Quote:
Originally Posted by Subsea
Does not make sense!
When phytoplankton grows it absorbs C/N/P in the ratio of 116/16/1.
When macro grows, it absorbs C/N/P in the ratio of 560/30/1. So, when macro absorbs ammonia it also must absorb phosphate and carbon in those ratios.
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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:P 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.