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Oxygen Starts A Deep-Sea Party & You're 580 Ma Late

By cmcclain on August 3, 2007.

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A day ~575 million years ago seemed like any other. Life was simple, not as in life was easy, but organisms were simple creatures. Then, geologically-speaking, BAMM!, complex life forms. Sure they were not the showy creatures of today, but the Ediacara biota (580Ma) of centimeter- to meter-sized eukaryotes, representing both some extant kingdoms and failed experiments, still are intriguing. So what events started the Ediacara party?

To answer this question we go to the Ediacaran animals in deposit on the Avalonn Peninsula in Newfoundland. The community is from a deep seafloor environment, several hundreds of meters deep, from the northern edge of Gondwana. Analyzed samples suggest deep-water anoxic conditions persisted before 580Ma, shifting toward a stable oxic period of a least 15 million years. The process is bit complex so as a list...
1) This shift in oxygen concentrations corresponds with the Gaskiers deglaciation
2) Glacial melting increased nutrient loads in the ocean.
3) This in turn promotes primary production and carbon burial
4) This increases atmospheric oxygen levels.
5) Which allows for oxygen concentrations large enough to allow for respiration of large, multicellular organisms.

Summary of and figures from Canfield et al. (2007, Science)

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Your link only goes to a dummary, and I was wondering...

How does this explain the delay in the oxygenation of the oceans? If the biota that is producing oxygen is in the oceans then you'd expect the oceanic oxygen to rise ahead of or with the atmosphere, not millions of years behind.

It looks rather like a reversal of cause and effect, the oceanic biota would have to have the nutrients before they could produce the causes of the nutrients? What am I missing here?