Seasonal Food Limitation of Detritivores in a Montane Stream: An Experimental Test
Seasonal Food Limitation of Detritivores in a Montane Stream: An Experimental Test
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山地溪流中碎屑动物的季节性食物限制：实验测试
DOI：
10.2307/1940589
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发表时间：
1991
期刊：
影响因子：
4.8
通讯作者：
J. Richardson
中科院分区：
文献类型：
--
作者：
J. Richardson
小溪中的许多食腐无脊椎动物物种几乎完全依赖落叶输入来满足其营养需求，但这种资源的浓度随季节变化很大。一项实验旨在检验粗颗粒碎屑进料器（粉碎机）的生产率受到季节性食物限制的假设，该实验使用重复的河边渠道进行，该渠道接收全叶碎屑的三种输入速率之一（等于自然落入山地溪流的速率，以及两个增加水平的输入）。当补充食物时，九种常见的碎纸机物种中的七种获得了显着更高的成年质量和/或更高的密度。 Malenka spp 的幼虫密度。当添加额外的食物时，Brillia retifinis 和 Brillia retifinis 的含量显着升高。高食品添加量下的视网膜光亮菌密度比“自然”处理下高 10 倍以上； B. retifinis 显然在该系统中扮演了逃犯的角色，并且凭借其较短的世代时间能够更好地跟踪资源丰度的变化。夏季后半段，在高和中度食物投入处理中，Zapada cinctipes 和 Z. haysi 的密度更高。当提供额外的食物时，其他类群的密度增加的趋势并不显着。底栖密度的大部分变化可归因于食物供应增加导致迁徙率下降。当添加食物时，测量成虫羽化时质量的八个分类单元中有六个明显更大（4-46％）。两种性别的体重都出现了这种增加，但在大多数物种中，雌性的体重增加比例更高。由于食物处理，成虫羽化时间没有发生可检测到的变化。大多数类群的生物量增加与普通粗碎屑消费者的生物量总体增加成比例。该模式的主要例外是 Brillia retifinis 代表的生物量百分比不成比例地增加，而 Zapada cinctipes 的代表减少。该社区对食物补充剂的反应表明食腐动物的食物限制。在添加食物的情况下，底栖生物量呈指数增长，这表明如果食物不受限制，生产力的范围。这些共存物种受益于与人口水平过程相关的空间尺度上食物供应的增强。自然条件下资源丰度的巨大季节性变化在粮食供应不足时期造成了瓶颈，即使在粮食丰富时期也限制了后续生产。
Many species of detritivorous invertebrates in small streams depend almost entirely on inputs of leaf litter for their nutritional requirements, however the concentration of this resource varies considerably seasonally. An experiment designed to test the hy- pothesis that productivity of coarse particle detritus feeders (shredders) is seasonally food limited was performed using replicate streamside channels that received one of three input rates of whole leaf detritus (rates equal to those naturally falling into montane streams, and two levels of increased inputs). Seven of the nine common shredder species attained significantly higher adult mass, higher densities, or both when food was supplemented. Larval densities of Malenka spp. and Brillia retifinis were significantly higher when additional food was added. Brillia retifinis densities were more than 10 x greater in high food additions than in the "natural" treatment; B. retifinis apparently fills a role as a fugitive in this system and is better able to track shifts in resource abundance by virtue of its short generation time. Zapada cinctipes and Z. haysi were more dense in high and intermediate food input treatments during the last half of the summer. Other taxa had nonsignificant trends to higher densities when extra food was provided. Most of the change in benthic densities can be attributed to decreased rates of emigration with increased food supply. Six of the eight taxa for which adult mass at emergence was measured were significantly more massive (4-46%) when food was added. Both sexes exhibited this increase in mass, but females gained proportionally more in most species. There were no detectable changes in the timing of adult emergence due to food manipulations. The biomass of most taxa increased in proportion to the overall increase in biomass of the common coarse-detritus consumers. The main exceptions to that pattern were a disproportionate increase in the percentage of the biomass represented by Brillia retifinis and a decrease in the representation of Zapada cinctipes. The responses of this community to food supplementation demonstrate food limitation of detritivores. The exponential increase in benthic biomass under food addition shows the scope for productivity if food were not limiting. These coexisting species benefitted from enhanced food supply on a spatial scale that is relevant for population level processes. The large seasonal variation in resource abundance under natural conditions creates bot- tlenecks during periods of low food supply, which constrain subsequent production even during periods when food is abundant.