The Occurrence and Distribution ofAquatic Fungi in Certain Ponds of

Varanasiby

RAM DAYAL & THAKUR JICollege of Agriculture, Banaras Hindu University, Varanasi, India

(with 2 figs .)

INTRODUCTION

A number of authors (PETERSON 1910, HARVEY 1925, LUND 1934,H6HNK 1935, TESTRAKE 1959, PERROT 1960, DICK & NEWBY 1961and DICK 1962, 1963) have made references to the distribution ofoccurrence of aquatic fungi from time to time . Most of the recordsand the literature are from foreign countries specially from Europeand America. Very little work on this aspect seems to have beenmade in India. Recently the studies of water fungi from the presentpoint of view have been done by DAYAL & TANDON (1962, 1963) .

Much of the information is about the dates and places of collectionin few published papers, but little is known regarding the occurrence,periodicity and environmental factors involved in the growth ofthese aquatic fungi. We, therefore, decided to evaluate the composi-tion of aquatic flora, over a period of time covering all seasons of theyear, in variety of freshwater habitats in relation to some of thefactors affecting the growth of these fungi in their natural environ-ments. The primary object was to collect sufficient record to de-termine whether this group of fungi constitutes part of the fungalflora of water; or whether species occur merely as ephemeral wateinhabitors. This study may also reflect some light on the infrequentcollections of such forms from our country .

It was not possible during the present study to distinguish be-

Received November 9th, 1964 .

548

tween those different stages of fungus which separately or collective-ly provide inocula in the isolation procedure. Thus resting spores,zoospores, gemmae or vegetative mycelium in varying degrees ofgrowth phase, might provide predominant type of inoculum at anyone type of collections . However, our experimental data revealedsome evidence of seasonal fluctuations in the frequency of isolationof these fungi. The data further gave evidence of different patternsof fluctuation for different species . Such fluctuations may well showvariations in either the effective inocula, or the amount of effectiveinoculum, present in the water at different seasons .

METHODS OF COLLECTION

A survey of the water fungi occurring in various lakes and poolsin the vicinity of Varanasi District was done from July 1963 to theend of April 1964. The study was confined to a small area of about4 miles with Varanasi at the centre . Water sample collections weremade from each pool on week basis and soil from various poolscontaining submerged twigs, fruits, leaves, stems and debris werealso brought to the laboratory . The material along with the waterwas then placed separately in large Petri-dishes with loosely fittingglass covers. The majority of the aquatic fungi cannot be isolateddirectly because they do not appear in sufficient quantity in nature .Hence a wide variety of baits were used (viz . freshly boiled houseflies, hemp seeds, twigs and leaves of various plants and tomatoes) .The same procedure and technique being used each time and ateach station. The baits were then removed after 24-36 hours andwashed with several changes of sterile distilled acidulated water .Finally they were placed in dishes containing sterile distilled waterand after some time mycelial growth was observed developing onthem. The dishes were kept at room temperature and when sexorgans were developed, their proper identification was made .

TOPOGRAPHICAL ACCOUNT OF THE AREA STUDIED

Site and SituationMISHRA (1944) and SINGH (1955) studied the topography of

Varanasi in detail. Varanasi enjoys a commanding position on thecrescent-shaped left bank of the Ganga (Latitude 25° 18' N andLongitude 83° 1' E) . The city is situated almost in the middle ofthe Ganga valley, not far away from the Vindhyan gates to the south .It communicates the surrounding country not only by the Ganga,

549

which is navigable by vessels of considerable size but also by severalroutes and numerous roadways . The Grand Trunk road skirts thecity proper as a great highway .

Climate and WeatherThe periodic climate of Varanasi is typical of the Upper Gangetic

plains with an annual average rainfall of 40" . The rainy season ex-tends from about the middle of June to September with a meanrelative humidity of about 88%. November marks the beginning ofthe cold weather and December and January are the coldest months .

SoilThe soil consists of a uniform deposit of an old alluvium on a bed

of "Kanker", the latter is locally exposed on the bank of Baruna . Thesoil is light being moderately porous and grey and brown colouredwith small rounded grits and calcareous nodules . The coarser soilis pale coloured .

Present TopographyThe present topography, however, does not present a dead level

or smooth surface . Even a few feet difference in the level of differentparts of the area under study breaks the monotony of the surface .The highest level is found in the north-eastern portion over the areaknown as Rajghat plateau which stands at over 275 ft . (+85 m) abovesea level and about 50 ft . (-x-15 m) above the surrounding country-side, being bounded by an abrupt break of slope with a cliff of moreimpressive size, overlooking the Ganga .

A close examination would show some very striking changes inthe physical landscape of Varanasi . Today one may find fewer tanksin the heart of the City and of those that are left, some are artificialand almost all are reduced in size. Most of the streams have beenconsiderably decreased in size and strength mainly on account ofthe growth of the city. The site of the former low lands and depres-sions which have either partly drained or filled up, is still at a lowlevel, though it has been mostly covered with human inhabitations .There are numerous artificial pools for collection of water to be usedfor irrigation purposes. Some of them are deep enough to retainsome water throughout the year .

GENERAL ECOLOGY OF THE POOLS STUDIED

The pools, lakes and other sources of water, where collections were

550

made may be classified into three main groups, viz ., (i) permanentponds, (ii) small pools having water all the year round exceptingsummer season, and (iii) cemented garden ponds .

The permanent pond was situated at a distance of about 3 milesfrom the city. The pond has an area of about 3 acres . The flora ofthe lake mainly consists of the following water plants : Azolla bi-panneta, Asteracantha longifolia, Aponogeton natans, Potamogetonpectinatus, Hydrilla verticillata, Allisma sp . . Marsilea sp ., Pistia sp .,Ipomoea aquatica and several other weeds . The pH of the water wasapproximately 8-8 .5. The pond was overhung by trees .

The second series of the water sources includes the ponds whichmostly retain the water during winter and rainy season but showsigns of draught in the summer months . The vegetation in themmainly comprises Jussiaea repens, Vallisneria spiralis, Cyperus ro-tundus, Cynodon dactylon, Alternanthera sp. The pH of the waterwas approximately 7.5-8.

The ponds which remain filled with water all the year round fallunder the third series. They were small cemented ponds meant forornamental purposes and storing water for garden use . Species ofLotus, Hydrilla, Asteracantha and Salvinia were generally grown inthem. The pH of water was approximately 7-7 .5 .

S . delicaS . ferax

S . litolaris

I . toruloides

A . oligacantha

A . colorata

A . conspicua

A . flagellate

A, imperfecta

A . proliferaA . proliferoSi

Dictyuchus sp .

A . laevis

Aphanomyces sp .

Allomyces sp.

Pythium sp .

M

1 2 3

5 6 7 S 9 10 11 12 13 14 15Percentage occurrence

Fig . 1 - The percentage of occurrence of 16 species of aquaticPhycomycetes .

55 1

SPECIES ISOLATED AND THEIR OCCURRENCE

Excluding the Chytridiales 16 species were collected during theten months of study and they are recorded in Table I . The oc-currence of these species in 120 collections (taken weekly from threestations) is also indicated. Irrespective of the abundance of growthand the number as well as types of baits on which the species ap-peared, it was treated as a single occurrence whenever it was recordedfrom a particular pond .

TABLE I.

Occurrence of aquatic Phycomycetes in 120 collections taken from three col-lecting stations at weekly intervals for ten months .

*Refers to new Indian record - Refers to no record.

Fig. 1 shows the percentage occurrence of 16 species at three typesof collecting stations . The total number of species has been expressedas a percentage of the total number of collections .

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Species

Permanent Temporary Cementedcollected

pond

pond

pondTotalno. of

occurrences(excludingChytridiales)

pH range8-8.5 7.5-8

7-7.5

SaprolegnialesSaprolegniaceaeSaprolegnia delica

- 1

- 1S. ferax

3 3

4 10*S.litolaris

3 -

1 4Isoachlya toruloides

4 2

1 7*Achlya oligacantha

- 1

- 1A. colorata

4 1

1 6S. conspicua

- 1

- 1A. flagellata

1 5

3 9A. imperfecta

- 1

1 2*A. prolifera

- 1

1 2*A. proliferoides

4 1

- 5Dictyuchus sp .

(non fruiting)

6 1

- 7Aphanomyces laevis

5 1

1 7Aphanomyces sp .

4 5

6 15BLASTOCLADIALESBlastocladiaceaeAllomyces sp .

- 3

1 4PERENOSPORALESPythiaceaePythium sp .

- 3

7 10

The most commonly occurring species in this investigation wasAphanomyces which occurred 15 times out of 120 collections made,followed by Saprolegnia ferax, Achlya flagellata, Isoachlya toruloidesand Pythium sp. They were found to be capable of growing on awide range of substrata .

PERIODICITY

The period of vegetative activity of water molds are quite marked .It was noted during the study that the species collected during themonths of October and November are doubtlessly favourable totheir growth but the reproductive phase extends up to the end ofJanuary. On the other hand, it was noted that the samples collectedin March and April produced identifiable growth only after 4 to5 months . It appears, therefore, that oospores were mostly dormantduring summer and did not germinate until August and September .This probably may be the reason for the infrequent collection ofsome of the species during the other parts of the year. Summariesof occurrence of other species also show a similar seasonal periodi-city. Fig. 2 shows that most of the Saprolegniaceae undergo dormancywith the approach of the high temperature during the months ofMay and June and germinate following the low temperature. Thegrowth pattern of all the species of Saprolegniales is more or lesssimilar. They undergo a summer period of dormancy during themonths of April, May and June while the winter growth period formost of the species does not begin until the middle of October .Allomyces shows a longer period of dormancy commencing earlier inwinter and ending later in summer. Species of Achlya are morepredominant throughout the investigation .

RESULTS AND DISCUSSION

LUND (1934) recorded the distribution of a group of species charac-teristically found in waters of high acidity . These species wereAplanes androgynus, Saprolegnia turfosa, S . litolaris, S . delica andS. diclina . He also recorded as typical over a wide range of hydrogen- .ion concentration : Achlya racemosa, A . racemosa var . stelligera (= Acolorata), Saprolegnia monoica and S. ferax . The only species ofSaprolegniaceae that he considered to be characteristic of alkalinewater was A. radiosa . He comments that waters with moderatelyacid, neutral or alkaline pH values, appeared to have no particularlydefined Saprolegniaceous flora . Considering the fact that LUND

553

worked entirely with aquatic samples, we find a close similaritybetween our conclusion and his statement .

The analysis of the data computed in Tables I and II and Figs . 1and 2, reveals a greater or lesser degree of fluctuation in the numberof species and total number of occurrences . However, some collec-tions yielded satisfactory result in the isolations made and while in

TABLE II .

Seasonal occurrence of aquatic Phycomycetes in 120 collections taken fromthree collecting stations at weekly intervals for ten months .

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-denotes no record

Year 1963 1964 Total

oc-currencesMonth

J A S O N D J F M A

SAPROLEGNIALESSaprolegniaceaeSaprolegnia

delica I -1 2 3 2 2

I10S. ferax

- -S. litolaris

- - 1 1 2 4Isoachlya toruloides - - 1 3 3 7Achlya oligacantha - - 1 1A. colorata I 1 2 2 6A. conspicua

- - 1 1A. flagellata

- 1 1

1

2 1 2 1 9A. imperfecta

- - 1 1 2A. prolifera

- - 1 1 2A. proliferoides

- - 1 1 1 2 5Dictyuchus sp.

(non fruiting) 2 - 1 2 2 7Aphanomyces laevis - - 1 1 3 2 7Aphanomyces sp . - 1 1

2

1 2 3 3 2 15BLASTOCLADIALESBlastocladiaceaeAllomyces sp .

- 1 2

1 4PERONOSPORALESPythiaceaePythium sp . 1-- 1 2 1 2 3 10Species total forSaprolegniales

- 2 5 - 5 7 6 13 19 18Species total forBlastocladiales

- 1 2 1 - -Species total forPeronosporales 1 -- 1 2 1 2 3Number of species - 3 7

1 3 7 5 10 12 10

some cases the species lists were numerically smaller, apparentfluctuations have not been significant . On this account we have laidlittle or no importance on the data obtained, where number ofspecies was less than one and where only one or two species wererecorded .

On the basis of the limits outlined above, we have tried to analysethe cause of these fluctuations. An examination of Table II showsthat the species lists are relatively constant, a majority of the "morecommon" species and the "less common" species being recordednearly every month . The graph (Fig. 2) indicates, however, that thefluctuation of the number of species is accompanied by a similarvariation in the species recorded for the order Saprolegniales . Thissuggests that the fluctuations are due to chance of occurrence ; butit will be seen that, in general, increase in the number of species isnot sufficient to account for the magnitude of the constant or decreasein number of species . Further, it can be noticed that slight variationoccurs in the number of species recorded in the sets of samples takenat the same time . Again the graph (Fig. 2) represents that the fluctu-ations of number of species are closely paralleled by the speciestotal of the order Saprolegniales .

A similar fluctuation also applies to the remaining orders Blas-tocladiales and Peronosporales . It is noticeable, however, that theydo not show any better correlation in either of them . This againsuggests that the "more common" species contribute most of thefluctuations .

It can be seen that in all the cases there are "peaks" in Augustand September and during the period of February to May ; and thereis "trough" during the period June to July . When most of the poolsdry up, there are very little chances for gemmae to withstand the sum-mer temperature. Probably the resting spores preserve the speciesduring the drying up, though they often occur sparingly . Moreoverduring the month of July, the zoospores become disturbed on accountof rains and are not isolated easily by any suitable technique . Thus,these two may be probable reasons for species not being recordedin the months of June and July .

Thus the consideration of fluctuations in the recorded frequencyshown by individual species tends to confirm the conclusion thatthe fluctuation in the species total are basically seasonal ; althoughin certain instances, in certain months, a difference of degree in thefluctuations suggests that local conditions such as vegetation of thepond, soil type, etc ., may influence the species total and also differentspecies may show different basic patterns of fluctuation .

555

556

19

is

17

16

15

14

13

7

6

5

4

3

1

Dashed and dotted line : species total for SaprolegnialesDashed line ; species total for Bla3tocladi- ,!,.,

ales .Solid line ; species total for Peronospo-

rales .Dotted line : Number of species .

S

01963

I

M

A1964

Fig. 2 - Graphic representation for seasonal occurrenceof aquatic Phycomycetes, for explanation see text .

SUMMARY

A survey of the Phycomycetous flora of the three types of thecollecting stations in Varanasi was made for about ten months . Thefollowing observations were made :

1 . An attempt was made to correlate the distribution of fungi in agroup of small ponds, lakes with the idea of their occurrence,periodicity and environmental factors involved in the growth ofaquatic fungi.

2. Sixteen species were recorded belonging to the Saprolegniales,Blastocladiales and Peronosporales .

3. There is distinct seasonal periodicity of growth which is mainlyrestricted to winter months .

4. The results indicate that the rarity of the many aquatic Phy-comycetes may not be only due to specificity of substratum butalso to temperature and the time needed for the maturation ofthe oospores .

5. The hydrogen-ion concentration of the ponds surveyed, has beenmeasured, which supports the view of wide occurrence of membersof Saprolegniales over a wide range of pH with the exception ofAllomyces sp. and Pythium sp. which probably prefer the loweralkalinity of water .

ACKNOWLEDGMENTS

The junior author is grateful to Dr . R. S . CHAUDHURI, D. Sc.,Principal, College of Agriculture, and Dr . M. S . PAVGI, for providingthe necessary laboratory facilities .

557

REFERENCES

DICK, M. W. & H. V. NEWBY, - 1961 - The occurrence and distribution ofSaprolegniaceae in certain soils of south-east England . I . Occurrence .Y . Ecol. 49 :403-19 .

DICK, M. W . - 1961 - The occurrence and distribution of Saprolegniaceaein certain soils of south-east England . II. Distribution within definedareas . Ibidem 50:119-27 .

DICK, M. W . - 1963 - The occurrence and distribution of Saprolegniaceaein certain soils of south-east England . III. Distribution in relation topH and water content . Ibidem 51 :75-81 .

DAYAL, R. & R. N.TANDON, - 1962 - Ecological studies of some aquatic Phy-comycetes . Hydrobiologia 20, 2:121-27 .& , 1963 - Ecological studies of some aquatic Phycomycetes .

II. Fungi in relation to the chemical factors of water . Ibidem 22 :344-30

HARVEY, J . V. - 1925 - A study of water molds and Phytium occurring in thesoils of Chapel Hill . Y. Elisha Mitchell sci. Soc . 41 :151-64.

HOHNK, W. - 1935 - Saprolegniales and Monoblepharidales aus der Umge-bung Bremens, mit besonderer Beriicksichtigung der Oekologie derSaprolegniaceae . Abh. Naturwiss. Ver. Bremen 29 :207-37.

LUND, A. - 1934 - Studies on Danish fresh water Phycomycetes, and noteson their occurrence, particularly relative to hydrogen-ion concentra-tion of the water . Kgl. Danske vidensk . Selsk. Skrift., Naturv. Math .,Afd . 9, 6:1-97.

MISHRA, R. - 1944 - The vegetation of Rajghat ravines . J. Indian bot. Soc.23:113-21 .

PETERSON, H. E . - 1910 - An account of Danish fresh water Phycomyceteswith biological and systematical remarks (in English) . Ann. mycol.

8 :494-560.PERROT, P. E . - 1960 - The ecology of aquatic Phycomycetes . Trans . Brit .

mycol. Soc . 43, 1 :20-30.SINGH, R . L. - 1955 - Benaras. A study in urban geography . Bhargava Bhus-

han Press, Varanasi .TESTRAKE, D. - 1959 - Eustraine distribution and saline tolerance of some

Saprolegniaceae . Phyton 12:147-52 .

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