Environmental and biotic factors affecting freshwater snail intermediate hosts in the Ethiopian Rift Valley region.
BACKGROUND
Knowledge of the distribution and habitat preference of freshwater snail intermediate hosts can provide information to initiate and set-up effective snail control programmes. However, there is limited research conducted on the factors driving the occurrence and abundance of freshwater snail intermediate hosts in the Ethiopian Rift Valley. Hence, in this study, we investigated how environmental and biotic factors influence the occurrence and abundance of the snail intermediate hosts in Ethiopian Rift Valley region.


METHODS
Data on freshwater snails, physico-chemical water quality parameters, physical characteristics of habitat, predators and competitors, and anthropogenic activity variables were collected from 174 sampling sites during the wet season of 2017 and 2018. Generalized linear models were used to identify the main environmental and biotic factors affecting the occurrence and abundance of the snail species.


RESULTS
It was found that Bulinus globosus (31.7%) was the most abundant snail species followed by Lymnaea natalensis (21.6%), Lymnaea truncatula (15.1%) and Biomphalaria pfeifferi (14.6%). Generalized linear models indicated that physico-chemical parameters (water temperature, turbidity, chlorophyll-a, dissolved oxygen, chemical oxygen demand, alkalinity, calcium, magnesium, nitrate and ammonia), physical habitat characteristics (water depth, canopy cover, macrophyte cover and substrate type) and biotic factors (abundance of predators and competitors) were found to be the main variables determining the occurrence and abundance of snail species in the Ethiopian Rift Valley region. In terms of anthropogenic activities, human settlement, farming, bathing and swimming, clothes washing, grazing, drainage of land, car washing, boating, fishing and silviculture were also important variables determining the occurrence and abundance of snail species in the region.


CONCLUSIONS
The findings reported herein suggest that integrated snail control strategies should be considered to control snails via protection of water bodies from disturbance by anthropogenic activities. In this way, it is possible to reduce the concentration of organic matter and dissolved ions in aquatic ecosystems which are conducive for the presence of snails.
['Olkeba|Beekam Kebede|BK|', 'Boets|Pieter|P|', 'Mereta|Seid Tiku|ST|', 'Yeshigeta|Mesfin|M|', 'Akessa|Geremew Muleta|GM|', 'Ambelu|Argaw|A|', 'Goethals|Peter L M|PLM|']
D000383:Agriculture D063147:Animal Distribution D000818:Animals D004199:Disease Vectors D017753:Ecosystem D005002:Ethiopia D005618:Fresh Water D011891:Rain D012621:Seasons D012908:Snails
Environmental and biotic factors Freshwater snails Generalized linear model