Caceres Cristian W, Fuentes Leopoldo S, Ojeda F Patricio
Departmento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla, 653, Santiago, Chile.
Departmento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla, 114-D, Santiago, Chile.
Oecologia. 1994 Sep;99(1-2):118-123. doi: 10.1007/BF00317091.
In this study we examined differences in feeding behevior of populations of the marine temperate herbivorous fish Aplodactylus punctatus, in three different localities off the Chilean coast, which differ qualitatively and quantitatively in food availability. We test whether food selection follows optimal foraging strategics, whether there is any modification of the fishes' digestive tracts in relation to their diets, and whether differences in diet quality affect the allocation of energy into reproduction and maintenance in these populations. Samples of this fish and of the understore algal assemblages were taken seasonally from May 1989 to February 1990. For each population we analyzed dietary composition, weight of the digestive tract and of the food content, the condition factor (K), and the gonadosomatic index (GSI). Our results showed that the diet observed in the three populations closely resembled the differences in macro-algal abundance and composition among the three localities studied. Local differences in diet quality were inversely related to the amount of food consumption and size of the digestive tract, suggesting that under differential conditions of food availability A. punctatus is able to compensate for variations in food quality through a flexibility in its digestive strategies. The nutritional status (K) of individuals, and their reproductive pattern (GSI) were directly related to diet quality. These results indicate that although A. punctatus is able to adjust its digestive processes to different algal food regimes, the digestive modifications observed in food-poor environments are not sufficient to compensate for the lack of food and allow fish to reach the nutritional status and reproductive output reached in a food-rich environment. This study represents the first natural experiment demonstrating a direct relationship among food availability, feeding patterns, digestive processes, and reproductive effort.
在本研究中，我们调查了分布于智利海岸三个不同地点的海洋温带草食性鱼类斑点阿氏鱼种群的摄食行为差异，这三个地点在食物可利用性方面存在质和量的不同。我们测试了食物选择是否遵循最优觅食策略，鱼类消化道是否会因其饮食而发生任何变化，以及饮食质量的差异是否会影响这些种群在繁殖和维持能量分配方面的情况。从1989年5月至1990年2月，按季节采集了这种鱼以及下层藻类组合的样本。对于每个种群，我们分析了饮食组成、消化道重量和食物含量、条件因子（K）以及性腺指数（GSI）。我们的结果表明，在这三个种群中观察到的饮食情况与所研究的三个地点大型藻类丰度和组成的差异非常相似。饮食质量的局部差异与食物消耗量和消化道大小呈负相关，这表明在食物可利用性不同的条件下，斑点阿氏鱼能够通过其消化策略的灵活性来补偿食物质量的变化。个体的营养状况（K）及其繁殖模式（GSI）与饮食质量直接相关。这些结果表明，尽管斑点阿氏鱼能够根据不同的藻类食物状况调整其消化过程，但在食物匮乏环境中观察到的消化变化不足以弥补食物的不足，也无法使鱼类达到在食物丰富环境中所达到的营养状况和繁殖产出。这项研究是第一个自然实验，证明了食物可利用性、摄食模式、消化过程和繁殖努力之间的直接关系。
