I’ve been so enamoured by the antiquity of stromatolites that I’ve missed the obvious.

When sea levels rose at the end of the ice age, things moved out of the way – corals grew to keep (approximate) pace with the sea level rise, mangrove forests moved, littoral molluscs and worms moved, river delta sediment height increased.

But what about stromatolites? Although we talk about them as incredibly ancient, they must have existed in their current locations for only a few thousand years at most, because environments change quite rapidly.

“Modern stromatolites are mostly found in hypersaline lakes and marine lagoons where extreme conditions due to high saline levels prevent animal grazing.”

Not only has sea level risen, but the presence or absence of hypersaline lakes is even more subject to fluctuation.

All of which begs the question – how do stromatolites move? How do they find the rare hypersaline environments that they need to grow?

They only live in a few locations – or perhaps that’s not true. Small stromatolites have been discovered in an open pit pond at an abandoned asbestos mine near Clinton Creek, Yukon, Canada. These are extremely young and presumably began forming soon after the mine closed in 1978. So where did they come from, the necessary microorganisms I mean? There’s even something resembling a stromatolite in Jenolan Caves, “Crayback stromatolite – Nettle Cave, Jenolan Caves, NSW, Australia”.

And that made me think of manganese nodules. Similar construction but totally different ecological niche. Unlike stromatolites, manganese nodules don’t have a layered construction. Or so I thought, then learnt that many stromatolites don’t have a layered construction either.

Manganese-Cycling Microbial Communities Inside Deep-Sea Manganese Nodules

The above paper … well, let’s just say that the figures in that paper are well worth seeing. They include family trees for the microorganisms found within manganese nodules. And pie charts of relative abundance. One of the main organisms found is the gram negative rods https://en.wikipedia.org/wiki/Shewanella.

mollwollfumble said:

I’ve been so enamoured by the antiquity of stromatolites that I’ve missed the obvious.

When sea levels rose at the end of the ice age, things moved out of the way – corals grew to keep (approximate) pace with the sea level rise, mangrove forests moved, littoral molluscs and worms moved, river delta sediment height increased.

But what about stromatolites? Although we talk about them as incredibly ancient, they must have existed in their current locations for only a few thousand years at most, because environments change quite rapidly.

“Modern stromatolites are mostly found in hypersaline lakes and marine lagoons where extreme conditions due to high saline levels prevent animal grazing.”

Not only has sea level risen, but the presence or absence of hypersaline lakes is even more subject to fluctuation.

All of which begs the question – how do stromatolites move? How do they find the rare hypersaline environments that they need to grow?

They only live in a few locations – or perhaps that’s not true. Small stromatolites have been discovered in an open pit pond at an abandoned asbestos mine near Clinton Creek, Yukon, Canada. These are extremely young and presumably began forming soon after the mine closed in 1978. So where did they come from, the necessary microorganisms I mean? There’s even something resembling a stromatolite in Jenolan Caves, “Crayback stromatolite – Nettle Cave, Jenolan Caves, NSW, Australia”.

And that made me think of manganese nodules. Similar construction but totally different ecological niche. Unlike stromatolites, manganese nodules don’t have a layered construction. Or so I thought, then learnt that many stromatolites don’t have a layered construction either.

Manganese-Cycling Microbial Communities Inside Deep-Sea Manganese Nodules

The above paper … well, let’s just say that the figures in that paper are well worth seeing. They include family trees for the microorganisms found within manganese nodules. And pie charts of relative abundance. One of the main organisms found is the gram negative rods https://en.wikipedia.org/wiki/Shewanella.

I don’t think the survival of stromatolites is a problem with changing sealevels. I examined them in Shark Bay where they are common and initially, they are just a slime held together by sand and would simply become detached to be moved by the tides to other locations which if suitable would be colonised. Obviously the larger, older and hardened ones would simply die and possibly added to the fossil record.