Land use/land cover change, physico-chemical parameters and freshwater snails in Yewa North, Southwestern Nigeria

Abstract

The management of ecosystem has been a major contributor to the control of diseases that are transmitted by snail intermediate hosts. The ability of freshwater snails to self-fertilize, giving rise to thousands of hatchlings, enables them to contribute immensely to the difficulty in reducing the endemicity of some infections in the world. One of the effects of land use/land cover change (LU/LCC) is deforestation, which, in turn, leads to the creation of suitable habitats for the survival of freshwater snails. This study was aimed at studying the land use/land cover change, physico-chemical parameters of water bodies and to understand the interplay between them and freshwater snails in an environment where a new industrial plant was established. Landsat TM, 1984, Landsat ETM+ 2000 and Operational land Imager (OLI) 2014 imageries of the study area were digitally processed using ERDAS Imagine. The land use classification includes settlement, water bodies, wetlands, vegetation and exposed surface. Dissolved oxygen, water temperature, pH, total dissolved solids and conductivity were measured with multipurpose digital meters. Snail sampling was done at each site for 30 minutes along the littoral zones, using a long-handled scoop (0.2mm mesh size) net once every month for 24 months. Independent t-test was used to determine the variation between seasons, Spearman’s rank correlation coefficient was used to test the relationship between physico-chemical parameters and snail species while regression was used to analyze the relationship between LU/LCC and freshwater snails. Species’ richness, diversity and evenness were examined using Margalef, Shannon Weiner and Equitability indexes. Snail species recovered include: Bulinus globosus, Bulinus jousseaumei, Bulinus camerunensis, Bulinus senegalensis, Bulinus forskalii, Amerianna carinatus, Ferrissia spp., Segmentorbis augustus, Lymnaea natalensis, Melanoides tuberculata, Physa acuta, Gyraulus costulatus, Indoplanorbis exuxtus and Gibbiella species. Out of the total snails recovered, M. tuberculata (2907) was the most abundant, followed by Lymnaea natalensis (1542). The highest number of snail species was recovered from Iho River while the least number of snails was recovered from Euro River. The mean and standard deviation of physico-chemical parameters of the water bodies were DO (2.13±0.9 mg/L), pH (6.80±0.4), TDS (50.58±18.8 mg/L), Temperature (26.2±0.9°C) and Conductivity (74.00±27.5 μS/cm). There was significant positive correlation between pH and B. globosus (r = 0.439; P<0.05). Dissolved oxygen showed significant positive correlation with B. globosus (r = 0.454; P<0.05) and M. tuberculata (r = 0.687; P<0.01). There was a positive significant relationship between LULCC and B. camerunensis (p<0.05). The positive relationship between LULCC and the abundance of B. globosus, B. jousseaumei was not significant. The area covered by water bodies increased from 3.72 to 4.51 kilometers; this indicates that, more suitable habitats were being created for the multiplication of freshwater snails. We therefore conclude that, increase in areas suitable for the survival of freshwater snails could lead to an increase in water-borne diseases caused by the availability of snail intermediate hosts.

Ecosystem Links: Macrophytes, Snail Preferences, and Trematode Transmission in Man-Made Water Bodies

“…Snail abundance varied significantly across the five parts of the study area characterized by different land uses, with the highest abundance observed in villages and the lowest in the farm section. Consistent with previous studies (Du et al, 2011; Lange et al, 2013; Oso & Odaibo, 2021), our findings underscore the profound impact of anthropogenic environmental changes on freshwater mollusc communities. Research suggests that snails tend to thrive in environments altered by human activities.…”

Spatial distribution, abundance, and infection rates of human schistosome-transmitting snails and related physicochemical parameters in KwaZulu-Natal (KZN) province, South Africa

“…Low dissolved oxygen levels indicate poor water quality from organic and anthropogenic pollution. Furthermore, low oxygen content in water affects the development of intermediate host snails hence reduction in snail abundance, egg size, and variations in shapes [ 37 ]. This low oxygen in water also increases the active organic decomposition of the sediments, leading to the suffocation and death of freshwater snails.…”

Effects of Land-Use and Environmental Factors on Snail Distribution and Trematode Infection in Ethiopia

“…The removal of vegetation for crop farming results in habitat fragmentation and increasing sunlight penetration. This creates favorable conditions for the survival of snail species and is expected to increase the risk of trematode infection [ 17 ].…”

“…The conversion of a forest ecosystem into agricultural land profoundly affects stream morphology, water chemistry, increased levels of siltation, altered nutrient dynamics, and hydrology [ 16 ]. This creates favorable conditions for the survival of snail species and is expected to increase the risk of trematode infection [ 17 ]. The widespread deforestation and degradation of natural habitats for crop farming and grazing of animals could also contribute to the loss of aquatic biodiversity including snail predators and competitors [ 14 ].…”