Ecology, Environment and Conservation Paper

HYDROGRAPHICAL FEATURES AND PRAWN FAUNA OF VELI- AUKULAM LAKE, TRIVANDRUM, KERALA, INDIA

B. Indira and K.V. Jayachandran

Abstract

Veli-Aukulam Lake (Long. 8° 3 I' 30" — 8° 32' 27" N and Lat. 76c 54' 39" — 67° 53' 44" E), Trivandrum, India, is now declared as one of the important tourist centres' where the recreational activities are at its maximum. The English Indian Clay Factory, situated on the eastern side of the Veli Lake, dump large quantities of Waste Clay into the lake. The bar mouth remains closed for most of the months and is opened only during the rainy season and remains so only for a few days. All these factors affect the stability of this ecosystem.The present paper reports the Hydrographical Features and Prawan fauna of the Aukulam Lake for a period of 12 months (from August 1980 to July 1981). The ranges of various hydrographical features recorded were : Water temperature — 27.25° (January and July) to 32.10°C (April) oxygen content — 4.0 (September) to 7.49 mg/1 (October); pH — 668 (January) to 7.98 (October); Salinity — 0.18 (August) to 4.37% (September); Phosphate phosphorus —2.95 (C.,ctober) to 8.45 pg at/I (August); Silicate silicon — 12.2 (September) to 19.65 pg at./I (February); Nitriate nitrogen — 0.71 (February) to 20.60 pg at/1(November); Nitrite nitrogen — 0.45 (March) to 5.55 pg at/1 (June). The prawn fauna recorded were Macrobrachium idella idella (Hilgendorf, 1898); M. idae (Heller, 1862); M. equidens (Dana, 1852); M. scabriculum (Heiler, 1862); M. veliense Jayachandran and Joseph, 1985; M. Josephi Jayachandran, 1989; Palaemon concinnus Dana, 1852; Penaeus indicus H. Milne Edwards, 1837; Metapenaeus affinis (H. Milne Edwards, 1837); M. dobsoni (Miers, 1878).When attempting future studies on the impact of tourism development on the Lake, this study will form the basal information pertaining to the conditions of the lake prior to the tourism activities for drawing up conclusions.