光倒刺鲃对水绵、轮叶黑藻、金鱼藻的摄食选择性及对水质影响

STUDY ON FEEDING PREFERENCE OF SPINIBARBUS HOLLANDI TO SPIROGYRA, HYDRILLA VERTICILLATA AND CERATOPHYLLUM DEMERSUM AND EFFECT ON WATER QUALITY

为探究生物操纵光倒刺鲃(Spinibarbus hollandi)控制大型丝状藻水绵藻华的有效性及安全性,研究了不同密度下(0、26、52、104 g/m3)光倒刺鲃对试验环境中水绵、轮叶黑藻、金鱼藻的摄食状况及对水质的影响,通过显微观察初步分析该鱼对水绵的摄食消化机制,进一步探究该鱼对摄食生物不同生长期的摄食偏好。结果表明:光倒刺鲃在低密度(26 g/m3)下,可高强度摄食水绵,且对3种水生植物的摄食选择性为:水绵>轮叶黑藻>金鱼藻;光倒刺鲃对两种生长时期的水绵均大量摄食,且喜食危害较大的成熟水绵,而对轮叶黑藻幼嫩叶片无显著摄食;其对水绵的消化机制与咽喉齿的机械破碎密切有关;在"鱼-草"共生条件下,各处理组营养盐出现先增后降的趋势,低密度组(26 g/m3)21d后,NH3-N、NO3-N、PO4-P均低于其初始水平;光倒刺鲃难以对浮游微藻产生滤食作用及前期营养盐上升,导致各处理组中叶绿素a较对照组(0 g/m3)均显著上升。预期在轮叶黑藻、金鱼藻等沉水植物为主的人工湖泊城市水景及水产养殖中,较低密度投放该鱼,可有效控制水绵泛滥,并兼顾水质,但在浮游微藻易暴发的水域中,不适于单一运用该鱼。

The research on the feeding preference of Spinibarbus hollandi with gradient density（0,26,52,104 g/m^3） to Spirogyra,Hydrilla verticillata and Ceratophyllum demersum and effect on water quality were carried out to study the feasibility and safety of the biomanipulation of controlling Spirogyra by S.hollandi.Moreover,the grazing preference of the fish to Spirogyra and H.verticillata in different growth stages were also carried out and the intestinal contents have been microscopically observed.The result showed that S.hollandi significantly reduced the biomass of Spirogyra in the low density（26 g/m^3） and feeding preference was： Spirogyra H.verticillata C.demersum.The fish prefer eating mature Spirogyra which has more harmful to environment and were harmless for young leaves of H.verticillata（stems6）.The digestion mechanism is related to mechanical crushing with pharyngeal tooth.The nutrient of treatments were raised and then decreased due to the fish-grass symbiotic system,NH3-N,NO3-N and PO4-P of the low density（26 g/m^3） were lower than the initial concentration after 21d,But the chl-a of all treatments were much higher than the control（0 g/m^3） after 21d.It expected that the appropriate low density is more useful in the application,which could effectively control Spirogyra and be harmless to water quality,but the single application of the fish could not be suitable in the aquatorium where micro phytoplankton boom frequently happen.