"The way that nutrients cycle through atmospheric, terrestrial, oceanic and associated biotic reservoirs can constrain rates of biological production and help structure ecosystems on land and in the sea. On a global scale, cycling of nutrients also affects the concentration of atmospheric carbon dioxide. Because of their capacity for rapid growth, marine microorganisms are a major component of global nutrient cycles. Understanding what controls their distributions and their diverse suite of nutrient transformations is a major challenge facing contemporary biological oceanographers. What is emerging is an appreciation of the previously unknown degree of complexity within the marine microbial community.
To understand how carbon and nutrients, such as nitrogen and phosphorus, cycle through the atmosphere, land and oceans, we need a clearer picture of the underlying processes. This is particularly important in the face of increasing anthropogenic nutrient release and climate change. Marine microbes, which are responsible for approximately half of the Earth's primary production, play an enormous role in global nutrient cycling."
(Arrigo, K.R., Marine microorganisms and global nutrient cycles. Nature 437, 349-355, 15 September 2005).
Figure and legend from- DeLong E.F. & Karl D.M.Genomic perspectives in microbial oceanography. Nature 437, 336-342 (2005).
As our countries and citizens grapple with the complex issue of global change, we must provide the best information we can about how marine microbes respond to and control atmospheric composition, and to do that we must begin by figuring out who is there and how the communities respond to "normal" environmental perturbations.
How to get there from here: Metagenomics
Recently, the merging of cultivation-independent gene sequences with contemporary genomic approaches (such as whole-genome shotgun sequencing) is providing a more comprehensive picture of the structure and function of indigenous microbial communities. Genomic approaches for studying natural microbial assemblages have been variously dubbed environmental genomics, population genomics, metagenomics or ecogenomics. Regardless of the moniker, all these approaches involve cultivation-independent genomic analysis of DNA extracted from naturally occurring microbial biomass.(DeLong, E.F.,Microbial community genomics in the ocean. Nature Reviews/Microbiology 3, 459-69, June 2005).
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Copyright on all images and material by Ed DeLong, 2005.