Mighty diatoms: Global climate feedback from microscopic algae

March 18, 2009

EAST LANSING, Mich. - Tiny creatures at the bottom of the food chain called diatoms suck up nearly a quarter of the atmosphere's carbon dioxide, yet research by Michigan State University scientists suggests they could become less able to "sequester" that greenhouse gas as the climate warms. The microscopic algae are a major component of plankton living in puddles, lakes and oceans.

Zoology professor Elena Litchman, with MSU colleague Christopher Klausmeier and Kohei Yoshiyama of the University of Tokyo, explored how nutrient limitation affects the evolution of the size of diatoms in different environments. Their findings underscore potential consequences for aquatic food webs and climate shifts.

"They are globally important since they 'fix' a significant amount of carbon," Litchman explained of the single-cell diatoms. "When they die in the ocean, they sink to the bottom carrying the carbon from the atmosphere with them. They perform a tremendous service to the environment."

Carbon dioxide buildup, due to a significant extent to burning fossil fuels and deforestation, is identified as the leading cause of climate change. Carbon dioxide is at its highest level in at least 650,000 years and rising, according to The National Academies, and only half of the CO2 produced now can be absorbed by plant life.

Litchman analyzed data from lakes and oceans across the United States, Europe and Asia and found a striking difference between the size of diatoms in freshwater and in marine environments. In oceans, diatoms grow to be 10 times larger on average than in freshwater and have a wider range of sizes.

One factor that affects growth is nutrient availability, Litchman said. The research shows that limitations by nitrogen and phosphorus exert different selective pressures on cell size. The availability of these nutrients depends on the mixing of water from greater depths. Using a mathematical model, Litchman and her colleagues found that when those nutrients are constantly limited and mixing is shallow, smaller diatoms thrive.

But when nitrate comes and goes, as often happens in roiling oceans, diatoms evolve larger to store nutrients for lean times. Deep mixing also benefits large diatoms. Depending on how intermittent the nitrate supply is and how deep the ocean mixes, there can be a wide range of diatom sizes. Size matters for the creatures that eat them and also for carbon sequestration, as large diatoms are more likely to sink when they die.

Changing climate could alter the mixing depths and delivery of nutrients to diatoms and their subsequent sizes with a cascade of consequences, Litchman said.

"On a global scale, increased ocean temperatures could make the ocean more stratified," she explained. "This would cause less mixing and create stronger nutrient limitation and less frequent nutrient pulses. A change like this would select for different sizes of diatoms. If smaller sized diatoms dominate, then carbon sequestration becomes less efficient and there may be more CO2 remaining in the atmosphere, which would exacerbate global warming."

Litchman and colleagues' research was supported by the National Science Foundation and the J.S. McDonnell Foundation. Their findings were published Feb. 24 in the Proceedings of the National Academy of Sciences.

Michigan State University

Diatoms: Biology and Morphology of the Genera
by F. E. Round (Author), R. M. Crawford (Author), D. G. Mann (Author)

Illustrated descriptions of over 250 genera of diatoms are presented for the first time in this wide-ranging volume. The introduction describes the diatom cell in detail, the structure of the wall (often extremely beautiful designs), the cell contents and aspects of life cycle and cell division. The generic atlas section is the first account of diatom systematics since 1928, and each generic description is accompanied by scanning electron micrographs to show the characteristic structure.

Diatoms of North America
by William Vinyard (Author)

Diatoms: Unnoticed Living Jewels in Water
by Dean W Blinn (Author), Sandra L Blinn (Author), Stephanie Strong (Illustrator)

This book is designed to introduce diatoms to younger generations and to enlighten them about how these “living jewels” help our planet function on a daily basis. Diatoms are in the group of plants called algae, and have typically been appreciated only by the scientists who study them and those who use them commercially. The significance of these mysterious tiny plants is especially important for the younger generations, because diatoms will forever play a critical role in the health of our planet. Most diatoms are smaller than the period at the end of this sentence, yet together they provide nearly 40% of the Earth’s oxygen and effectively help reduce global warming on our planet. Diatoms also help us in learning about the past, solving crimes, manufacturing household products,...

The Diatoms: Applications for the Environmental and Earth Sciences
by John P. Smol (Editor), Eugene F. Stoermer (Editor)

This much revised and expanded edition provides a valuable and detailed summary of the many uses of diatoms in a wide range of applications in the environmental and earth sciences. Particular emphasis is placed on the use of diatoms in analysing ecological problems related to climate change, acidification, eutrophication, and other pollution issues. The chapters are divided into sections for easy reference, with separate sections covering indicators in different aquatic environments. A final section explores diatom use in other fields of study such as forensics, oil and gas exploration, nanotechnology, and archaeology. Sixteen new chapters have been added since the first edition including introductory chapters on diatom biology and the numerical approaches used by diatomists. The...

The Diatom World (Cellular Origin, Life in Extreme Habitats and Astrobiology)
by Joseph Seckbach (Editor), Patrick Kociolek (Editor)

Diatom biology, genomics and ecology are becoming more relevant to the human species. While there have been recent compilations of some of the applied aspects of diatoms, and the dizzying pace of taxonomic revisions, this new volume bring us up to date on their classification, biology and ecology, as well as covering the topics of genomics and applied uses. In this collection, some of the leaders in diatom research present either new information or summarize recent research efforts on a wide range of topics, including the tree of life of diatoms, their classifications, the wide habitats and ecological spectra the group exploits, as well as the beauty of their form. This volume celebrates the diversity, emerging areas of research and fascinating ecology of the diatoms bringing this group...

Diatoms to Dinosaurs: The Size and Scale of Living Things
by Chris McGowan (Author), Julian Mulock (Illustrator)

In "Diatoms to Dinosaurs," Chris McGowan takes the reader on a fascinating journey through the natural world, and examines life in all its various forms. He imparts the excitement of discovery and the joy of understanding as he demonstrates the central importance of size and scale to the survival of living organisms.McGowan investigates a wide range of size-related phenomena, from the gliding mechanism of diatoms to blood pressure problems of dinosaurs. Questions asked -- and answered -- include: Will we ever see giant insects the size of pterodactyls? Why are ants so much stronger relative to body size than elephants? What do a clam, a condor, a tortoise, and a sturgeon have in common? How did the skeleton of a 28-ton Apatosaurus support its weight? How can blood get from the heart to...

A Treatise On The Diatomaceae: Containing Introductory Remarks On The Structure, Life History, Collection, Cultivation And Preparation Of Diatoms (1896)
by Henri Van Heurck (Author), Wynne E. Baxter (Translator)

This book is a facsimile reprint and may contain imperfections such as marks, notations, marginalia and flawed pages.

Automatic Diatom Identification (Series in Machine Perception and Artifical Intelligence)
by Hans Du Buf (Editor), Micha M. Bayer (Editor)

[Series in Machine Perception and Artificial Intelligence, Volume 51> First book to deal with automatic diatom identification. Provides the necessary background information concerning diatom research, useful for both diatomists and non-diatomists.

The diatoms: A photomicrographic book
by G. W Prescott (Author)

Discusses the structure, uses, and reproduction of diatoms, algae distinctive for their cell walls made of silica.

Diatoms: Ecology and Life Cycle (Environmental Science, Engineering and Technology)
by James C. Compton (Editor)

Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Diatom communities are a popular tool for monitoring environmental conditions, past and present, and are commonly used in studies of water quality. This book presents topical research data in the study of diatoms, including the role of environmental factors in shaping diatom frustule; marine diatom communities; diatom classification methods; an analysis of the diatom flora of lakes, ponds and streams of the Kuril Islands; the ecological information of diatoms provides information on the reconstruction of palaeo-environments; and, the regulatory influences of diatoms on benthic invertebrates.