Occurrence of Cosmarium species in Khadakpurna reservoir , Buldana district – Maharashtra , India

The present investigation deals with the study of genus Cosmarium from Khadakpurna reservoir, It is constructed on Khadakpurna River of Godavari basin near Garkhed village, Deulgaon Raja tehsil in Buldana district, Maharashtra, India. During this study period twelve different species of Cosmarium has been described viz. 1. Cosmarium pygmaeum Archer, 2. Cosmarium portianum Arc. var. nephroideum Witter., 3. Cosmarium reniforme (Ralfs) Arch., 4. Cosmarium subprotumidum Nordst. var. gregorii Roy et Biss., 5. Cosmarium polygonum (Naeg.) Arch., 6. Cosmarium hammeri Reinsch var. Schmidlei Gronblad et Scott, 7. Cosmarium regnellii Wille, 8. Cosmarium lundellii Delp. var. ellipticum W. et G.S. West, 9. Cosmarium awadhense Prasad et Mehrotra, 10. Cosmarium undulatum Corda ex Ralfs var. minutum Wittr. Forma Suxena et Venkateswarlu. 11. Cosmarium calcareum Witter. 12. Cosmarium furcatospermum W. et G.S. West. All these taxa are reported first time from the reservoir. Such species occurrence in freshwater, hence these water body is indicated oligotrophic or some cases mesotrophic also and it is useful for irrigation, fisheries and with normal treatment it is useful for drinking purposes.


Introduction
Desmids occur exclusively in fresh water particularly in standing water such as ponds, lakes or shallow pools.The highest desmids diversity is found in mesotrophic, slightly acidic to slightly alkaline water bodies like moorland pools, peat, pits fen hollows [1,2].The genus Cosmarium belongs to Placoderm desmid [3].It is free floating, occurs in fresh water ponds.Usually it occurs abundantly in mucilaginous masses along the walls of reservoirs in winter.The plant body consists of a small, flat cell.Length of the cell is one and half times greater than the breath.The cells are deeply divided in the middle by a short isthmus that contain nucleus.Each semicell has at least one central chloroplast (usually 2 or 4) with pyrenoids.In this complex genus the cells are much variable.All are constricted in the middle leading to its bi-lobed appearance [4].More members of algal species can indicate water pollution and such study of assessing the quality of water as a part of investigation of algal diversity of Khadakpurna reservoir.

Material and methods
Water samples were collected from four different locations L-1 Takarkhed, L-2 Garkheda, L-3 Singaon Jha and L-4 Gavhan regularly at monthly intervals using clean sterilized plastic bottles.Samples of fresh water algae were collected with the help of phytoplankton net mesh and preserved in 4% Formalin.Khadakpurna Reservoir is constructed on Khadakpurna River of Godavari basin near Garkhed village, Deulgaon Raja Tehsil in Buldana District, State Maharashtra, India.It is situated at 20°9' 30" N and 76°4' 30" E, only 60 km away from district place.The dam is about 2160 meters in length with catchment area of 5133.18 km 2 .The project is having 160.606Million cubic meters (mcum) capacity of water storage, which includes 93.404 Million cubic meters live, and 67.202 Million cubic meters dead water stocks.Collected algal sample were studied in department of Botany G.S. College, Khamgaon, District Buldana (M.S.).

Results and discussion
The taxonomic study of the collected specimens revealed the presence of 12 of the Placoderm desmid genus Cosmarium from Khadakpurna reservoir were observed which are described as follows.

Cosmarium subprotumidum Nordst. var. gregori Roy et Biss.
Cell small, a little longer than broad, sinus narrowly linear; semicells trapiziform, upper half narrowed to broadly truncate apex, sides with 3 faintly bigranulate crenations and apex with 3-4 slight undulation; cell wall with somewhat radially arranged granules within the margin, generally in pair above but single further away, center with tumour above the isthmus, consisting of relatively larger granules disposed in irregular vertical series; chloroplast axile with one pyrenoid in each semicell.Cell 28 µm long, lat.cell 21 µm long, lat.isthmus 4.5 µm long [5].

Cosmarium regnellii Wille
Cell very small, a little longer than broad deeply constricted, sinus narrow with slightly dilated extremity; semicells subhexagonal, basal angles more or less sub-rectangular, sides parallel, upper angles broad and oblique, apex truncate and straight; cell wall smooth; each semicell with an axile chloroplast and one pyrenoid.Cell 11 µm long, lat.cell 8.6 µm long, lat.isthmus 2.5 µm long [5].

Conclusion
Cosmarium species were identified on the basis of morphology and cell measurement.Predominantly species occurred during winter season, gradually occurrence decreased in summer season and the density of Cosmarium is very low in rainy season which may be due to contamination of agriculture, domestic waste, organic and inorganic effluents.Most of the species in present study found at L-3 and L-4 site because it is not much deeper.