Ecology of Phytoplankton of the Volta Lake

✍ Scribed by S. Biswas

• Publisher: Springer
• Year: 1972
• Tongue: English
• Weight: 445 KB
• Volume: 39
• Category: Article
• ISSN: 1573-5141
• DOI: 10.1007/bf00047189

✦ Synopsis

A correlation between the dissolved oxygen and phytoplankton was observed in the newly created Volta Lake although a similar correlation was not observed in the Volta River before the impoundment (BISWAS, 1966a) . The lake was initially filled with an opalescent brown flood water rich in iron (BIswAs, 1966b) . The resulting decrease in transparency lowered the photosynthetic activity of the phytoplankton . Changes in the physico-chemical conditions were most pronounced during the second year of development of the lake . The aim of this paper is to examine these changes in relation to the phytoplankton .

Methods

Observations were made at Ajena, an offshore station 3 km from the dam . Samples were collected with a closing type water bottle during the late morning or early afternoon each week .

The transparency of water was determined by means of a glossy white Secchi disk, 20 cm in diameter and suspended by a graduated cable . The disk was gradually lowered into the water and the depth at which it went out of sight was noted . The disk was then pulled up and the depth at which it was just visible was again noted . The average of these two depths gave the measurement of Secchi disk transparency . Under sunny conditions such measurements were made on the shaded side of the boat (WELCH, 1948) .

A Lovibond Nessleriser was used for the determination of the colour of water directly and the total iron content by the Thio-