Toxicity of Methanol to Fish, Crustacean, Oligochaete Worm, and Aquatic Ecosystem

Abstract

Static renewal bioassays were conducted in the laboratory and in outdoor artificial enclosures to evaluate toxic effects of methanol to one teleost fish and two aquatic invertebrates and to limnological variables of aquatic ecosystem. Ninety-six-hour acute toxicity tests revealed cladoceran crustacea Moina micrura as the most sensitive to methanol (LC50, 4.82 g/L), followed by freshwater teleost Oreochromis mossambicus (LC50, 15.32 g/L) and oligochaete worm Branchiura sowerbyi (LC50, 54.89 g/L). The fish, when exposed to lethal concentrations of methanol, showed difficulties in respiration and swimming. The oligochaete body wrinkled and fragmented under lethal exposure of methanol. Effects of five sublethal concentrations of methanol (0, 23.75, 47.49, 736.10, and 1527.60 mg/L) on the feeding rate of the fish and on its growth and reproduction were evaluated by separate bioassays. Ninety-six-hour bioassays in the laboratory showed significant reduction in the appetite of fish when exposed to 736.10 mg/L or higher concentrations of methanol. Chronic toxicity bioassays (90 days) in outdoor enclosures showed a reduction in growth, maturity index and fecundity of fish at 47.49 mg/L or higher concentrations of methanol. Primary productivity, phytoplankton population, and alkalinity of water were also reduced at these concentrations. Chronic exposure to 1527.60 mg/L methanol resulted in damages of the epithelium of primary and secondary gill lamellae of the fish. The results revealed 23.75 mg/L as the no-observed-effect concentration (NOEC) of methanol to freshwater aquatic ecosystem.

Acute Toxicity of Synthetic Pyrethroid Cypermethrin to Some Freshwater Organisms

“…We did not find any report of sensitivity of oligochaet worms to pyrethroids. But it has been found that these organisms are relatively more tolerant than crustaceans and fish to organic pollutants (Kaviraj et al 2004). Results of the present study also confirm it.…”

Ecotoxicological effects of jute retting on the survival of two freshwater fish and two invertebrates

“…Branchiura sowerbyi grows over decomposing substrates and is habituated to survival under anoxic conditions. In addition, this worm is more tolerant of organic pollutants than fish and cladocerans (Bhunia et al 2003;Kaviraj et al 2004). But crustaceans, both cladocerans or copepods, have always been found more sensitive to organic (Kaviraj et al 2004) or inorganic metallic (Das and Kaviraj 1994) pollutants than fish and oligochaet worms.…”

Use of formalin in intensive aquaculture: properties, application and effects on fish and water quality

“…Some of the most common effects on fish resulting from methanol toxicity are the hyperactivity and convulsion, as well as, respiratory distress, reduction in growth and impairment of reproductive performance (Kaviraj et al . and authors cited therein).…”

“…; Kaviraj et al . ). LC 50 is an indicator of acute toxicity and corresponds to the concentration able to kill fifty percentage of the exposed organisms (Mayes & Barron ; Rand ).…”