Nitro! - Kolisa Sinyanya

Kolisa Sinyanya: PhD candidate in Oceanography at University of Cape Town, UCT OceanWomxn Fellow, Black Women In Science South Africa Fellow 2019, TEDx Speaker, FameLab Cape Town Runner Up 2018, As seen on TV @CNN Inside Africa! #OceanWomxn #MthathaBoffin #PhDLife

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Her Research: Kolisa studies phytoplankton and their critical role in the carbon cycle. Phytoplankton are the microscopic bacteria, protists, and single celled plants that essentially make life on earth possible. They live their lives, in oceans and fresh water, harnessing the sun’s rays through photosynthesis to grow and reproduce. Photosynthesis takes carbon dioxide (CO2) out of the atmosphere and turns it into nutrients, oxygen is released as a by-product. There are so many phytoplankton (mainly in the oceans) doing their thing that 50-85% of the global oxygen we all breathe comes from phytoplankton! (That’s the life on earth possible bit). When they die, the phytoplankton, little carbon containing particles, release their carbon back into the atmosphere or sink to the bottom of the ocean where they are compressed for hundreds or thousands of years. Sinking to the bottom exports or removes their carbon from the system and is called drawdown.

It is important for us to understand how the carbon cycle works, especially in a warming planet. Knowing more helps us make predictions of how the ocean will be in the future, estimate how productive the ocean is now and how ocean productivity might change in the future and affect food security - the fish stocks and other foods that are harvested from the ocean. Understanding the carbon cycle also helps scientists advise policy makers who are writing the laws and regulations to slow climate change.

Kolisa is studying phytoplankton carbon uptake in the Indian Ocean’s Agulhas Current marine system between Port Elizabeth and East London, South Africa. To study how carbon uptake is measured is a bit tricky but so fascinating, so stay with us here…

Phytoplankton use different forms of nitrogen depending on the species, size and other factors. The primary forms of nitrogen they use are nitrate and ammonia. The bigger phytoplankton species prefer nitrate and nitrate use is a sign that carbon export, or drawdown, will happen. The smaller species have higher preference for ammonia which does not lead to carbon drawdown into the deep ocean. So we need to measure how much nitrate is being used versus how much ammonia is being used. Kolisa can do this by looking at different isotopes of nitrogen. Isotopes are the same chemical element with a different number of neutrons. Nitrogen exists as two stable isotopes 1) nitrogen-14 (14N) which is 99.6% of all nitrogen, and 2) nitrogen-15 (15N) that has an extra neutron. 14N is easier to use in photosynthesis and is more rapidly taken up by phytoplankton, 14N is more enriched in ammonia. 15N is not as readily taken up and the waters become enriched in this isotope, 15N is more enriched in nitrate. So if we find more 15N in a phytoplankton there is is more nitrate use, which is likely to lead to drawdown. More14N, more ammonia use, less carbon drawdown.

Kolisa collects ocean samples and measures the ratio of 15N:14N which can be written as δ15N (‰). The more 15N in the sample compared to 14N, the higher the δ15N. Higher δ15N indicates there is more nitrate use, which is likely to lead to carbon drawdown. She can determine what specific phytoplankton communities exist in ocean samples and which communities have high or low δ15N. This leads to developing mathematical models of the entire system and visualize which phytoplankton communities are in the waters, how much carbon uptake happens, how much drawdown is taking place, and at what rates per day, per hour. It’s truly amazing.

Her Superpowers:

  • Pluck an individual phytoplankton out of a ocean sample! Flow cytometry helps.

  • Measure the difference of a single neutron to determine what type of nitrogen phytoplankton ate days go. 15N has one more neutron than 14N, isotope analysis mass spectrometry helps.

  • Extrapolation! From her nitrogen measurements she can determine carbon capture and draw down and eventually model an entire ocean system!

Her Heroes: “Women In STEM. They inspire me to become one of the best Black women oceanographers on Earth.”

Rank list of what it takes to succeed: Hard work, communication, curiosity, creativity. What else? Working smart, time management and persistence.

Background of her card: Special thanks to Allison Cusick @womanscientist for the phytoplankton picture we used for a background. She helps run a fabulous citizen science programme @FjordPhyto as well as womanscientist.com. Science is generally wonderful for how international and open to sharing it is.

Connect: Twitter@Kolie_Yola Insta@kolieyola LinkedIn@Kolisa Yola Sinyanya

All SuperScientists, Current, Marine, WomenJustin Yarrow