is there any reason that there is a great capacity for high productivity in the water in estuaries?
Estuaries are nutrient rich. The nutrient richness is due to river runoff and the mixing of salt and fresh water. The nutrient allows microorganism to grow easily and not in a limited fashion. These microorganism becomes food for the zooplankton. Phytoplankton will also grow well. The plankton then become food for the bigger fauna such as fish.
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