Phosphorus Dynamics, Eutrophication and Fisheries in the Aquatic Ecosystems in India

Phosphorus (P) is the most limiting nutrient element in the inland aquatic ecosystems. In Indian context also, many water bodies are deficient in the readily available form of the nutrient. The present effort was to understand the P-dynamics in relation to fish production. While feed and fertilizer are the main inputs of P for the culture systems, the element is accumulated in the bottom mud to a great extent. Fish harvests accumulate 10-20% of P. In culture systems with water exchange, significant amount of P flows with the discharge/exchange water. The wetlands, rivers and reservoirs in the country show gradual accumulation of the element and eutrophication is becoming a serious concern mostly due to anthropogenic activities. East Kolkata wetlands are a unique example where fish is used as the bio-remediating agent. In general, mangrove plants also have good capacity to recover from adverse effects of commercial shrimp farming. There is scope to utilize advanced mathematical models to optimize the production and at the same time, conserve the resources. As a whole, there is ample scope for improvement and to understand the P-dynamics in different water resources of India.