[jeffkrol]

C4 mechanisms in aquatic angiosperms: Comparisons with terrestrial C4 systems

In aquatic plants, C4 photosynthesis is found in about 4% of tested species, occurs within a single cell, and reduces the effects of photorespiration especially when water column concentrations of oxygen are high and CO 2 are low (Bowes et al. 2002)

Haven' t read it yet as I have no access atm


Never mind not important.. and old.

Anyways more fun..

http://www.esalq.usp.br/lepse/imgs/conteudo_thumb/CAM-Photosynthesis-in-Submerged-Aquatic-Plants.pdf

I'm trying to find if there is an updated list of C4 or CAM aquatics.
Not having a lot of luck.

 

[Deanna]

Does this help:

CAM photosynthesis is also found in aquatic species in at least 4 genera, including Isoetes, Crassula, Littorella, Sagittaria, and possibly Vallisneria, being found in a variety of species e.g. Isoetes howellii, Crassula aquatica.

?

I take this into consideration, for my Dwarf Sag, when contemplating changes.
Source

 

[jeffkrol]

C4 mechanisms in aquatic angiosperms: Comparisons with terrestrial C4 systems



Haven' t read it yet as I have no access atm


Never mind not important.. and old.

Does this help: ?

I take this into consideration, for my Dwarf Sag, when contemplating changes.
Source

DISCUSSION In the total of 13 species tested, only three exhibited marked diurnal titratable acidity fluctuations.That malic acid could account for most of these changes and that they occurred only in chlorophyll-containing tissues lends confidence to the view that CAM metabolism was occurring in these plants.Thus, Isoetes kirkii, Lilaeopsis lacustris (bothendemic to New Zealand), and Vallisneria spiraliscan be added to the list of aquatic CAM species.Lilaeopsis is the first known aquatic member of the family Umbelliferae shown to possess CAM characteristics....
Other aquatics have been shown to have limited capacities (i.e., below the levels usually defined as CAM) for nocturnal accu-mulations of malate or increases in titratable acidity: Hydrilla verticillata L.f. Royle (Holaday &Bowes 1980) and Scirpus subterminalis Torr (Beer& Wetzel 1981).

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https://www.tandfonline.com/doi/pdf/10.1080/00288330.1988.9516295

Thanks.. Seems like it really needs an update...
Not a very popular topic..
Interesting "complication"

Facultative crassulacean acid metabolism (CAM) plants: powerful tools for unravelling the functional elements of CAM photosynthesis

Abstract. Facultative crassulacean acid metabolism (CAM) describes the optional use of CAM photosynthesis, typically under conditions of drought stress, in plan

academic.oup.com

In many species with CAM, its expression is not optional. CAM is part of the constitutive pre-set processes of development and growth (Kluge and Ting, 1978; Osmond, 1978, 2007; Nobel, 1988; Winter and Smith, 1996a, b). As photosynthetic tissues mature, CAM always eventually develops, irrespective of environmental conditions. But even in these constitutive CAM plants, a small facultative CAM component may be detectable. In young tissues with still minimal expression of CAM, drought stress can accelerate the ontogenetic increase in dark CO2 fixation in a reversible manner (Winter et al., 2008, 2011), demonstrating that the categories of constitutive and facultative CAM are, in reality, endpoints of a continuum between CAM that is fully controlled by ontogeny and CAM that is controlled by environmental stress.

 

[Deanna]

Too far on the periphery. It's interesting, but probably only useful, in terms of optimizing for it, to a closed system, such as what we do. I don't recognize any of those plants (which isn't saying much) on the list as being crop-type plants, so no money benefit.

I run CO2 24/7, and this is among the reasons.

 

[jeffkrol]

Too far on the periphery. It's interesting, but probably only useful, in terms of optimizing for it, to a closed system, such as what we do. I don't recognize any of those plants (which isn't saying much) on the list as being crop-type plants, so no money benefit.

I run CO2 24/7, and this is among the reasons.

sort of the point of my endeavor is thinking that "maybe" with the proper understanding of which plants used which type of photosynthesis one could say have group A for non-CO2 tanks Group B for CO2.
injected ect.
Not even sure that makes sense atm..
Then I ran into another consideration .. CO2 vs bicarbonate use.
pffft....
But led me to the below fun read

Underwater Photosynthesis of Submerged Plants – Recent Advances and Methods

We describe the general background and the recent advances in research on underwater photosynthesis of leaf segments, whole communities, and plant dominated aquatic ecosystems and present contemporary methods tailor made to quantify photosynthesis and carbon fixation under water. The majority of...

www.frontiersin.org

Studies of photosynthesis by aquatic and submerged wetland plants are few compared with research on photosynthesis in air, but underwater systems are attracting more attention. Light and CO2 availability under water are often low to submerged plants. Low CO2 together with impeded escape of O2 can result in high photorespiration as a component determining net photosynthesis. Focus studies of contrasting species and systems are required to develop our understanding of “models” since the environment under water is more complex than in air and there is a diversity of photosynthetic mechanisms (i.e. C3, C4, CAM, and bicarbonate use) in aquatic species.

note: can split CAM into constitutive and facultative CAM I suppose.
Even learing a whole new language..which I'll forget by tomorrow..

Finally, each species was assigned to one of four life-form groups: (1) isoetids and creeping plants, (2) short elodeids (≤1 m tall), (3) tall elodeids (>1 m tall), and (4) floating-leaved plants (lemnids) using morphological descriptions in Schou et al. (2017).

Isoetid - Wikipedia

en.wikipedia.org

elodeid

: A stem plant that completes its entire life cycle submerged, or with only its flowers above the waterline .

isoetid
n. (context botany English) A rosette plant that completes its entire life cycle submerged.
Wikipedia

Isoetid
Isoetids are aquatic plants or wetland plants named for their superficial similarity to the quillworts, Isoetes. They occur in wetlands and on shorelines with low nutrient availability. Owing to their slow growth rates, they are also often found in areas with low rates of sediment deposition. Many have evergreen leaves, and CAM photosynthesis. Often they are exposed during periods of low water. Common examples include Lobelia dortmanna and Eriocaulon septangulare.

That's what I get for specializing in fungi in college..



At least it was in the 201X years

 

[ElleDee]

Too far on the periphery. It's interesting, but probably only useful, in terms of optimizing for it, to a closed system, such as what we do. I don't recognize any of those plants (which isn't saying much) on the list as being crop-type plants, so no money benefit.

I run CO2 24/7, and this is among the reasons.

Facultative CAM plants are something of a botanical marvel, and I remember my plant physiology prof's take distinctly: It's a neat trick, but incredibly costly to the plant and switching between photosynthetic pathways is more of last resort survival tool.

CAM is always slower than c3 and c4, but enables survival. If you have a choice, you'd pick the other one every time, so I expect the optimization is to keep these plants out of CAM.

 

[Deanna]

Facultative CAM plants are something of a botanical marvel, and I remember my plant physiology prof's take distinctly: It's a neat trick, but incredibly costly to the plant and switching between photosynthetic pathways is more of last resort survival tool.

CAM is always slower than c3 and c4, but enables survival. If you have a choice, you'd pick the other one every time, so I expect the optimization is to keep these plants out of CAM.

Yes, but I don't view the choice as ours. It's up to the plants. So, like many other parts of the hobby, providing what the plant may, or may not, want is what I prefer to do. If the Dwarf Sag wants to store CO2 in the dark, I want to make sure that it is there but, again, this is not my primary reason for running CO2 24/7. There will always be some CO2 available if we shut it off at lights out, but I like to keep it at a consistent level. As an analogy, I like to provide the plants with plentiful NH4, which is less costly to use than NO3, but I also want NO3 present in case they want a snack.

Then I ran into another consideration .. CO2 vs bicarbonate use.

Same consideration as what @ElleDee just pointed out, but with a twist. Some plants will use it, but it’s expensive. The twist is that, if our pH starts moving below ~6.0, the HCO3 may be primarily CO2, making HCO3 far less available.