Marine Microbial Ecology

Marine environments are often low in nutrients, favoring oligotrophic microbes that tend to have smaller cell sizes compared to their freshwater counterparts.

Tidal activity causes salinity fluctuations in estuaries and coastal areas, supporting an abundance of halotolerant microbes. These regions become intermittently anoxic due to high respiration rates, allowing sulfate-reducing bacteria to thrive and produce hydrogen sulfide.

The upper 100 to 200 meters of pelagic marine waters contain the photic zone, where nutrients are continuously recycled through the microbial loop.

Small heterotrophic microbes consume the dissolved organic matter in the sea, which includes photosynthate from photoautotrophs and particulate debris from cell lysis.

Larger heterotrophic protists feed on smaller microbes and generate particulate organic matter for larger plankton.

Marine environments often experience disruptive changes. For instance, oil spills may stimulate blooms of hydrocarbon-degrading bacteria.

Global warming is expanding oxygen-minimum zones by increasing stratification and reducing oxygen delivery to deeper layers, disrupting marine ecology.