Petus Caroline, Collier Catherine, Devlin Michelle, Rasheed Michael, McKenna Skye
Centre for Tropical Water and Aquatic Ecosystem Research, Catchment to Reef Research Group, James Cook University, Townsville, QLD 4811, Australia.
School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia.
Mar Environ Res. 2014 Jul;98:68-85. doi: 10.1016/j.marenvres.2014.03.006. Epub 2014 Mar 19.
Stretching more than 2000 km along the Queensland coast, the Great Barrier Reef Marine Park (GBR) shelters over 43,000 square km of seagrass meadows. Despite the status of marine protected area and World Heritage listing of the GBR, local seagrass meadows are under stress from reduced water quality levels; with reduction in the amount of light available for seagrass photosynthesis defined as the primary cause of seagrass loss throughout the GBR. Methods have been developed to map GBR plume water types by using MODIS quasi-true colour (hereafter true colour) images reclassified in function of their dominant colour. These data can be used as an interpretative tool for understanding changes in seagrass meadow health (as defined in this study by the seagrass area and abundance) at different spatial and temporal scales. We tested this method in Cleveland Bay, in the northern GBR, where substantial loss in seagrass area and biomass was detected by annual monitoring from 2007 to 2011. A strong correlation was found between bay-wide seagrass meadow area and biomass and exposure to turbid Primary (sediment-dominated) water type. There was also a strong correlation between the changes of biomass and area of individual meadows and exposure of seagrass ecosystems to Primary water type over the 5-year period. Seagrass meadows were also grouped according to the dominant species within each meadow, irrespective of location within Cleveland Bay. These consolidated community types did not correlate well with the exposure to Primary water type, and this is likely to be due to local environmental conditions with the individual meadows that comprise these groupings. This study proved that remote sensing data provide the synoptic window and repetitivity required to investigate changes in water quality conditions over time. Remote sensing data provide an opportunity to investigate the risk of marine-coastal ecosystems to light limitation due to increased water turbidity when in situ water quality data is not available or is insufficient.
大堡礁海洋公园（GBR）沿着昆士兰海岸绵延2000多公里，庇护着超过43000平方公里的海草草甸。尽管GBR具有海洋保护区的地位并被列入世界遗产名录，但当地的海草草甸正面临水质下降的压力；海草光合作用可用光照量的减少被确定为整个GBR海草损失的主要原因。已开发出通过使用根据其主导颜色重新分类的中分辨率成像光谱仪（MODIS）准真彩色（以下简称真彩色）图像来绘制GBR羽状水类型的方法。这些数据可作为一种解释工具，用于理解不同空间和时间尺度下海草草甸健康状况的变化（在本研究中由海草面积和丰度定义）。我们在GBR北部的克利夫兰湾对该方法进行了测试，在那里，通过2007年至2011年的年度监测发现海草面积和生物量大幅减少。发现整个海湾的海草草甸面积和生物量与暴露于浑浊的原生（以沉积物为主）水类型之间存在很强的相关性。在这5年期间，各个草甸的生物量和面积变化与海草生态系统暴露于原生水类型之间也存在很强的相关性。海草草甸还根据每个草甸内的优势物种进行分组，而不考虑其在克利夫兰湾内的位置。这些合并的群落类型与暴露于原生水类型的相关性不佳，这可能是由于构成这些分组的各个草甸的当地环境条件所致。这项研究证明，遥感数据提供了调查水质状况随时间变化所需的全景窗口和重复性。当没有现场水质数据或数据不足时，遥感数据提供了一个机会来调查海洋 - 海岸生态系统因水体浊度增加而面临光照限制的风险。
