Super goby helps salvage ocean dead zone

A resilient fish is thriving in an inhospitable, jellyfish-infested region off Africa's south-west coast. And crucially it is helping to keep the local ecosystem going, and to preserve an important fishery.

The Benguela ecosystem lies off the coast of Namibia. It exists in waters only 120 metres deep that used to be a rich sardine fishery, but in the 1960s the sardine population crashed because of overfishing and environmental factors, and the region was invaded by algal blooms and swarms of jellyfish.

The algae have used up almost all the oxygen in the water, leaving the bottom half with oxygen levels below 10 per cent, far too little for most sea creatures. At about 80 per cent, levels are almost normal in the upper waters – but those regions are thick with jellyfish and algae, and therefore unwelcoming to most other life.

What's more, when the algae die they sink to the bottom and decay, releasing large quantities of the poisonous gas hydrogen sulphide. Nevertheless, local fish called bearded gobies have flourished in Benguela. Until now, nobody has understood how they survive it.