Feeding and control of blue-green algal blooms by tilapia (Oreochromis Niloticus)

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• 作者：Kaihong Lu ; Chunhua Jin ; Shuanglin Dong ; Binhe Gu and Stephen H. Bowen
• 关键词：tilapia ; eutrophication ; blue ; green algal blooms ; biomanipulation ; ingestion ; digestion ; nutrients
• 刊名：Hydrobiologia
• 出版年：2006
• 出版时间：September, 2006
• 年：2006
• 卷：568
• 期：1
• 页码：111-120
• 全文大小：285 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Hydrobiology
  Ecology
  
• 出版者：Springer Netherlands
• ISSN：1573-5117

文摘

Outbreak of blue-green algal blooms, with associated unsightly scum and unpleasant odor, occurs frequently in eutrophic lakes. We conducted feeding experiments to study ingestion and digestion of Microcystis aeruginosa by tilapia (Oreochromis niloticus) under laboratory conditions and field testing to reduce Microcystis blooms by stocking tilapia in Lake Yuehu and other eutrophic waters in Ningbo, China between 2000 and 2003. Our results show that tilapia was capable of ingesting and digesting a large quantity of Microcystis. Digestion efficiency ranged from 58.6 to 78.1% at water temperature of 25 °C. Ingestion rate increased with increasing fish weight and water temperature. Intensive blooms occurred in Lake Yuehu in both 1999 and 2000. The lake was stocked with silver carp (Hypophthalmichthys molitrix), bighead (Aristichthys nobilis) and a freshwater mussel (Hyriopsis cumingii) at a total biomass of 9.8 g m?3 in early 2001, and tilapia at 3–5 g m?3 in April of 2002. From June to October, average phytoplankton density decreased from 897.6×106 cells l?1 in 2000 to 291.7×106 cells l?1 in 2001 and 183.0×106 cells l?1 in 2002. Compared to 2000, the annual average phytoplankton biomass in 2001 and 2002 decreased by 48.6% and 63.8%, respectively. The blue-green algal biomass which made up 70% of the total phytoplankton biomass in 2000 was reduced to 22.1% in 2001 and 11.2% in 2002. Meanwhile, Secchi depth increased from 20–50 cm to 55–137 cm during the same time period. Similar results were observed in some other eutrophic waters. For example, algal bloom disappeared about 20 days after tilapia fingerlings were stocked (8–15 g m?3) to a pond in Zhenhai Park. Chlorophyll a concentration and phytoplankton production declined dramatically whereas water transparency increased substantially. However, the impacts of tilapia on nitrogen and phosphorus dynamics in natural lakes need further investigation. Our studies revealed that stocking tilapia is an effective way to control algal blooms in eutrophic waters, especially in lakes where nutrient loading cannot be reduced sufficiently, and where grazing by zooplankton cannot control phytoplankton production effectively.