The Environmental Impact of Marine Shrimp Farming Effluents and Carrying Capacity Estimation At Kung Krabaen Bay, Eastern Thailand

Abstract

Water quality parameters in marine shrimp farms around Kung Krabaen Bay were surveyed from 1989-1994. The average transparency was 0.425 m± 0.024 in shrimp ponds, 0.680 m±0.012 in the water supply canal, 1.008 m± 0.110 in Kung Krabaen Bay and 1.635 m± 0.530 in the surrounding coastal areas. Total ammonia-nitrogen was 0.120 mg/I± 0.0012 in shrimp ponds, 0.032 mg/1±0.002 in the water supply canal, 0.017 mg/1±0.001 in the bay, 0.012 mgn±0.001 in coastal waters and 0.401 mg/1±0.002 in discharge canals. Total bacterial plate count was 19,003 CFU/ml±15.4 in the bay and 23,801 CFU/ml±l 7.33 in the discharge canal. Total area of the farms engaged in intensive marine shrimp farming at Kung Krabaen Bay was around 142.76 ha. The total effluent discharge loading into the bay was around 67,400 ton/ha/crop. The BOD and ammonia loading were 699.60 kg/ha/ crop and 12.81 kg/ha/crop, respectively. Carrying capacity of Kung Krabaen Bay, which has a total water surface area of 640 ha, was estimated using a mass balance model. Ammonia-nitrogen in receiving water or in the bay was set as the optimum safe concentration for sea water standard at 0.1 mg/1. The carrying capacity for intensive marine shrimp farming loading at Kung Krabaen Bay can be allowed upto 543.93 ha. The water balance model for carrying capacity and water quality prediction in the bay were discussed in detail.