It has been shown that freshwater pelagic mysid shrimps capture zooplankton at a higher rate in light than in darkness. This has been suggested to be due to facilitation of visual predation on evasive zooplankton prey. To test this hypothesis with Baltic mysid shrimps, and to see whether pelagic (migrating) and littoral (non-migrating) mysids differ in this respect, we compared the feeding rates of Mysis mixta and Praunus flexuosus on the copepod Acartia spp. As light conditions change radically from the beginning of summer to late autumn at the Baltic latitudes, we conducted the experiments during three different times of the year to determine if there was a seasonal response to light in mysids. The feeding rates of pelagic mysids were significantly higher in total darkness than in light. In contrast, the feeding rates of littoral mysids did not differ in the dark and the light in the three different seasons. The decreased feeding of pelagic mysids under well-lit conditions may be an adaptation to avoid visual predation by pelagic fish. In contrast, littoral mysids, which live in the well-lit layer throughout the day, do not show a similar response. The fact that light did not increase feeding in either of the mysid species indicates that these mysid species do not use vision in capturing prey, but rely mainly on mechano-reception.

中文翻译：

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光对远洋和沿海糠虾摄食率的影响：摄食成功与避免捕食之间的权衡

已经表明，淡水中上层糠虾在光照下比在黑暗中捕获浮游动物的速率更高。这被认为是由于促进了对逃避的浮游动物猎物的视觉捕食。为了用波罗的海糠虾检验这一假设，并查看远洋（迁徙）和沿海（非迁徙）糠虾在这方面是否有所不同，我们比较了米西斯 mixta 和 Praunus flexuosus 在桡足类 Acartia spp 上的摄食率。由于波罗的海纬度从夏初到深秋的光照条件发生了根本性的变化，我们在一年中的三个不同时间进行了实验，以确定糠虾中是否存在对光的季节性反应。远洋糠虾的摄食率在完全黑暗中明显高于在光中。相比之下，三个不同季节在黑暗和光照条件下，沿海糠虾的摄食率没有差异。在光线充足的条件下，减少对远洋糠虾的摄食可能是为了避免远洋鱼类的视觉捕食。相比之下，全天生活在光线充足的层中的沿海糠虾没有表现出类似的反应。光没有增加任何一种 mysid 物种的摄食这一事实表明这些 mysid 物种在捕捉猎物时不使用视觉，而主要依靠机械接收。