A N N A L E S H I S T O R I C O - N A T U R A L E S M U S E I N A T I O N A L E S H U N G A R I C I Tomus 6 6 . Budapest 1 9 7 4 .

Filamentous Algae in Városligeti-tó, Budapest

B y L . H A J D Ú , Budapest

Abstract — From the Városligeti-tó (Budapest) five filamentous algal species were identified of wich Spirogyra crassoidea T R A N S E A U and Oedogonium tyrolicum W I T T -R O C K are new in the Hungarian Flora. W i t h Spirogyra crassoidea i t is not possible to ascribe taxonomic value either to the length of the spore or tha t of cell for a corre­lat ion of + 0,6594 (p < 1%) between them. A relationship is suggested to exist bet­ween a rapid decrease of water level and the spore formation of Spirogyra. — 8 figures.

Flor is t ical data

I n the autumn of 1972 I observed a thick-threaded Spirogyra i n the Városligeti-tó (-ornamental pond of Budapest town park). The specimen was unfortunately on the vegetative state. I n 1973 I examined tha t part of the pond which was covered w i t h concrete thoroughly hoping to f ind also specimens i n the proliferative state wi thout whicht i t is impossible to identify the species. I n the course of m y studies in the lake I identified the following five filamentous algal species :

1. Spirogyra crassoidea T R A N S E A U ( = S. ellipsospora var . crassoidea T R A N -S E A U ) — The vegetat ive cells have w id ths o f 1 1 8 — 1 4 8 jum, and lengths of 2 0 1 — 3 1 4 pm. The cross-wall is s t ra ight and each cell contains 5 — 8 spi ra l chloroplasts. Copula t ion is ladder shaped, the copula t ing cells do no t swell . The copula t ion channel averaging 2 7 pm i n w i d t h , is formed j o i n t l y b y the t w o partners. The zygotes are three-axed, e l l ip t ic , the i r centers are often indented and thus suggestive o f h u m a n blood cell (F ig . 1 ) . The length o f the spore is 1 1 2 — 1 5 7 , 5 pm, the w i d t h 1 2 9 — 1 5 8 jitm. The external w a l l of the spore is t h i n , i t s surface is smooth. The mesosporium is b rownish and on i ts surface small poin ts arranged i n i r regular p a t t e r n are visible under the immers ion lens.

I n Augus t the cells contained m a n y calcium oxalate crystals w h i c h often meas­ured up to 2 0 jtim (F ig . 2 ) . The pyrenoids were about 1 0 pm i n diameter. The de­sc r ip t ion we l l conforms to the data i n the l i te ra ture .

N e a r l y every author dealing w i t h the systematics of the Spirogyra genus agrees i n tha t i n the case o f in te rca la r i ly g rowing cells the cel l- length is o f no i m ­portance f rom taxonomica l v iew-po in t . L A N G E R ( 1 9 3 4 ) for instance wri tes the f o l l o w i n g : " I neglected to pub l i sh the lengths o f the cells. These are, namely, o f no impor tance , since the leng th o f the cell is the func t ion o f the age o f the cell and as such cannot be taken for a diagnostic character o f the species". Since bo th cells and spores have f a i r l y constant w id ths (Table 1) the l eng th o f the spore is to change i n con fo rmi ty to the leng th o f the cell ( f rom the abundant plasma o f a long cell a long spore develops). I succeeded i n p r o v i d i n g mathemat ica l evidences for th i s

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( S V Á B 19G7) : 16 para l le l measurements offered evidences for a close l inear correla­t i o n ( + 0 , 6 5 9 4 p < l % ) between cell- length and spore-length. Th i s implies t h a t w i t h Spirogyra crassoidea the l eng th o f the spore as we l l as the leng th o f the cell no taxonomic value can be set on.

Table 1. Average w id ths and lengths o f Spirogyra crassoidea cells resp. spores, and the i r respective va r i a t i on coefficients.

average CV

w i d t h o f spore 131,0 pm 7-6% w i d t h o f cell 137,0 pm 18,8% length o f cell 252,6 pm 5 9 , 1 % length o f spore 193,7 pm 67,7%

I t is seen i n the table t h a t the wid ths o f spores show the least percentual de­v i a t i o n . Consequently, out of the four diagnostic characters, th is is the most r e l i ­able one ( S O K A L & S N E A T H 1963). Ce l l -wid th is not so reliable ye t u t i l izable , wh i l e on the basis o f cell- and spore-length i t is impossible to differentiate the taxons i n the present case.

Pigs. 1 — 3 . Spirogyra crassoidea T R A N S E A U : 1 = state of proliferation, 2 = calcium oxalate crystals, 3 = pyrenoid. — Pigs. 4 — 5. Cladophora glomerata (L.) K Ü T Z , 4 = habitus pictu­

re, 5 = basal holdfast. — Figs. 6 — 8. Oedogonium tyrolicum W I T T R O C K .

On the basis of H O R T O B Á G Y I ' S algal catalogue (the state i n November , 1973) th i s species is new i n the H u n g a r i a n F lo ra .

2. Oedogonium tyrolicum W I T T E O C K . — Monoecious, i n the f i l ament the oogo-nia are formed i n ones. T h e y are ova l , w i t h an ova l aperture on the i r upper par t s . The oospores are round-e l l ip t ica l , smooth-wal led and do no t f i l l the oogonium complete ly . The a n t h e r i d i u m is a l i t t l e narrower t h a n the f i lament . The apical cell is b l u n t l y rounded. The vegetat ive cells measure 75—113 b y 14—25 ^ m , the oogonium is 48—53 pva wide and 73—104 pm long ( M R O Z I N S K A — W E B B 1969: 57—10 pm i n length) . The oospores are 45—52 pm wide, 52—10pm long ( M R O Z L N S -

K A — W E B B 1. c : 4 0 — 4 7 i t m long). W i t h the except ion o f the t w o data for l eng th near ly a l l t axonomic features wel l f i t i n w i t h the specimens found (Figs. 6—8). The species l i v e d a t tached to the leaves o f Najas minor .

On the basis of H O R T O B Á G Y I ' S algal catalogue th i s species is new i n the H u n ­gar ian F lo ra .

3. Aphanochaete repens A B R A U N — I t was found to grow as an ep iphy ton on Oedogonium f i laments . The 10 pm long and 7 pm wide cells fo rmed s t ra ight on occasion r a m i f y i n g threads. On each cell a hair measuring up to 60 pm originates w h i c h is onion- l ike th ickened at i t s base.

4. Cladophora, glomerata ( L . ) K Ü T Z . — The bu lk o f the algal ma t on the b o t t o m o f the pond was formed b y th is species. The apical cell is 45—60 ^um t h i c k . The colo­n y is o f acropetal organizat ion (Fig 4). I n cul ture i t developed holdfasts as i l lus t r a ­ted i n F i g . 5. There were numerous epiphytes, chief ly dia toms on the f i laments .

5. Hydrodictyon reticulatum ( L . ) L A G E R H . ( = H. utriculatum R O T H and H. tenel-lum R O T H ) — This alga o f peculiar cons t ruc t ion is abundant i n eutrophic waters ( K O L 1956, S Ö R E N S E N 1950).

Ecological data

The Városligeti-tó of Budapest is a temporary water. I t is filled w i t h tap water yearly once from the watersystem and has neither out- or inflow. One t h i r d of the bot tom of the pond is covered w i t h concrete, and from its other parts the sludge is reved by dredg­ing. I n 1973 subsequent to dredging the pond was filled only later, on March 30.

B y the t i m e summer set i n a t h i c k algal web had developed on the b o t t o m of the pond , w h i c h consisted o f the fo l lowing three layers. Lowes t d o w n were Hydrodictyon colonies embedded in to a half-anaerobic deposit smell ing o f hydrogen sulphide. This was covered b y a t h i ck , loose, coarse-textured Cladophora ma t . The algal ma t was not o f equal thickness everywhere and there were furrows t o some dep th on i ts surface. The bright-green Spirogyra tu f t s were carried in to th is furrows and b y c l imb ing on one another formed re la t ive ly massive conical heaps. On August 10 the amount o f algae found on a quadrate meter surface o f the b o t t o m amounted to 1,8 k g fresh-weight resp. 0,48 k g d r y weight i n the average o f three samples.

A l t h o u g h i n the p o n d Spirogyra was freuqent i n the vegetat ive fo rm, i n the conjugat ing f o r m i t was on ly seldom observed. The m a j o r i t y o f them does not reach the stage o f zygospore fo rmat ion . I examined a 2 m 2 spot covered w i t h Spirogyra i n a med ium advanced stage o f conjugat ion for three weeks and found the process to have progressed on ly i n the case o f a few f i laments and no t even $ then were spores produced. Accord ing to m y observations pro l i fe ra t ion occurs f i rs t o f a l l i n places near to the water surface. This is evidenced also b y the fact t h a t spore-formation is more frequent i n case the water level o f the p o n d decreases-

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r e l a t ive ly fast. (The water o f the pond oozed away i n t o the g round due to an a r t i f i -ca l g roundwater drainage i n September. Under a 1 0 cm water layer a Spirogyra m a t o f 5 m 2 size was found where the process i n 8 0 per cent o f the cases reached the stage of spore fo rma t ion . F r o m th is m a t we have abundant sample b o t h d r ied and f o r m a l i n conserved one. A t the t ime of spore fo rma t ion there were numerous epi thytes on the Spirogyra threads ( P A N K O W 1 9 6 1 ) .

The algal ma t o f the pond was ve ry u n i f o r m . Spots oi Ohara vulgaris L . and Najas minor were o n l y occasionally found. Ceratophyllum demersum was re la t ive ly numerous. I n Augus t the algal ma t becomes gradua l ly separated f rom the b o t t o m and is d r i f t ed to and f rom on the water surface. This i n our case was due to the cir­cumstance t h a t the oxygen bubles produced b y way of ass imilat ion passed easily t h r o u g h the coarse-textured, loose Cladophora m a t ye t some of them got captured •among the small Hydrodictyon-nets below and among the Cladophores passing up­wards the l i t t l e bal loon rearranges the threads o f the ma t : f r om the b o t t o m an emp­t y , g radua l ly g rowing , Cladophora-walled cone passes upwards w i t h Hydrodictyon a t i t s top . Reaching the surface the t op o f the cone opens and later on becomes •completely detached f rom the b o t t o m as a consequence of the smallest wave-m o t i o n .

References

H O R T O B Á G Y I , T . : Catalogus et Iconographia Algarum Hungáriáé i n Ins t i tu tum Bot. U n i v . Agr . Gödöllő (status Nov. 1973, Manuscript).

K A D L U B O W S K A , J . Z. (1972): Zygnemaceae in Flora Slodkovodna Polski P W N Krakow. p . 1 - 4 3 1 .

K O L , E . (1956) : Comparative algological and hydrobiological studies in rice fields in Hun­gary - Acta Bot. Hung., 2: 309-363 .

B A N G E R , S. (1934): Monographische Bearbeitung der Spirogyren m i t besonderer Berück­sichtigung der Vorkriesungarisehen Verhältnisse — Folia Cryptogamica, 1: 1253 — 1306.

M R O Z I N S K A - W E B B , T. (1969) : Oedogoniales in Flora Slodkovodna P o l s k i - P W N Krakow, p. 1-659.

P A N K O W , H . (1961): Über die Ursachen des Fehlens von Epiphyten auf Zygnemalen. — Arch. Protistenk., 105: 417-444 .

I S O K A L , R. R. & S N E A T H , P. I I . A . (1963): Principles of Numerical Taxonomy. - Free­man and Co., San Francisco — London, p . 1 — 359.

•SÖRENSEN, I . (1950): Studies in the Ecology of Hydrodictyon ret iculatum (L.) Lagerh. - Oikos, 2: 197-212.

S V Á B , J . (1967): Biometriai módszerek a mezőgazdasági kutatásban — Mezőgazd. Kiadó, Budapest, p . 1 —498.

V A N D E N H O E K , C. (1963) : Revision of the European species of Cladophora — Leiden, E. J . Brill, p . 1-248.

Author's address: Dr . L . H A J D U Botanical Department of the Hungarian Natural History Museum H — 1146 Budapest, Vajdahunyadvár Hungary