The use of field studies to investigate selective processes in fish early life history
The use of field studies to investigate selective processes in fish early life history
复制标题
利用实地研究来调查鱼类早期生命史的选择性过程
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
T. Miller
中科院分区：
文献类型：
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作者：
T. Miller
世纪初，密歇根湖的鱼类区系包括7种或7种本地深水ciscoes（白鲑科：鲑形目），它们主导着密歇根湖的浮游食物网（Kitterton和Crowder，1986年）。然而，到20世纪60年代末，湖中的六个物种已经灭绝，只有一种名叫Coregonus hoyi的河豚仍然存在。本地思科行业协会的衰落可能是由两种外来鱼类的综合影响造成的：海洋七鳃鳗的寄生，Petromyzon marinus，以及高度食鱼的Alewife的竞争，Alosa pseudo-harengus。由于这两个物种的饮食结构有很大的重叠，因此来自艾雷夫斯的竞争会特别激烈。随着浮游动物丰度的增加，浮游动物的丰度和大小下降。为了应对这一变化，有证据表明，生态和形态的变化在膨胀（克劳德，1984年，1986年）。Crowder（1984）提供了1960年和1979年两次收集的膨胀鱼鳃耙数量的数据，分别是在灰腹鱼数量达到峰值之前和之后（图7.1）。Crowder检验的零假设是两个采样期之间鳃耙数量没有差异。他可以拒绝零假设，并得出结论，在20年的时间里，膨胀鱼中鳃耙的平均数量显著减少。
At the beginning of the 20th century the fish fauna of Lake Michigan included seven species or stocks of native deep-water ciscoes (Coregonidae: Salmoniformes) which dominated the lake’s planktonic food web (Kitchell and Crowder, 1986). However, by the late 1960s, six of the species were extinct in the lake and only bloater, Coregonus hoyi, remained. The decline of the native cisco guild may have been caused by the combined effects of two exotic fish species: parasitism by the sea lamprey, Petromyzon marinus, and the competition from the highly planktivorous alewife, Alosa pseudo-harengus. Competition from alewife would have been particularly intense because there was a large dietary overlap between the species. As alewife abundance increased, the abundance and size of Zooplankton declined. In response to this change, there is evidence for both ecological and morphological shifts in bloater (Crowder, 1984, 1986). Crowder (1984) presented data on gill raker number in bloaters collected in 1960, prior to the peak abundance of alewife, and in 1979, after alewife had reached their peak (Fig. 7.1). The null hypothesis that Crowder tested was one of no difference in gill raker number between the two sampling periods. He could reject the null hypothesis and conclude that there had been a significant reduction in the average number of gill rakers in bloaters over the 20 year period.