I. C. ONYEMA
Abstract
Investigations into the physico-chemical characteristics of the overlying waters and microalgal assemblage of the mudflat sediment at Tarkwa bay was carried out to cover two seasons (February - August, 2003). A total of 49 species belonging to 25 genera were recorded. Diatoms formed the most abundant, diverse and frequent group making up 42 species from 20 genera. The blue-green algae made up 4 species from 2 genera, euglenoids 2 species from 2 genera and the green algae recorded 1 species. Among the diatoms the biraphinids (13 taxa) were the numerically more important group with Nitzschia (7 taxa) and Navicula (5 taxa) being more prominent. The abundance of the biraphidineae could be due to their motility and ability to manoeuvre through the sediment. Habour related activities, human waste discharges and refined oil spill pollution common in the area could have resulted in reduced diversity and imposed stress that probably shifted the microalgae community from its natural association to favour a more tolerant community structure.