Types of Pond Algae

What Are Algae?

Algae are single-celled, photosynthetic organisms that do not flower and lack roots, stems, leaves, and vascular tissue. The three main types of algae are planktonic algae (suspended in the water), filamentous algae (floating mats of algae on the water), and macroalgae/stoneworts (plant-like algae that grow in the water). Each type has its own unique characteristics that can be used to properly identify it, which can aid in creating an effective algae treatment plan. For the most part, copper-based algaecides are the best treatment for any algae. Trout, koi, and channel catfish are copper sensitive, so other algaecides such as Cape Furl, with the active ingredient sodium carbonate peroxyhydrate, are the next best thing.

Planktonic Algae

In general, these algae appear as pea soup or a paint spill. They turn the water green, bluish, or blue-green, and the organisms do not link together. Swirls in the algae can be seen in some cases as well, making it look almost like a marble or geode pattern. They also may stick to rocks, sticks, or the shoreline. Some scientific names for planktonic algae are Anacystis, Chlamydomonas, Chlorella, Closterium, and Euglena.

Filamentous Algae

Also known as Anabaena, Lyngbya, Oscillatoria, Pithophora, or Spirogyra, these organisms start out by growing on rocks, sticks, or other things on the bottom of a stagnant water column. These algae link together to form strings and mats that appear much like hair or cotton and are bright to medium green. Once they are formed together, these strings and mats of algae will catch and trap the oxygen they are producing. This will cause them to float and often bubble as they settle on the surface.

Chara Algae (Native macroalgae)

Although it appears much like a submerged plant, Chara is indeed a type of algae. These algae have stem and leaf-like structures and may be loosely attached to the sediment on the bottom of the water body, but they are not truly rooted. The leaf- like structures grow at regular intervals on the stems that branch out.

Chara grows in clear water that’s one to three feet deep and can create large mats on the bottom. Chara can be a nuisance in shallow beach areas, where it grows densely when other rooted plants might not. Usually it is gray green in appearance and has a musky odor that becomes especially noticeable if it’s crushed. When left in the sun to dry, Chara will turn an ashy color; this is because the algae have calcium deposits on their whorls. As Chara matures, the calcium deposits get thicker, making this type of algae tougher to treat later in the season.

Starry Stonewort (Invasive macroalgae)

Starry stonewort is an invasive algae that, much like Chara, resembles a submerged plant. These algae are a medium green color and appear gelatinous or slightly translucent. Tiny, white, star-shapes among the stem and leaf-like structures give them their name and are the best way to properly identify these algae. As with stoneworts, starry stonewort algae branch and the branchlets grow at regular intervals.

Algae Treatment in Ponds

Many different types of pond algae can be treated with the same products. All algae can be effectively controlled using copper algaecides like Mizzen. If copper-sensitive fish are present, Cape Furl can be used to kill planktonic or filamentous algae. Chara and stoneworts will only be controlled with the use of copper.

It is important to note that no more than half of a pond should be treated for algae at a time. Wait two weeks before treating the other half. This is because as algae die, they deplete the oxygen supply of the pond, which can cause a fish kill. If the organisms are only around the perimeter of the water body, the entire perimeter may be treated all at once. Be sure to read all product labels prior to using.

Conclusion

Although there are many types of algae in ponds, the most common are planktonic, filamentous, Chara, and stonewort. The biggest differences are, of course, their appearances; planktonic turns the water greenish blue or looks like a spill, whereas filamentous forms stringy mats that float. Chara and starry stonewort both resemble submerged plants but are in fact algae with branch and leaf-like structures. Chara has calcium deposits and appears grayish green, while starry stonewort is gelatinous and produces tiny, white, star-shapes near the base of the branchlets.