What microscopic algae is this?

[ahouseofscales]

Hello,

I run a reef tank in the classroom I teach in. Over the past few days, it has developed a pretty bad algae problem. The water is bright green, although there is minimal build up on any of the tank surfaces. We are cutting back light and feed to start, but I have been spending the day trying to ID this algae so I know what we are dealing with.

I spun down a water sample in the centrifuge at 5000 rpm for 15 minutes. I examined the resulting pellet under the microscope. The cells didn't become visible until I hit 400x mag, and they were very small. 1000x mag with oil show the cells well.

400x mag

1000x mag w/ oil

The cells are round and transparent, with a slight green tinge. The pellet to the naked eye was bright green.

Does anyone know what these might be?

Thanks!

Edit: I forgot to mention that these cells were moving, but not directionally. It was more like a slow shaking movement.

 

[Gumbies R Us]

Following along as I am curious to see what this is as well!!

 

[jbholasingh]

Its very difficult to tell from the picture but i would say its a type of unicellular free floating cyanobacteria based on the size. Synechococcus comes to mind but without genetic testing there's really no way to tell for sure.

By the time this message finds you I'm sure it would of cleared up. Sponges,ciliates, copepods will reproduce and devour most phytoplankton in a short period of time.

 

[Glenner’sreef]

If this sample came from the glass wall of your tank. A common algae is “green film algae”. This algae reproduces quickly under the right conditions. My Sea Stars and snails particularly like these hours old versions of this particular algae. I’m guessing easier to digest. Your microscope image may be a young version of “Green Film Algae”???