Abstract

Comparisons over 6 years of three Norwegian fjord populations of the deep-water scyphomedusa Periphylla periphylla are presented. A minor part of the population in Lurefjord is migrating to the surface during night, which benefits mating encounters by increasing abundance per unit volume and decreasing the distance between individuals. Simulations using a typical water-column density profile and Stoke’s law show that fertilized eggs released in the surface quickly reach a depth where light is insufficient for visual predators. Consequently, the distribution of the smallest juveniles was strongly skewed towards higher depths in all three fjords studied. Mature females in Sognefjord were 4–5 times less abundant than in Lurefjord and Halsafjord, but due to a larger size and strong exponential relationship between size and number of mature oocytes, the potential recruitment rate as recruits m⁻² year⁻¹ was not much different from the other two fjords. Nevertheless, the observed number of small (<1 cm) juveniles was 18–31 times higher in Sognefjord than in the other two fjords, and it is assumed that the deeper habitat (up to 1300 m) compared to the other fjords (up to 440 and 530 m) is a superior habitat for the early development of P. periphylla.

中文翻译：

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深水海Per Periphylla periphylla的繁殖力和早期寿命

摘要

挪威峡湾深水三头扇贝的三个挪威峡湾种群过去6年的比较被提出。Lurefjord的一小部分人口在夜间迁移到地面，这通过增加单位体积的丰度和缩短个体之间的距离而受益于交配。使用典型的水柱密度分布和斯托克定律进行的模拟表明，释放在地表的受精卵会迅速到达一个深度，在该深度处的光不足以捕食肉食动物。因此，在所研究的所有三个峡湾中，最小的未成年人分布都强烈偏向更高的深度。Sognefjord的成熟雌性比Lurefjord和Halsafjord的雌性少4-5倍，但是由于更大的大小以及成熟卵母细胞的大小与数量之间的指数关系，所以新兵在m - ² 年^-1与其他两个峡湾没有太大的不同。尽管如此，松恩峡湾观察到的小型（<1 cm）幼体数量是其他两个峡湾的18-31倍，并且据推测，与其他峡湾（高达1300 m）相比，栖息地更深（最大1300 m）。 440和530 m）是P.periphylla早期发育的优越栖息地。