| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1
Faculty of Science, Institute of Biology and Ecology, 34000 Kragujevac, Serbia and Montenegro
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESERVOIR CHARACTERISTICSRESULTSDISCUSSIONLITERATURE CITED |
|---|
This paper presents results of a mycological survey conducted in five large reservoirs in Serbia (Sjenica, Barje, Gara
i, Meðuvrje and Ov
ar-Kablar) that have different hydrobiological and production characteristics. The sampling was conducted in March, June, August and October 2002. Quantitative analysis of fungal communities showed that the average number of colony-forming units in these reservoirs was 1966–5682/L of water. The highest number of CFUs was found in the 
-mesosaprobic (Class III) Ovar-Kablar Reservoir and the lowest was in the oligosaprobic (Class I) Sjenica Reservoir. CFUs were higher in samples taken near lake bottoms and in littoral zones rich with macrovegetation than in the middle depths. In these reservoirs 48 species were identified from 720 isolates. The dominant genera were Penicillium, Aspergillus, Cladosporium, Fusarium, Rhizopus, Mucor, Phoma and Verticillium. The autochthonous aquatic fungal community comprised these species: Achlya americana, A. diffusa, A. racemosa, Dictyuchus sterile, Isoachlya toruloides, Leptomitus lacteus, Pythium ultimum, Saprolegnia ferax, S. hypogyna and S. monica. My results indicate that aquatic fungi on the whole are better represented in lakes with a higher trophic status.
Key words: allochthonous, autochthonous aquatic fungi, reservoir
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESERVOIR CHARACTERISTICSRESULTSDISCUSSIONLITERATURE CITED |
|---|
). They help to degrade autochthonous and allochthonous organic substances, ensuring food for certain invertebrates and fish (Bärlocher 1980, 1981). Fungi directly and indirectly can affect the abundance of other hydrobionts due to their exclusively osmotic type of nutrition, cellular absorptive surface and resistance to unfavorable factors (Sen 1988a, b). Fungi alter their environment by emitting toxins and antibiotics, by causing changes of acidity and aeration and by affecting the process of water self-purification in different trophic chains (Hynes et al 1974). Some aquatic fungi also are capable of parasitizing water plants and animals, including fish (Khulbe 2001). The study of the ecology of aquatic fungi, together with other traditional components of aquatic ecosystems, is an important step forward in the development of hydrobiological research (Fedorov 1987).
Few studies of fungi in aquatic ecosystems have been undertaken in Serbia (Rankovi 1994, Vukojevi and Frani-Mihajlovi 1994, 
omi et al 1996). The important role of fungi as structural and functional components of biohydrocenoses and the fact they only have begun to be studied in Serbia prompted me to perform the current investigation.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESERVOIR CHARACTERISTICSRESULTSDISCUSSIONLITERATURE CITED |
|---|
i, Meðuvrje and Ovar-Kablar. They differ in hydrological, productivity and other characteristics. Water quality varies from lake to lake (Stankovi 2002). Sjenica is of the oligosaprobic type (Class I); Barje is of the - to ß-mesosaprobic type (Class I–II); Garai is of the ß-mesosaprobic type (Class II); Meðuvrje is of the ß-to -mesosaprobic type (Class II–III); and Ovar-Kablar is of the -mesosaprobic type (Class III).
I monitored the qualitative and quantitative composition of fungal communities in these lakes, recorded distribution of the isolates and established seasonal dynamics. Water samples were taken at four or five points in the reservoirs, following the seasons: in March (M), June ( J), August (A), and October (O) 2002. The samples came from water at the bottom of the reservoirs (L1), from the middle depths (L2), from the surface of open lakes (L3) and from water overgrown with macrophytes near the shore at a depth of 20–30 cm (L4). Water was collected with a 2 L Ruttner sampler. Samples were processed the same day they were collected using the dilution plate technique, adding 2 mL of water on malt-agar culture medium in Petri dishes with three replications. The number of colony-forming units (CFUs) was determined. Pure cultures were isolated according to standard mycological methods by reseeding on selective substrates: potato-dextrose agar (PDA), Czapek’s agar (CzA) and malt agar (MA) (Booth 1971). All cultures were incubated at 25 C (±2 C) under day-night light exposure. Stock cultures were kept in the culture collection of the Faculty of Science, Institute of Biology, Kragujevac.
Autochthonous aquatic fungi were studied by direct microscopic examination of material collected by baiting with seeds of Cannabis sativa, cellophane and nail pieces (Arnold 1968). The method reported by Dix and Webster (1995) was used to isolate aquatic hyphomycetes. Species were identified using standard keys: Middleton 1943, Raper and Thom 1949, Cooke 1963, Raper and Fennel 1965, Coker 1969, Seymour 1969, Gilman 1971, Barnet and Hunter 1972, Dick 1973, Batko 1975, Khuble 2001.
|
RESERVOIR CHARACTERISTICS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESERVOIR CHARACTERISTICSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Barje was constructed by damming the Veternica River. The dam is 74 m high. The lake has a volume of 47 000 000 m3. The reservoir is 673 m above sea level. Water is of the oligo- to ß-mesosaprobic type (Class I–II).
Garai was formed by damming the upper course of the Velika Bukulja River on Mount Bukulja. The reservoir is 377 m above sea level and has a volume of 1 400 000 m3. The lake is surrounded by luxurient vegetation and covers an area of 45 ha. It is 1500 m long, 300 m wide and 26 m deep. Its quality is classified as ß-mesosaprobic type.
Meðuvrje is the largest reservoir on the Western Morava River. The volume is 18 500 000 m3. Its greatest depth (measured near the dam) is 23 m. Its area is 1.5 km2. At the time of its formation, Meðuvrje inundated 150 ha, including 50 ha of fertile fields. Due to sedimentation, the volume has shrunk (up to 50%) and water quality has deteriorated. The major polluters are upstream settlements and industrial plants. Water quality fluctuates within limits of the ß-mesosaprobic and -mesosaprobic zones (Class II–III).
Ovar-Kablar Reservoir was formed by construction of a concrete dam on the Western Morava River. The dam is 45 m long and 12 m high. The lake is 9 km long and 40–100 m wide. Its volume is 3 070 000 m3. The lake is 292 m above sea level. Because Ovar-Kablar is the most downstream reservoir on the Western Morava, it is subject to all runoff from its watershed, which in a number of places lacks a forested cover and is characterized by considerable erosion. As the reservoir has filled with sediments, water quality has deteriorated to poor, fluctuating within the boundaries of the -mesosaprobic zone (Class III).
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESERVOIR CHARACTERISTICSRESULTSDISCUSSIONLITERATURE CITED |
|---|
). The averages of CFUs isolated from different reservoirs differ significantly. Statistical analysis indicated that the greatest average number of CFUs (5682/L) was recorded at locality L1 in the -mesosaprobic Ovar-Kablar Reservoir, the least number (1966/L) at locality L3 in the Sjenica Reservoir. The number of CFUs was greater near the bottoms. CFUs rinse from bottom deposits, which accounts for the number of CFUs at depths; in fact the number of CFUs was especially high in reservoirs with a high trophic status (Ovar-Kablar and Meðuvrje), probably due to the presence of quantities of mud rich in organic compounds favorable for the development of certain fungi. The density of CFUs in littoral samples, overgrown with macrophytic vegetation, was higher than at middle depths and at the surface in open water. This is attributable to the presence of substrates suitable for growth of fungi (soil, plant remains, etc.).
|
). The maximal average number (11 478 CFUs/L) was recorded at locality L1 in the Ovar-Kablar Reservoir. The minimal number of spores was recorded in June from all reservoirs, the lowest value (243 spores/L) being recorded at locality L3 in the Sjenica Reservoir. The number of CFUs increased again in October; Sjenica Reservoir CFUS doubled from June measurements. Similar seasonal patterns were observed in samples taken from all five reservoirs.
|
). Forty-eight species were identified from 720 isolates. The majority of them were encountered rarely, while certain genera were common. Members of the genus Penicillium were common in all samples. Especially abundant were the species P. verrucosum, P. chrysogenum, P. canescens and P. thomii, at the bottom. Species of the genus Aspergillus were encountered frequently, especially in samples from highly trophic reservoirs. Of the genus Aspergillus, the best represented species were A. flavus, A. fumigatus and A. niger. Species of the genus Trichoderma predominated in eutrophic reservoirs, occurring most often at the bottom and in littoral samples. The best represented species of this genus was T. viride. The genus Phoma occurred mainly at the surface and almost was absent near the bottom. Like the genus Aureobasidium, it was best represented in the oligotrophic Sjenica Reservoir. Species of the genus Mucor were encountered most often in littoral water overgrown with macrophytes and most frequently were present in eutrophic lakes (Ovar-Kablar, Meðuvrje and Garai). The genus Cladosporium was present with varying frequency in the majority of samples regardless of the time and place of sampling. The best represented species were C. cladosporides, C. herbarum and C. oxysporum. The greatest diversity, on the whole, was observed in March and October. Colorless colonies of sterile mycelium also were isolated commonly.
|
Of autochthonous aquatic fungi, I isolated 10 species from the orders Saprolegniales, Leptomitales and Peronosporales. The distribution of this group is provided (TABLE III
). The greatest number of isolated species belonged to the Saprolegniales, and the dominant genera were Achlya and Saprolegnia. The greatest number of species (10) was isolated from the eutrophic Ovar-Kablar Reservoir, the smallest number (six) from the oligotrophic Sjenica Reservoir. Certain species such as Achlya americana, A. racemosa and Saprolegnia ferax were found in all lakes, and the species Saprolegnia ferax often was represented. The species Leptomitus lacteus and Pythium ultimum were found individually in reservoirs with high trophic status. Monitoring seasonal dynamics, we did not observe any regularity in the distribution of these fungi. On the whole the distribution of aquatic fungi was sporadic with significant occurrence in water near the shore.
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESERVOIR CHARACTERISTICSRESULTSDISCUSSIONLITERATURE CITED |
|---|
. In addition the trophic status is important. Similar data have been reported by Voronin (1989) in his investigations of lakes in Estonia. Thus the greatest number of CFUs is from samples from the Ovar-Kablar (-mesosaprobic) and Meðuvrje (- to ß-mesosaprobic) reservoirs. In all lakes, the greatest abundance of fungal CFUs came from the lower depths, which is confirmed by a study of the Gru
a Reservoir (Rankovi 1994), where the most fungi were isolated from samples taken in the spring and fall. It can be surmised that the increased number of fungi at these times is related to the death of macrophytic vegetation and introduction of soil fungi during heavy rain in the fall and early spring. Due to stronger and more frequent water motion, a greater number of fungi from the depths are circulated. A certain seasonal distribution of fungi also was observed in the Vlasina Reservoir (Vukojevi and Frani-Mihajlovi 1994).
The genera that were isolated as dominant from Serbian reservoirs (Penicillium, Aspergillus, Cladosporium, Fusarium, Rhizopus, Mucor, Phoma and Verticillium) were also for the most part those isolated from waters of the Neretva River in Bosnia-Herzegovina (Ristanovi 1973a), from lakes in Estonia (Voronin 1989) and from Grua Reservoir (Rankovi 1994), where species of the genus Penicillium likewise were dominant. The fungi that I isolated from Serbia belong mainly to the category of transient accidental micro-organisms, according to ecological classification of aquatic heterotrophic micro-organisms (Park 1972a). Transient and accidental micro-organisms can develop sporadic activity and "soil fungi" may participate in microbiological processes in bodies of water (Park 1972b). Moreover the ability of certain soil fungi (species of the genera Fusarium, Botrytis and Chaetomium) to live in sea and river water has been demonstrated (Alton 1985). Thus depending on the trophic status of the lake, fungi known as soil species can participate with typical aquatic (autochthonous) fungi in microbiological processes transpiring in lake ecosystems. It should be noted finally that some of the isolated fungi (i.e., Phoma herbarum and species of the genera Fusarium and Aureobasidium) have been recorded as pathogenic to fish (Hörter 1960, Ross et al 1975).
Of autochthonous aquatic fungi, the genera Achlya and Saprolegnia were dominant in the majority of my samples. They also were isolated in Blelham Tarn in the UK (Dick 1966) and in Lake Skadar in Montenegro (Ristanovi 1973b).
The greatest number of fungal species (10) was isolated from the eutrophic Ovar-Kablar Reservoir, the smallest number (seven) from the Sjenica Reservoir. The trophic status of the reservoir might influence the abundance of these fungi.
Achlya americana was found in the majority of samples and did not occur in seasonal patterns or in certain microcenoses but still was widely disseminated. It also was found in Dow Lake in America (Miller and Ristanovi 1969). Achlya racemosa was isolated only in March from two reservoirs. It also was recorded in a small number of samples from Blelham Tarn (Dick 1966). Dictyuchus sterile was found in the oligotrophic Sjenica Reservoir at all localities and in all samples but only in March in the Barje and Garai reservoirs. In North America it was mentioned by Miller (1964) as occurring in microcolonies in the oligotrophic Mountain Lake in Virginia.
Species of the genus Saprolegnia (S. ferax, S. hypogyna and S. monica) were found without any regularity with regard to the place or time of appearance. They can cause saprolegniosis in fish under certain conditions.
The fungus Leptomitus lacteus was found in the zone of macrovegetation in Meðuvrje and Ovar-Kablar. It usually is encountered in polluted river water, according to Johnson (1956). On the other hand, Miller (1964) found it in the clean Mountain Lake and Dick (1966) recorded it in Blelham Tarn.
Inasmuch as species of the genus Pythium also occur in soil (Middleton 1943), it can be presumed that their distribution depends in some measure on arrival of allochthonous material from around the lakes. The species P. ultimum was found at localities.
My results indicate that aquatic fungi on the whole better are represented in lakes with a higher trophic status, phenomena also reported by Gönczol (1987). Mycological studies of reservoirs are important from both the mycological and ecological perspectives because the presence of certain species can be an indicator of water quality.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
1 E-mail: rankovic{at}kg.ac.yu
|
LITERATURE CITED |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESERVOIR CHARACTERISTICSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Arnold GR. 1968. Methods of collection and studying freshwater hyphomycetes. Mycol Phytopath 2:158–160.
Bärlocher F. 1980. Leaf-eating invertebrates as competitors of aquatic hyphomycetes. Oecologia 47:303–306.[CrossRef]
———. 1981. Fungi of the food and the feces of Gammarus pulex. Trans Brit Mycol Soc 76:160–165.
Barnet H, Hunter B. 1972. Illustrated Genera of Imperfect Fungi. Minneapolis, Minnesota: Burgess Publ. Co. 241 p.
Batko A. 1975. Zarys hydromikologii. Warszawa: Panstwowe Wudawnichtwo Naukowe. 417 p.
Booth C. 1971. Fungal Culture Media. In: Booth C, ed. Methods in Microbiology. London and New York: Academic Press. 4:49–94.
Coker WC. 1969. The Saprolegniaceae. Chapel Hill: The University of North Carolina Press. 201 p., 63 pl.
Cooke BW. 1963. A laboratory guide to fungi in polluted water, sewage, and sewage treatment systems. Public Health Service Publ. 999-WP-1. 132 p.
Czeczuga B. 1991. Studies of aquatic fungi. XVIII. Aquatic fungi in Lake Sniardwy and eighteen neighbouring lakes. Int Revue Ges Hydrobiol 76:121–135.[CrossRef]
omi Lj, Rankovic B, Barbi F. 1996. Fungi in Grua reservoir. Arch Hydrobiol Spec Issues Advanc Limnol 48: 105–111.
Dick WM. 1966. The Saprolegniaceae of the Environ of Blelham Tarn: sampling techniques and estimation of propagule numbers. J Gen Microbiol 42:257–282.[Medline]
———. 1973. Saprolegniales. In: The fungi—an advanced treatise 4B. Ainsworth GC, Sparrow FK, Sussman AS, eds. New York: Academia Press. p 323–509.
Dix NJ, Webster J. 1995. Fungal Ecology. New York: Chapman & Hall. 549 p.
Fedorov VD. 1987. Aktuelnoe i neaktuelnoe v gidrobiologii. Biol nauki 8:6–26.
Gilman IS. 1971. Soil Fungi. Ames, Iowa: The Iowa State Univ. Press. 450 p.
Gönczol J. 1987. Ecological observations on aquatic hyphomycetes of Hungary. Acta Bot Hung 1–2:41–49.
Hörter R. 1960. Fusarium als Erreger einer Hautmycose bei Karpfen. Zs f Parasitenkunde 20:355–358.
Hynes HBN, Kaushir NR, Lock MA. 1974. Benthos and allochtonous organic matter insteam. J Fish Res Board Can 31(5):545–553.
Johnson TJ. 1956. Notes on fungi from Mississippi. I. Aquatic phycomycetes. Am Mid Natural 55(1):184–193.[CrossRef]
Khuble RD. 2001. A manual of aquatic fungi (Chytridiomycetes and Oomycetes). Delhi, Daya. 255 p.
Middleton J. 1943. The taxonomy, host range and geographic distribution of the genus Pythyum. Lancaster, UK: Mem. Torrey Bot. Club. 171 p.
Miller EC. 1964. Annoted list of aquatic phycomycetes from Mountain Lake Biological Station, Virginia. Va J Sci 16(3):219–228.
———, Ristanovic B. 1969. Studies on Saprolegniaceous Filamentous Fungi. Oh J Sci 69(2):105–109.
Park D. 1972a. Methods of detecting fungi in organic detritus in water. Trans Brit Mycol Soc 58(2):281–290.
———. 1972b. On ecology of heterotrophic microorganisms in freshwater. Trans Brit Mycol Soc 58(2):291–299.
Rankovi B, omi Lj, Simi S. 1994. Populacija gljiva u akumulacionom jezeru Grua. Konferencija Zas tita voda ’94. Zbornik radova. p 110–116.
Raper KB, Thom C. 1949. A manual of the Penicillium. Baltimore, Maryland: The Williams & Wilkins Co. 875 p.
———, Fennel DI. 1965. The genus Aspergillus. Baltimore, Maryland: The Williams & Wilkins Co. 686 p.
Ristanovi B. 1973a. Mikroorganizmi reke Neretve i nekih njenih pritoka. II deo. Sezonska distribucija Phycomycetes. Ekologija 7(1):55–68.
———. 1973b. The population of fungi in Scadar Lake with Special emphases on aquatic phycomycetes. Microbiol 10(1):53–61.
Ross AJ, Yasutake WT, Leek S. 1975. Phoma herbarum, a fungal plant saprophyte, as a fish pathogen. J Fish Res Board Can 32(9):1648–1652.
Sen B. 1988a. Fungal parasitism of planctonic algae in Sherwater III. Fungal parasites of centric diatoms. Arch Hydrobiol Suppl 79(2–3):167–175.
———. 1988b. Fungal parasitism on planctonic algae in Shearwater V. Fungal parasites of the green algae. Arch Hydrobiol Suppl 79(2–3):185–205.
Seyomour RI. 1969. The genus Saprolegnia Beichefte zur Nova Hedwigia 124 p.
Stankovic S. 2002. Serbian lakes—a limnology monograph. Belgrade, 167 p.
Voronin LV. 1989. Saprotrophic fungi in Estonia lakes. Mycol Phytopath 23(3):197–202.
Vukojevi J, Frani-Mihajlovi D. 1994. Mikopopulacija Vlasinskog jezera i slivnog podruja. Konferencija Zastita voda ’94. Zbornik radova. p 210–214.
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
