Phytoplankton diversity in the Parangipettai coastal waters, southeast coast of India.

An investigation was carried out during June 2005 to May 2007 on hydrography, composition and community structure of phytoplankton including chlorophyll a in Parangipettai coastal waters (southeast coast of India). Air and surface water temperatures varied from 25.5 to 31.2 °C and from 25 to 29.3°C, respectively. Salinity values varied from 5 to 33.1‰ and the pH ranged between 7.2 and 8.3. Dissolved oxygen content varied from 3.1 to 7.9 mg l-1 while the light extinction coefficient values (LEC) ranged between 1.8 and 11.0 cm. The range of inorganic nutrients viz., nitrate, nitrite, phosphate and silicate were: 6.5 - 27.0 µM; 1.0 - 8.9 µM; 0.1 - 3.0 µM and 15.0 - 140 µM, respectively. The range of chlorophyll a was: 2.0 - 7.5 µg l-1. Presently, 117 phytoplankton species representing different classes viz: Bacillariophyceae (66); Dinophyceae (22); Cyanophyceae (19); Chlorophyceae (7) and Chrysophyceae (3) were recorded. The phytoplankton cell abundance varied from 0.14 to 132 cells ml-1, with peak diversity (3.52 bits ind.-1) during summer season. The maximum abundance was found during summer season coinciding with the stable hydrographical conditions. Canonical Correspondence Analysis was applied in this study for discriminating environmental factors effecting on phytoplankton community at species level.

Phytoplankton diversity in Pichavaram mangrove waters from south-east coast of India.

The results of an investigation carried out during September 2002 to August 2003 on hydrography, composition and community structure of phytoplankton including chlorophyll ‘a’ (Chl-a) content and primary productivity (PP) of the Pichavaram mangrove (South-east coast of India) are reported. Atmospheric and surface water temperatures varied from 30.0 to 34.8oC and from 29.7 to 34.2oC respectively while the light extinction coefficient values (LEC) (K) ranged between 3.2 and 14.9. Salinity values varied from 9.6 to 35.4‰ and the pH ranged between 7.2 and 8.6. Variation in dissolved oxygen content was from 3.2 to 6.5 ml l-1. The ranges of inorganic nutrients viz., nitrate, nitrite, phosphate and silicate were: 7-36.23, 0.31-5.46, 0.28-3.70 and 12.26-56.64 μM respectively. Chlorophyll ‘a’ content ranged between 0.20 and 105.60 ;g l-1 and the ranges of gross and net primary productivities (PP) were: 16.54-826.8 and 11.52-610.2 mg C m-3 hr -1respectively. Presently a total of 94 species of phytoplankton were identified. Among these, the diatoms formed predominant group. Population density of phytoplankton varied from 400 to 3,21,000 cells-1. While the peak diversity (5.23 bits / ind.) of the phytoplankton was observed during summer season, the maximum population density was found during summer season coinciding with the stable hydrographical conditions.

Seasonal variations in physico-chemical characteristics of Pichavaram mangroves, southeast coast of India.

All the physico-chemical parameters such as temperature, salinity pH, dissolved oxygen and nutrients like nitrate, nitrite, inorganic phosphate and reactive silicate were studied in Pichavaram mangroves, southeast coast of India, for a period of two years (April 2000-March 2002). Air and surface water temperatures varied from 27 degrees C to 38 degrees C and from 26 degrees C to 37 degrees C. Salinity varied from 3.0 per thousand to 33.0 per thousand and the pH ranged between 7.2 and 8.2. Variation in dissolved oxygen content was from 2.4 to 5.0 ml l(-1). Concentrations of nutrients viz nitrates (9.50 to 32.12 microM), nitrites (1.07 to 5.99 microM), phosphates (0.73 to 2.36 microM) and reactive silicates (22.1 to 89.8 microM) also varied independently.