At http://phys.org/print358144586.html …. the end of Permian extinction event resulted in the demise of 90 per cent of marine life. It is thought that ocean venting played a role, releasing hydrogen sulphide that wiped out the dominant form of life at the time and allowed a minority form to become the majority thereafter.
The end of Permian mass extinction was accompanied by climate change (meaning upheaval and atmospheric loading) and a build-up of anoxic zones in the oceans. The research here sets out to provide support for the proposal above and modelling was part of the process used. They conclude that the oceans were not necessarily stripped of life – well, 10 per cent of marine life did survive. They are not of course talking about fish and seals or anything remotely larger than an inch, and they avoid the question of what caused the venting.