phytogeogr. Suec. 37
results, especially when an organism is too small in volume to make up a dominant part of the plankton community, but, nevertheless, has a very high recurrence frequency, and thus is, numerically, the most characteristic feature. Unfortunately fre
quency counting (M.-B. Florin, 1944 and 1946) has not been resorted to in the present investigation.
Using approximate quantitative analyses the plankton communities have been named after the dominant plant and animal. These denominations, therefore, giye a short characterization of the com
munity. For example, the community found in Malmsjon on Sept. 21, 1947, has been designated the " Tabellaria flocculosa v. asterionelloides - Eudiap
tomus graciloides community". Nevertheless, the results of the qualitative analyses should also be shown, and, in accordance with Thunmark's sugges
tions (1945a, pp. 51-42, and 1945b, p. 104), the communities have also been defined by reference to the number of species of Ohlorococcales and des
mids, both of which are ecologically important. The differences between oligotrophic and eutrophic lakes are thus defined by Thunmark as a qualitative variation in composition of the plankton (cf. also Lillieroth, 1950, p. 35).
When the expressions "very poor in desmids" or
"moderately rich in Ohlorococcales", etc., are used, it should be remembered that definite numbers are referred to, as given below (Thunmark 1945 ) :
Extremely rich in species Very rich in species . . . Moderately rich in species Moderately poor in species . Very poor in species . Without species . . . . . .
Number of species
>25 1 6-25 1 1-15 6-10 1-5 0
The previously mentioned plankton community, collected in Malmsjon on Sept. 21, 1947, would thus be classified "Tabellaria flocculosa v. asterionel
loides- Eudiaptomus graciloides community-very poor in Ohlorococcales, very rich in desmids". Ex
pressed in this way, the designation of the com
munity, according to Thunmark, serves to throw light on important ecological features.
The presence of a required number of taxa within
Bedrock 1 1 either Chlorococcales or desmids, i.e. a minimum of
15, is a prerequisite for the calculation of the ratio of Chlorococcales to desmids, and for the construc
tion of a quantitative ecological characterization.
Thunmark ( 1 945 b, pp. 55-64, and Table I) defines this as the Chlorococcal-Desmidial Quotient (Ch/D Q), and Nygaard (1949, pp. 7-9) as the chloro
phycean quotient.
In his paper of 1 949, N ygaard has proposed the Compound Index, i.e. the ratio of Myxophyceae +
Chlorococcales + Centrales to Desmidieae for the char
acterization of a phytoplankton community, the first group being of a eutrophic, the second group -of an oligotrophic character (see also Nygaard,
1 955).
It is, however, difficult to construct the quo
tients, because the systematical position of many varieties and formro described is not definitely worked out, e.g. in Pediastrum and Scenedesmus.
Moreover, the ecological valence of these numerous taxa is practically unknown, as well as their im
portance in calculating the quotient. The separa-
tion between euplanktic and tychoplanktic species is also sometimes a rather difficult problem.
In the present paper the author has adhered to the concept of plankton communities according to Thunmark ( 1945 b), but is, however, inclined to suspect that the communities defined by Thunmark only represent seasonal aspects of one single com
munity.
Concerning the terms oligotrophy and eutrophy the author adheres to Foogri ( 1954), and Findenegg ( 1955).
On account of the inadequate series of physical, chemical, and biological analyses, the present in
vestigation of the plankton of fresh and brackish water in the eastern part of Sodermanland is in
complete. Nevertheless, this material may be of some value as a supplement to limnological in
vestigations from other parts of Sweden which have been published since 1949, e.g. S. Lillieroth, 1 950; A.
Almestrand & Asta Lundh, 195 1 ; Asta Lundh, 1951;
S. Thunmark, 1952, K. Thomasson, 1949 and 1953;
E. Teiling, 1 955; and N. Quennerstedt, 1955.
B E D R O C K The bedrock of the Soderta1je area is composed
mainly of Archaean rock, chiefly "Sormland gneiss"
(Tornebohm, 1862, Lindstrom, 1898, Magnusson, Granlund and Lundqvist, 1 957).
The bedrock surface is characterized by fissures, which cross the rock floor in varying directions, although very old NW -SE fracture lines, formed during the Algonkian Age, and mainly younger E-W thrust lines, predominate.
These fissures divide the bedrock into a mosaic structure of small-scale blocks, dislocated in hori
zontal and vertical direction to a varying extent.
The edges of the northern parts of the blocks often form impressive precipices.
One of the small-scale blocks is the Malmsjo block (Fig. 2 and Pl. 1 }. On its northern raised part, from now on termed the Malmsjo plateau, there are five shallow lakes at fairly high altitudes: Langa Acksjon, Lilla Acksjon, Fagelsjon, Barsjon, and Malmsjon (at altitudes from 67 to 5 1 m). On its gradua�ly sloping, southern part, here called the Masnaren plain, the
lakes MiaTen and Masnaren are located, 28 and 27.5 m respectively. The plateau is bounded in the east and west by rift valleys of the above men
tioned NW -SE direction. During the Ice Age the glaciers by their flowing southwards eroded and excavated these rift valleys of which the east one now is occupied by inlets of Lake Malaren (0.3 m);
the west one contains the twin lakes Turingen and Lill-Turingen. (5.9 m). Upon the plateau the Soder
talje esker runs, forming the eastern shore of Malm
sjon.
The dynamic genesis of the detailed topography of eastern Sodermanland is still not quite clear, but valuable contributions have been made to this problem by G. Andersson ( 1 903), S . De Geer ( 1910), Asklund ( 1 923), G. De Geer (1932), Wiman ( 1 935), and Ebba Hult De Geer ( 1 948). The Sodertorn peninsula has well-preserved fissure lines, and is described by G. De Geer ( 1 932) as a horst-like rock mass. There are certain morphological simi
larities between the Sodertorn peninsula and the A cta Phytogeog1·. Su.ec. 37
1 2 Post-glacial History w
FIG. 2. Schematic section through the raised Malmsjo plateau and the bordering rift valleys. From W to E ea. 12 km.
bedrock blocks of the Sodertalje area W of the Sodertalje rift valley.
Analysing the morphology of the Stockholm re
gion, Ebba De Geer points out (op. cit. , p. 390)
' ' . . . the simple but peculiar land-forms that a flat rock-floor may assume when burst asunder and split up into a true bedrock mo�aic by sharp j oints. It is really like a ragged mosaic floor, with the single plates displaced from their original coherent position and
their common, even level, whereby, as they are seldom quite horizontal, each flat plate must slope in one direction or another, and each of them thus be a monocline. Our bedrock surface is thus, as well known, a mixture of very old and rather young features: On the one hand the horizontal roof of the ancient baselevel plane in a more or less well-preser
ved state, on the other hand, it is intersected by ver
tical cuts of joint series and fault lines of the very youngest character. This is repeated in minute detail in local blocks and in greater areas as 11 whole. "
N O T E S O N T H E P O S T - G L A C I A L H I S T O R Y After the recession of the last ice-sheet eastern
Central Sweden (Fig. 1 0) was at the bottom of the Late-glacial Sea, the level of which was about 150 m above present sea level. The ice-eroded rock floor lay covered by moraine and glacial clay.
Due to isostatic rise, the highest parts of eastern Central Sweden emerged towards Littorina period, and formed an archipelago of the Littorina Sea.
The nearest mainland shore was found in western Sodermanland and in the nearby province of Narke.
From this time onwards wave action affects the shore- belt, and it must be remembered that every part of the present land surface has been influenced by this process in its two facies: erosion and accum
ulation. The surf removed the glacial clay and the transportable parts of the moraine and esker gravel, and deposited it on the still submerged areas, e.g. in the rift valleys. The eskers, formerly steep
A cta Phytogeog1·. Suec. 37
and high, were levelled down to the present soft hills.
Due to this continuous action the Malmsjo plat
eau at the present time consists of naked ice
eroded and ice-polished rocks and outwashed mor
aine, poor in nutrient substances, whilst adjacent to the Sodertalje esker are sandy areas. Only in shallow basins are there thin layers of primitive moraine and wa;rved clay under the lake sediments.
The lower lying land, e.g. the Masnaren plain, is to a large extent covered by clayey strata which are partly the results of the abrasion of the Malmsjo plateau and overlie the autochtonous moraine and glacial clay. Through these strata there emerge numerous small rocks and moraine hillocks.
In connection with studies on Post-glacial changes of level in Central Sweden, and in order to elucidate the vegetational history of this region in relation to
8.C. - 8000 c �
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Post-glacial History 13
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Fw. 3. Diagram illustrating the coast displacement in Narke and Sodermanland, in late Quaternary time, showing likewise the altitudes of the examined lakes at the time for their isolation from the Baltic basin.
Schematic diagram. The graph illustrates the displacement of a point on the coast-line as the result of the changes of level between Late-glacial and modern time. The examined locations have been placed at the graph according to the height of their overflow threshold. The position along the abscissa indicates the time for the origin of the lakes in relation to the different stages of the Baltic. The indicated main levels have been obtained by joining the highest levels recorded during the different oscillations of the coast (the Yoldia- (Preboreal), Ancylus-, Mastogloia-, and the complex Littorina
transgressions, etc.). No account has been taken to the possible minimum levels of the shore. The interrupted line represents the complex Littorina transgression with at least three different peaks (LI, LII, and LIII). Scale of time approximate.
Coast displacement according to S. Florin ( 1 944 and 1950). Baltic stages according to Munthe ( 1 940) and others. Pollen zones according to Jessen (1935).
the development of the Baltic Sea, S. Florin and the author have collected series of samples for pollen and diatom analyses from ancient lake sediments of Fagelsjon, Barsjon, Malmsjon, and Lill-Turingen.
Raised beaches have been levelled, and put in re
lation with different stages of the Baltic. Ancylus Lake lagoons and Littorina Sea lagoons have been discovered, and dated by means of diatom and pol
len analyses. The below records concerning these investigations may be of some importance for the elucidation of the conditions of this area.
Langa Acksjon
At the level of the overflow threshold of Langa Acksjon (67 m), of Malmsjo plateau, a distinct ancient raised beach is situated. This was formed during a slightly brackish transition stage of the
Baltic between the Ancylus and the Littorina pe
riods, the Mastogloia Sea, about 5500 B .C. (Fig. 4).
This raised beach, about 10 m above the Littorina level, has been observed in many places all over the eastern part of S Central Sweden (E. Nilsson, 1926, G. De Geer, 1932, S. Florin, l 944).
The highest shore-line of the Littorina Sea in the Sodertalje area, (M.-B. and S. Florin, 1940; S. Flo
rin, 1943, p. 397 ff. , Fig. 3) is situated at about 56 m and below this level which was maintained for a long period, thick sedimentary deposits were spread over wide surfaces.
Fagelsjon
Fagelsjon, of Malmsjo plateau, with the overflow threshold at 58 m, is situated slightly above the highest raised beach of the Littorina Sea (L I), Acta Phytogeogr. Suec. 37
14 Post-glacial History
Fagelsjon C M
225 250
300
350
·
· · · L acusfrine gy ff)a con taining NymphceaFresh-wafer sedimenls
JZll
JZI
FIG. 4. Fagelsjon, parish of Turinge, Sodermanland . Alti
tude 58 m. Highest level of the Littorina Sea at 56 m. No influence of brackish water from the Littorina Sea in this basin.
Stratigraphical survey carried out on Aug. 10, 1939.
Pollen and diatom analyses unpublished. On the right pollen zones mainly according to Jessen ( 1 935).
In Jessen's zone system for Danish pollendiagrams zone V corresponds to the Boreal period (about 6000 to 7000 B.C.), zone VI corresponds to the early Atlantic period (about 4500 to 6000 B.C.) , zone VII to the Atlantic period (about 2300 to 4500 B.C.), zone VIII to the Sub
boreal period (about 2300 to 500 B.C.), and zone IX to the Sub-atlantic period (500 B.C. to recent time). In the dia
grams of the present paper the zone limit VI/VII has been put at the rational border for Tilia, and the zone limit VII/VIII at the decline of Ulmus. For symbols see Fig. 7.
and has, consequently, never been a part of this sea.
A series of samples from the deeper sediments of the ancient Fagelsjo were collected from the quag
mire at the north-eastern part of the lake by S.
Florin and the author on Aug. 10, 1939. A Hiller core sampler was used. The stratigraphy was as follows (Fig. 4) :
The top layers consist of peat downwards grad
ing into:
Acta Phytogeogr. Suec. 37
225-356 cm Gyttja, at first yellow-brown, below green
ish, about 325 cm, and below, olive-green, and of algal mud type.
357-362 cm Clay-gyttja, sandy.
363-364 cm Gyttja-clay, grey-white, without sand.
365-375 cm Coars� sand, clayey, grey, rich in glimmer.
380 cm Drill on stone.
A pollen diagram from Fagelsjon (unpublished) shows a level of discontinuity at the beginning of the Littorina time (i.e. when the continuous Tilia curve begins at about 365 cm) , and lacustrine con
ditions in that part of the diagram which corres
ponds to the Littorina maximum. The fossil diatom flora at 360 cm and 375 cm consists of oligohalobic indifferent fresh-water species :
Achnanthes lanceolata, A . lanceolata v. elliptica, A . lanceolata v . heterovalvata, A . Ostrupii, Amphora ova
lis v. libyca, A . ovalis v. pediculus, Galoneis silicula, Oyclotella comta, Oymbella sinuata, Diploneis ovalis, Epithemia Muelleri, E. sorex, E. zebra, Eunotia sp.,1 Fragilaria brevistriata, F. construens, F. pinnata, Gomphonema sp., Melosira ambigua, Navicula crucicula v. minor, N. Jentzschii, N. Jarnefelti, N.
oblonga, N. pupula v. rectangularis, N. pseudoscuti
formis, Neidium iridis, Nitzschia denticula, Ope
phora Martyi, Rhopalodia gibba, Stauroneis sp., Synedra ulna, and Tabellaria sp.
Oymbella sinuata, Navicula Jentzschii, and Ope
phora Martyi belong to the so-called Ancylus forms (se also p. 15). Their occurrence in the investigated sedi:r;nents of Fagelsjon was unimportant.
The origin of Fagelsjon a.nd its oldest inland-lake sediments date from pre-Littorina time, i.e. about 5000 B.C. Even the sand layer at the bottom of the strata belongs to the lake stage.
Barsjon
Diatom communities noted in the gyttja dep�sits from Barsjon (54 m), of Malmsjo plateau, and de
scribed below, indicate that the Littorina Sea at its highest level extended as a shallow bay into the basin of this lake which formed a rather secluded lagoon.
A series of samples for pollen and diatom anal
yses was collected from the western mire by S . Florin and the author o n Aug. 9 , 1939. A Hiller core sampler was used.
1 Some species of Eunotia are halophobic.
Post-glacial History 1 5
Barsjon
CM o•t.
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350
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400
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550 L L L I l l L
0 0
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. .
FIG. 5. Barsjon, parish of Turinge, Sodermanland. Altitude 54 m. Highest level of the Littorina Sea at 56 m. A slight influence of brackish water from the maximum stage of the Littorina Sea at about 465 cm in the diagram (Clypeus
lagoon).
Stratigraphical survey carried out on Aug. 9, 1939.
Pollen-analytical investigation unpublished. Diatom-ana
lytical investigation by M.-B. Florin. Pollen zones mainly according to Jessen ( 1 935) on the right (cf. Fig. 4). For symbols see Fig. 7.
1 Diatoms characteristic of the Ancylus Lake are mostly rather demanding species and ecologically of a different nature than the halophobic diatom flora of the upland lakes of recent days. The same difference in the composition of the diatom flora has been clearly shown in the sediments · of some ancient lakes of Kilsbergen highlands. The bottom flora is there of halophobic char
acter, and the overlaying strata contain a mixture of halophilous, mesohalobic, and freshwater diatoms of An
cylus Lake type, indicating the Pre-boreal transgression in that region (M.-B. Florin, 1944).
The stratigraphy was as follows (Fig. 5):
The top layers consist of peat grading below into : 325-459 cm Yellow-brown coarse gyttja, fartherst down
lighter and more grey -green.
460-469 cm Light olive-green fine detritus gyttja, in
termixed with a small amount of fine sand.
470--479 cm Brown-green gyttja, with increasing macro
scopic organic remains and decrease of sand.
480-484 cm Light olive-green fine detritus gyttja, inter- mixed with a small amount of fine sand.
485-504 cm Light olive-green fine detritus gyttja.
505-509 cm Clay gyttja.
510-527 cm Coarse sand.
528-539 cm Grey-white clay, of a buttery consistency.
540-555 cm Warved clay, with alternating grey-blue and grey-pink warves of one cm thickness.
In the deepest part of the core from Barsj on was thus noted about 15 cm of warved clay, covered by 1 1 cm of grey-white clay of buttery consistence . Diatoms between 510-515 cm.-The coarser sand located between 510-527 cm, has been washed down from the first islands rising from the Ancy
Ius Lake. The diatom flora at 515 cm is more or less characteristic of the later shallower stage of the Ancylus Lake:I
Amphora ovalis, Oocconeis disculus, Diploneis domb
littensis v. subconstricta, D. Mauleri, Epithemia Hyndmanni, Gyrosigma attenuatum, G. Kuetzingii, Mastogloia Smithii v. lacustris, Melosira arenaria, M. islandica, M. islandica subsp. helvetica, Navicula fennoscandica, N. Jentzschii, N. scutelloides, Ope
phora Martyi, and Stephanodiscus astraea, forming together 4 4 % of the total of the diatoms.
Of the remaining 56 % Amphora oval is v. pediculus, Oocconeis cf. diminuta, form 24% of the total of the diatoms. If occurring in great quantities the two latter have been characterized by the author as typical of very shallow bays of the Ancylus Lake,
"Ancylus lagoon" (cf. in S. Florin, 1948, Fig. 44, p. 98). The remaining 32 % are oligohalobic indif
ferent fresh-water diatoms and halophilous types.
These two groups have not been separated in the diagram .
Diatoms between 485-495 cm. -In the gyttja at 485 and 495 cm slightly brackish-water diatoms from pre-Littorina time were noted, such as Oocco
neis pediculus, Mastogloia elliptica, M. Smithii, Navicula crucicula v. minor, Rhoicosphenia curvata, artd Synedra tabulata, forming 2 % of the total of A cta Phytogeogr. Suec. 37
