Water HyacinthEichhornia crassipes(Mart.) Solms-Laubach Dynamics and Succession in the Nyanza Gulf of Lake Victoria (East Africa): Implications for Water Quality and Biodiversity Conservation

John Gichuki,Ally Said Matano,Reuben Omondi,Priscillar Boera,Tsuma Jembe,Ayub Ofulla,Tom Okorut

doi:10.1100/2012/106429

Abstract

This study, conducted in Nyanza Gulf of Lake Victoria, assessed ecological succession and dynamic status of water hyacinth. Results show that water hyacinth is the genesis of macrophyte succession. On establishment, water hyacinth mats are first invaded by native emergent macrophytes, Ipomoea aquatica Forsk., and Enydra fluctuans Lour., during early stages of succession. This is followed by hippo grass Vossia cuspidata (Roxb.) Griff. in mid- and late stages whose population peaks during climax stages of succession with concomitant decrease in water hyacinth biomass. Hippo grass depends on water hyacinth for buoyancy, anchorage, and nutrients. The study concludes that macrophyte succession alters aquatic biodiversity and that, since water hyacinth infestation and attendant succession are a symptom of broader watershed management and pollution problems, aquatic macrophyte control should include reduction of nutrient loads and implementing multifaceted approach that incorporates biological agents, mechanical/manual control with utilization of harvested weed for cottage industry by local communities.

Highlights

Macrophytes are higher plants that grow in ecosystems whose formation has been dominated by water and whose processes and characteristics are largely controlled by water
The study concludes that macrophyte succession alters aquatic biodiversity and that, since water hyacinth infestation and attendant succession are a symptom of broader watershed management and pollution problems, aquatic macrophyte control should include reduction of nutrient loads and implementing multifaceted approach that incorporates biological agents, mechanical/manual control with utilization of harvested weed for cottage industry by local communities
This study provides compelling evidence to show that macrophyte succession has the capacity to alter aquatic biodiversity in the lake

Summary

Introduction

Macrophytes are higher plants that grow in ecosystems whose formation has been dominated by water and whose processes and characteristics are largely controlled by water. Water hyacinth Eichhornia crassipes, a perennial aquatic herb which belongs to the pickerelweed family (Pontederiaceae), is a native of tropical America This assumption is based on the prevalence of other species of Eichhornia spp. the more primitive Eichhornia paniculata (Spreng.) Solms and Eichhornia paradoxa (Mart.) Solms, in this area. The weed has flourished in Lake Victoria due to absence of natural predators as insects, fish, and other biota and due to favorable environmental conditions. It is associated with major negative economic and ecological impacts to the Lake Victoria region. We describe a form of macrophyte ecological succession which culminated in the control of water hyacinth in the Nyanza Gulf of Lake Victoria in 2008

Methodology

Results and Discussion

Station Asembo Bay—D

Conclusion