Grazing catfish, fishing birds, and attached algae in a Panamanian stream
Grazing catfish, fishing birds, and attached algae in a Panamanian stream
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在巴拿马溪流中吃草的鲶鱼、捕鱼的鸟类和附着的藻类
DOI：
10.1007/bf00002465
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发表时间：
1989
影响因子：
1.4
通讯作者：
S. D. Cooper
中科院分区：
文献类型：
--
作者：
M. Power;T. Dudley;S. D. Cooper
在食性鱼类丰富的溪流中，附着的藻类往往沿深度梯度发展出惊人的变化，浅水（<20厘米）有高生长的作物带，而较深底物上有稀疏生长的作物带。巴拿马中部一条溪流的实验结果支持了这样一种假设，即当食草鱼类为了躲避浅水的捕食者而放弃那里积累的食物资源时，直立藻类作物的垂直变化就会出现。当巴拿马中部一条溪流中的38块含藻类的岩石从浅水（<20厘米）转移到深水（>20厘米）时，藻类被放牧的鲶鱼迅速消耗。从三个溪流池中取出鲶鱼，并将其留在三个对照池中。去除鲶鱼10 d后，去除池深区和浅区藻类生长量相似，而对照池浅区藻类生长量高于深区。鲶鱼被暴露在露天的围场中与渔鸟接触。在三个系列的围栏中，大多数在浅围栏（10和20厘米）中的鲶鱼在14天后消失，而在深围栏（30和50厘米）中的鲶鱼则没有。其他几组被关在笼子里8天的鲶鱼表现出不同的行为，这取决于它们是被喂食还是挨饿。饥饿的鲶鱼被放回家里的池塘后，比喂食的鲶鱼花更多的时间进食。尽管饥饿程度明显增加，但饥饿的鲶鱼不会冒险进入浅水区获取藻类。这些结果支持了这样一种观点，即捕食者引起的某些区域的食草动物的回避可以在流水群落中产生空间格局。
SynopsisIn streams where algivorous fishes abound, striking variation of attached algae often develops along depth gradients, with bands of high standing crops in shallow water (<20 cm) and sparse standing crops on deeper substrates. Experimental results from a stream in central Panama support the hypothesis that vertical variation in algal standing crops arises when grazing fishes avoid predators in shallow water by forgoing food resources that accumulate there. When 38 rocks bearing algae in a stream in central Panama were transferred from shallow (<20 cm) to deeper (>20 cm) water, algae were rapidly consumed by grazing catfish. Catfish were removed from three stream pools and left in place in three control pools. Ten days after catfish removal, algal standing crops in deep and shallow areas of removal pools were similar, while algal standing crops were higher in shallow than in deep areas of control pools. Catfish were exposed to fishing birds in open-topped enclosures. In one of three series of these pens, most catfish in shallow pens (10 and 20 cm) disappeared after 14 days, while catfish in deeper pens (30 and 50 cm) did not. Other groups of catfish which were caged 8 days showed differences in behavior depending on whether they had been fed or starved. After their release into their home pool, starved catfish spent more time feeding than did fed catfish. Despite their apparently increased hunger levels, starved catfish did not venture into shallow water to obtain algae. These results support the view that predator induced avoidance by grazers of certain areas can produce spatial pattern in the flora of flowing water communities.