In semi‐arid floodplain wetlands, planktonic metabolism, a balance of gross primary productivity of phytoplankton (GPP) and planktonic respiration (PR), may be affected by hydrology, geomorphology, carbon, and microbial communities. Understanding relationships between these factors helps develop effective water and land management plans for these wetlands. In this study, variations in planktonic metabolism and microbial carbon substrate utilization were investigated in the semi‐arid floodplain wetlands of the Macquarie Marshes, south‐eastern Australia, by comparing three geomorphologically distinct zones with different historical inundation frequencies (zones 1: moderate, 2: low, and 3: very low). Floodplain soil samples collected from each zone were inundated artificially in controlled laboratory conditions. GPP and PR were determined using biological oxygen demand methods. Biolog EcoPlates™ were used to assess microbial utilization of carbon substrate. Among the zones examined, zone 1 had the highest GPP and lowest PR, while zone 3 had the lowest GPP and highest PR. GPP/PR showed zones 1 and 2 autotrophic, and zone 3 heterotrophic. EcoPlates showed the highest and lowest microbial activity in zone 3 and zone 1 respectively, indicating a strong link between microbial carbon substrate utilization and PR for heterotrophy in the rarely inundated zone. Inundation of drier wetland zones may lead to a large pulse in PR, at least for a short period of time, potentially leading to anoxic water events. When making decisions for environmental water allocations, the antecedent hydro‐geomorphological and microbial condition of the targeted wetlands should be considered to help predict expected aquatic ecosystem responses.

中文翻译：

---

半干旱洪泛区湿地对浮游生物的浮游代谢和微生物碳底物的利用

在半干旱洪泛区湿地中，浮游生物代谢，浮游植物总初级生产力（GPP）和浮游呼吸（PR）的平衡可能会受到水文，地貌，碳和微生物群落的影响。了解这些因素之间的关系有助于为这些湿地制定有效的水和土地管理计划。在这项研究中，通过比较三个具有不同历史淹没频率的地貌不同区域（区域1：中度，2），研究了澳大利亚东南部麦格理沼泽湿地的半干旱洪泛区湿地浮游代谢和微生物碳底物利用的变化。 ：低，而3：非常低）。从每个区域收集的洪泛区土壤样品在受控的实验室条件下被人工淹没。GPP和PR是使用生物需氧量方法确定的。Biolog EcoPlates™用于评估碳底物的微生物利用。在检查的区域中，区域1具有最高的GPP和最低的PR，而区域3具有最低的GPP和最高的PR。GPP / PR显示区域1和2是自养的，区域3是异养的。EcoPlates分别在区域3和区域1中显示了最高和最低的微生物活性，表明在极少被淹没的区域中，微生物碳底物的利用与PR的异养关系密切相关。较干燥的湿地带被淹可能至少在短时间内导致PR的大脉冲，从而可能导致缺氧水事件。在决定环境用水分配时，