Environmental effect of fishpen culture operation of milkfish (Chanos chanos) to the euthropication of brackishwater rivers in sector 2 of Lingayen Gulf [Philippines]

The study was conducted to determine the immediate effect of the continuous intensive culture of milkfish to the eutrophication of estuaries or brachiswater rivers of Dagupan City, Binmaley and Lingayen in Pangasinan [Philippines] which are part of Sector 2 in Lingayen Gulf. Specifically, the study aimed to determine the signicant relationships between the continuous days of milkfish culture operation and the concentrations o nutrients such as ammonia, nitrite, and phosphate and the concentrations of chlorophyll-a and phaeopigment and the relationships between the nutrients and the total pigments. Results showed a significant positive relationship between the continuous operation of milkfish pen culture and the nutrient concentrations of the rivers indicating the accumulation of nutrients such as ammonia, nitrite and phosphate resulting from the release of waste from uneaten and excess feeds, excretory products and probably from domestic wastes and other non-point sources. The significant and positively moderate to high relationship between nutrient concentrations and chlorophyll-a and phaeopigment concentrations of the river water indicates an increase in primary productivity or phytoplankton production in all three coastal areas. There was a high production of golden brown algae or diatoms, followed by blue-green algae, green algae and dinoflagellates in the rivers of Binmaley, Lingayen and Dagupan City which is an indication of water euthropication in areas where there is a continuous intensive culture of milkfish in fishpens. Results also showed a negative environmental impact on the water quality of brackishwater rivers in Sector 2 of Lingayen. Hence, the regulation of milkfish pen culture is highly recommended for the sustainable management of the coastal and inland water resources of Pangasinan.