Department of Ecology and Environmental Science, Umeå University, 90187 Umeå, Sweden.
Department of Ecology and Environmental Science, Umeå University, 90187 Umeå, Sweden.
Sci Total Environ. 2018 Feb 15;615:608-614. doi: 10.1016/j.scitotenv.2017.09.070. Epub 2017 Oct 6.
An increasing number of short-term laboratory studies on fish reports behavioral effects from exposure to aquatic contaminants or raised carbon dioxide levels affecting the GABA receptor. However, how such GABAergic behavioral modifications (GBMs) impact populations in more complex natural systems is not known. In this study, we induced GBMs in European perch (Perca fluviatilis) via exposure to a GABA agonist (oxazepam) and followed the effects on growth and survival over one summer (70days) in replicated pond ecosystems. We hypothesized that anticipated GBMs, expressed as anti-anxiety like behaviors (higher activity and boldness levels), that increase feeding rates in laboratory assays, would; i) increase growth and ii) increase mortality from predation. To test our hypotheses, 480 PIT tagged perch of known individual weights, and 12 predators (northern pike, Esox lucius) were evenly distributed in 12 ponds; six control (no oxazepam) and six spiked (15.5±4μgl oxazepam [mean±1S.E.]) ponds. Contrary to our hypotheses, even though perch grew on average 16% more when exposed to oxazepam, we found no significant difference between exposed and control fish in growth (exposed: 3.9±1.2g, control: 2.9±1g [mean±1S.E.], respectively) or mortality (exposed: 26.5±1.8individuals pond, control: 24.5±2.6individuals pond, respectively). In addition, we show that reduced prey capture efficiency in exposed pike may explain the lack of significant differences in predation. Hence, our results suggest that GBMs, which in laboratory studies impact fish behavior, and subsequently also feeding rates, do not seem to generate strong effects on growth and predation-risk in more complex and resource limited natural environments.
越来越多的短期鱼类实验室研究报告称，暴露于水生污染物或升高的二氧化碳水平会对 GABA 受体产生行为影响。然而，这种 GABA 能行为改变（GBM）如何影响更复杂的自然系统中的种群尚不清楚。在这项研究中，我们通过暴露于 GABA 激动剂（奥沙西泮）在欧洲鲈鱼（Perca fluviatilis）中诱导 GBM，并在复制的池塘生态系统中观察一个夏季（70 天）的生长和存活情况。我们假设预期的 GBM，表现为类似抗焦虑的行为（更高的活动和大胆水平），会增加实验室测定中的摄食率，会；i）增加生长和 ii）增加被捕食的死亡率。为了检验我们的假设，480 条带有 PIT 标签的已知个体重量的鲈鱼和 12 条捕食者（北方狗鱼，Esox lucius）均匀分布在 12 个池塘中；六个对照组（无奥沙西泮）和六个加标组（15.5±4μgl 奥沙西泮[平均值±1S.E.]）。与我们的假设相反，尽管暴露于奥沙西泮的鲈鱼平均生长增加了 16%，但我们在生长（暴露组：3.9±1.2g，对照组：2.9±1g[平均值±1S.E.]）或死亡率（暴露组：26.5±1.8 尾池塘，对照组：24.5±2.6 尾池塘）之间没有发现暴露组和对照组之间的显著差异。此外，我们还表明，暴露组中的捕食者的猎物捕获效率降低可能解释了捕食风险没有显著差异的原因。因此，我们的研究结果表明，在实验室研究中影响鱼类行为并随后影响摄食率的 GBM，在更复杂和资源有限的自然环境中似乎不会对生长和捕食风险产生强烈影响。
