challenges faced by photosynthetic aquatic organisms?

Question

anybody knows?

Answer 1

I have a BA in biology but I studied mostly human biology. I would guess that aside from the usual predators, shelter etc challenges, the p.a.o's would face challenges from anything that would block the sun. First, depth. They would be confined to a plane in the water that the sun could penetrate. That would limit growth of organisms that do not move around to the continental shelf. But that could be problematic because murky water from animals stirring up the bed would reduce the amount of light. Pollution would be greater nearer the shore too. Boating traffic would block the suns rays to a damaging extent in heavy traffic areas. If a p.a.o. was "parked" under a favorite spot for larger fish and mammals to frequent that would interfere with the sun's rays as well.
Then there is heat. The heat is greater and varies more nearer the surface. Photosynthetic organisms would have to adapt for temperature fluctuation.
In summary, I think the biggest challenge would be the depth, then the interference from mud, pollutants and other organisms, and finally the temperature variations.
Just a guess, good luck.

Answer 2

Predators

Answer 3

Not enough light.