Australian Rivers Institute, Nathan Campus, Griffith University, 170 Kessels Road, Nathan, Brisbane, Queensland 4111, Australia.
Australian Rivers Institute, Nathan Campus, Griffith University, 170 Kessels Road, Nathan, Brisbane, Queensland 4111, Australia; Landscape Sciences, Department of Environment and Science, PO Box 5078, Brisbane, Queensland 4001, Australia.
Sci Total Environ. 2018 Sep 15;636:1470-1479. doi: 10.1016/j.scitotenv.2018.04.195. Epub 2018 May 5.
Terrestrial particulate nutrients transported during flood events are known to indirectly fuel phytoplankton blooms in rivers, lakes and coastal waters, although the mechanisms are poorly understood. Quantifying the response of phytoplankton to nutrients in sediments eroded from catchments is fundamental to prioritizing areas for erosion control. This study developed a novel bioassay technique for rapidly assessing the effects of nutrients released from suspended sediments on the growth of marine and freshwater phytoplankton communities. A range of sediment slurries were placed in bioassay bottles within dialysis tubing in the presence of phytoplankton and their photosynthetic efficiency (F/F) was measured over 72 h. This allowed an assessment of the effects of dissolved nutrients released from sediments without the confounding effects of suspended sediments. Chlorophyll a concentrations were also measured for comparison with F/F. Our study showed F/F was an effective method for measuring phytoplankton responses to sediment slurries. Photosynthetic efficiency was a more sensitive response metric than chlorophyll a. Applying the method to a range of suspended sediments from two tropical catchments in Australia that drain into Great Barrier Reef coastal waters, we identified a subset of sediment types (~40%) that increased F/F under the bioassay conditions. These sediments have the potential to stimulate marine and freshwater phytoplankton growth under the loads simulated in this study. The bioassay has the advantage of being a rapid and relatively simple method where a large number of sediments can be simultaneously tested for a phytoplankton response. To our knowledge this is the first time F/F has been used to assess phytoplankton responses to sediments in a bioassay. This approach advances the use of F/F as a sensitive indicator of phytoplankton responses to nutrients and could be used to develop indices of the relative risk various sediments pose, hence support decision making for erosion control measures.
陆地颗粒养分在洪水事件中被运输，已知会间接为河流、湖泊和沿海水域的浮游植物繁殖提供燃料，尽管其机制尚未得到充分理解。量化从集水区侵蚀的沉积物中养分对浮游植物的响应对于优先控制侵蚀的区域至关重要。本研究开发了一种新颖的生物测定技术，用于快速评估悬浮沉积物释放的养分对海洋和淡水浮游植物群落生长的影响。在存在浮游植物的情况下，将一系列沉积物悬浮液置于透析管内的生物测定瓶中，并在 72 小时内测量其光合作用效率（F/F）。这使得可以评估从沉积物中释放的溶解养分的影响，而不会受到悬浮沉积物的干扰。还测量了叶绿素 a 浓度以与 F/F 进行比较。我们的研究表明，F/F 是测量浮游植物对沉积物悬浮液响应的有效方法。光合作用效率是比叶绿素 a 更敏感的响应指标。将该方法应用于从澳大利亚两个流入大堡礁沿海水域的热带集水区的一系列悬浮沉积物中，我们确定了一组（约 40%）沉积物类型在生物测定条件下可以增加 F/F。在本研究模拟的负荷下，这些沉积物有可能刺激海洋和淡水浮游植物的生长。生物测定具有快速且相对简单的方法的优点，可以同时测试大量沉积物以获得浮游植物的响应。据我们所知，这是首次使用 F/F 来评估生物测定中浮游植物对沉积物的响应。这种方法推进了使用 F/F 作为浮游植物对养分响应的敏感指标，并可用于开发各种沉积物相对风险的指数，从而支持侵蚀控制措施的决策。
