What Effect Does UV Have on Algae?
Quickly, UV has lots of effects on algae and you can read that as phytoplankton, too; known damage includes the inhibition of photosynthesis, both the dark and the light reaction, inhibition of nitrogenase activity - nitrogenase is the enzyme that fixes nitrogen and creates nitrogen a form that's useable for organisms. Other biologists have shown reductions in motility in phytoplankton, which can effect whether the plankton are going to go up or down in the water column. It can promote some kinds of pigment synthesis and for others there can be a change in ecosystem dynamics. My favorite story there is work that's done by someone named Bothwell up in Canada, where they were looking at UV effects on algae that lived in a shallow stream. And what they did was they put up Plexiglas boxes. Some were like the ones I'm going to show you in a few minutes. They left them up to see what the change they had in the community. Well, now if you screen for UV, algae usually do much better, they grow faster. But some student, he's going to blame it on the student; he left these screens up too long. When Bothwell came back and looked at it, he found that actually there were no algae or very few under the screens where the UV was lost. And it turns out the flies that fed on the algae were even more sensitive to the UV than the algae. And so as soon as the UV was lowest, the flies went nuts and they just grazed the algae clean. So, what this is meant to illustrate that UV can change the ecosystem dynamic because not everything reacts the same way or with the same magnitude to UV damage.