鱼饵对铜绿微囊藻生长的影响

Effect of Fish Bait on Microcystis aeruginosa Growth

分别取0,0.1,0.2,0.5和1.0 g不同粒径(原状,0.15 mm<d≤0.85 mm和d≤0.15 mm)的鱼饵加入到400 mL无氮磷M11培养基中,研究鱼饵粒径和投加量与营养盐释放之间的关系.结果表明,水体中ρ(TP),ρ(DOP),ρ(NH4+-N)和ρ(TN)随着鱼饵投加量增加而显著升高(P﹤0.05);同一投加量条件下,鱼饵粒径对水体ρ(TN)和ρ(TP)影响不大(P﹥0.05).同时,另外选用0,0.05,0.10,0.20和0.50 g原状鱼饵研究铜绿微囊藻在鱼饵培养基溶液中的生长状况.结果发现,当鱼饵投加量在0～0.2 g时,随着鱼饵释放可利用营养盐水平的提高,藻细胞最大现存量随鱼饵投加量的增加逐渐增大;鱼饵释放的NH4+-N和溶解性正磷酸盐(DOP)是铜绿微囊藻吸收利用的主要氮磷形态.鱼饵的投加造成铜绿微囊藻生长延缓期延长,但鱼饵营养盐释放达到平衡后接入藻种,延缓期延长的现象消失,鱼饵中营养盐的溶失和矿化过程消耗了大量溶解氧,是出现藻类生长延缓期延长的重要原因.

Five different dosages（0,0.1,0.2,0.5 and 1.0 g） of fish bait with three different grain sizes（original,0.15 mm d≤0.85 mm,and d≤0.15 mm） were added into 400 mL of M11 culturing medium without nitrogen and phosphorus.The aim was to explore the nutrient release characteristics with different grain sizes and dosages.The results indicated that the concentration of total phosphorus（TP）,orthophosphate（DOP）,total nitrogen（TN） and ammonia nitrogen（NH4 ＋-N） in water increased significantly with the increase of fish bait dosages（P 0.05）.Grain size had negligible effects on the concentration of total phosphorus（TP） and total nitrogen（TN） in water with the same dosage.At the same time,Microcystis aeruginosa was introduced into the culturing medium to investigate the effect of fish bait addition（0,0.05,0.10,0.20 and 0.50 g） on algae growth.It was found that the biomass of Microcystis aeruginosa increased with increasing dosage and available nutrient concentrations ranging between 0 and 0.2 grams.Further experimental results indicated that ammonia nitrogen and orthophosphate were the main fractions of nutrients used by Microcystis aeruginosa.It was also found that Microcystis aeruginosa growth lag phase was extended several days with the presence of fish bait,but this phenomenon disappeared when vaccinations were conducted with balanced nutrient release conditions.The most probable reason for this is that the process of dissolution,mineralization,and nutrient release greatly reduced dissolved oxygen availability in the medium,which restrained the algal growth to some degree.