The Web of Life (19-1) Microbes in the Ocean

 Microbes in the Ocean

A bewildering swirl of tiny creatures dominates life in the oceans. More numerous than the stars in the universe, these organisms serve as the foundation of all marine food webs, recycling major elements, and producing and consuming about half of the organic matter generated on Earth. ~ American marine biologists Virginia Armbrust & Stephen Palumbi

Microorganisms permeate Earth’s oceans. Microbial communities both drive the world’s biogeochemical dynamics and respond to changes in the environment.

Microbes are responsible for virtually all the photosynthesis that occurs in the ocean, as well as the cycling of carbon, nitrogen, phosphorus and other nutrients and trace elements. They literally run the oceans. ~ American marine biologist Mary Ann Moran

In providing the fundamental productivity of the oceans, marine plankton are crucial to the planetary gyre of life. As well as playing an integral role in the global carbon cycle, phytoplankton provide half of the atmospheric oxygen generated, with land plants producing the other half.

Marine bacteria influence Earth’s environmental dynamics in fundamental ways. These large-scale consequences result from the combined effect of countless interactions occurring at the level of the individual cells. At these small scales, the ocean is surprisingly heterogeneous, and microbes experience an environment of pervasive and dynamic chemical and physical gradients. Many species actively exploit this heterogeneity, while others rely on gradient-independent adaptations. ~ American microbial ecologist Roman Stocker

The top 60 microns of the ocean is a lively layer of microbial life. The microlayer communities that literally cover the oceans are dominated by microbes that form biofilms. This creates a durable skin housing phytoplankton and others. Storms disrupt continuity, but the miniature mariners ride it out.

Phytoplankton do more than just ride out turbulence. They use it to congregate, going with the flow to swim to social interactions.

Cell motility can prevail over turbulent dispersion to create strong fractal patchiness, where local phytoplankton concentrations are increased more than 10-fold. ~ English aquatic microbial ecologist William Durham et al

The microbial microlayer is crucial to the ocean absorbing carbon dioxide. Pollutants, such as pesticides, can become trapped there, disrupting the microbial congregation and changing its local composition. Unseen ocean ecosystems are more fragile than has been appreciated.