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Re: Aquatic Plants Digest V3 #23

On Tue, 13 Jan 1998, George Booth wrote:

> I wonder if any of the scientists among us have any info on how much CO2 plants 
> use when they are strongly photosynthesizing?  I have evidence of how fast it 
> diffuses into the atmosphere.   

Do consultants ever count as scientists?  Well, philosophic questions aside,
I have some data on maximum carbon fixation rates from Raven, that I've 
attached here.  I hope my tab settings don't mess with everyones displays:)

Organism				Conditions		C fixation
Anacystis nidulans			CO2 saturation		250 
(planktonic freshwater cyanobacterium)

Chlorella sp. 				Do.			900
(planktonic freshwater chlorophycean)

Coccolithus huxleyi 			Do.			200
(planktonic marine prymnesiophyte)

Laminaria hyperborea 			Young sporophyte	2,800
(haptophytic marine phaeophyte)		lamina

Macrocystis pyrifera			Young sporphyte		4,000
(haptophytic marine phaeophyte)		frond

Saccorhiza bulbosa 			Young sporophyte	3,800
(haptophytic marine phaeophyte)		frond

Fucus vesiculosus 			Young apex of		3,300 
(haptophytic marine phaeophyte)		sporophyte
					Older base of		1,570

Porphyra umbilicalis 						3,550
(haptophytic marine rhodophyte)

Chondrus crispus 						2,050
(haptophytic marine rhodophyte)

Ulva lactuca 							4,100
(haptophytic marine ulvophycean)

Codium fragile 							3,790
(haptophytic marine ulvophycean)

Chara corallina				CO2 saturation		1,200
(rhizophytic freshwater charophycean)

Potamogeton polygonifolius 		Do.			3,000
(rhizophytic freshwater magnoliophyte)

Vallisneria asiatica						1,400
(rhizophytic freshwater magnoliophyte)

Hydrilla verticillata						1,600
(rhizophytic freshwater magnoliophyte)

Cymodocea nodosa						2,900
(rhizophytic marine magnoliophyte)

Posidonia oceanica 						1,700
(rhizophytic marine magnoliophyte)

Montastrea annularis						5,220
(haptophytic marine coral)

The C fixation rate is in nanomoles per square meter of plant surface per 
second.  The list covers quite a variety of plants, and it looks to me 
like their fixation rates can be ranked as:

coral > surface-attached plants > rooted plants > plankton

The plankton average 450.  Rhizophytes (rooted plants) average 1,967.  
Haptophytes (surface-attached plants) average 3,218.  The one coral on 
the list was 5,220.

The fixation rates by freshwater rooted plants on the list (P. 
polygonifolius, Val. asiatica and Hydrilla) span the range for the rooted
plants.  I think if I picked a number to represent the group, I'd use 
1,500 instead of the average of 1,967.

I haven't (yet anyway) tried reducing these rates down to anything more 
meaningful, and I'm not sure if that's possible.  If there is any 
interest in it, then I suppose I could give that a try.

The reference for the table is
	Raven, John A, 198?.  Energetics and transport in aquatic 
	   plants.  MBL Lectures in Biology, V. 4.  Alan R. Liss, Inc
	   New York.

The values are in Table 5.7 on page 236.

Roger Miller
"So many numbers, so little time."