A new study published this month in the journal Nature Communications has shown that diatoms can withstand population collapse in an acidified environment by conserving valuable energy normally used for carbon dioxide consumption.
Diatoms are a type of microscopic plankton called phytoplankton, the most common of the four plankton types and are the foundation for many aquatic food webs, also being responsible for 40 percent of the total carbon sequestered in our oceans and the release of about 20 percent of the world’s breathable oxygen. Fossil evidence suggests that diatoms originated during or before the early Jurassic period, about 150 to 200 million years ago.
The impacts of ocean acidification on diatoms had not been completely understood prior to this study, which was conducted by Researchers at the Institute for Systems Biology (ISB) and entitled ” Ocean Acidification Conditions Increase Resilience of Marine Diatoms,”.
“To date, the effects of ocean acidification on diatoms have been mixed, mainly because of the complex interactions between the biology and physical chemistry. We decided to take a new and different approach to this biological question by exposing the diatom to a stress test,” said Dr. Jacob Valenzuela, a postdoctoral fellow in ISB’s Baliga Lab and lead author on the study. “By using a systems biology approach in conjunction with a stress test, we were able to demonstrate diatom resilience increases under ocean acidification conditions,” Valenzuela said.
In the study, researchers observed that diatoms of the species (Thalassiosira pseudonana) at a lower pH were consistently more capable of adopting the appropriate cellular function in relation to their environment — a phenomenon that staves off population collapse.
Ocean acidification results from the continued burning of fossil fuels by humans, increasing the levels of carbon dioxide in the Earth’s atmosphere. Most of the carbon dioxide that is released into the atmosphere ultimately ends up in the oceans, where it combines with seawater to produce carbonic acid. This increases the acidity of the water (lowering its pH) which can have detrimental effects to marine species.
Climate change-induced ocean acidification may make diatoms more resilient, but it could also have adverse effects on other phytoplankton populations, potentially shifting them from stable to sensitive, Valenzuela said. The impacts of such a foundational shift may ripple throughout the marine ecosystems. The experimental framework developed in this study may be extended to evaluate the effects of many potential climate change-related threats on the microbial diversity of our most sensitive environmental habitats.
If diatoms were to shrink or explode in population abundance, there would be significant implications for marine food webs and beyond. For instance, coral reefs and fisheries rely on stable phytoplankton communities to feed higher organisms along the food chain like krill, fish and whales. Understanding how diatoms will respond to the impacts of climate change, and in particular ocean acidification, will be critical in predicting future outcomes that guide proactive conservation efforts.
Jacob J. Valenzuela, Adrián López García de Lomana, Allison Lee, E. V. Armbrust, Mónica V. Orellana, Nitin S. Baliga. Ocean acidification conditions increase resilience of marine diatoms. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-04742-3
Diatoms – Credit: Trent L. Schindler