Eutrophication in a tropical estuary: Is it good or bad?

Abstract

Coastal eutrophication is defined as the increase of rate of organic supply into an estuary. In the recent global discussion, eutrophication is seen as a negative situation, in fact, it has positive impacts such as increase in primary production which lead to the increase of fisheries production and hence, community income. This paper promotes a simple diagram called eutrophication-benefit curve which correlates between levels of eutrophication and its benefits to both ecological and economical aspects. In the beginning of eutrophication process, environment gets benefit from the increase of the nutritional state of the water which leads to the increase of primary production and fisheries production. This is obvious in the comparison between northern and southern coast waters of Java Island, showing a higher primary production and phytoplankton biomass and hence fisheries production in the northern coast waters of Java compared to those of the southern coast waters of Java. However, the rapid increase of eutrophication level of the northern coast waters of Java Island causes eutrophication negative effects such as oxygen depletion, algae bloom and disturbance of coral reef ecosystems. This paper shows the optimum level of eutrophication level that can give benefit to both ecological and social environment.