Emiliania huxleyi

Hardangerfjord bloom 2020

Cwall99 lg

Bloom in the Barents Sea

Emiliania huxleyi, often abbreviated as E. huxleyi, is a species of coccolithophore found in ocean waters worldwide. It is a unicellular, eukaryotic phytoplankton covered with uniquely decorated calcareous plates known as coccoliths. This species plays a significant role in the global carbon cycle and marine ecosystems, making it a subject of extensive scientific research.

Description

E. huxleyi is characterized by its spherical shape and the presence of calcite scales, known as coccoliths, which cover its surface. These coccoliths are intricately patterned, contributing to the organism's ability to scatter light, which can give the water a milky appearance during blooms. The size of an individual cell typically ranges from 4 to 10 micrometers in diameter.

Ecology and Distribution

E. huxleyi is found in a wide range of marine environments, from tropical to polar waters, indicating its broad ecological tolerance. It thrives in both open ocean and coastal areas, often forming large blooms that can be seen from space. These blooms not only affect the marine food web but also play a crucial role in biogeochemical cycles, particularly the carbon cycle. Through the process of photosynthesis, E. huxleyi absorbs carbon dioxide from the atmosphere, some of which is then sequestered to the ocean floor as the coccoliths are shed and sink.

Role in the Carbon Cycle

The carbon cycle is significantly influenced by the activities of E. huxleyi due to its dual role in organic carbon fixation through photosynthesis and inorganic carbon precipitation through the formation of calcium carbonate coccoliths. This dual role helps regulate atmospheric CO2 levels and contributes to global climate regulation. Additionally, the sinking of coccoliths to the seafloor after the death of E. huxleyi cells facilitates the transfer of carbon from the surface to the deep ocean, a process known as the biological pump.

Research and Importance

Scientific interest in E. huxleyi has increased due to its sensitivity to changes in sea temperature and acidity, making it an important indicator species for studying the impacts of climate change on marine ecosystems. Furthermore, its extensive blooms have implications for fishery dynamics, nutrient cycling, and the albedo effect, whereby large blooms can increase the reflectivity of the water surface, potentially influencing local climate patterns.

Challenges and Threats

The changing global climate poses threats to E. huxleyi populations by altering ocean temperature, chemistry, and currents, which can impact bloom dynamics and distribution. Ocean acidification, in particular, affects the availability of carbonate ions necessary for coccolith formation, potentially threatening the survival of this species and its role in carbon sequestration.

Conclusion

Emiliania huxleyi is a key species in marine ecosystems with a significant impact on the global carbon cycle and climate regulation. Its study provides valuable insights into the functioning of marine ecosystems, the impacts of climate change on oceanic life, and the potential feedback mechanisms to the global climate system. As such, continued research on E. huxleyi is essential for understanding and mitigating the effects of global environmental changes on marine biodiversity and global biogeochemical cycles.