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首页> 外文期刊>Estuarine Coastal and Shelf Science >Changes in water clarity in response to river discharges on the Great Barrier Reef continental shelf: 2002-2013
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Changes in water clarity in response to river discharges on the Great Barrier Reef continental shelf: 2002-2013

机译：根据大堡礁大陆架上的河流流量，水的净度变化：2002-2013年

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Water clarity is a key factor for the health of marine ecosystems. The Australian Great Barrier Reef (GBR) is located on a continental shelf, with >35 major seasonal rivers discharging into this 344,000 km(2) tropical to subtropical ecosystem. This work investigates how river discharges affect water clarity in different zones along and across the GBR. For each day over 11 years (2002-2013) we calculated 'photic depth' as a proxy measure of water clarity (calibrated to be equivalent to Secchi depth), for each 1 km2 pixel from MODIS-Aqua remote sensing data. Long-term and seasonal changes in photic depth were related to the daily discharge volumes of the nearest rivers, after statistically removing the effects of waves and tides on photic depth. The relationships between photic depths and rivers differed across and along the GBR. They typically declined from the coastal to offshore zones, and were strongest in proximity to rivers in agriculturally modified catchments. In most southern inner zones, photic depth declined consistently throughout the 11-year observation period; such long-term trend was not observed offshore nor in the northern regions. Averaged across the GBR, photic depths declined to 47% of local maximum values soon after the onset of river floods, and recovery to 95% of maximum values took on average 6 months (range: 150-260 days). The river effects were strongest at latitude 14.5 degrees-19.0 degrees S, where river loads are high and the continental shelf is narrow. Here, even offshore zones showed a >40% seasonal decline in photic depth, and 17-24% reductions in annual mean photic depth in years with large river nutrients and sediment loads. Our methodology is based on freely available data and tools and may be applied to other shelf systems, providing valuable insights in support of ecosystem management. (C) 2016 The Authors. Published by Elsevier Ltd.
机译：净水是海洋生态系统健康的关键因素。澳大利亚大堡礁（GBR）位于大陆架上，有超过35条主要的季节性河流排入这344,000 km（2）的热带至亚热带生态系统。这项工作研究了河水排放如何影响GBR以及整个GBR不同区域的水质清晰度。对于MODIS-Aqua遥感数据中每1 km2的像素，我们针对11年（2002-2013年）的每一天，都将“光深”计算为水净度的代用量度（校准为等效于Secchi深度）。在统计上消除了波浪和潮汐对光深的影响之后，光深的长期和季节性变化与最近河流的日排放量有关。在整个GBR中和沿GBR，光深与河流之间的关系不同。它们通常从沿海地区下降到近海地区，并且在经过农业改良的集水区中靠近河流的地区最为坚固。在大多数南部内陆地区，在整个11年的观察期内，光合深度一直下降；这种长期趋势在海上和北部都没有观察到。在整个GBR中，平均光深在河流洪水爆发后很快降至当地最大值的47％，恢复到最大值的95％平均需要6个月（范围：150-260天）。在北纬14.5度到19.0度之间，河水负荷高，大陆架狭窄，对河流的影响最大。在这里，即使在河床养分和沉积物负荷较大的年份中，即使是近海区域，其光合深度季节性下降幅度也超过40％，而年平均光合深度下降幅度为17-24％。我们的方法基于可免费获得的数据和工具，并且可以应用于其他架子系统，从而为支持生态系统管理提供有价值的见解。 （C）2016作者。由Elsevier Ltd.发布

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