Southern Ocean Carbon Cycle
Recent scientific discovery shows that manganese, and not only iron, can affect how plankton that performs photosynthesis grows.
It offers insight into the idea that the Southern Ocean represents a key region that helps to foster understanding of how the climate works. The plankton performing photosynthesis in this region largely contributes to the control of CO2 in the atmosphere.
However, what are the factors that limit or advance the growth of plankton? A new study shows that manganese, combined with micronutrient iron, now plays a huge role. These results bear concerns for existing understanding of the past ice ages.
Usually, plankton is a term to describe tiny organisms which typically drift with ocean and sea currents. Though insignificant in size, they are crucial to our planet because of their larger quantities.
For instance, planktons that photosynthesize called phytoplankton produce half of the atmosphere’s oxygen and bins huge quantities of CO2. Because Antarctica’s South Ocean region boasts highly rich nutrients, a phytoplankton can flourish there. This makes the area key in controlling CO2 concentrations in the atmosphere.
Though there’s abundance of other nutrients, scientists have held the assumption that the quantity of available micronutrient iron will determine whether a phytoplankton would thrive in the said Ocean or not.
Research teams from GEOMAR ocean enter research center and United Kingdom’s Oceanography Center, in a recent study in Nature Communications journal, show that in certain Southern Ocean regions, manganese, other than iron, limits phytoplankton growth.
According to Dr. Browning from GEOMAR, who led the study, the finding is important to understand future changes and past phytoplankton.
The study involved incubating seawater with manganese and iron trace additions.
Past research shows a large share of phytoplankton growth in Southern Ocean regions was a significant contributor to the beginning of the different ice ages and witnessed a good 2.58million years ago. The more phytoplankton, the more they bind CO2, and remove them from our atmosphere.
Consequently, global temperatures declined. According to Dr. Browning, it is important that scientists understand the processes regulating the growth of plankton in South Ocean’s regions.
Combined with iron, manganese is an essential micronutrient that photosynthetic organisms require, from oak trees to algae. However, in most ocean regions, there is enough manganese for phytoplankton, so manganese in no way limits phytoplankton growth
Southern Ocean’s remote regions showed much lower concentrations of manganese when measured. During a mission on RRS JAMES, between Antarctica’s peninsula and del Fuego in Nov. 2018, Dr. Browning’s team took samples of the water.
They took the water samples as well as the phytoplankton to conduct experiments regarding which nutrients impact growth and nutrients that do not. According to Dr Browning, this helped them demonstrate that phytoplankton growth may be limited by manganese.
Even after the mission, the team deployed more model calculations to analyze rising concerns the results create. Here, they discovered that manganese limitation was most likely more widespread in the ace ages than it presently is. As Dr. Browning concludes, this will help to understand some missing links in the past ice ages.