Kekerengū Bank

Natural gas, most commonly methane, can seep out of the seabed as bubbles. Specialised bacteria use methane and sulfides to generate energy - a process that is called chemosynthesis. These bacteria can be seen as grey mats on the seabed. Carbonates (the white rocks) are deposited out of solution due to the bacteria altering water conditions in the area.

The carbonate rocks then form infrastructure for other specially adapted marine organisms to move into the area. Certain mussels and tubeworms can form symbiotic relationships with the bacteria - meaning they help and rely on each other; the bacteria provide the energy for them, while the tubeworms and mussels provide shelter for the bacteria. This is particularly helpful for the bacteria, as those organisms can filter through much more of the gas-rich sea water than the bacteria can access alone, meaning the bacteria can make even more energy to share!

Bigger things like crabs, shrimp and squat lobsters eventually move into the seep neighbourhoods, living with the mussels and tubeworms. The whole interconnected community can’t survive without the gas seeping out of the seabed, and the bacteria that can use the gas for energy.

These unique and fascinating biological communities could possibly be how life all began! They offer a rich oasis of life on the otherwise sparse and barren deep ocean floor. Unfortunately, they are often damaged by bottom trawling from the fisheries industry. More research is needed to develop strong environmental management plans to protect these special ecosystems.

You may notice that the Glendhu and Honeycomb virtual GeoTrip (linked below) shows more life at the seeps. This is because the Kekerengū Bank field his shallower, despite having a higher rate of fluid seep. This means it exists within a frequently trawled fishing zone, whereas Glendhu and Honeycomb are deeper and not impacted.

See if you can spot different species. Which ones do you think settled at the seep site first? Fish or mussels? Basket stars or crabs? How old do you think it is? (hint: tubeworms grow super slowly and live for a really long time!)