First recorded bloom of Navicula Bory in a mangrove habitat of Karachi

Discolouration of sands and other marine substrata caused by benthic diatoms have been reported by Aleem (1950) Eaton and Moss (1975), Sullivan (1980), Maple (1983), Navarro (1983) and Wah and Wee (1988). However, this is for the first time such a phenomenon is being reported from a mangrove habitat of Karachi. It was caused by a pennate diatom Navicula cancellata Donkin.

Agar from Gracilaria lichenoides and Gracilaria confervoides from Ceylon

"Agar-agar" is a name derived from the jelly obtained from certain red algae in Malaya. In Sri Lanka agar is prepared from the red seaweeds Gracilaria confervoides and Gracilaria lichenoides. They are commonly known as Sri Lanka moss and the local names are "kandha parsi or sanchow parsi". The uses of agar are given together with details of the method of extraction of this substance from Gracilaria lichenoides and Gracilaria confervoides.

Physical and chemical characteristics of major aquatic ecosystems in the Victoria and Kyoga lake basins

The physical-chemical characteristics of any aquatic ecosystem include pH, conductivity, and temperature, water transparency, nutrient and the chlorophyll-a levels. Physical and chemical factors of any ecosystem determine the type and quality of flora present in it and these forms the basis on which the system operates. The elements required in largest amounts for plant productions are carbon, phosphorus, nitrogen, and silicon, which is important for diatoms as a major component of the cell wall. Nutrients may limit algal productivity in the tropics despite the high temperature there allowing rapid nutrient recycling. Nutrients most likely to be limiting African lakes are nitrogen (Talling & Talling 1965; Moss 1969; Lehman & Branstrator 1993, 1994) and phosphorus (Melack.et al l982; Kalff 1983) while silicon may limit diatom growth (Hecky & Kilham 1988). The objective of the study is to investigate the impact of physical-chemical characteristics on the distribution and abundance of organisms in the major aquatic ecosystems.