INDIAN HYDROBIOLOGY, VOL.1 No.2, JUNE, 1996.
PECULAR LIMNOLOGICAL FEATURES OF A SOFT WATER RESERVOIR IN SOUTH INDIA - A. SREENIVASAN, Hydro biological Research Station, Madras -600 010, pp. 61 -68.
Abstract: A soft water impoundment in Southwest Tamilnadu, Pechiparai has a stable thermal stratification. Oxygen depletion parallels thermal stratification and an anoxic bottom is common. A high bottom accumulation of free CO2 and bicarbonates is peculiar to this unpolluted soft water reservoir. The bottom iron content is high.
ECOLOGY OF THE ROTIFERS OF THE PITCHAVARAM MANGROVES, SOUTHEAST COAST OF INDIA. A.C. GOVINDASAMY AND L. KANNAN, Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India. - pp. 69 - 76.
Abstract: Rotifers form a vital source of energy as secondary producers in the aquatic food-chain and serve as indirect source of food to other organisms, occupying still higher trophic levels. A total of 22 species and one variety of rotifers belonging to 13 genera were identified from the Pitchavaram Mangroves. Brachionus angularis, Keratella cochlearis. K. procurva, K. tropica and Lecane luna occurred throughout the year and the genus Brachionus was numerically abundant. Maximum number of rotifer species was encountered during the summer season when the species diversity and richness were high. Environmental parameters were either positively or negatively correlated with the total rotifer population.
TROPICAL PHYTOPLANKTON PRODUCTION. K. KRISHNAMURTHY, R. SANTHANAM, V. SUNDARARAJ, L. KANNAN, G. ILANGOVAN, P. MANI, C.S. V.RAMACHANDRA RAO, N. GODHANTARAMAN, & C. KALIYAPERUMAL , Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India.
Abstract: Relative phytoplankton potential was estimated at Parangipettai formerly known as Porto Novo (11 Deg 29, lat: 79 Deg 49'ELong) India over a period of 20 years between 1972 and 1991. For this study, four interconnected aquatic biotopes viz. neritic, estuary, backwater and mangroves were chosen. A total of 330 species of phytoplankton were recorded from these various biotopes listed above. Out of these, it would appear that about 70 species could form blooms in these biotopes. The dominant genera (consisting of not less than 6 species in each genus) recorded were Chaetoceros, Rhizosolenia, Coscinodiscus, Nitzschia, Navicula, Biddulphia, Pleurosigma, Bacteriastrum, Protoperidinium, Ceratium, Gonyaulax and Pyrocystis. Among these, the genus Protoperidinium recorded the highest number of species (34). Neritic biotope recorded the highest number (about 160) of phytoplankton species. Daily observations on gross and net production and respiration of total phytoplankton and nannoplankton showed interesting variations. The contribution of nannoplankton in total phytoplankton production was higher in the estuary than in the sea.
The percentage of nannoplankton contribution to the primary production in the sea and in the estuary was estimated between 23.53% and to 91.67%. This was about the same in local waters and in other areas round the world. The relationship between the cell size and productivity was also worked out in the present study. In the sea, the maximum production was usually during February and it coincided with the abundance of phytoplankton cells of mean size, 10 µm. In the estuary, it was usually during April with cells of mean size 15 µm.
The variations in the phytoplankton production during normal, drought and flood years have been also discussed. The N:P ratio of the water showed a wide range of variation. In estuary, the N:P ratio was usually ranging between 15:1 and 30:1. In mangroves the N:P ratio was usually ranging between 10:1 and 25:1. Movement of resident species between the different biotopes was traced and highlighted.