Water Hyacinth and Vembanad Lake

Current Context

Rapid growth of water hyacinth has severely affected parts of Vembanad Lake in Kerala.

Water Hyacinth

1. Scientific name: Eichhornia crassipes.
2. Origin: Native to South America.
3. Nature: A free-floating freshwater aquatic plant.
4. Appearance: Has broad, glossy leaves and attractive lavender/purple flowers.
5. Habitat: Grows rapidly in still or slow-moving, nutrient-rich freshwater.
6. Global spread: It has become an invasive species across tropical and subtropical regions of the world.

Useful Applications:

1. Phytoremediation: Can absorb certain pollutants and heavy metals from contaminated water.
2. Compost: Plant biomass can be converted into compost and organic manure.
3. Handicrafts: Fibrous plant material can be used for baskets, mats and decorative products.

Why Water Hyacinth is an invasive alien species?

1. Rapid reproduction: It can multiply extremely quickly under favourable conditions.
2. Dense mats: Forms thick floating layers over the water surface.
3. Habitat alteration: Competes with native aquatic plants and alters aquatic habitats.
4. Nutrient enrichment: Excess nutrients from agricultural runoff and sewage can promote its growth.
5. Light blockage: Reduces sunlight reaching submerged plants.

Ecological and Economic Impacts

1. Biodiversity loss: Crowds out native aquatic vegetation and affects associated fauna.
2. Water quality: Dense growth can deteriorate water quality.
3. Navigation: Makes movement of boats difficult.
4. Fisheries: Alters fish habitat and can interfere with fishing activities.
5. Mosquito breeding: Dense vegetation can create favourable stagnant-water conditions for some vectors.
6. Irrigation: Can obstruct canals and water-management infrastructure.

Management Measures

1. Mechanical removal: Remove large floating mats from affected waterways.
2. Nutrient control: Reduce sewage and agricultural nutrient inflow into water bodies.
3. Biological control: Explore scientifically tested biological-control agents where ecologically appropriate.
4. Biomass utilisation: Convert safely collected biomass into compost or other useful products.
5. Regular monitoring: Use remote sensing and field surveys to identify new infestations early.
6. Integrated management: Combine physical, biological and nutrient-management approaches rather than relying on removal alone.

Vembanad Lake

Geographical Features

1. Location: Located along the Kerala coast and extends across several districts.
2. Type: A large brackish-water backwater/wetland system connected to the Arabian Sea.
3. Freshwater input: Major rivers including Pamba, Manimala, Achankovil and Meenachil drain into the lake system.

Unique Features

1. Below-sea-level farming: The Kuttanad region contains extensive paddy cultivation in areas below sea level.
2. Coconut landscape: Coconut plantations are a prominent feature around the backwaters.
3. Boat races: The famous Vallam Kali, including the Nehru Trophy Boat Race, is associated with Kerala’s backwater culture.
4. Wetland ecosystem: Supports fisheries, agriculture, tourism and diverse aquatic biodiversity.

Conservation Significance

1. Ramsar Site: Vembanad-Kol Wetland was designated a Ramsar site in 2002.
2. Migratory birds: The wetland provides habitat for numerous resident and migratory birds.
3. Kumarakom Bird Sanctuary: Located on the eastern bank of Vembanad Lake and is an important bird habitat.
4. Livelihoods: Supports fishing, agriculture, inland navigation and tourism.

FAQs

Q1. What type of plant is water hyacinth?
Ans: A free-floating freshwater aquatic plant that is highly invasive.

Q2. What is the scientific name of water hyacinth?
Ans: Eichhornia crassipes.

Q3. Where is water hyacinth native to?
Ans: South America.

Q4. Why is water hyacinth harmful when it grows uncontrollably?
Ans: It forms dense mats that block sunlight and water flow, reduce oxygen and compete with native aquatic species.

Q5. Why is Vembanad Lake important?
Ans: It is a major Ramsar wetland supporting fisheries, agriculture, migratory birds, tourism and backwater ecosystems.

Q6. Which bird sanctuary is associated with Vembanad Lake?
Ans: Kumarakom Bird Sanctuary, located on the eastern bank of the lake.