30 June, 2022
- By Catarina Carrao
“I will miss exploring the campus nooks and corners,
which often surprise me with new discoveries and encounters”
Dr. Ananya Ashok
Today, we visited Dr. Ananya Ashok, a recent PhD graduate from the Biological Oceanography Lab of Prof. Susana Agustí's research group. She is now preparing to leave KAUST to a new adventure in the land of the channels, tulips, and windmills – the Netherlands. But not before sharing with us all the details of her prolific PhD…
Dr. Ashok when joining Prof. Agusti's laboratory, started her studies collaborating in a project with KFUPM to document carbon burial in coastal ecosystems by adding a perspective to the petroleum sinks of the coastal areas of the Arabian Gulf in the last 100 years. Just like a National Geographic documentary, her first publication (Ashok, et al. 2019), revealed that these sediments are quite important for Petroleum Hydrocarbons (TPH) trapping. In fact, according to Ananya “we estimated around 60000 (59,799) megagrams (1 Mg = 1.10 ton) of TPHs buried in the top few centimeters of sediments”, which represented a snip-shot of time of just 2.5 decades: from 1990 – 2015. As such, the results of her studies revealed that perturbing just the top layer of such habitats could risk the re-emission of several thousand tons of buried pollutants.
Next, she was collaborating in Agusti’s project aiming to develop methodologies based on stable isotopes tracers. Ananya participated in applying these techniques to study the accumulation and transfer of oil-derived contaminants into the coral-reef food chain, using Cavity-Ring Down Spectroscopy (CRDS).
She explained us that this technique was initially proposed to measure CO2, H2O, and methane in the atmosphere (Crosson 2008); but it quickly found application in aquatic carbon cycling. This is because, at the beginning of Ananya's PhD studies, data came to light that wild-corals seemed to have very high concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) in their tissues - meaning they were "accumulating" these pollutants from unknown sources. Also, it was not known the processing pathways or the toxic impact on corals from such exposure. Furthermore, the analytical techniques available to measure the concentrations of such harmful pollutants were very complex, expensive, or even unsafe, due to the usage of radioactive compounds. As such, the need to find new ways to study such damaging contaminants in a simpler and safer way was quite pressing, she told us.
As such, she joined a collaborative project between RSRC and the Australian Institute of Marine Sciences (AIMS), that allowed her to conduct experiments using the state-of-the-art marine aquarium facilities at SeaSIM and Prof. Duarte’s Carbon Isotopes laboratory. By using stable-carbon isotope labeling of PAHs (13 and 12C), CRDS reveal to be the perfect technique to evaluate the concentrations and movement of these pollutants through aquatic organisms and biological systems.
Since some of these oil-associated contaminants have a lipophilic-base, they can accumulate in the body lipids of exposed organisms; and, can be transferred along food chains. When PAHs accumulate in corals through their food sources, corals tissue samples can then be combusted and converted to its gaseous components; and CRDS lasers then measure the concentration of total and individual stable carbon isotopes in the referred samples. In Ananya’s words, “this technique can detect up to parts per billion level concentrations of carbon in a sample, essentially providing greenhouse-gases analysis centered on a laser-based spectroscopic technique” – take that, Star Wars laser fans!
Ananya’s PhD work has set a new paradigm to evaluate the effect of pollutants in coral reefs - not only by water-diffusion, but through the trophic transfer of food chain risk.
Just like the junk food that we sometimes eat has adverse effects on our health; corals and aquatic organisms also suffer from the same evil - but in a much more problematic way, because they don’t have a choice. In Ananya’s words, “We now know that food-chains play an important role in how corals accumulate these chemicals, and may even be the missing piece of the puzzle on why they have such concentrations in natural environments”.
Ananya hopes that her work provides the impetus for further research on the trophic transfer of risks of pollutants. Furthermore, CRDS technical sensitivity, versatility and robustness can assist other aquatic-marine pollution studies by evaluating not only PAHs, but also other emerging pollutants (e.g., polychlorinated biphenyls, or even microplastics). This makes it a valuable tool for regulatory agencies to assess the risk of these harmful chemicals in the marine environment. And, that is exactly where Ananya will direct her drive in her future role as a consultant for environmental policies at the European level. She aims to apply her scientific acumen to establish resilient bridges between science and environment-climate policies.