Temporal variation of energy reserves in mayfly nymphs (Hexagenia spp.) from Lake St Clair and western Lake Erie
Temporal variation of energy reserves in mayfly nymphs (Hexagenia spp.) from Lake St Clair and western Lake Erie
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圣克莱尔湖和伊利湖西部蜉蝣若虫（Hexagenia spp.）能量储备的时间变化
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发表时间：
2003
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影响因子：
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通讯作者：
D. W. Schloesser
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作者：
J. Cavaletto;T. Nalepa;D. Fanslow;D. W. Schloesser
摘要1.我们分析了穴居小蜂(Hexagenia spp.)能量储备(脂和糖原)和体长-体重关系的变化。1997-99年度，将圣克莱尔湖的现有人口与劳伦斯五大湖伊利湖西部的恢复人口进行比较。此外，我们还测量了水柱和沉积物中水温和潜在食物的变化。2.尽管圣克莱尔湖和西伊利湖的六角鱼若虫的脂类和糖原水平总体平均值没有显著差异，但两湖的季节模式存在差异。在圣克莱尔湖，浓度在早春最高，全年下降，在所有3年的研究中在秋季达到最低水平。相比之下，伊利湖西部的水平在春季较低，夏季达到最大值，然后在秋季下降。长度-体重关系的季节性模式类似于脂肪和糖原的季节性模式。3.总脂占干重的百分比在若虫发育阶段直到变态和出水前才有所增加。但主要的储备脂三酰甘油随发育阶段呈系统性增加。在发育的最后阶段，三酰甘油下降，可能是由于能量消耗及其转化为变态和繁殖所需的其他生化成分的结果。4.潜在食物指标(水柱中的藻类荧光和沉积物中的叶绿素a和叶绿素a/脱藻素比率)表明，圣克莱尔湖的六角藻的食物来源是底栖动物，特别是在早春，而在伊利湖西部，若虫的食物来源是水柱，在春末和夏天定居在湖底。
SUMMARY 1. We analysed changes in energy reserves (lipid and glycogen) and length–weight relationships of burrowing mayflies (Hexagenia spp.) in 1997–99 to compare an established population in Lake St Clair with a recovering population in western Lake Erie of the Laurentian Great Lakes. In addition, we measured changes in water temperature and potential food in both water columns and sediments. 2. Although overall mean values of lipid and glycogen levels of Hexagenia nymphs from Lake St Clair and western Lake Erie were not significantly different, there were differences in seasonal patterns between the two lakes. In Lake St Clair, levels were highest in early spring, declined throughout the year, and reached their lowest levels in fall during all 3 years of study. In contrast, levels in western Lake Erie were lower in spring, increased to a maximum in summer, then declined in fall. Seasonal patterns in length–weight relationships were similar to those for lipid and glycogen. 3. Total lipid as a percentage of dry weight did not increase with developmental stage of nymphs until just prior to metamorphosis and emergence from water. However, the major reserve lipid, triacylglycerols, increased systematically with development stage. In the final stage of development, triacylglycerols declined, probably as a result of energy consumption and its conversion to other biochemical components for metamorphosis and reproduction. 4. Indicators of potential food (algal fluorescence in the water column and chlorophyll a and chlorophyll a/phaeophytin ratio in sediments) suggest that Hexagenia in Lake St Clair have a food source that is benthic based, especially in early spring, whereas in western Lake Erie nymphs have a food source that is water column based and settles to the lake bottom during late spring and summer.