Abstract
The potential productivity and growth potential in Shatt al-Arab estuary were determined at two selected stations, up and down stream Basrah city centre, Iraq during spring 1985 and 1986. These biological parameters were used as indication on the influence of the city drainage on the estuary. Physico-chemical parameters and major nutrients were measured. Significant correlations were found between some studied parameters and the tide, while the assimilation number show no correlation to the tide and to the sampling time.