大型溞和金鱼藻对三种微藻增殖的影响

为了解生物操纵和恢复水生植被的抑藻效果,分别以大型溞(Daphnia magna)和金鱼藻(Ceratophyllum demersum)作为浮游动物和大型沉水植物的代表,以小环藻(Cyclotella sp.)、小球藻(Chlorella vugaris)和铜绿微囊藻(Microcystis aeruginosa)作为浮游植物的代表,在温度25℃、光照度2 600-3 000 lx和光暗比14 h∶10 h的条件下,研究三种藻共培养和单一加入大型溞、金鱼藻以及同时加入大型溞和金鱼藻时各自生物量的变化。结果表明:三种藻共培养时,最终铜绿微囊藻占总藻细胞数的95.9%,成为优势种;单一加入大型溞或金鱼藻时,三种藻的增长被显著抑制,特别是铜绿微囊藻,最终小球藻占优势,单一加入大型溞的抑制效果更好;同时加入大型溞和金鱼藻时,大型溞的数量增加了55.6倍,金鱼藻的质量增加了42%,三种藻提前进入衰减状态,小环藻、小球藻和铜绿微囊藻达到最大藻细胞密度时的增殖抑制率分别为36.02%、-5.46%、99.91%,大型浮游动物和沉水植物的联合作用能更好地控制浮游藻类的增殖。

Effects of Daphnia magna and Ceratophyllum demersum on the growth of three microalgae

Daphnia magna and Ceratophyllum demersum were selected as the representative of zooplankton and submerged macrophyte and Cyclotella sp., Chlorella vugaris and Microcystis aeruginosa were selected as the representative of phyto-plankton to evaluate the inhibition effect of biomanipulation and aquatic vegetation restoration on algae.The biomass of D.magna, C.demersum and algae were studied with temperature of 25 ℃, illumination ranged from 2600 to 3000 lx and light dark ratio 14 h∶10 h.The experiments were treated in the following three circumstances: co-culture of three species of algae; co-culture of three species of algae with D.magna or C.demersum in; co-culture of three species of algae with D.magna and C.demersum in simultaneously.The results indicated that M.aeruginosa became the dominant species finally and accounted for 95.9% of the total algae cells in the three species mixed cultured condition.When the three species of al-gae were co-cultured with D.magna or C.demersum in, the growth of the three species of algae was significantly inhibi-ted, especially M.aeruginosa was inhibited strongest and C.vugaris became the dominant species in the end.The effect of algae inhibition was better when the three species of algae were co-cultured with D.magna in singly.When D.magna and C.demersum were co-cultured with the three species of algae simultaneously, the number of D.magna increased by 55.6 times and the quality of C.demersum increased by 42%.All the algae reached the state of decay in advance in this condi-tion.When the cell density of Cyclotella sp., C.vugaris and M.aeruginosa reached the maximum, the growth inhibition rates were 36.02% , -5.46% , 99.91% , respectively.The increasing of algae could be controlled far better by adding large zooplankton and submerged macrophytes simultaneously than singlely.