Freshwater leeches (Hirudinea) as a screening tool for detecting organic contaminants in the environment

Abstract

In earlier work, we found that leeches from an industrially polluted creek bioaccumulated chlorophenols to much higher concentrations than other resident benthic invertebrates and fish. We suggested that leeches may have significant potential as biomonitors for these and other organic contaminants in the environment. In this study, we compared the bioaccumulation and depuration of 16 organic compounds, including eight chlorophenols (CPs), lindane, DDT and four derivatives, benzothiazole (BT) and 2-(Methylthio)benzothiazole (MMBT) for three species of leeches. Dina dubia had the highest bioaccumulation capacity for most contaminants, but residues persisted longest in Erpobdella punctata. Helobdella stagnalis appeared capable of degrading some compounds. Half lives of CPs, DDT and DDT derivatives were generally longer than one month. In contrast, half lives were only 1 day for lindane, 1-2.5 days for MMBT and 7 days for BT despite very high initial tissue concentrations of the latter two compounds. Bioconcentration factors for contaminants in leeches were higher than those reported for other aquatic organisms. Half lives for lindane, DDT and DDT derivatives were consistent with the literature for other organisms, but half lives for CPs were much longer. The results suggest that leeches would be excellent biomonitors of both continuous and intermittent contamination of a waterway with CPs and DDT, as they retain these compounds for long periods after exposure. Their usefulness as a screening tool for lindane and benzothiazoles would be limited to chronically contaminated environments.

Bioaccumulation of Phenol, Guaiacol and Some Chlorophenols by Selected Freshwater Species of Leeches

“…These findings are in agreement with results obtained by Metcalfe et al (1984Metcalfe et al ( , 1988, who observed effective bioaccumulation of chlorophenols by the leeches D. dubia, Helobdella stagnalis and E. punctata. They suggested that the high body burdens in the leeches might have been associated with a very slow elimination of di-, tri-and tetrachlorophenols from their bodies, which had half-lives of 25-40 days.…”

Hirudinea (Annelida) species and their ecological preferences in some running waters and lakes

“…They are invertebrate predators, and they are also an important component of the food chain in freshwater ecosystems (Sket and Trontelj 2008). Metcalfe et al (1988) determined that bioaccumulation in Hirudinea is higher than in other benthic groups and also higher than in fish in industrially polluted running waters hence Hirudinea species can have a part to monitor organic contaminants. Macova et al (2009) also carried out a study on polychlorinated biphenyl which accumulates in animal tissues and indicated that genus Erpobdella is a good sensor indicator of polychlorinated biphenyl contamination in rivers.…”

The use of leeches to monitor aquatic PCB contamination at Mid-Canada radar line site 050: Four years post-remediation

“…as bioindicators (Metcalfe et al 1984(Metcalfe et al , 1988. Few organoxchlorines were found in leeches above the detection limit, except for PCBs which were significantly higher in leeches collected near Site 050 compared to the control site.…”