Search

The aquatic ecosystem harbours a variety of micro-organisms, among which water-borne conidial fungi occupy an important place. Their occurrence in freshwater habitat has great significance in the decomposition of submerged plant materials, nutrient release and productivity. Their occurrence and frequency to extreme temperatures and pH may have a profound effect on fungal community composition and metabolic activities. The present paper deals with the diversity of conidial aquatic fungi from different unexplored freshwater bodies flowing through different elevations (1000-1500 m) in district Nainital, Kumaun Himalaya. Comparative study of species composition in different seasons, sporulation temperatures and pH conditions was also carried out. In all, 18 species of conidial fungi belonging to 14 genera were recorded, out of which maximum species (11 species) were recorded in both rainy (July to September) and winter seasons (November to December). Anguillospora crassa, Beltrania rhombica, Campylospora chaetocladia, Cylindrocarpon aquaticum, Helicomyces roseus and Tetracladium setigerum were isolated only during rainy season; Alatospora acuminata, Clavariopsis aquatica, Clavatospora tentacula, Lemonniera pseudofloscula, L. terrestris and Tetrachaetum elegans were isolated only during winter season while Lunulospora curvula, L. cymbiformis, Setosynnema isthmosporum, Tetracladium marchalianum and Triscelophorus acuminatus were isolated in both rainy and winter seasons. The preferred pH and the sporulation temperature ranged from 6-7 and 15-20 °? respectively. The results of the present study are clearly indicating fungal species composition variations along pH, temperature, seasonal and altitudinal gradients and the sites selected for this exploratory investigation are being undertaken for the first time.

Assessment of different sources of carbon and nitrogen in terms of dry weight biomass of four selected aquatic hyphomycetes viz; Flagellospora penicilloides Ingold, Pestalotiopsis submersus Sati and Tiwari, Tetrachaetum elegans Ingold and Tetracladium marchalianum De Wildeman was made for their nutritional requirements. Eight carbon sources and ten nitrogen sources were singly added to the basal media in order to provide 4g of carbon and 1g of nitrogen per litre of distilled water. Among carbon compounds glucose and sucrose were found to be most suitable sources of carbon for all the four fungal isolates, where as fructose proved good for T. marchalianum, P. submersus and F.penicilloides fairly. Cellulose was found a poor source of carbon for the growth of all these isolates. The inorganic sources of nitrogen were found as good nitrogen sources with preference for ammonium ions. Suitability of amino acids was found variable from species to species for nitrogen. T.elegans and T.marchalianum had their maximum growth in asparagines, whereas, P. submersus had their highest growth in proline. Cysteine was observed as a good source of nitrogen for almost all the fungal isolates used. Anova calculated for these observed data showed significant variations in the dry weight production of different fungal species grown in different sources of carbon and nitrogen(P<0.01).