Interesting idea and I bet no one has tried it. One reason is that whole organism analysis with the analytical methods you mention would likely give uninterpretable data.
I feel like ICP-OES would be pretty easy though for inorganics. I’m a chemical engineer, not a chemist, and i specialize in inorganic particles (like catalysts, battery materials, etc) so maybe i’m missing something because my organic/bio chemistry isn’t top notch but i do know a couple chemists who worked in testing labs for cannabis and i know they run tests like ICP and HPLC on plants to determine trace metals, cannabinoids, etc. so i figured it might work on phytoplankton and algae as well. maybe an extraction step would be needed, this is probably where it would get tricky, but a full digestion for ICP is worth a shot imo
I think if we see high amounts of a certain element in say dinos relative to other algae we could do some trial and error to figure out if it needs this element to thrive. for example i’ve seen lots of people say dinos like iron to support the theory of “no water changes when fighting dino” since you want them to be iron limited. you could then develop some filtration to strip Fe from the water and allow other organisms to re establish themselves while dino destabilizes. Obviously everything needs these elements so you wouldn’t wanna take it all out, but just temporarily create a limiting environment for the nuisance algae.
