At http://physorg.com/news/2011-03-mystery-ocean-sediment.html … I haven’t seen much on further research on this but it is worth airing again the original missive. Research by an international team of scientists has revealed the role fish play in the production of sediments on the sea floor. The research took place in tropical warm water around the Bahamas. It specifically interacts on the carbonite sediments that contain critical records of changes in ocean chemistry and shifts in climate – even perhaps on evidence supporting Ice Age changes in oxygen isotopes. That was the sort of thing I was expecting to pop up – but does not seem to. These are important in understanding sediments in the geological past, we are informed in a study in PNAS, which clarifies the discovery of a new source of marine carbonate and one that has major implications in the understanding of the origins of such sediments. These include chalk and limestone formations in the deep past.
Until this study it was believed that fine grained carbonates were derived primarily from direct precipitation out of seawater or from the breakdown of skeletons and shells of marine invertebrates and algae/plankton. It now seems that a large volume of carbonate crystals are precipitated inside the intestines of marine fish – and excreted at high rates. Whilst its origins are in fish guts it is also dervied from calcium in the sea water fish drink, or absorb.
Production estimates for fish were compared against published rates of mud production. This revealed that fish guts are a direct source of most fine grained carbonate. It seems fish guts now play a contributory role in the laying down of chalk in the Cretaceous period [dinosaur era], as well as Jurassic limestones etc. This may be a problem as the chalk is thought to have been laid down slowly in a uniformitarian timescale, rather than as a result of upheaval on the sea bed. If so, there were ‘massive’ levels of production in the Cretaceous in order to account for chalk beds hundreds of feet think in lowland England, and the other side of the Channel. Is that realistic? Do we have fossil evidence of huge numbers of fish swimming in Cretaceous seas?
The press release ends, and the article itself, with the obligatory reference to modern global warming.