Relative to other ecosystems, how productive is a hydrothermal vent?

	These vent bacteria, as the primary producers, play the same role green plants do in terrestrial habitats.

With respect to microbes, vents are probably one of the most biodiverse communities we could ever find. In such a small space, there are so many niches with respect to temperature, metals, oxygen or the lack thereof- all being different factors that might select for certain microbial communities. Vent water exits in different ways - through diffuse flow or warm vents (e.g. 10 to 30 °C) after it has mixed with cooler seawater or it can exit as primary hydrothermal fluid with no mixing through chimneys at temperatures exceeding 360° C. These chimneys are called "smokers" and are made up of sulfide minerals.

Scientists were surprised to find animals— like this dense population of shrimp— living around deep sea vents.

We can look at the surfaces of the vent animals, or rocks, or inside chimney sulfides with an electron microscope and see they're covered with bacteria. We've just begun to culture these, while those we can't culture are being characterized using molecular approaches. The outer surface of a chimney is not very hot, but a couple millimeters in, the temperature may rise very significantly, the pH changes, there's no oxygen, and that's where you find a lot of the high temperature microorganisms. People have reported that within the walls of a smoker chimney you can have as many as one hundred million cells per gram. Surface seawater generally contains maybe a million cells per milliliter (gram) of water while cold ocean bottom water has around ten thousand cells per milliliter.
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Photos: WHOI