Study on the water quality conservation in ponds used abundant waterfowl and/or Common Cormorant

据报道，在日本，许多池塘在冬季使用大量的迁徙水禽，水质恶化。然而，关于水禽及其他水鸟对水环境影响的研究却很少。为了阐明水禽对水质的影响，我们在几个湖泊进行了水禽生物量与水质的关系研究。宫岛沼（M）、L.Izunuma附近的饲养池（I）、东京港鸟类保护区的淡水池（T）、卡塔诺鸭池（K）、约纳戈水鸟保护区的咸淡水池。这些池塘是日本典型的水禽养殖池塘，除K池塘外，TN、DTN和NH_4-N浓度均随水禽生物量的增加而增加。TP和Chl-a浓度在春季上升，不久后水鸟飞走。NH_4-N浓度与水禽生物量有直接关系。冬季水禽活动使部分池塘中NO_3-N浓度升高，但NO_3-N的来源可能是农田。此外，在日本武藏百合森林公园的山田大沼池，还研究了鸬鹚对水质的影响。该池塘的水质恶化，普通鸬鹚，和重水华微囊藻持续从6月至10月。叶绿素a浓度在400 mg/m^3以上。

It was reported that water quality in many ponds using abundant migratory waterfowl in winter period in Japan were deteriorated. However, there are few study on the effect of waterfowl and other waterbird to the water environment. In order to clarify the effect of waterfowl to water quality, we studied the relationship between water quality and waterfowl biomass at several lakes, such as L. Miyajimanuma (M), Feeding Pond near L.Izunuma (I), Fresh Water Pond in Tokyo -port Bird Sanctuary (T), Katano Kamoike Pond (K), and brackish pond in Yonago Waterbird Sancutuary. These ponds were typical ponds using abundantly waterfowl in Japan.TN, DTN and NH_4-N concentrations were increased with the increase of waterfowl biomass, except Pond K. TP and Chl-a concentrations increased in spring, soon after waterfowl fly away. NH_4-N concentration related directly with waterfowl biomass. NO_3-N concentration also increased in several pond in winter period with residence of waterfowl, however, the origin of the NO_3-N seemed to be agriculture land. COD and DOC concentrations also increased after waterfowl fly away in several ponds.The effect on Common Cormorant to water quality was also studied at Yamada-Onuma Pond in the Mushashiyuryo Forest Park. Water quality of this pond was deteriorated by Common Cormorant, and heavy water bloom by Microcystis sp. continued from June to October. Above 400mg/m^3 of Chl-a concentrations were observed in this period.