Methane vents

Methane vents (cold seeps) are extremely surreal places in the deep sea. Methane springs are places where methane-rich water escapes. One would think that life under these hostile conditions would be virtually impossible.  But the opposite is the case. In contrast to the rest of the deep sea floor, which is sparsely populated, these gas springs are often true oases in the deep sea. But if you want to survive here, you have to be highly specialised. The chemo trophic bacteria present there are able to use chemosynthesis to convert methane and hydrogen sulphide into organic compounds, which serve as a food source for the other methane source inhabitants and their visitors.

Until now, it was known that tube worms and mussels were abundant there. But now a surprising discovery has been made, as an international team of researchers found that methane sources play a crucial role when it comes to the nurseries of deep-sea predatory fish and rays. In sharks, a distinction is made between viviparous species, egg-laying species and those that incubate their eggs in their bodies. There are also these differences between rays. True rays lay eggs, whereas in almost all other ray species, the young hatch from the egg in the womb of the mother.

Egg-laying shark and ray species seem to like to use the solid structures of the limestone outcrops of the methane springs to provide shelter for their eggs in the otherwise very muddy seabed of the deep sea. In Chile, researchers found several generations of giant egg capsules of the deep-sea ray.

In this surreal world of the deep, fossilised egg capsules of the cat shark were even found, which the researchers dated to 35 million years ago.

Due to the importance of these methane sources as nurseries for aquatic species, the researchers would like to see them placed under protection.

Photo source: NOAA

By Fatima Kutzschbach