Morphology of some body organs of juvenile river prawns (Macrobrachium macrobrachion) exposed to hydrated lime under laboratory condition

Abstract

Agro-based chemicals are in enormous use today to boost agricultural production and also recently in diverse environmental remedial activities. This study therefore aimed at assessing the potential toxicity and impact of hydrated lime [Ca(OH)₂] on the morphology of some organs of the river prawn used as the test organism. The prawns were exposed to 0.0, 20.0, 40.0, and 80.0 mg/L of Ca (OH)₂ for a period of two weeks using static renewal bioassay to assess its sub-lethal effect under laboratory conditions. The bioassays were monitored throughout the exposure period with the water quality status determined. The organs of exposed prawns were analyzed using photomicrography and the results showed that the gills had degenerations and necrosis in all exposed concentrations. The muscle had degenerations at 40 mg/L while the toxicant had no impact on the carapace at all concentrations used after the exposure period. This implies that Ca (OH)₂ is generally low in toxicity for prawns but could be lethal to aquatic life if exposed at prolonged, low and steady concentrations. General observations show that further research on application rates will ensure best practices in the use of this lime in prawn culture to boost growth and development of juveniles.

Keywords: hydrated lime, chronic toxicity, prawn culture, body organs, morphology