Impact of Water Hyacinth (Eichhornia crassipes) Infestation on Water Quality and Growth of a Benthic Mollusc Pachymelania aurita Müller (Gastropoda: Melaniidae): Experimental Evaluation

Abstract

Background: Bio-invasion has been considered as a significant component of global change and one of the major causes of species extinction and great economic loses. Invasive species like water hyacinth are of interest to ecologists, biological conservationists and natural resources managers due to their rapid spread, threat to biodiversity and damage to ecosystems. Objectives: In this study, the impacts of water hyacinth infestation on water quality and growth of benthic gastropods, Pachymelania species under experimental conditions were studied for six months by a fortnightly data collection and analyses. Methods: Five different experimental setups with varying degrees of water hyacinth stand and cover were used to establish probable impact on water quality and growth of the animals. Results: Low dissolved oxygen and significantly higher alkalinity values were observed in experiment five which had the highest water hyacinth stand. The results recorded for adults and juveniles indicated that the animals were affected by the density of water hyacinth stand.  In adults, average length and body weight were highest in experiment 2, while the lowest values were recorded in the control experiment. Juveniles recorded the highest overall average length and body weight in experiment 3, while the lowest values were recorded in the control experiment and experiment 3 respectively. Condition factor, K was highest in experiment 2 and lowest in experiments 4 and 5. Conclusion: This study shows that floating macrophytes are inimical to the growth and development of gastropods when present in large expanse and pose a lot of challenges to artisanal fishery.

Keywords: Water hyacinth, Water quality, gastropods, Artisanal fishing, socio-economic impact