Algae Bloom

 

These beautiful golden spheres are single colonies of the golden algae synura. Like all other organisms, synura is able to reproduce and one colony eventually turns into two. But when conditions are right, reproduction happens a lot more frequently and what used to be a few colonies can quickly turn into an enormous algae bloom. Even though each synura colony is microscopic and only measures around 20-30 microns in diameter. Their large numbers in an algae bloom are able to turn the water in their freshwater habitats a yellowish brown color. A bloom of synura like the one in the image usually happens in spring and fall when the water is cold. But not all algae will bloom in cold water.

These ones are called haematococcus and blooms like the ones in the images above usually occur with warmer water temperatures around 20 degrees centigrade, or 68 degrees fahrenheit. Haematococcus algae are single celled but each cell is about the same size as an entire colony of synura. These algae are actually a type of green algae, but due to a high concentration of the red pigment astaxanthin their green color are often partly or completely hidden. Besides turning the cells partially or totally red, astaxanthin helps to protect the cells from UV radiation a bit like sunscreen. You have probably seen a bloom of these algae before as the red color of the bottom of an unchlorinated pool or a birdbath.

These single celled organisms are technically not an algae, or at least not entirely, because euglenas are in fact both part animal and part plant. They get their green coloration from chloroplasts and are thereby able to acquire food by photosynthesis like plants. But euglenas are also able to acquire nutrients from their environment, like animals. These organisms like nutrient rich waters and can sometimes be seen as a sticky green blanket on ponds in the summer, or even turning entire bodies of water green.


All three of the organisms we have just looked at are able to move using thin whip like structures called flagella. Together with very primitive eyes they are able to sense light direction and intensity, which allows them to move to the optimal place for photosynthesis.

A narrated video showing the three organisms from this blogpost in motion.