Leading ocean scientists have expressed shock at the state of the world's seas and fear another significant extinction event could be around the corner.
27 experts from different disciplines have been meeting in the United Kingdom to collate data and discuss changes in the world's oceans.
One of the experts, Professor Ove Hoegh-Guldberg of the Global Change Institute at the University of Queensland, says many of the measurement stations which are reporting rapidily dropping ocean oxygen levels are in the Pacific.
He says worrying large scale changes are happening which have the hallmarks of some of the previous periods on earth when ecosystems have collapsed.
"If we are on that road, then we need to get off it as soon as possible because that type of scenario is something that once you've triggered it there's no turning back."
Professor Hoegh-Guldberg says the scientists' report will be presented to the United Nations.