Posted by / Thursday, 11 May 2023 / No comments

What are the characteristics of invasive alien species like water hyacinth, water lettuce, papyrus reed and hornwort in fishery habitats


(Water hyacinth)



Invasive alien species have become a major problem in many parts of the world. These non-native species often spread quickly and cause significant ecological, economic, and social damage. In this article, we will identify and describe some alien invasive species such as water hyacinth, Papyrus reed, water lettuce, and more. We will explore their morphology, mode of propagation, growth and development.


Water hyacinth (Eichorniacrassipes)

Water hyacinth is one of the common alien invasive species in the world. The leaves of the plant are bright green and the flower is purple in colour.  Its leaf is fan-shaped. It also has thick and spongy stalks and the roots are thick and fibrous. The leaves are oval to heart-shaped and can reach up to 20 cm in length.

The water hyacinth plant is able to quickly adapt to its environment. It can also by a variety of methods. One common way by which it spread is by the use of water currents. It can also be spread by the wind. Humans also constitute a major mode of spread when they when they transport the plant from one location to another. Typically, the seeds of the water hyacinth plant can thrive for many years so it can reproduce rapidly through the seeds.

One important characteristic about the water hyacinth is that, it can grow and develop rapidly. Within a space of weeks, the plant can form dense mats to cover an entire water body. When this happens, the amount of light available for other species is reduced. This subsequently reduces the amount of oxygen available for other species. This can lead to a decrease in biodiversity and a decrease in the number of fish in the area.

(Papyrus reed)
Papyrus reed (Cyperus papyrus)

Another important alien invasive species is called Papyrus reed. This water plant is very tall, sometimes up to 15 feet. It has a triangular shaped stem and ribbon-like leaves. The leaves are long and narrow. The mode of propagation for this plant is through rhyzomes. The rhyzomes are underground and can produce new shoots. This plant thrives in wet soil and shallow water. It takes just 90 days for the plant to mature. This invasive alien species is a huge problem for the fishing industry. This is because the reeds can clog up fishing rods, reels, and nets. The plant can inhibit the movement of fish. Is also serves as a barrier to the level of oxygen in the water. The low levels of oxygen can affect the health of the fish.

Kariba weed (Salviniamolesta)

Another type of alien invasive species is called Salviniamolesta. It is commonly called Kariba weed. The plant is native to South America and can propagate and spread very quickly when first introduced to new bodies of water. The Kariba weed has a bright green colour and floats freely on the water body forming a dense mat across the surface of the water. It can grow up to a height of 20cm. The Kariba weed is easily spread by the wind, birds, and other animals. The weed spreads quickly to new water bodies and once it is established at a new place, it overpowers other plants in the area and distorts the biodiversity of the area. Since Kariba weed can easily and quickly grow and spread over the top of the water. It is able to hamper the movement of boats on the water. It can also clog fishing nets and other fishing equipment. Other problems that Kariba weeds can cause include the ability to clog water in-lets and outflows. Like other alien invasive species, it can reduce the amount of oxygen in the water and thereby disturbing the quality of water.

(Water lettuce)

Water lettuce (Pistiastratiotes)

There is also another invasive alien speices, Pistia stratiotes, commonly called water lettuce. This is a floating aquatic plant. Its colour is bright green. It has an oval-shape. This plant is native to tropical areas in Africa and in Asia. Its mode of seed dispersal is by the wind and water. Its seeds are dispersed by wind and water. New plants of the water lettuce can also be formed through the small fragments of stem, root, or leaf. For a healthy growth, water lettuce needs light, nutrients, and good temperature. In about two weeks. Water lettuce is a huge problem for fish habitat and an interference fish life. The reason is that it can clog the motors of boats. It reduces the oxygen levels in the water since it is able to spread and cover the surface of the water. Once oxygen level is reduced, aquatic life is affected because it reduces the amount of food left for other life forms including those of fish.

Hornwort (Ceratophyllum sp.)

Hornwort is also an invasive alien species worth mentioning in this discussion. It is common in still or slow-moving freshwater habitats. The plant is green. It does not have true roots, stems and leaves, like other plants. Rather, it is made up of flattened shoots. These shoots branch out from a central stem. The floats in water. It is propagated by substrate. Hornwort is problem for fish habitat. Since it grows quickly and is able spread much faster, it covers the surface of the water and blocks sunlight. This reduces the level of oxygen in the water. This is a big problem to fish because they cannot easily find their way around to be able to find food. They are also not able to avoid their predators.


Alien invasive species have been identified to cause a lot of damage to the environment, which can lead to a huge economic loss to aquatic ecosystems and subsequently great loss to the state. This is only so, if they are not properly managed. Governments all over the world, including those in Nigeria and Ghana, must develop strategies to control them if they cannot be prevented.

Also read: 

The characteristics of fish habitats like freshwater, brackish water and marine water bodies

How to identify and describe common fisheries organisms

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