What is the Difference Between Freshwater Algae and Marine Algae

The main difference between freshwater algae and marine algae is that freshwater algae are found growing underwater on rocks and mud in streams and rivers whereas marine algae grow in the sea.

Freshwater algae and marine algae are two types of algae that live in water. They belong to the kingdom Protista. In addition, the complex forms of freshwater algae are the Charophyta in the Division of Green algae such as Spirogyra and stoneworts. However, the most complex forms of marine algae include seaweeds.

Key Areas Covered

1. What are Freshwater Algae
   • Definition, Characteristics, Importance
2. What are Marine Algae
   • Definition, Characteristics, Importance
3. Similarities Between Freshwater Algae and Marine Algae
   • Outline of Common Features
4. Difference Between Freshwater Algae and Marine Algae
   • Comparison with Key Differences

Key Terms

Freshwater Algae, Marine Algae

What are Freshwater Algae

Freshwater algae are the algae that live in freshwater. Generally, algae are simple, aquatic, plant-like organisms. Therefore, they do not have true roots, stems, and leaves. Most algae are microalgae that are microscopic. Other algae grow like filaments or mats. Algae contain chlorophyll in order to undergo photosynthesis. More importantly, algae produce oxygen through photosynthesis. They absorb nutrients and heavy metals from water, purifying water. They are also valuable indicators of environmental quality as algae are sensitive to pH, temperature, and nutrient levels.

Figure 1: Freshwater Algae

Furthermore, algae are abundant in slower streams rather than in fast rivers. There are three types of freshwater algae: green algae, red algae, and diatoms. In general, green algae look like green hair flowing inside the water such as in Spirogyra. Audouinella is an example of red algae that especially grows in shaded places. Usually, diatoms form phytoplankton along with cyanobacteria forms slimy layers on rocks.

What are Marine Algae

Marine algae are the types of algae that grow in the sea. The most complex forms of marine algae are seaweeds. Seaweed is essentially macroalgae that exclusively grows in marine habitats. In addition, there are four types of marine algae: green algae, red algae, brown algae, and phytoplankton. Of these, brown algae, also known as dusky plants, are the most common type of seaweed with a brown or yellow-green color. The appearance of the seaweed resembles non-arboreal, terrestrial plants.

Figure 2: Red Algae

Moreover, seaweeds have root-like structures called holdfasts, anchoring algae to the surface. Their plant body is a thallus and the leaves are known as blades. Further, the strips are the stem-like structures in seaweeds. Generally,  large brown algae are the kelp. Kelp is the most commonly consumed seaweed, containing many important vitamins and minerals such as vitamin K, vitamin A, vitamin C, folate, vitamin E, vitamin B12, vitamin B6, niacin, thiamin, riboflavin, pantothenic acid, magnesium, iron, iodine, calcium, sodium, phosphorus, and zinc. 

Similarities Between Freshwater Algae and Marine Algae

• Freshwater algae and marine algae are two types of algae that live underwater under different salinity.
• Both belong to the kingdom Protista.
• Moreover, both groups have microalgae and macroalgae.
• Algae are the basis of most aquatic food webs.

Difference Between Freshwater Algae and Marine Algae

Definition

Freshwater algae refer to the algae, growing underwater on rocks and mud in streams and rivers while marine algae refer to the algae that live in the sea.

Habitat

Usually, freshwater algae grow in freshwater while marine algae grow in the sea.

Examples

Some examples of freshwater algae include green algae, red algae, and phytoplankton, while some examples of marine algae are seaweed red algae, brown algae, and phytoplankton.  

Conclusion

In brief, freshwater algae are the types of algae that live in freshwater. Some examples of freshwater algae include green algae, red algae, phytoplankton, etc. In contrast, marine algae are the types of algae that live in seawater. Some examples are seaweed and phytoplankton. Therefore, the main difference between freshwater algae and marine algae is their habitat.

References:

1. Freshwater algae. Native plants. (n.d.). Retrieved September 19, 2022.
2. Marine algae. (n.d.). Retrieved September 19, 2022.

Image Courtesy:

1. “Водоросли пресноводного водоема 2” By Alexander Klepnev – Own work (CC BY 4.0) via Commons Wikimedia
2. “Red algae (Gracilaria sp.) (48737220543) ” By Rickard Zerpe – Own Work (CC BY 2.0) via Commons Wikimedia