Phytoplankton is the kind of plankton that does photosynthesis. Calling it photoplankton does make sense.

Photosynthesis is the process of making sugar from carbon dioxide and water, using the energy from light. Oxygen is a waste product. Photosynthesis is a very complicated and it only happens in cells that are alive. So even if water was around after the cells had dried out and died, it wouldn’t happen.

Some living things can dry out, but not really be dead. Check out this animal called the tardigrade or “Water bear” here .

There are a few organisms that can survive being mostly dried out such as certain microscopic animals and some plants. These organisms still have at least 1% of their water and stop doing anything. They stop eating, growing, or reproducing. Phytoplankton is not known to have the ability to survive without water so the process of drying it will cause it to die. Even if it could survive being dry, they wouldn’t be able to produce oxygen until water was added back. You may be thinking about the freeze-dried plankton that people feed to fish. This plankton has all the water removed which is a process which definitely kills the plankton. An important thing to realize is that all cells are mostly water and while some can survive for a long time without water, they can’t do the things cells normally do anymore.

No. If phytoplankton dries out, it is dead.