Effects of land use on intermediate snail host fauna, abundance, distribution and cercariae infection rate in Omo-Gibe river basin, Ethiopia

Abstract Background: Land use and land cover change significantly affects biodiversity, abundance and distribution of intermediate snail host fauna. In Omo-Gibe river basin the extent of land-use change is high due to anthropogenic activities leading to habitat change of freshwater snail intermediate hosts. Most intermediate snail hosts of human Schistosome parasites belong to two genera, Biomphalaria and Bulinus. In Addition, Lymnea spp. is another important host of Fasciola which causes fasciolasis in domestic animals and human. This study aims to assess the effects of land-use on the distribution and abundance of freshwater snail intermediate hosts and cercariae infection rates of fresh water intermediate snail hosts in Omo-Gibe River basin, Ethiopia.Methods: This study was conducted in Omo-Gibe river basin in 130 sampling sites which include rivers, lakes, dams, stream, wetlands and irrigation ditches. At each site data on land use, anthropogenic activities, freshwater snail abundance and species diversity, and water samples were collected. Snails were collected from each sampling sites using a scoop (20cm x 30cm) with a mesh size of 300µm. Snails were sorted by genus on Enamel pan using forceps and preserved in labeled vials containing 75% ethanol. Live snails collected from the same habitat were sorted carefully and put in clean plastic buckets half filled with water. Afterwards, snails were provided with fresh lettuce leaves and maintained in the laboratory. Snails were then identified morphologically to family, genus and to species level. Each snail was examined for cercaria shedding by placing in a petri dish containing water and exposed to the sun for 2 hours. Cercariae were morphologically identified by microscopy. ArcGIS software of version 10.3.1 was used to map snail distribution and data were analysed using SPSS version-20.Results: The results obtained in this study shows clearly that land use change affect the distribution and abundance of fresh water snails in Omo-Gibe river basin. Fresh water snails were more abundant in farmland and settlement areas. Of the total 2,559 freshwater snails collected from 130 surveyed sites in Omo-Gibe river basin, 1749 (68.34%) belongs to medically important snail species. Biomphalaria spp.914 (35.7%),, Lymnea spp.439 (17.1%),, Physa spp. 343(13.4%) and Bulinus spp 53 (2%)). Sphaeriidae group accounted for 810 (31.6%) of the collected specimens. Biomphalaria pfeifferi was the predominant species of the total snail sampled from lakes, wetlands, rivers and irrigation ditches. Biomphalaria pfeifferi was the most infected snail species by different cercariae. Bulinus globosus and L.natalensis were infected by more than one and same type of cercariae. However, none of B. sudanica and P. acuta specimens was infected by trematode.Conclusions: The results of this study revealed that land use change altered the abundance, distribution and diversity of medically important fresh water snails in the study area. In general medically important freshwater snails which include: Biomphalaria spp, Bulinus spp and Lymnaea spp were collected from lakes, rivers, wetlands, irrigation ditches.. The medically important snail species found infected by cercaria are L. natalensis, B. pfeifferi and B. globosus. Biomphalaria pfefferi was the predominant species and highly infected by cercariae. Higher infection rate was observed in snails collected in Farmland (16.59%) and Grassland (36.6%).

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Susceptibility of 7 freshwater gastropod species in Zimbabwe to infection with Gastrodiscus aegyptiacus (Cobbold, 1876) Looss, 1896 : short communication

Journal of the South African Veterinary Association ◽

10.4102/jsava.v75i4.481 ◽

2004 ◽

Vol 75 (4) ◽

Cited By ~ 3

Author(s):

S. Mukaratirwa ◽

I.F. Munjere ◽

M. Takawira ◽

G. Chingwena

Keyword(s):

Intermediate Host ◽

Post Infection ◽

Experimental Period ◽

Freshwater Snail ◽

Wide Distribution ◽

Snail Species ◽

Intermediate Hosts ◽

Biomphalaria Pfeifferi ◽

Experimental Conditions ◽

Bulinus Globosus

Gastrodiscosis outbreaks due to Gastrodiscus aegyptiacus were recorded in horses in the vicinity of Harare, Zimbabwe, in the absence of Bulinus forskalii, B. senegalensis and Cleopatra sp. which are considered to be the only intermediate host snails. This suggested the possibility of other snail species acting as intermediate hosts in the life cycle of the trematode. A study was carried out to determine the susceptibility of 7 freshwater snail species to infection with G. aegyptiacus. First generation (F-1) of 5 freshwater pulmonate snail species, Bulinus tropicus, Bulinus globosus, Biomphalaria pfeifferi, Helisoma dyuri and Physa acuta that were bred in the laboratory, and 2 prosobranch snail species, Melanoides tuberculata and Cleopatra sp. that were collected from the field were used in this study. Data pertaining to mortalities and cercariae shedding were recorded throughout the experimental period. The prosobranch snails, M. tuberculata and Cleopatra sp. were susceptible to G. aegyptiacus with a minimum prepatent period of 45 days and 54 days, respectively. Bulinus tropicus, P. acuta and H. duryi were susceptible as evidenced by the presence of different generations of rediae and mature cercariae on dissection at 59 days post-infection although attempts to induce the snails to shed from 28 days post-infection did not produce cercariae. Bulinus globosus and Bio. Pfeifferi were refractory to infection. The results revealed the ability of G. aegyptiacus to infect M. tuberculata, Cleopatara sp., B. tropicus, P. acuta and H. duryi under experimental conditions and this may explain the recorded outbreaks of gastrodiscosis in equine populations in Zimbabwe in the absence of the known intermediate hosts. Bulinus tropicus is considered as the most likely major intermediate host of G. aegyptiacus because of its wide distribution in Zimbabwe and is well adapted to a wide variety of environments.

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Survey of Fresh Water Snails in Vandeikya Local Government Area, Benue State Nigeria

Asian Journal of Research in Zoology ◽

10.9734/ajriz/2019/v2i330066 ◽

2019 ◽

pp. 1-8

Author(s):

T. S. Atsuwe ◽

J. I. Chikwendu ◽

V. U. Obisike

Keyword(s):

Local Government ◽

Fresh Water ◽

Freshwater Snail ◽

Local Government Area ◽

Freshwater Snails ◽

Snail Species ◽

Biomphalaria Pfeifferi ◽

Factors Affecting ◽

Water Ph ◽

Bulinus Globosus

A survey was carried out in Vandeikya Local Government Area of Benue State, Nigeria from April-July 2017 to determine availability of freshwater snails of and their preferred habitats. A total of 289 fresh water snails of four different genera were collected across 27 streams in the 7 districts in Vandeikya LGA. Water pH, water temperature and water velocity were also measured. Lenistislibycuswas found to be the most abundant freshwater snail species accounting for 40.83% of the total freshwater snails. Melanoidestuberculata was the second most abundant accounting for 29.411% of the total snails population sampled, Biomphalaria pfeifferi accounted for 17.99% while Bulinus globosus was significantly lower in abundance than the other snails, accounting for only 11.77%. By location, Mbaduku district had highest abundance of snails 84 (29.1%). The effect of the nature of the substratum on the availability of freshwater snails revealed that habitats with rocky substratum favoured the presence of snails accounting for 181(62.7%) freshwater snail collected.Our understanding of factors affecting the availability and abundance of freshwater snails in nature can prove useful in snail control which is integral for the control of the diseases for which they serve as intermediate host.

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Detection of land use change in the Laohahe River Basin of West Liaohe River based on remote-sensing images

Geo-information Science ◽

10.3724/sp.j.1047.2009.00125 ◽

2010 ◽

Vol 11 (1) ◽

pp. 125-131

Author(s):

Xiuqin FANG ◽

Liliang REN

Keyword(s):

Remote Sensing ◽

Land Use ◽

Land Use Change ◽

River Basin ◽

Remote Sensing Images ◽

Liaohe River

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Historic and Simulated Desert-Oasis Ecotone Changes in the Arid Tarim River Basin, China

Remote Sensing ◽

10.3390/rs13040647 ◽

2021 ◽

Vol 13 (4) ◽

pp. 647

Author(s):

Fan Sun ◽

Yi Wang ◽

Yaning Chen ◽

Yupeng Li ◽

Qifei Zhang ◽

...

Keyword(s):

Land Use ◽

Land Use Change ◽

Markov Model ◽

River Basin ◽

Arable Land ◽

Current Trend ◽

Ecological Crisis ◽

Tarim River ◽

Tarim River Basin ◽

Desert Oasis

The desert-oasis ecotone, as a crucial natural barrier, maintains the stability of oasis agricultural production and protects oasis habitat security. This paper investigates the dynamic evolution of the desert-oasis ecotone in the Tarim River Basin and predicts the near-future land-use change in the desert-oasis ecotone using the cellular automata–Markov (CA-Markov) model. Results indicate that the overall area of the desert-oasis ecotone shows a shrinking trend (from 67,642 km2 in 1990 to 46,613 km2 in 2015) and the land-use change within the desert-oasis ecotone is mainly manifested by the conversion of a large amount of forest and grass area into arable land. The increasing demand for arable land for groundwater has led to a decline in the groundwater level, which is an important reason for the habitat deterioration in the desert-oasis ecotone. The rising temperature and drought have further exacerbated this trend. Assuming the current trend in development without intervention, the CA-Markov model predicts that by 2030, there will be an additional 1566 km2 of arable land and a reduction of 1151 km2 in forested area and grassland within the desert-oasis ecotone, which will inevitably further weaken the ecological barrier role of the desert-oasis ecotone and trigger a growing ecological crisis.

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