Chemistry of Macro

[Subsea]

In a thread on RC, I had a short conversation with an individual that talked chemistry I can understand.



#16
Subsea
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Join Date: Dec 2006
Location: Austin, Tx
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Quote:
Originally Posted by Dan_P
Let’s ignore the carbon part of this comparison because CO2 is abundant for phytoplankton and macro algae. The 30:1 and 16:1 N ratios both tell a similar story. More nitrogen is needed than phosphorous. That’s the big picture and a generalization of elemental needs.

Organisms can also build up reservoirs of these elements in times of plenty, throwing off the ratio. Similarly, rate of growth disturbs the ratio. The stoichiometric ratio is a rough number of what an organism needs, on average but not necessarily what it absorbs.

Organisms in general absorb material with wide range of stoichiometric ratios and eliminate the excess. Organism use material for biomass, the elements of which are reflected in the stoichiometric ratio. The elements absorbed for energy production may not. The biomass stoichiometry is instructive but does not reflect what an organism absorbs, just what its elemental goal is.

Patrick Castille said:
Spot on. Macro is a sponge and it will absorb what is in the water. “Eliminate the excess” is interesting and explains why some macro is so messy with giving off DOC.

When I first starting growing macro, it was to produce a fresh live food from the sea. Red Ogo, Gracilaria Parvispora, has been a mainstay of Hawaiian diet for centuries. After setting up 10K gallons of tumble culture in my greenhouse, I found out that the high sulfur content of Trinity aquifier water ruined the marketability of Red Ogo as a human food.

Dan P said:
Interesting example. Too bad about the sulfur.

Another reason that algae exude DOC is that they cannot turn off photosynthesis when production of carbohydrate exceeds the demand. So, these organisms dump it to the water. This might be viewed as intermittent carbon dosing or potentialy intermittent poisoning of coral (some sugars are toxic to certain coral).


__________________
Laissez les bons temps rouler,
Patrick Castille

Current Tank Info: 10,000G. Greenhouse Macro Growout
Last edited by Subsea; Today at 05:54 AM.

 

[Subsea]

In an article that @Dana Riddle wrote on Advanced Aquaria, he clarified how organic carbon dosing grows bacteria, which is a nutrient export mechanism when coupled with a protein skimmer. He also clarified how carbon dioxide grew coral by combining the inorganic & organic world thru photosynthesis. Carbon dioxide dissolves in water to increase bicarbonate alkalinity to be converted into glucose which is organic biomass, “carbon for the reef”.

https://www.advancedaquarist.com/2016/9/aafeature

 

[Subsea]

If macro is a sponge and it absorbs everything in the water but only needs certain elements to grow, what happens to excess absorbed but not utilized. DOC is the culmative name given to that excess that can taint water yellow.


https://www.tandfonline.com/doi/pdf/10.1080/09670262.2013.875596
DANIEL C.O. THORNTON
Department of Oceanography, Eller O & M Building, Texas A & M University, College Station, TX 77843-3146, U.S.A.
(Received 30 March 2013; revised 3 September 2013; accepted 3 September 2013)
[The partitioning of organic matter (OM) between dissolved and particulate phases is an important factor in determining the fate of organic carbon in the ocean. Dissolved organic matter (DOM) release by phytoplankton is a ubiquitous process, resulting in 2–50% of the carbon fixed by photosynthesis leaving the cell. This loss can be divided into two components: passive leakage by diffusion across the cell membrane and the active exudation of DOM into the surrounding environment. At present there is no method to distinguish whether DOM is released via leakage or exudation. Most explanations for exudation remain hypothetical; as while DOM release has been measured extensively, there has been relatively little work to determine why DOM is released. Further research is needed to determine the composition of the DOM released by phytoplankton and to link composition to phytoplankton physiological status and environmental conditions. For example, the causes and physiology of phytoplankton cell death are poorly understood, though cell death increases membrane permeability and presumably DOM release. Recent work has shown that phytoplankton interactions with bacteria are important in determining both the amount and composition of the DOM released. In response to increasing CO2 in the atmosphere, climate change is creating increasingly stressful conditions for phytoplankton in the surface ocean, including relatively warm water, low pH, low nutrient supply and high light. As ocean physics and chemistry change, it is hypothesized that a greater proportion of primary production will be released directly by phytoplankton into the water as DOM. Changes in the partitioning of primary production between the dissolved and particulate phases will have bottom-up effects on ecosystem structure and function. There is a need for research to determine how these changes affect the fate of organic matter in the ocean, particularly the efficiency of the biological carbon pump.]

While the above is more detailed than reefers normally get, “Inquiring minds want to know”.

@Scuba_Steve @lapin @Lasse
So, if these DOC compounds of photosynthesis are carbohydrates, lipids & proteins, when we grow macro algae, do we carbon dose our reef tanks? Also, does macro DOC grow bacteria and ultimately feed corals as a live food.

 

[Subsea]

Will a moderator please move this thread to the chemistry forum.

This would be good topic to discuss with @Randy Holmes-Farley

 

[Subsea]

@Dan_P

I am glad you came over. This thread was inspired in part by comments from you. Inquiring minds want to know.

I see where you are discussing dosing with Randy. He is a wealth of knowledge and a
“gentleman & a scholar”.