Shallow lakes at risk: Nutrient enrichment enhances top-down control of macrophytes by invasive herbivorous snails
Shallow lakes at risk: Nutrient enrichment enhances top-down control of macrophytes by invasive herbivorous snails
复制标题
浅水湖泊面临风险：营养物富集增强了入侵草食性蜗牛对大型植物的自上而下的控制
DOI：
10.1111/fwb.13649
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发表时间：
--
影响因子：
2.7
通讯作者：
Ge Gang
中科院分区：
文献类型：
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作者：
Liu Ying;He Liang;Hilt Sabine;Wang Rui;Zhang Huan;Ge Gang
在浅水湖泊中，沉水植物可以稳定清澈的水环境，防止浮游植物大量繁殖。营养丰富可以促进它们的丰富。然而，在水营养物浓度超过临界阈值时，世界各地许多湖泊的沉水植物已经崩溃，对重要的生态系统功能产生了负面影响。这种下降背后的机制是复杂的，并受到争议。我们进行了围隔和实验室实验，以调查自上而下的影响，入侵草食性蜗牛（福寿螺）对本地沉水植物（苦草）在低和中等营养处理。我们测试了水体中营养物的添加对螺食草性的影响是否受到浮游植物和附生植物的遮蔽、水生植物元素组织含量和螺营养物释放的影响。我们发现食草性螺对水生植物具有强烈的自上而下的负面影响，水体中营养物的富集放大了这种影响，导致更高的水生植物消耗率。在中等营养水平下，水生植物消耗快，钉螺生长好于低营养水平。此外，蜗牛处理有较高的氮浓度在水中导致负反馈loop.Our研究结果表明，蜗牛草食性可能会增加的机会，水生植物崩溃和浅水湖泊的转变，以浑浊的状态，这种影响发生在较低的蜗牛密度时，营养物质浓度增加。因此，浅水湖泊受到营养负荷预计增加和入侵食草软体动物扩散的严重威胁。
In shallow lakes, submerged macrophytes can stabilise clear‐water conditions and prevent phytoplankton blooms. Nutrient enrichment can promote their abundance. Above critical thresholds in water nutrient concentrations, however, submerged macrophytes have collapsed in many lakes worldwide with negative consequences for important ecosystem functions. The mechanisms behind this decline are complex and subject to debate.We conducted mesocosm and laboratory experiments to investigate the top‐down effect of invasive herbivorous snails (Pomacea canaliculata) on native submerged macrophytes (Vallisneria natans) under low and moderate nutrient treatment. We tested whether effects of nutrient addition to the water column on snail herbivory were influenced by shading by phytoplankton and epiphyton, macrophyte elemental tissue content and snail nutrient release.We found that herbivorous snails had strong negative top‐down effects on macrophytes, which were amplified by nutrient enrichment in the water column leading to higher macrophyte consumption rates. In moderate nutrient treatment, macrophyte consumption was faster and snails grew better than in low nutrient treatment. Additionally, snail treatments had higher nitrogen concentrations in the water leading to a negative feedback loop.Our results suggest that snail herbivory may increase the chance for macrophyte collapse and shifts of shallow lakes to turbid states, and this effect occurs at lower snail densities when nutrient concentrations increase. Shallow lakes are thus severely at risk from projected increases in nutrient loading and spread of invasive herbivorous molluscs.