jzrapp
commented
7 years ago Hi @pbuttigieg, I would say there is more than one possibility to encounter brownish colored sea ice: 1) Yes, could be algae growing in the ice. You would usually expect the bulk of the biomass in the lower/bottom part of the sea ice ~bottom 10-20 cm, which can then show a brown/greenish coloration. Ice floes may flip over during ice movement and so the color is sometimes also seen from top. e.g. Lange, B. A., Michel, C., Beckers, J. F., Casey, J. A., Flores, H., Hatam, I., et al. (2015). Comparing springtime ice-algal chlorophyll a and physical properties of multi-year and first-year sea ice from the Lincoln Sea. PLoS One 10, e0122418. doi:10.1371/journal.pone.0122418. Boetius, A., Anesio, A. M., Deming, J. W., Mikucki, J., and Rapp, J. Z. (2015). Microbial ecology of the cryosphere : sea ice and glacial habitats. Nat. Rev. Microbiol. 13, 677–690. doi:10.1038/nrmicro3522.
2) Sea ice may carry sediment, which can be incorporated during formation and freeze-up close to the shore or over shallow shelf areas. e.g. Wegner, C., Wittbrodt, K., Hölemann, J. A., Janout, M. A., Krumpen, T., Selyuzhenok, V., et al. (2017). Sediment entrainment into sea ice and transport in the Transpolar Drift: a case study from the Laptev Sea in winter 2011/2012. Cont. Shelf Res. 141, 1–10. doi:10.1016/j.csr.2017.04.010.
3) I've heard and read about certain algae that also populate ice surfaces or the ice-snow interface, which can result in red/brownish color. However, they've been, to my knowlege, only reported for glacier ice and snow.
The reddish colour in snow originates from blooms of algae that belong to the Chlamydomonaceae family. More recently, algae belonging to the Zygnematophyceae have been detected that occupy vast areas of ice surfaces when the snow cover is lost during the summer. Both types of algae produce strong secondary pigmentation during summer, which is suggested to be a mechanism to adapt to the harsh conditions of snow and ice surfaces, while reducing the ice albedo.
taken from Boetius, A., Anesio, A. M., Deming, J. W., Mikucki, J., and Rapp, J. Z. (2015). Microbial ecology of the cryosphere : sea ice and glacial habitats. Nat. Rev. Microbiol. 13, 677–690. doi:10.1038/nrmicro3522.
pbuttigieg
@jzrapp - could you define this? Assuming some sort of algae growth.