Antarctic Algae Secrets: How They Thrive in Extreme Cold

Greg Howard
22nd March, 2024

Antarctic Algae Secrets: How They Thrive in Extreme Cold

Image Source: Natural Science News, 2024

Key Findings

  • In Antarctica's WAP, a diatom called Actinocyclus thrives in cold, fresh coastal waters
  • Actinocyclus has a unique metabolism that helps it grow and manage stress during blooms
  • Offshore diatoms adapt to iron scarcity with special proteins and reduced iron reliance
Understanding how tiny marine plants called phytoplankton survive in the frigid waters off the coast of Antarctica is not just a question for marine biologists—it's a puzzle with implications for the entire planet's climate. Phytoplankton in the Southern Ocean play a critical role in absorbing carbon dioxide from the atmosphere and thus help regulate our climate. However, the survival tactics of these organisms in the face of rapid environmental changes have been somewhat of a mystery. Now, scientists from the University of North Carolina at Chapel Hill have shed light on this mystery by investigating the metabolic strategies of diatoms, a type of phytoplankton, in the Western Antarctic Peninsula (WAP)[1]. The WAP is a place of extremes and rapid change, where the water's physical and chemical properties vary dramatically from the coast to the open ocean. This variability affects the composition and productivity of the local plankton communities. Diatoms are particularly interesting because they are responsible for large phytoplankton blooms that have significant effects on the region's food web and carbon cycling. The recent study took a close look at the metabolic profiles of phytoplankton across different regions of the WAP using a technique called metatranscriptomics. This method involves sequencing the RNA of organisms to understand which genes are active and thus what metabolic processes are occurring. This approach allows scientists to understand how organisms respond to their environment at the molecular level. The findings revealed that in the coastal, southern regions of the WAP, where the water is colder and fresher, a particular centric diatom called Actinocyclus was thriving. Actinocyclus had a unique metabolic profile, investing heavily in growth and energy production, as well as in mechanisms to cope with stress. This robust metabolic activity is likely what enables it to dominate during bloom conditions. Further offshore, in the shelf and slope regions, diatoms faced iron limitation—a common challenge in the Southern Ocean[2]. Iron is a crucial nutrient for many cellular processes, including photosynthesis. The study found that diatoms in these iron-limited regions were using a range of strategies to cope with the scarcity of iron. These included the production of iron-starvation induced proteins and other adaptations to reduce their reliance on iron-containing proteins. These findings align with previous research that highlighted the importance of iron for phytoplankton in the Southern Ocean and how they have adapted to low iron conditions[2]. Moreover, they complement studies that have shown the impact of sea-ice conditions on plankton biodiversity and carbon cycling in the region[3], and how changes in temperature and iron availability could shift the community composition and biogeochemical processes[4]. The study's results also suggest that the differences in water properties across the shelf are more influential on the phytoplankton community than the differences between the southern and northern regions of the WAP. However, as the climate continues to change, these patterns could shift, leading to changes in the distribution and function of diatom communities. This research is particularly important as it helps predict how phytoplankton communities might respond to future changes in ocean conditions caused by climate change. Since phytoplankton are at the base of the marine food web and play a critical role in global carbon cycling, understanding their survival strategies is vital for predicting the future health of marine ecosystems and global climate regulation. In summary, the study by the University of North Carolina at Chapel Hill provides a window into the metabolic life of diatoms in the rapidly changing waters of the WAP. By understanding the molecular basis for the survival and dominance of certain diatom species in this variable environment, scientists can better anticipate the effects of ongoing climate change on marine ecosystems and their role in the global carbon cycle.

EcologyPlant ScienceMarine Biology

References

Main Study

1) Molecular physiology of Antarctic diatom natural assemblages and bloom event reveal insights into strategies contributing to their ecological success.

Published 19th March, 2024

https://doi.org/10.1128/msystems.01306-23

Related Studies

2) Widespread use of proton-pumping rhodopsin in Antarctic phytoplankton.

https://doi.org/10.1073/pnas.2307638120

3) Decline in plankton diversity and carbon flux with reduced sea ice extent along the Western Antarctic Peninsula.

https://doi.org/10.1038/s41467-021-25235-w

4) Molecular underpinnings and biogeochemical consequences of enhanced diatom growth in a warming Southern Ocean.

https://doi.org/10.1073/pnas.2107238118


Related Articles

An unhandled error has occurred. Reload 🗙