The perils of unpalatable periphyton: Didymosphenia and other mucilaginous stalked diatoms as food for tadpoles
The perils of unpalatable periphyton: Didymosphenia and other mucilaginous stalked diatoms as food for tadpoles
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DOI：
10.1080/0269249x.2014.924436
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发表时间：
2014-01-01
期刊：
影响因子：
1.8
通讯作者：
Lind, A. J.
中科院分区：
文献类型：
--
作者：
Furey, P. C.;Kupferberg, S. J.;Lind, A. J.
在全球各地的河流中，双胞藻的繁殖正在变得普遍。在加利福尼亚州的内华达山脉，Didymphenia和其他产生粘多糖茎的分类群(如Gomphoneis、Cymbella)可以主导底栖环境，特别是在大坝下游改变的水文和热状况中。我们比较了在两个锡尔兰河水系--美洲河和羽毛河--的成对河段，一个自由流动的河段和另一个受管制的河段中，茎状硅藻的流行率。在受管制的河段，短期发电造成每日流量波动，附生生物的生物量由Didymphenia(低极磁释放造成凉爽的夏季温度)或其他茎状硅藻分类群(温度较暖)主导。基于生物量，非调控部位的围生植物组合与调控部位的围生植物组合明显不同，在计入调控部位的茎类属后，非调控部位的Gomhonema属是造成这种差异的原因。我们在一个影响饮食和温度制度的析因实验中，评估了粘多糖对一只大型放牧动物--山脚黄腿青蛙的蝌蚪--的影响。在16.6摄氏度的日平均温度下，蝌蚪在Didymphenia占主导地位的附生植物上吃草时体重下降(72小时相对变化为-16.1+/-7.2%)。在19.9℃(类似于未调节的河流条件)下，蝌蚪摄食Didymphenia的速度与摄取较高蛋白质对照附生植物的速率相似，但前者不生长(对照附生植物的相对变化为4.3+/-5.4%比30.7+/-3.4%)。当摄食以粘性柄硅藻为主的围植生物时，蝌蚪的重量损失为21.0±9.2%(冷)和16.6+/-5.6%(暖)。研究结果表明，在水文或热力作用下，附生植物组成的变化对向食草动物转移能量有重要影响。
Proliferations of Didymosphenia geminata are becoming prevalent in rivers around the globe. In the Sierra Nevada of California, Didymosphenia and other taxa that produce mucopolysaccharide stalks (e.g., Gomphoneis, Cymbella) can dominate benthic environments, particularly in the altered hydrologic and thermal regimes downstream of dams. We compared the prevalence of stalked diatoms in paired reaches, one free-flowing and the other regulated, within two Sierran river systems, the American and Feather Rivers. In the regulated reaches, short-term power generation caused daily flow fluctuations and periphyton biovolume was dominated by either Didymosphenia (where hypolimnetic releases created cool summer temperatures) or other stalked diatom taxa (where temperatures were warm). Periphyton assemblages from the unregulated sites were significantly different from the regulated reaches based on biovolume, with Gomphonema being the genus at unregulated sites contributing to the dissimilarities after accounting for the stalked genera from the regulated reaches. We evaluated the consequences of mucopolysaccharides for a large-bodied grazer, tadpoles of the foothill yellow-legged frog (Rana boylii), in a factorial experiment manipulating diet and thermal regime. At 16.6 degrees C mean daily temperature, tadpoles lost weight (72h relative change of-16.1 +/- 7.2%) when grazing on periphyton from a Didymosphenia-dominated site. At 19.9 degrees C (similar to unregulated river conditions), tadpoles grazed Didymosphenia at a rate similar to tadpoles consuming higher protein control periphyton, but the former tadpoles did not grow (relative change of 4.3 +/- 5.4% vs 30.7 +/- 3.4% for control periphyton). When tadpoles were fed periphyton dominated by mucilaginous stalked diatoms other than Didymosphenia, tadpole weight loss was 21.0 +/- 9.2% (cool) and 16.6 +/- 5.6% (warm). The results illustrate that hydrologically or thermally mediated shifts in periphyton composition can have significant implications for the energy transferred to grazers.