Algae

Pond scum. Most likely so thick because of fertilizer runoff.

Algae are found the world over, generally aquatic, but not always. They thrive in warm water and cold water, saltwater and freshwater. Most are photosynthetic—same as plants—using sunlight to power chemical reactions used to create carbohydrates. They range from small, single-celled organisms up to large kelps over a hundred feet in length. Green, red, and brown algae are prominent, but they are by no means the only colors. Algae exist on every continent on earth, and live in every climate.

Algae are not a single clade (a clade is a group comprised of an ancestor and all its descendants). They didn’t evolve from one common ancestor. They arrived at the present day from different evolutionary paths, but they shared enough common characteristics that they were combined into a single group, though a solid definition of an alga is hard to come by.

Since we live in a landlocked county I feel that discussing oceanic algae is not pertinent to this blog, so I’m going to focus on those found in freshwater ecosystems. (This will also help limit the length of this blog.)

Algae provide important functions in many ecosystems. They are often the primary producers in an aquatic ecosystem. Primary producers are at the bottom of the food chain. Algae are eaten by larger organisms such as zooplankton, which in turn are eaten by fish, which may be eaten by larger fish, and so on up the food chain. Algae allow fish to thrive and thus allow us to catch fish for both food and sport.

Most of the algae that people might see around the region in rivers, creeks, streams, ponds, lakes, etc. are generally green algae. (The green color gives it away.) They’re by no means the only algae present, they’re just easily noticeable. The green algae are those most closely related to plants, and are the group from which plants emerged from.

Algae can be a good indication of the overall health in an aquatic system. Algal growth is dependent on several factors: nutrient availability, light level, pH, temperature, etc. Any one of these can limit algal growth, but the most important one is nutrient availability. Increasing the nutrients available in a waterway will increase the number of algae present. This can lead to algal blooms, which can be unsightly at best and harmful at worst. Many of these blooms are the direct result of human impacts on the environment. Over applying fertilizer to fields, orchards, and lawns can be washed into nearby waterways. Livestock manure can make its way into creeks running through pastures. All of these can lead to algal blooms. Best way to control algal blooms? Control the nutrients leaching into streams, lakes, and rivers.

A look at the variety of saltwater algae.
Generally called seaweeds.

While being ecologically important algae are also useful for many other things. Many types of seaweed are used as food. Agar is derived from red algae, and is used as a thickening agent in petri dishes and many types of food.

Algae can also be used as a pollution control. They can treat sewage by removing many of the toxic and harmful components. Algae “scrubbers” can be used to clean water by pulling out the excessive nutrients present. They can also be used to capture the fertilizer runoff from farms before it enters water systems. These algae could in turn be used as fertilizer on the same fields.

Algae may provide the best option for biofuel production for a variety of reasons. Algae are fairly easy to grow and can be grown in areas unsuitable for other plants. They can be grown using wastewater and sewage. Algae have faster growth rates than land plants because their structure is so much simpler. 

I realize that this is a fairly simplistic look at algae. But the subject is far too large to adequately cover in a single blog post, so instead I aimed for a quick overlook of many things relating to algae to peak your interest. Hopefully it provides enough of an intro to make you seek out more information on algae. They are fascinating and an important part of many ecosystems. Their possible roles in helping solve some of mankind’s problems are also exciting.