The Hydrochemistry and Plankton Dynamics of a Closed Eutrophic Tropical Lagoon

Abstract

The hydrochemistry and plankton dynamics of the Kuramo lagoon was investigated between November 2000 and
August 2001. Whereas the lagoon remains low brackish (S°/oo < 4.39°/oo) and alkaline (pH > 7.8) all through the
sampling period, the dissolved oxygen (DO) and biochemical oxygen demand (BOD5) values (< 3.50 mgl-1; > 21
mgl-1) indicated stress. Although nutrient levels at the lagoon were high (NO3- N > 1.58 mgl-1; PO4-P < 0.35 mgl-1;
SO42- > 449.9 mgl-1), heavy metal values were low (Fe < 1.91 mgl-1, Cu < 0.32 mgl-1, Pb Trace). The occurrence of
Nitzschia palea, Cyclotella meneghiniana, Gomphonema parvulum, Pinnularia pyrum, P. gibba (diatoms), Euglena viridis,
Lepocinclis texta (euglenoids), Microcystis aeruginosa, M. flos-aquae (cyanobacteria), Brachionus