There has been a lot of talking about climate change in the last years. But what do we know about the impact of climate change on diatoms? Here is a short summary of some of the research on the consequences of climate change on diatoms.
Climate change and in particular the augmentation of carbon dioxide (CO2) in the air has huge consequences on life in the ocean. Nowadays, the major source of air pollution comes from traffic emissions.
Carbon dioxide is constantly absorbed into the water, so the more there is in the air, the more enters the ocean. When CO2 concentration in water increases, water becomes more acidic and organisms that live in it suffer the consequences of the changing environment. Some species will thrive, some will die, most of them will have to adapt.
Diatoms are an extremely important contributor to the marine food web. Through photosynthesis they create 40% of the total organic matter produced in the ocean, the phytoplankton, that is then eaten by many other organisms, such as krill, fish, whales, etc. Many scientific projects research and experiment in the lab the consequences that the increased acidification of oceans will have on marine ecosystems, as it will indirectly impact our ways of life as well.
Although the direct impact of an increasing concentration of carbon dioxide would be an increase in diatoms growth, the indirect consequence of the former would be deleterious. Indeed, when acidification increases in water, all the nutrients that diatoms and other primary producers need to survive and grow, will be affected. Some become unavailable or limiting, like iron or nitrogen, whereas others become toxic.
The answer is far from being simple. The consequence of water acidification could be dwarfed by the effect of decreased availability of nitrogen, an essential nutriment for diatoms. On the other hand, the effect of water acidification on diatom performance could also depend on access to sunlight, which would imply a gradient of impact with light decreasing with the distance from the surface. The good news is that it looks like increased CO2 concentration in water also increases diatoms capacity for resilience4, which means that diatoms could be able to tolerate a certain amount of water acidification without a drastic change in their community composition. At least to a certain point.
uk-air.defra.gov.uk/air-pollution/causes
Physical and biogeochemical modulation of ocean acidification in the central North Pacific.
John E. Dore, Roger Lukas, Daniel W. Sadler, Matthew J. Church, and David M. Karl
PNAS: 106 (30) 12235-12240. 2009.
https://www.pnas.org/content/106/30/12235
Interactive Effects of Ocean Acidification and Nitrogen-Limitation on the Diatom Phaeodactylum tricornutum.
Wei Li, Kunshan Gao, and John Beardall PLoS One: 7(12): e51590. 2012.
https://journals.plos.org/plosone/article…
Ocean acidification conditions increase resilience of marine diatoms.
Jacob J. Valenzuela, Adrián López García de Lomana, Allison Lee, E. V. Armbrust, Mónica V. Orellana & Nitin S. Baliga. Nature Communications: volume 9, Article number: 2328. 2018.
https://www.nature.com/articles/s41467-018-04742-3