Abstract This paper analyses the spatial distribution and some aspects of the reproductive biology of the common marine cladoceran Evadne nordmanni in the southern Barents Sea. Samples were collected in summer seasons at four coastal sites off the Kola Peninsula. The numerical occurrence of E. nordmanni as a percentage of total mesozooplankton abundance ranged between 0.03 and 63%. Maximum population density was recorded in shallow water locations with high water temperature. Non-breeding females and juveniles dominated all study sites. Relative abundances of males, parthenogenetic females and gamogenetic females were low and never exceeded 10% of the total population density. Canonical Correspondence Analysis revealed significant influences of surface temperature and sampling depth on the distribution of E. nordmanni. Mean body length of gamogenetic females was higher than those of parthenogenetic females. Mean fecundity of parthenogenetic females was rather stable across the study locations (8.3 ± 0.1 late-stage embryos per female). The average size of late-stage embryos varied between 121 μm and 165 μm. Positive correlations between the average size of late-stage embryos/fecundity and female body length were found suggesting that larger females invest more energy in egg production. The species is well adapted to Arctic conditions in the southern Barents Sea. It is more likely that E. nordmanni reproduces intensively in late spring and continues into September.

中文翻译：

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北极水域海洋枝角类动物 Evadne nordmanni 繁殖模式的夏季变异性

摘要 本文分析了巴伦支海南部常见海洋枝角类动物Evadne nordmanni 的空间分布和生殖生物学的某些方面。样本是在夏季在科拉半岛附近的四个沿海地点收集的。E. nordmanni 的数量占中浮游动物总丰度的百分比介于 0.03 和 63% 之间。在水温高的浅水区记录了最大的人口密度。非繁殖雌性和幼鱼在所有研究地点占主导地位。雄性、孤雌生殖和雌性生殖的相对丰度较低，从未超过总种群密度的 10%。典型对应分析揭示了表面温度和采样深度对 E. nordmanni 分布的显着影响。雌性的平均体长高于孤雌生殖的雌性。孤雌生殖雌性的平均生育力在整个研究地点相当稳定（每个雌性有 8.3 ± 0.1 个晚期胚胎）。晚期胚胎的平均大小在 121 μm 和 165 μm 之间变化。发现晚期胚胎的平均大小/繁殖力与雌性体长之间呈正相关，表明体型较大的雌性在产蛋上投入了更多的能量。该物种非常适应巴伦支海南部的北极条件。E. nordmanni 更有可能在晚春集中繁殖并持续到 9 月。晚期胚胎的平均大小在 121 μm 和 165 μm 之间变化。发现晚期胚胎的平均大小/繁殖力与雌性体长之间呈正相关，表明体型较大的雌性在产蛋上投入了更多的能量。该物种非常适应巴伦支海南部的北极条件。E. nordmanni 更有可能在晚春集中繁殖并持续到 9 月。晚期胚胎的平均大小在 121 μm 和 165 μm 之间变化。发现晚期胚胎的平均大小/繁殖力与雌性体长之间呈正相关，表明体型较大的雌性在产蛋上投入了更多的能量。该物种非常适应巴伦支海南部的北极条件。E. nordmanni 更有可能在晚春集中繁殖并持续到 9 月。