Ecological and Socioeconomic Characteristics of Integrated Aquaculture Practices in Yingbin Bay, Hainan Province, China

Abstract

This study focuses on two types of integrated aquaculture systems used in Yingbin Bay, Hainan Province, China: a shrimp (intensive) and abalone system, and a shrimp (semi-intensive), seaweed and duck system. The specific goals of the study were to 1) evaluate water and sediment quality in ponds for these two integrated farming systems; 2) determine common farming methods in the region through interviews with farmers; and 3) evaluate effects of integrated culture on water quality in Yingbin Bay. In order to accomplish these goals, a combination of on-site water and soil quality analysis, as well as interviews with twenty-two farmers, were conducted from March to June 2006. The two integrated systems varied greatly in their design and management. The shrimp and abalone system was comprised of three intensive shrimp ponds that were fed by abalone effluent and groundwater. The shrimp, seaweed and duck system was comprised of one semi-intensive shrimp pond and one seaweed and duck pond. The farmer used the seaweed and duck pond for biofiltration of his shrimp effluent, such that water was recirculated between the two ponds. Both integrated systems were able to maintain water quality adequate for shrimp growth. However, both systems failed to meet Global Aquaculture Alliance’s standards for total phosphorus and total suspended solids. The seaweed and duck pond was hypothesized to have lower nutrient concentrations relative to all of the shrimp ponds in the study due to seaweed’s ability to uptake nutrients, but nitrate and total phosphorus concentrations were much higher in the seaweed and duck pond than in the shrimp ponds. Other nutrient parameters in the duck and seaweed pond were found in concentrations similar to those in the intensive shrimp ponds. Total ammonia and phosphate concentrations decreased downstream through the Yingbin Bay culture area, implying that water quality improved on an upstream to downstream gradient. This may be the result of aquaculture activities utilizing nutrients flowing downstream. However, total phosphorus, and COD concentrations did not decrease (and in some cases increased). In particular, high total phosphorus concentrations were observed throughout the study ponds and bay in April (as high as 1.70 mg/L); phosphate concentrations did not increase as dramatically, indicating that the phosphorus source was not inorganic fertilizer. According to the results of farmer interviews, farmer perceptions of water quality in the bay varied. Shrimp farmers believed that the bay had significant water quality problems, especially in terms of nutrients and disease. Seaweed farmers perceived no nutrient problems, but felt that physical water quality parameters, such as temperature and salinity, were not adequate for seaweed growth. Almost all farmers interviewed were interested in receiving help from universities and the government in order to develop better production systems. Given that farmers interviewed perceived problems with environmental quality in the bay and were interested in learning new and better management techniques, there are opportunities for researchers to work with Yingbin Bay farmers to adjust pond management techniques in order to increase productivity and improve water quality.