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Climate-indicator potential of algae species revealed

Micromonas could be used as an indicator of climate change according to new research (photo: Worden Lab/Joint Genome Institute); Science

Thu, 09 Apr 2009

Tiny algae organisms living in the world's oceans could be used as an important indicator of climate change, according to new findings by an international team of scientists.

Micromonas could be used as an indicator of climate change, according to new research (photo: Worden Lab/Joint Genome Institute)

The team, which included Dr Thomas Mock from the University of East Anglia, carried out the first DNA sequencing of genomes from the previously overlooked phytoplankton group Micromonas. They found that it thrives in oceans ranging from tropical to polar and in conditions that are predicted outcomes of climate change. These include increased separation of the upper ocean layer from deep nutrient-rich waters due to increased temperature. This will cause a reduced mixing between both layers, resulting in the reduction of nutrients in surface waters where phytoplankton lives.

The study, published this week in the journal Science, shows that while other larger phytoplankton species such as Diatoms may not grow well under these conditions, the tiny Micromonas species - which is a fifth of the size of a human blood cell - can thrive under low concentrations of nutrients and is very well adapted to lower nutrient conditions, and therefore may become more dominant.

Co-author Dr Mock, of the School of Environmental Sciences, said: "This research shows that we need to look very carefully in the oceans because things that have been previously overlooked, such as the Micromonas species, may have a significant impact in the future ocean."

Although the existence of Micromonas was first reported in the 1950s, until now little has been known about it. Scientists overlooked it because of its size and lower abundance under past and current conditions of the oceans. Only the use of modern molecular technologies revealed its presence in almost all the world's oceans.

"If Micromonas and other tiny phytoplankton species dominate the future ocean, it might also have a significant impact on the entire marine food web because the food source for all other organisms will change," said Dr Mock.

About five years ago researchers from institutions in Europe, America and Australia started surveying Micromonas across the world's oceans. They selected two different strains for this genome project, one from the English Channel and another one from waters around Australia. Sequencing was done at the Joint Genome Institute (JGI), part of the US Department of Energy, which also funded the research.

This study also reveals new insights into the evolution of Micromonas and also higher plants because it retains characteristics that are believed to have been present in the last common ancestor of green algae and land plants. Micromonas has genes which are evolutionary associated with leaf development in higher plants.

The project was led by Dr Alexandra Z Worden of the Monterey Bay Aquarium Research Institute in California, and Dr Igor V Grigoriev of JGI.