Antarctic krill are the dominant metazoan in the Southern Ocean in terms of biomass; however, their wide and patchy distribution means that estimates of their biomass are still uncertain. Most currently employed methods do not sample the upper surface layers, yet historical records indicate that large surface swarms can change the water colour. Ocean colour satellites are able to measure the surface ocean synoptically and should theoretically provide a means for detecting and measuring surface krill swarms. Before we can assess the feasibility of remote detection, more must be known about the reflectance spectra of krill. Here, we measure the reflectance spectral signature of Antarctic krill collected in situ from the Scotia Sea and compare it to that of in situ water. Using a spectroradiometer, we measure a strong absorption feature between 500 and 550 nm, which corresponds to the pigment astaxanthin, and high reflectance in the 600–700 nm range due to the krill's red colouration. We find that the spectra of seawater containing krill is significantly different from seawater only. We conclude that it is tractable to detect high-density swarms of krill remotely using platforms such as optical satellites and unmanned aerial vehicles, and further steps to carry out ground-truthing campaigns are now warranted.

中文翻译：

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斯科舍海南极磷虾反射光谱的实验测定

就生物量而言，南极磷虾是南大洋的主要后生动物；然而，它们广泛而零散的分布意味着对它们的生物量的估计仍然不确定。目前使用的大多数方法都不会对上表层进行采样，但历史记录表明，大型地表群可以改变水的颜色。海洋彩色卫星能够对表层海洋进行天气观测，理论上应该提供一种探测和测量表层磷虾群的手段。在我们评估远程探测的可行性之前，必须更多地了解磷虾的反射光谱。在这里，我们测量收集到的南极磷虾的反射光谱特征原位来自斯科舍海，并将其与原位水。使用分光辐射计，我们测量了 500 到 550 nm 之间的强吸收特征，这对应于色素虾青素，以及由于磷虾的红色而在 600-700 nm 范围内的高反射率。我们发现含有磷虾的海水的光谱与仅海水有显着差异。我们得出的结论是，使用光学卫星和无人机等平台远程检测高密度磷虾群是容易处理的，现在需要采取进一步措施开展地面实测活动。