Department of Ecology, Evolution and Behavior, University of Minnesota, USA.
School of Biological Sciences, University of Nebraska-Lincoln, USA.
Sci Total Environ. 2019 Feb 20;652:736-743. doi: 10.1016/j.scitotenv.2018.10.225. Epub 2018 Oct 17.
Hypoxia in aquatic ecosystems is often a result of anthropogenic activities, such as increased nutrient loading, originating from agriculture or urbanization, as well as global warming. Aquatic invertebrates are especially important in ecosystems due to their central role in secondary production and in dynamics of food webs. To better understand impacts of oxygen availability on key physiological processes in invertebrates, we conducted a literature search and synthesized the findings of published studies. We found 55 studies that quantified impacts of hypoxia on feeding, growth, reproduction and respiration rates in 54 different aquatic invertebrate species. We applied non-linear regression models which took into account phylogenetic correlation in the data set. Fitting Michaelis-Menten models, we found that there were differences in how different processes responded to a decline in oxygen availability. Respiration rates were halved at highest oxygen concentration (6.44 mg O/L), followed by reproductive (3.66 mg O/L), growth (1.77 mg O/L) and, finally, feeding rates (0.77 mg O/L). Our findings confirm observations that reproduction is highly sensitive as organisms quickly reduce their reproductive output when exposed to stressful conditions. As long as they have sufficient reserves, organisms continue growing even under stressful conditions, and we confirmed that growth was not very sensitive to a decline in oxygen availability. We discuss potential impacts of global warming on oxygen availability and demand for aquatic macroinvertebrates. Given that oxygen availability is declining in many ecosystems, we can expect that organismal responses will be increasingly compromised with potential consequences for ecosystems and the services they deliver.
水生生态系统中的缺氧通常是人为活动的结果，如农业或城市化导致的营养物质负荷增加，以及全球变暖。水生无脊椎动物在生态系统中尤为重要，因为它们在次级生产和食物网动态中起着核心作用。为了更好地了解氧气可用性对无脊椎动物关键生理过程的影响，我们进行了文献检索，并综合了已发表研究的结果。我们发现了 55 项研究，这些研究量化了缺氧对 54 种不同水生无脊椎动物物种的摄食、生长、繁殖和呼吸速率的影响。我们应用了考虑到数据集内系统发育相关性的非线性回归模型。拟合米氏-门坦模型后，我们发现不同过程对氧气可用性下降的反应存在差异。呼吸速率在最高氧气浓度（6.44mg O/L）时减半，其次是繁殖（3.66mg O/L）、生长（1.77mg O/L），最后是摄食速率（0.77mg O/L）。我们的研究结果证实了这样的观察结果，即繁殖对环境胁迫高度敏感，因为当生物体暴露在压力条件下时，它们会迅速减少繁殖输出。只要它们有足够的储备，即使在压力条件下，生物体也会继续生长，我们证实生长对氧气可用性的下降并不十分敏感。我们讨论了全球变暖对水生大型无脊椎动物氧气可用性和需求的潜在影响。鉴于许多生态系统中的氧气可用性正在下降，我们可以预期生物体的反应将越来越受到影响，这可能对生态系统及其提供的服务产生潜在影响。
