Assessing the effects of tropical wood leachate to Desmodesmus subspicatus, Lemna minor and Daphnia magna

Abstract

Ghana has a long history as a major supplier of high-value hardwood timber and wood products to many countries. The research seeks to assess the effects of tropical wood leachates to aquatic organisms. Hence, five wood samples were selected; Mahogany (Khaya ivorensis), Cedrela (Cedrela odorata), Emire (Terminalia ivorensis), Wawa (Triplochiton scleroxylon) and Ceiba (Ceiba pendandra) from Oboyow forest reserve in Eastern Region- Ghana to assess their toxicity to aquatic organisms. Toxicity tests: Algal (Desmodesmus subspicatus) Duckweed (Lemna minor) and crustacean (Daphnia magna) were carried out using exposures to concentrations of 20, 30, 45, 67 and 100% v/v wood leachate in control media. The high levels of phenols measured in the various wood leachates was the main cause of toxicity. The percentage median Inhibition Concentration (%IC50) of the various wood leachate, ranged from 21.5 - 55.6% with mahogany exhibiting the highest toxicity and wawa the lowest. All the wood leachates were toxic to the aquatic organisms. The %IC50 showed both confirmed and potential toxicity among the various wood leachates and established that there was significant difference between various wood leachate toxicity.