Fish-mediated plankton responses to increased temperature in subtropical aquatic mesocosm ecosystems: Implications for lake management
Fish-mediated plankton responses to increased temperature in subtropical aquatic mesocosm ecosystems: Implications for lake management
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鱼类介导的浮游生物对亚热带水生中生态系统温度升高的反应：对湖泊管理的影响
DOI：
10.1016/j.watres.2018.07.055
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发表时间：
2018
期刊：
影响因子：
12.8
通讯作者：
Zhang Yongdong
中科院分区：
文献类型：
--
作者：
He Hu;Jin Hui;Jeppesen Erik;Li Kuanyi;Liu Zhengwen;Zhang Yongdong
尽管气候变暖可以通过改变食物网中自上而下和自下而上的过程以及生物地球化学循环来加强浅水湖泊的富营养化，但最近在温带地区的研究也表明，在无鱼系统中，温度上升的不利影响会减弱。虽然清除食游动物鱼类可能有助于缓解温带浅水湖的富营养化，但不确定在较温暖的气候中是否也能实现类似的缓解。在一个为期4个月的亚热带温度下的中游实验中，我们比较了浮游动物和浮游植物群落在有鱼和没有鱼的情况下对气候变暖的响应。我们假设，1)鱼类和浮游植物将受益于变暖，而浮游动物将在有鱼的中层生态系统中受到影响，2)气候变暖将有利于浮游动物的生长，但会减少没有鱼类的中层生态系统的浮游植物生物量。我们的结果表明，气候变暖和鱼类的存在对浮游植物和浮游动物都有显著的交互作用。在有鱼的中游生态系统中，鱼和浮游植物的生物量在加热处理中增加，而水蚤和总浮游动物的生物量下降。气候变暖降低了大型浮游动物占浮游动物总生物量的比例，降低了浮游动物/浮游植物生物量的比例，但增加了叶绿素/总磷的比例，表明浮游动物对浮游植物的捕食压力有所缓解。同时，气候变暖导致有鱼类存在的系膜体内TP浓度增加了3倍。结果表明，气候变暖有可能通过自上而下(食草动物的丧失)和自下而上(营养物质的增加)效应来促进浅水湖泊的富营养化。然而，在没有鱼类的中游生态系统中，大型水蚤在浮游动物总生物量中没有下降，这支持了鱼类捕食是温暖湖泊大型水蚤丰度较低的主要驱动因素的结论。在无鱼中，浮游植物的生物量和营养水平不受温度的影响。我们的研究表明，在亚热带湖泊中，捕杀鱼类以缓解富营养化的变暖效应可能是潜在的好处，尽管从长远来看，在这些湖泊中快速招募鱼类可能对成功构成挑战。
Although it is well established that climate warming can reinforce eutrophication in shallow lakes by altering top-down and bottom-up processes in the food web and biogeochemical cycling, recent studies in temperate zones have also shown that adverse effects of rising temperature are diminished in fishless systems. Whereas the removal of zooplanktivorous fish may be useful in attempts to mitigate eutrophication in temperate shallow lakes, it is uncertain whether similar mitigation might be achieved in warmer climates. We compared the responses of zooplankton and phytoplankton communities to climate warming in the presence and absence of fish (Aristichthys nobilis) in a 4-month mesocosm experiment at subtropical temperatures. We hypothesized that 1) fish and phytoplankton would benefit from warming, while zooplankton would suffer in fish-present mesocosms and 2) warming would favor zooplankton growth but reduce phytoplankton biomass in fish-absent mesocosms. Our results showed significant interacting effects of warming and fish presence on both phytoplankton and zooplankton. In mesocosms with fish, biomasses of fish and phytoplankton increased in heated treatments, while biomasses ofDaphniaand total zooplankton declined. Warming reduced the proportion of largeDaphniain total zooplankton biomass, and reduced the zooplankton to phytoplankton biomass ratio, but increased the ratio of chlorophyllato total phosphorus, indicating a relaxation of zooplankton grazing pressure on phytoplankton. Meanwhile, warming resulted in a 3-fold increase in TP concentrations in the mesocosms with fish present. The results suggest that climate warming has the potential to boost eutrophication in shallow lakes via both top-down (loss of herbivores) and bottom-up (elevated nutrient) effects. However, in the mesocosms without fish, there was no decline in largeDaphniaor in total zooplankton biomass, supporting the conclusion that fish predation is the major driver of low largeDaphniaabundance in warm lakes. In the fishless mesocosms, phytoplankton biomass and nutrient levels were not affected by temperature. Our study suggests that removing fish to mitigate warming effects on eutrophication may be potentially beneficial in subtropical lakes, though the rapid recruitment of fish in such lakes may present a challenge to success in the long-term.