Chapman Lauren J, Kramer Donald L
Department of Biology, McGill University, 1205 Dr. Penfield Avenue, H3A 1B1, Montreal, Quebec, Canada.
Oecologia. 1991 Jul;87(2):299-306. doi: 10.1007/BF00325270.
We studied the rainy season dispersal of the fish Poecilia gillii (Poeciliidae) from pools in a steepgradient, intermittent stream in Santa Rosa National Park, Costa Rica. The stream consisted of about 20 pools separated by dry streambed except during two floods and subsequent brief periods of flow. Individually recognizable tags permitted mark-recapture estimates of population size and information on individual movements. The first flood was very severe, with pools losing an average of 75% of their populations (range 12-99%). Most of the lost fish died by becoming trapped in desiccating pools. Males and juveniles were more likely to be lost than were females. Population loss was negatively related to pool volume and positively related to streambed slope. In addition, population loss was positively related to preflood population size when the effects of pool volume and slope were removed indicating that pools with higher densities lost more fish. Of the fish recaptured after the flood, the average proportion found in the pool in which they had been tagged varied from 16%-96%, depending on the area of the stream. Of fish that moved, 92% went downstream. The second flood was less severe though stream flow lasted as long, and there was little effect on the pool populations. Involuntary flushing during the flood and voluntary departure apparently interacted to produce the observed patterns.
我们研究了哥斯达黎加圣罗莎国家公园一条坡度陡峭、间歇性溪流中的吉利食蚊鱼（食蚊鱼科）在雨季从水塘中的扩散情况。这条溪流由大约20个水塘组成，除了两次洪水及随后的短暂水流期外，水塘之间由干涸的河床隔开。可单独识别的标记使得能够通过标记重捕法估计种群数量，并获取个体移动的信息。第一次洪水非常严重，水塘中平均损失了75%的种群数量（范围为12%-99%）。大多数损失的鱼因被困在干涸的水塘中而死亡。雄性和幼鱼比雌性更容易损失。种群损失与水塘体积呈负相关，与河床坡度呈正相关。此外，在去除水塘体积和坡度的影响后，种群损失与洪水前的种群大小呈正相关，表示密度较高的水塘损失的鱼更多。在洪水后重新捕获的鱼中，在其被标记的水塘中被发现的平均比例从16%到96%不等，这取决于溪流的区域。在移动的鱼中，92%向下游移动。第二次洪水没那么严重，尽管溪流持续流动的时间一样长，并且对水塘中的种群几乎没有影响。洪水期间的非自愿冲刷和自愿离开显然相互作用，产生了观察到的模式。
