LAKE VICTORIA

Confronting The Water Hyacinth

ROBERT BOB OKELLO

Presentation Outline

• Location of L. Victoria

• What is the water hyacinth

• Origin w.r.t L. Victoria

• Factors for its bloom

• Ecological & Economic effects

• Control & Economic benefits

• Conclusion

Location of L. Victoria

• East Africa (Uganda, Tanzania & Kenya)

• Area: 68,800 km²

• Elevation: 1,134 m

• Width: 250 km

• Largest tropical lake in the world

• World's 2nd largest freshwater lake by surface area

What is Water Hyacinth?

• Botanically known as Eichhornia crassipes

• Free-floating perenial aquatic plant (Hydrophyte)

• Native to Amazon

• Highly Problematic & invasive outside native range

• Overall effects of the Water hyacinth are still unknown

What is Water Hyacinth?

Classification

Kingdom: Plantae

(Unclassified): Angiosperms

(Unclassified): Monocots

(Unclassified): Commelinids

Order: Commelinales

Family: Pontederiaceae

Genus: Eichhornia

Species: E. crassipes

How did it get to L. Victoria?

• Introduced in the region by the Belgian colonists to Rwanda

• In the 1980s

• To beautify their holdings

• This slowly advanced to lake Victoria by natural means

• Aid of the River Kagera

• First sighted in 1988

Why Has it Flourished?

• Optimum growth temperatures (25o-30o)

• Optimum PH of 5.0 – 7.5 (L. Vic = Fresh)

• Optimal salinity (<15% of sea water)

• The plant produces numerous viable seeds

• Shallow shores in Uganda with muddy bottoms thus providing perfect growth conditions

• No competitors

Detrimental Effects

• Invasion of fish breeding grounds• Aquatic habitat colonisation (80% of Uganda’s shoreline

infested)• Creates anoxic (total depletion of oxygen) conditions in the

lake• Creates breeding grounds for female anopheles mosquitoes

(malaria)• Fishing dificulties• Navigational challenges for water vessels

Control Measures

1. Chemical Control• Herbicides are used• Expensive on large scale• Have detrimental effects

on the environment• Health related issues

Control Measures

2. Physical Control• Land based machines

(bucket cranes, drag lines/boorm)

• Aquatic based machinery (aquatic weed harvester, dredges, vegetation shredder)

Control Measures

3. Biological Control• Use of water hyacinth eating

pests/insects• Neochetina eichhorniae (mottled

water hyacinth weevil)• Megamelus scutellaris (USD’s

Agricultural research)

Economic Uses

• Bioenergy (1 hec = 70metric tonnes of biogas. 1Kg = 730litres of biogas )

• Phytoremediation (Waste water treatment) – roots naturally absorb pollutants e.g. Lead, mercury

• Food source – it’s a carotene-rich vegetable• Also a source of animal feeds• Medicinal value (Tonic effect) – medicating

horse skin.• Source of organic fertiliser• For making Furniture, hand bags and ropes • Small scale paper production• Job opportunities

References

http://sabahionline.com/en_GB/articles/hoa/articles/features/2013/09/27/feature-02

http://www.economist.com/node/110585

http://en.wikipedia.org/wiki/Eichhornia_crassipes

http://en.wikipedia.org/wiki/Water_hyacinth_in_Lake_Victoria

http://aciar.gov.au/files/node/2292/pr102chapter21.pdf

http://en.wikipedia.org/wiki/Lake_Victoria

http://en.wikipedia.org/wiki/Lake_Victoria#Water_hyacinth_invasion

http://www.businessdailyafrica.com/image/view/-/1308408/medRes/282736/-/maxw/600/-/8hjvc/-

/DnKisumuCounty1607xx.jpg