Paul Jenny S, Nestlerode Janet A, Jarvis Brandon M
U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Gulf Ecosystem Measurement and Modeling Division, 1 Sabine Island Drive, Gulf Breeze, Florida 32561, United States.
Estuaries Coast. 2024 Sep 1;47(6):1376-1387. doi: 10.1007/s12237-024-01401-3.
Hypoxia is one of the predominant water quality issues affecting estuaries and coastal ecosystems and its impact is often monitored using benthic macroinvertebrates. The M-AMBI (Multivariate AZTI Marine Biotic Index) is an index that meets the needs of small and large-scale monitoring as it is scalable. However, gaps remain as to the sensitivity of M-AMBI to hypoxia as few studies are available. Using Pensacola Bay in the northern Gulf of Mexico (USA) as a case study, we sought to evaluate the time scales over which benthic macrofauna respond to dissolved oxygen conditions from May through September 2017. Combined continuous DO monitoring and benthic sampling identified important differences in DO exposure on benthic habitat condition based on both the duration and frequency of low oxygen. We identified periods of 7 to 31 days as critical windows of exposure prior to a measurable benthic response, and that both duration and exposure to varying low oxygen conditions as well as the recovery period of oxygen to > 5 mg L are important to benthic habitat health. While the duration of exposure to DO from < 2 mg L to near anoxia remains an important factor in benthic health, benthic organisms can better tolerate periods of low oxygen when reoxygenation occurs after a short time interval. More research is needed to better quantify the relationship between oxygen stress and recovery on benthic habitats, particularly in systems where low DO exposure and recovery can vary over timescales of hours to days.
缺氧是影响河口和沿海生态系统的主要水质问题之一，其影响通常使用底栖大型无脊椎动物进行监测。M-AMBI（多元AZTI海洋生物指数）是一种可扩展的指数，满足了小规模和大规模监测的需求。然而，由于可用研究较少，M-AMBI对缺氧的敏感性仍存在差距。以美国墨西哥湾北部的彭萨科拉湾为例，我们试图评估2017年5月至9月期间底栖大型动物对溶解氧条件作出反应的时间尺度。连续的溶解氧监测和底栖采样相结合，基于低氧的持续时间和频率，确定了溶解氧暴露对底栖生境条件的重要差异。我们确定7至31天的时间段为可测量的底栖反应之前的关键暴露窗口，并且低氧条件的持续时间和暴露以及氧气恢复到>5mg/L的恢复期对底栖生境健康都很重要。虽然溶解氧从<2mg/L暴露至接近缺氧的持续时间仍然是底栖健康的一个重要因素，但当在短时间间隔后发生复氧时，底栖生物能够更好地耐受低氧期。需要更多的研究来更好地量化氧气胁迫与底栖生境恢复之间的关系，特别是在溶解氧低暴露和恢复在数小时至数天的时间尺度上可能变化的系统中。
