Marine ecosystems are being affected by numerous environmental challenges around the globe. Critically important components of marine systems are microbes, which provide services in nutrient cycling, food webs and other functions. Information on microbial functions may provide important clues to stressors and the nutrient status of marine habitats. However, being small and similar in morphology, it is difficult to quantify and evaluate microbial populations and their functions. Thus, we still have a lot to learn about the roles and functions of marine microbes, and how to apply this knowledge to determine how microbial communities affect and are affected by global environmental change.
Advances in genomic and molecular biology techniques, and advances in in situ instrumentation, have provided new types of information at high species resolution and spatio-temporal resolution in the environment. For example, molecular techniques have identified an intriguing new symbiotic nitrogen-fixing cyanobacterium that is symbiotic with a picoplanktonic alga, which is widespread in the oceans, and is reminiscent of the evolution of chloroplasts. Furthermore, comprehensive microbial community microarrays (often called “DNA chips”) have been designed and applied to detect gene expression of the major marine microbial strains and substrains, to determine community-level responses to perturbations of nutrients associated with physical mixing. These approaches provide very sensitive indicators for the physiological nutrient status of many microbial populations, and provide an additional tool for detecting environmental change and investigating the factors that cause change. Coupled with increasing abilities to deploy in situ automated laboratories and autonomous vehicles, we have a new level of understanding the roles of functions of microbes and their responses to environmental perturbations in the marine environment.
