Abnormal levels of carbon dioxide in the North Atlantic are being linked to the rapid growth of plankton population in the ocean over the past 45 years, according to a study featured in the journal Science.
A team of marine researchers, led by associate professor Anand Gnanadesikan of Johns Hopkins University, discovered that the population of microscopic marine alga known as Coccolithophores in the North Atlantic experienced a tenfold increase from 1965 to 2010.
This recent finding contradicts earlier assumptions made by scientists that the phytoplankton would find it difficult to produce plates from calcium carbonate as ocean waters become increasingly more acidic.
Dr. William Balch, a researcher at the Bigelow Laboratory for Ocean Sciences and one of the authors of the study, explained that the results show the importance of conducting long-term time-series observations of oceans in order to find out how marine microorganisms deal with the effects of climate change and prove that the ocean garden is indeed undergoing some changes.
"We never expected to see the relative abundance of coccolithophores to increase 10 times in the North Atlantic over barely half a century," Balch said.
"If anything, we expected that these sensitive calcifying algae would have decreased in the face of increasing ocean acidification."
Balch added that the carbon-limited microorganisms, instead, seem to make use of the excess carbon from carbon dioxide to help speed up the growth of their population.
As far as the fast growth rate of coccolithophores goes, lead researcher Gnanadesikan said that this could be beneficial to larger creatures that consume the phytoplankton even though it remains unclear what those creatures are.
He said it is troubling that their research shows just how little information is available regarding the complex functions of ecosystems.
The findings of the Johns Hopkins University-led study underscore the possibility that ecosystems could undergo sudden and rapid changes.
Gnanadesikan said it is possible that current scientific models may be too conservative in portraying how such systems react to changes in the climate.
Impact of Phytoplankton Bloom on the Environment
Historically, rapid population increases involving coccolithophores corresponded with high carbon dioxide levels and warm interglacial periods of the Earth.
Since phytoplankton species depend on carbon dioxide in order to complete their photosynthesis, abundance in available CO2 would allow these microscopic organisms thrive and grow at a faster rate than normal.
This in turn can greatly reduce the levels of CO2 in the atmosphere as well as lower the average temperatures in the world.
Scientists closely monitor the growth of microorganisms in the oceans to find out sudden changes in environmental conditions.
Even slight deviations from the distribution, density or development rate of a given species, such as coccolithophores, could already be an indication of climate and environmental changes.
Some coccolithophores are also known to outcompete other phytoplankton species as they can often thrive in harsher environments such as in warmer and nutrient-poor bodies of water.
This could potentially cause an imbalance in the ecosystem, especially among creatures that depend on the formation of other microorganisms that the coccolithophores have outcompeted.