An increase in the water temperature of the world’s oceans of around six degrees Celsius — which some scientists predict could occur as soon as 2100 — could stop oxygen production by phytoplankton by disrupting the process of photosynthesis.
Credit: NOAA MESA Project.
Posted: 01 Dec 2015 06:41 AM PST
Falling oxygen levels caused by global warming could be a greater threat to the survival of life on planet Earth than flooding, according to researchers from the University of Leicester.
A study led by Sergei Petrovskii, Professor in Applied Mathematics from the University of Leicester’s Department of Mathematics, has shown that an increase in the water temperature of the world’s oceans of around six degrees Celsius — which some scientists predict could occur as soon as 2100 — could stop oxygen production by phytoplankton by disrupting the process of photosynthesis.
Professor Petrovskii explained: “Global warming has been a focus of attention of science and politics for about two decades now. A lot has been said about its expected disastrous consequences; perhaps the most notorious is the global flooding that may result from melting of Antarctic ice if the warming exceeds a few degrees compared to the pre-industrial level. However, it now appears that this is probably not the biggest danger that the warming can cause to the humanity. “About two-thirds of the planet’s total atmospheric oxygen is produced by ocean phytoplankton — and therefore cessation would result in the depletion of atmospheric oxygen on a global scale. This would likely result in the mass mortality of animals and humans.” The team developed a new model of oxygen production in the ocean that takes into account basic interactions in the plankton community, such as oxygen production in photosynthesis, oxygen consumption because of plankton breathing and zooplankton feeding on phytoplankton. While mainstream research often focuses on the CO2 cycle, as carbon dioxide is the agent mainly responsible for global warming, few researchers have explored the effects of global warming on oxygen production…
Yadigar Sekerci, Sergei Petrovskii. Mathematical Modelling of Plankton–Oxygen Dynamics Under the Climate Change. Bulletin of Mathematical Biology, 2015; DOI: 10.1007/s11538-015-0126-0
This undated handout image provided by Karl Bruun, Nostoca Algae Laboratory, photo courtesy of Nikon Small World, shows a number of marine diatom cells (Rhizosolenia setigera), which are an important group of phytoplankton in the oceans. Much of life on Earth depends on tiny plant plankton. They are the foundation of the bountiful ocean food web, make half the world’s oxygen and suck up harmful carbon dioxide. A new study published Monday in the journal Nature Climate Change demonstrates that ocean acidification could dramatically impact the world’s plankton. Karl Bruun/Nostoca Algae Laborator/Nikon Small World/AP/File
A new study suggests that rising carbon dioxide in the ocean is causing a spike in population of microscopic marine alga.
By Beatrice Gitau, Staff / November 28, 2015
Phytoplankton, micro-organisms that float, as opposed to swim, are rapidly thriving in the North Atlantic, suggesting an environmental shift that defies previous scientific predictions. Scientists have long thought that the number of plankton species would decline due to increased acidity in the oceans. However, over the last four decades or so they have grown to be much more in abundance, a new study indicates. The study, led researchers from Johns Hopkins University, shows a ten-fold increase in the number of coccolithophores, single-celled algae with a limestone shell, that are found throughout the planet’s oceans between 1965 and 2010, and a particularly sharp spike since the late 1990s. “Something strange is happening here, and it’s happening much more quickly than we thought it should,” Anand Gnanadesikan, associate professor in the Morton K. Blaustein Department of Earth and Planetary Sciences at Johns Hopkins, and also one of the study’s five authors said, in a news release. During their study, the team, analyzed Continuous Plankton Recorder survey data from the North Atlantic Ocean and North Sea since the mid-1960s. This revealed that higher carbon dioxide levels in our planet’s oceans may be causing an increase in the population of coccolithophores. “Our statistical analyses on field data from the CPR point to carbon dioxide as the best predictor of the increase in coccolithophores,” Sara Rivero-Calle, a Johns Hopkins doctoral student and lead author of the study said. “The consequences of releasing tons of CO2 over the years are already here and this is just the tip of the iceberg.” According to William M. Balch of the Bigelow Laboratory for Ocean Sciences in Maine, a co-author of the study, scientisits have long expected that increasing ocean acidification acidity due to higher carbon dioxide would suppress these chalk-shelled organisms. The new study shows, it didn’t. “Coccolithophores have been typically more abundant during Earth’s warm interglacial and high CO2 periods,” said Balch. “The results presented here are consistent with this and may portend, like the ‘canary in the coal mine,’ where we are headed climatologically.” A study last summer projected that the balance of various plankton species will radically change as the world’s oceans increase in acidity over the next 85 years. The Christian Science Monitor reported, “By 2100, ocean acidification will have grown to such an extent that some species of phytoplankton ‘will die out, while others will flourish’“….
Posted: 27 Nov 2015 07:23 AM PST
Globally, phytoplankton absorb as much carbon dioxide as tropical rainforests and so understanding the way they respond to a warming climate is crucial, say scientists. A new study from the University of Exeter, published in the journal Ecology Letters, found that phytoplankton — microscopic water-borne plants — can rapidly evolve tolerance to elevated water temperatures. Globally, phytoplankton absorb as much carbon dioxide as tropical rainforests and so understanding the way they respond to a warming climate is crucial. Phytoplankton subjected to warmed water initially failed to thrive but it took only 45 days, or 100 generations, for them to evolve tolerance to temperatures expected by the end of the century. With their newfound tolerance came an increase in the efficiency in which they were able to convert carbon dioxide into new biomass.
The results show that evolutionary responses in phytoplankton to warming can be rapid and might offset some of the predicted declines in the ability of aquatic ecosystems to absorb carbon dioxide as the planet warms…. The underlying mechanism for the ability to tolerate warmer temperatures was an increase in the efficiency in which the alga was able to convert carbon dioxide into new biomass by reducing rates of respiration (production of carbon dioxide). It is this shift in the relative rates of respiration and photosynthesis that enabled the phytoplankton to cope with warmer temperatures. While these experiments focused on a single species and strain of phytoplankton, the researchers believe that the rapid evolution of carbon-use efficiency will apply to other species of phytoplankton and substantially improve models describing ecological and biogeochemical effects of climate change.
Daniel Padfield, Genevieve Yvon-Durocher, Angus Buckling, Simon Jennings, Gabriel Yvon-Durocher. Rapid evolution of metabolic traits explains thermal adaptation in phytoplankton. Ecology Letters, 2015; DOI: 10.1111/ele.12545