湖泊科学   2020, Vol. 32 Issue (6): 1817-1826.  DOI: 10.18307/2020.0621. 0

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YU Jinlei, YANG Liu, XIA Manli, HOU Yuanzhang, HE Hu, GUAN Baohua, LIU Zhengwen. Effects of bitterling fish on the relationships between submerged macrophytes and mussel. Journal of Lake Sciences, 2020, 32(6): 1817-1826. DOI: 10.18307/2020.0621.
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2019-10-31 收稿
2020-03-20 收修改稿

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(1: 中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室, 南京 210008)
(2: 暨南大学生态学系水生生物研究所, 广州 510632)
(3: 同济大学环境科学与工程学院, 上海 200092)
(4: 中国科学院大学中丹科研教育中心, 北京 100049)

Effects of bitterling fish on the relationships between submerged macrophytes and mussel
YU Jinlei1 , YANG Liu1 , XIA Manli1,2 , HOU Yuanzhang3 , HE Hu1 , GUAN Baohua1 , LIU Zhengwen1,2,4
(1: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China)
(2: Department of Ecology and Institute of Hydrobiology, Jinan University, Guangzhou 510632, P. R. China)
(3: College of Environment Science and Engineering, Tongji University, Shanghai 200092, P. R. China)
(4: Sino-Danish Center for Education and Research, University of Chinese Academy of Sciences, Beijing 100049, P. R. China)
Abstract: Submerged macrophytes play an important role in stabilizing the water environments, thus restoration of submerged macrophytes has been the key to the restoration of shallow eutrophic lakes. Meanwhile, mussel stocking has been conducted as a parallel measure for submerged macrophytes restoration, because the filter-feeding mussels can improve and maintain a higher water clarity which it will enhance the growth of macrophytes. However, mussels, acting as an important spawning substrate for bitterling, may also facilitate the population development of bitterling fish (the common name for cyprinid fishes from the subfamily Acheilognathinae). The effects of bitterling fish on aquatic ecosystems are not clear. In the present study, we conducted an outdoor mesocosm experiment to study the effects of bitterling fish on water quality, the growth of submerged macrophytes and the attached periphyton, and the relationship between mussel and macrophytes. Three treatments were set with 4 replicates for each group, they are control (without mussel and bitterlings), mussels (with Sinanodonta woodiana), and mussel-bitterlings treatment (with both A. woodiana and Acheilognathus macropterus), meanwhile all the mesocosms were planted with equal density and biomass of Vallisneria denseserrulata. The results showed that the presence of bitterlings significantly increased the concentrations of total phosphorus, total dissolved phosphorus, suspended solids (TSS, OSS and ISS) and Chl.a of phytoplankton, but not for total nitrogen and total dissolved nitrogen. At the end of the experiment, the growth rate (both RGR and total individual), root-shoot biomass ratio, and maximum leaf length of macrophytes did not differ significantly between the mussel and control mesocosms, while the mean individual biomass of macrophytes in the mussel group was significantly higher than that of the controls which may be related to the higher biomass of periphyton on the surface of macrophytes leaves, though not significant compared with the controls. However, the presence of bitterlings did not significantly affect the mussel-macrophytes relationships. In comparison with the mussel's treatment, although bitterlings did not affect the RGR and total individuals of macrophytes, the maximum length of leaves was higher in the mussel-bitterling mesocosms than mesocosms with mussels, while the root-shoot biomass ratio was lower. These changes may be caused by the much higher concentrations of nutrients, suspended solids, Chl.a of phytoplankton and biomass of periphyton on the surface of leaves induced by the bitterlings which may boosted the growth of macrophytes leaves. Our results have important implications for lake management and restoration: bitterling is a small omnivorous fish which is widely distributed in lakes in the middle and lower reaches of Yangtze River. Moreover, they are highly correlated with submerged macrophytes and recovered quickly after lake restoration, so the monitoring and management of the small omnivorous fish, like bitterling in our study, should be strengthened when restoring and managing of shallow lakes.
Keywords: Bitterling    mussel    Vallisneria denseserrulata    lake restoration    submerged macrophytes    omnivorous fish

1 材料与方法 1.1 试验设置

1.2 样品采集与分析

 $RGR = 1000 \times {\rm{ln}}({W_{\rm{f}}}/{W_{\rm{i}}})/d$ (1)

1.3 数据分析

2 结果 2.1 水体营养盐浓度

 图 1 试验期间不同处理组的总氮、总溶解氮、总磷和总溶解磷浓度随时间的变化 Fig.1 Concentrations of total nitrogen, total dissolved nitrogen, total phosphorus and total dissolved phosphorus in different treatments during the experiment

2.2 水体Chl.a浓度

 图 2 试验期间不同处理组的水体叶绿素a浓度 Fig.2 Concentrations of chlorophyll-a in different treatments during the experiment
2.3 水体悬浮质浓度

 图 3 试验期间不同处理组的总悬浮质、总有机悬浮质和总无机悬浮质浓度随时间的变化 Fig.3 Concentrations of total suspended solids, organic suspended solids and inorganic suspended solids in different treatments during the experiment

2.4 附着藻类

 图 4 密刺苦草叶片表面附着藻类生物量 Fig.4 The biomass of periphyton on the surface of V. denseserrulata
2.5 密刺苦草

 图 5 密刺苦草在试验结束时的相对生长率(RGR)和总株数 Fig.5 The relative growth rate (RGR) and total plant individuals of V. denseserrulata at the end of the experiment

 图 6 试验结束时密刺苦草的根冠比、最大叶长和单株平均生物量 Fig.6 Root-shoot dry biomass ratio, maximum leaf length and mean individual biomass of V. denseserrulata at the end of the experiment
3 讨论

4 结论

1) 在密刺苦草为主的系统中，与对照组相比，背角无齿蚌(河蚌组)的出现未显著改变水体营养盐、Chl.a和悬浮颗粒物浓度.

2) 河蚌对密刺苦草的生长(RGR)、繁殖(总株数)、根冠比和最大叶长均无显著性影响，而河蚌显著增加了苦草的单株生物量(P < 01);此外，苦草叶片表面附着藻生物量也高于对照组(但差异不显著，P > 0.05).

3) 鳑鲏(大鳍鱊)的出现(河蚌+鳑鲏组组)，不仅引起试验系统营养盐、Chl.a和悬浮物浓度显著升高，而且还促进了植物表面附着藻的生长，其附着藻生物量显著高于河蚌组.

4) 虽然河蚌+鳑鲏组的水体营养盐和植物表面附着藻生物量均显著高于河蚌组，但这并未显著影响密刺苦草的生长和繁殖.然而从湖泊生态修复效果的长效维持角度考虑，过多的鳑鲏可能会进一步加剧水体营养盐和Chl.a浓度升高，促进植物表面附着藻的生长，通过遮光效应(较高的浮游植物和附着藻类生物量)阻碍沉水植物生长和种群发展.因此，在湖泊生态修复中，应加强鳑鲏等小型杂食性鱼类的监测与管理; 并开展进一步研究，评估鳑鲏等小型杂食性鱼类在浅水湖泊生态系统中的地位与作用.

5 参考文献