Recently, corals on the Great Barrier (GBR) have suffered mass bleaching. The link between ocean warming and coral bleaching is understood to be due to temperature-dependence of complex physiological processes in the coral host and algal symbiont. Here we use a coupled catchment-hydrodynamic-biogeochemical model, with detailed zooxanthellae photophysiology including photoadaptation, photoacclimation and reactive oxygen build-up, to investigate whether natural and anthropogenic catchment loads impact on coral bleaching on the GBR. For the wet season of 2017, simulations show the cross-shelf water quality gradient, driven by both natural and anthropogenic loads, generated a contrasting zooxanthellae physiological state on inshore versus mid-shelf reefs. The relatively small catchment flows and loads delivered during 2017, however, generated small river plumes with limited impact on water quality. Simulations show the removal of the anthropogenic fraction of the catchment loads delivered in 2017 would have had a negligible impact on bleaching rates.

最近，大堡礁（GBR）上的珊瑚遭受了大规模的漂白。据了解，海洋变暖与珊瑚白化之间的联系是由于珊瑚宿主和藻类共生体中复杂的生理过程与温度有关。在这里，我们使用流域-水动力-生物地球化学耦合模型，结合详细的黄原虫光生理学，包括光适应，光适应和活性氧积累，来研究自然和人为集水量是否对GBR上的珊瑚褪色有影响。在2017年的雨季中，模拟显示，在自然和人为负载的共同作用下，跨架水质梯度在近海礁石和中层礁石上形成了相反的黄原虫生理状态。但是，2017年的集水量和载流量相对较小，产生的小河羽对水质的影响有限。模拟显示，去除2017年交付的人为流域负荷中的一部分，对漂白率的影响可以忽略不计。