Photoplankton and Oxygen levels

[STYRBJORN]

Most "phytoplankton" are blue-green algae! Just google Phytoplankton. You will learn more about the wee critters than you ever wanted to know.
Autotrophic, mixotrophic, . . . Wha'? My A-level biology looks seriously past its sell-by date.

[Dorts]

Originally Posted by STYRBJORN

Most "phytoplankton" are blue-green algae! Just google Phytoplankton. You will learn more about the wee critters than you ever wanted to know.
Autotrophic, mixotrophic, . . . Wha'? My A-level biology looks seriously past its sell-by date.

The cyanobacteria are true prokaryotic bacteria, sometimes included in bacterioplankton, sometimes in phytoplankton because they photosynthesize.

My point was simply that when talking of phytoplankton and the production of oxygen, cyanobacteria should, I think, be given a special mention rather than being 'lumped' under the general term of 'phytoplankton'.

And perhaps any research into the effects that warming may have on phytoplankton should look at bacterioplankton generally and cyanobacteria specifically as they have, and still do play such an important part in oxygen production.
Dorts.

[animartco]

Originally Posted by Dorts

The cyanobacteria are true prokaryotic bacteria, sometimes included in bacterioplankton, sometimes in phytoplankton because they photosynthesize.

My point was simply that when talking of phytoplankton and the production of oxygen, cyanobacteria should, I think, be given a special mention rather than being 'lumped' under the general term of 'phytoplankton'.

And perhaps any research into the effects that warming may have on phytoplankton should look at bacterioplankton generally and cyanobacteria specifically as they have, and still do play such an important part in oxygen production.
Dorts.

Another point- I think- that should be remembered about cyanobacteria, is that they are anaerobic. I may be wrong about this but I think they are more often found in algae in oxygen poor or badly polluted water? In healthy water the plants are a healthy green green, not bluish or redish. (although of course some highly evolved plnts have red leaves.) Remember, when plants, with the aid of bacteria, first evolved, there WAS no free oxygen, whereas modern algae require oxygen to breathe. Therefore it follows that if the amount of green algae is replaced by blueish or red, the oxygen content of the water has falllen. This is a suggestion for discussion, not a categorical statement.

[Dorts]

Originally Posted by animartco

Another point- I think- that should be remembered about cyanobacteria, is that they are anaerobic. I may be wrong about this but I think they are more often found in algae in oxygen poor or badly polluted water? In healthy water the plants are a healthy green green, not bluish or redish. (although of course some highly evolved plnts have red leaves.) Remember, when plants, with the aid of bacteria, first evolved, there WAS no free oxygen, whereas modern algae require oxygen to breathe. Therefore it follows that if the amount of green algae is replaced by blueish or red, the oxygen content of the water has falllen. This is a suggestion for discussion, not a categorical statement.

I make no apology for a 'copy and paste' with this piece as it says it far better than I can, but it does, I hope, answer the above, particularly the last para:

"Cyanobacteria
The Cyanobacteria are one of several major groupings of bacteria:

•Proteobacteria (mostly Gram-negative)
•Firmicutes and Actinobacteria (Gram-positives)
•Cyanobacteria
They were formerly known as "blue-green algae" - but this is a misleading name! Algae are eukaryotic organisms, not prokaryotes like Cyanobacteria. Cyanobacteria are interesting for a number of reasons:

They are photoautotrophs, able to use CO2 as their sole carbon source and light as their energy source. However, unlike other photosynthetic bacteria, Cyanobacteria use the same photosynthetic pathway as eukaryotic cells such as algae and higher plants (the "C3" or "Calvin" cycle). (Other photosynthetic bacteria use different light-harvesting pigments (bacteriochlorophyll) and metabolic pathways). Even more interesting is that we now know from DNA sequencing that eukaryotic chloroplasts evolved from Cyanobacteria, presumably after millions of years of symbiotic association.

Microbes are the predominant photosynthetic organisms in most aquatic environments. In aerobic conditions, (e.g. shallow water), algae, diatoms and Cyanobacteria predominate. In anaerobic conditions (polluted or eutrophic waters), other photosynthetic bacteria are dominant."

My research shows that this very complex subject is still a very active branch of science, so definative answers to the OP are probably not possible, only speculative, but nevertheless the question of any effect that warming of the oceans may have on this complex group of plants and animals is certainly of much interest.
Dorts.

[STYRBJORN]

Excellent post Dorts. The only comment I would add is that biochemically complex eukaryotes could only evolve in the highly oxygenated atmosphere which was a result of the activity of the prokaryotic cyanobacteria. The Big Question then is "can eukaryotes survive without the activity of prokaryotes?" If not WE ARE DOOMED! Don't mow the lawn, don't do the spring cleaning, don't part chop the old car. JUST GO OUT AND GET WRECKED!

Ahem. Part way there already.

Ric

[Dorts]

Originally Posted by STYRBJORN

. JUST GO OUT AND GET WRECKED!

Ric

Sounds like a good idea Ric, I may well join you!
Dorts.

[animartco]

Originally Posted by STYRBJORN

Excellent post Dorts. The only comment I would add is that biochemically complex eukaryotes could only evolve in the highly oxygenated atmosphere which was a result of the activity of the prokaryotic cyanobacteria. The Big Question then is "can eukaryotes survive without the activity of prokaryotes?" If not WE ARE DOOMED! Don't mow the lawn, don't do the spring cleaning, don't part chop the old car. JUST GO OUT AND GET WRECKED!

Ahem. Part way there already.

Ric

Er, quite! We do still have them fortunately, but there are not enough to take over and keep the Earth oxygenated if the forests are gone. If oxygen drops below the levels that allow modern plants to photosynthesize, life on Earth will be wiped out, and what is left of the cyanobacteria would hardly have time to get the planet reoxygenated let alone start much of an evolution, before the sun turns into a red giant and roasts them.

[Dorts]

Originally Posted by animartco

If oxygen drops below the levels that allow modern plants to photosynthesize, life on Earth will be wiped out, .

It may be worth pointing out how close we came to this outcome with the recent historically very low levels of CO2 at 240ppm. Plants stop growing at levels below 200ppm.
Thankfully CO2 levels are now rising.
Oxygen is settled at around 21%, and this level has mystified scientists for many years, as it appears there is something going on we have yet to fully understand that has been able to keep this level so well balanced and stable for so long.
Dorts.

[STYRBJORN]

All higher forms of life wiped out. Nowt left but bacteria and fundamentalists.

[animartco]

Originally Posted by Dorts

It may be worth pointing out how close we came to this outcome with the recent historically very low levels of CO2 at 240ppm. Plants stop growing at levels below 200ppm.
Thankfully CO2 levels are now rising.
Oxygen is settled at around 21%, and this level has mystified scientists for many years, as it appears there is something going on we have yet to fully understand that has been able to keep this level so well balanced and stable for so long.
Dorts.

Yes, Oxygen levels do appear stable, at sea level, and up and down some way from that. But IS there a measurable change at ocean depths and in the upper atmosphere? The system of 'clines' means that the oxygen levels remain constant for the bulk of life on Earth. 'Clines' of any sort are like interfaces through which some sort of osmosis takes place. For instance benthic clines would filter oxygen upwards if levels dropped in the body of water above, and if for instance there was only that one gas being exchanged the cline would correspondingly drop in depth.