In the Arctic, seasonal patterns in seawater biochemical conditions are shaped by physical, chemical, and biological processes related to the alternation of seasons, i.e. winter polar night and summer midnight sun. In summertime, CO₂ concentration is driven by photosynthetic activity of autotrophs which raises seawater pH and carbonate saturation state (Ω). In addition, restriction of photosynthetic activity to the euphotic zone and establishment of seasonal stratification often leads to depth gradients in pH and Ω. In winter, however, severely reduced primary production along with respiration processes lead to higher CO₂ concentrations which consequently decrease seawater pH and Ω.

Many calcifying invertebrates incorporate other metals, in addition to calcium, into their skeletons, with potential consequences for stability of the mineral matrix and vulnerability to abrasion of predators. We tested whether changes in seawater chemistry due to light-driven activities of marine biota can influence the uptake of Mg into calcified skeletons of Arctic Bryozoa, a dominant faunal group in polar hard-bottom habitats. Our results indicate no clear differences between summer and winter levels of skeletal MgCO₃ in five bryozoan species despite differences in Ω between these two seasons. Furthermore, we could not detect any depth-related differences in MgCO₃ content in skeletons of selected bryozoans. These results may indicate that Arctic bryozoans are able to control MgCO₃ skeletal concentrations biologically. Yet recorded spatial variability in MgCO₃ content in skeletons from stations exhibiting different seawater parameters suggests that environmental factors can also, to some extent, shape the skeletal chemistry of Arctic bryozoans.

在北极，海水生化条件的季节性模式是由与季节交替有关的物理，化学和生物过程影响的，即冬季极夜和夏季午夜太阳。在夏季，CO ₂浓度受自养生物的光合作用的驱动，这提高了海水的pH值和碳酸盐饱和状态（Ω）。此外，将光合作用活动限制在富营养区和建立季节性分层通常会导致pH和Ω的深度梯度。但是，在冬季，一次生产的严重减少以及呼吸过程会导致较高的CO ₂浓度，从而降低海水的pH和Ω。

许多钙化无脊椎动物将钙以外的其他金属结合到骨架中，这对矿物质基质的稳定性和易被捕食者磨损具有潜在的后果。我们测试了由于海洋生物群的光驱动活动引起的海水化学变化是否会影响Mg向北极Bryozoa钙化骨骼中的摄取，北极Bryozoa是极地硬底生境中的主要动物群。我们的结果表明，尽管这两个季节之间的Ω差异，但五种苔藓动物的夏季和冬季骨骼MgCO ₃含量之间没有明显差异。此外，我们无法检测到所选苔藓动物骨骼中MgCO ₃含量的任何深度相关差异。这些结果可能表明北极苔藓动物能够控制MgCO₃骨骼浓度生物。然而，从表现出不同海水参数的台站骨骼中MgCO ₃含量记录的空间变异性表明，环境因素也可以在一定程度上影响北极苔藓动物的骨骼化学。