Biological characteristics of the improved extensive shrimp system in the Mekong delta of Vietnam |
| |
| Authors: | Nguyen Tho Roel Merckx Vu Ngoc Ut |
| |
| Institution: | 1. Vietnamese Academy of Science and Technology, Ho Chi Minh City Institute of Resources Geography, Ho Chi Minh City, Vietnam;2. Faculty of Bioscience Engineering, Department of Earth and Environmental Sciences, Division Soil and Water Management, Katholieke Universiteit Leuven, Heverlee, Belgium;3. Department of Applied Hydrobiology, College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam |
| |
| Abstract: | Low and unstable shrimp yields of the improved extensive shrimp system has been a tremendous obstacle for economic development in the coastal areas of Southern Vietnam. To investigate the biological characteristics of this system, ponds in the coastal Cai Nuoc district, Mekong delta of Vietnam, were monitored. Results showed that the system was not optimal for shrimp. While chlorophyll a (chl a) (1.51–37.2 μg L?1), phytoplankton density (6333–974 444 cells L?1) and zooplankton density (7.1–517.2 ind L?1) were abundant and comparable to shrimp farms elsewhere, zoobenthic community was very poor (7–1971 ind m?2). Toxin‐producing cyanobacteria (Oscillatoria limosa, Oscillatoria formosa, Anabaena sp. and Phormidium tenue) were found. Total bacteria and Vibrios were present in large numbers (respectively 1.04 × 105 and 6.64 × 102 CFU mL?1 in pond water, 6.33 × 105 and 9.47 × 103 CFU g?1 in sediment). Presence of toxin‐producing organisms, poor zoobenthic community and abundance of Vibrios all can enhance shrimp susceptibility to diseases. The following measures are recommended to improve the situation: (1) complete testing of seeds for pathogens, (2) not to incorporate fish into shrimp ponds and (3) applying no‐culture breaks and pathogen‐killing chemicals. |
| |
| Keywords: | bacteria Mekong delta phytoplankton shrimp zoobenthos zooplankton |
|
|
