Crossland N O
Shell Research Limited, Sittingbourne, Kent, United Kingdom.
Ecotoxicol Environ Saf. 1988 Dec;16(3):279-92. doi: 10.1016/0147-6513(88)90057-7.
The finding that trout apparently consumed more invertebrates than were produced in the Horokiwi stream has been described as "Allen's paradox." One explanation for this is that invertebrate sampling techniques underestimate the standing crop. If so, trout growth might be a relatively sensitive indicator of the effects of toxic chemicals on the productivity of experimental ponds. In a replicated pond experiment, methyl parathion was applied at concentrations toxic to invertebrates but not to fish. Three 50-m3 ponds were treated at 40 micrograms liter-1 and three at 10 micrograms liter-1, and there were three untreated controls. Each pond was stocked with eight small, individually marked rainbow trout. The fish were removed by electrofishing 3 weeks after treatment. Mean growth rate of fish in control ponds was 6.3% per day, 4.3% per day in ponds treated with 10 micrograms liter-1, and 3.7% per day in ponds treated with 40 micrograms liter-1. Effects were significant at the 1% level. The standing crop of invertebrates was apparently insufficient to support the growth of the fish, an indication that the active, predatory rainbow trout is more efficient at sampling invertebrates than standard limnological procedures.
鳟鱼明显消耗的无脊椎动物数量超过了霍罗基维溪流中无脊椎动物的产量，这一发现被称为“艾伦悖论”。对此的一种解释是，无脊椎动物采样技术低估了现存生物量。如果是这样，鳟鱼的生长可能是有毒化学物质对实验池塘生产力影响的一个相对敏感的指标。在一项重复池塘实验中，以对无脊椎动物有毒但对鱼类无毒的浓度施用甲基对硫磷。三个50立方米的池塘以40微克/升的浓度处理，三个以10微克/升的浓度处理，还有三个未处理的对照。每个池塘放养八条单独标记的小虹鳟鱼。处理3周后通过电捕鱼将鱼捞出。对照池塘中鱼的平均生长率为每天6.3%，在以10微克/升处理的池塘中为每天4.3%，在以40微克/升处理的池塘中为每天3.7%。在1%的水平上，影响是显著的。无脊椎动物的现存生物量显然不足以支持鱼类的生长，这表明活跃的捕食性虹鳟鱼在采样无脊椎动物方面比标准的湖沼学方法更有效。
