Water hyacinth (
            Eichhornia crassipes
            ) infestation cycle and interactions with nutrients and aquatic biota in Winam Gulf (Kenya), Lake Victoria

AbstractFollowing a four-year annual praziquantel treatment campaign the resulting prevalence ofS. mansoniwas seen to differ among individual villages along the Kenyan shore of Lake Victoria. We have investigated possible inherent differences in snail-related aspects of transmission among such 10 villages, including six persistent hotspot (PHS) villages (≤30% reduction in prevalence following repeated treatments) located along the west-facing shore of the lake, and four PZQ-responding (RESP) villages (>30% prevalence reduction following repeated treatment) along Winam Gulf. When taking into account all sampling sites and times and water hyacinth presence/absence, shoreline-associatedB. sudanicafrom PHS and RESP villages did not differ in relative abundance or prevalence ofS. mansoniinfection. Water hyacinth intrusions were associated with increasedB. sudanicaabundance. The deeper water snailBiomphalaria choanomphalawas significantly more abundant in the PHS villages and prevalence ofS. mansoniamong villages both before and after control was positively correlated withB. choanomphalaabundance. Worm recoveries from sentinel mice did not differ between PHS and RESP villages, and abundance of non-schistosome trematode species was not associated withS. mansoniabundance.Biomphalaria choanomphalaprovides an alternative, deepwater mode of transmission that may favor greater persistence ofS. mansoniin PHS villages. As we found evidence for ongoingS. mansonitransmission in all 10 villages, we conclude conditions conducive for transmission and reinfection occur ubiquitously. This argues for an integrated, basin-wide plan for schistosomiasis control to counteract rapid reinfections facilitated by large snail populations and movements of infected people around the lake.

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Water Hyacinth (Eichhornia crassipes) infestation, interactions with nutrients, aquatic biota and a control weevil in Winam Gulf, Lake Victoria, Kenya

10.31730/osf.io/r67yj ◽

2019 ◽

Author(s):

DENNIS OTIENO ◽

Nyaboke Hilda ◽

Nyamweya Chrispine ◽

Cyprian Odoli ◽

Christopher Aura ◽

...

Keyword(s):

Water Quality ◽

Water Hyacinth ◽

Lake Victoria ◽

Soluble Reactive Phosphorus ◽

R Package ◽

Abiotic Factor ◽

Economic Activities ◽

Fish Samples ◽

Winam Gulf ◽

The Government

Lake Victoria just like many other lakes is affected by water hyacinth which resides in several bays for the better part of the year. This weed affects several economic activities of the locals and denies the government revenue every year from blue economic activities related to the lake. This paper explores the interaction of water hyacinth with biotic and abiotic factor and the efficiency of the introduced weevils in its control with an aim of advising on the best way to tackle the menace of the weed. Water quality samples were collected and compared from the time of water hyacinth arrival and sinking within Winam gulf. Water hyacinth was collected and damages resulting from the weevils as well as the number of weevils recorded. Fish samples were also collected using experimental gill nets. Water quality was analyzed for Ammonium, Soluble Reactive Phosphorus, Nitrates and Nitrates. Data was then analyzed using R- package. Results indicated that the weevils inhibits nutrient uptake by17% within the first four weeks, hyacinth increase the nutrient levels in the gulf almost three fold after decaying and sinking. Weevils also increased the sinking rate of water hyacinth through destruction of the petioles and leaves. There was a significantly higher fish numbers during the weed infestation than when the weed was absent. In conclusion water hyacinth impacts both biotic and abiotic factor and the weevils alone cannot be depended upon to eradicate the weed.

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