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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 6912

Trevor G. Piearce, Caroline J. Langdon, Andrew A. Meharg, and Kirk T. Semple; Yellow earthworms: distinctive pigmentation associated with arsenic- and copper-tolerance in Lumbricus rubellus. Soil Biol.Biochem. 34:1833-1838, 2002

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Lumbricus rubellus Hoffmeister, inhabiting soil at the 19th century Devon Great Consols mine at Tavistock, Devon, UK, show high tolerance to Cu- and As-toxicity and frequently have a striking yellow coloration. Specimens from this site (mature and immature) and from an uncontaminated site on Lancaster University campus (mature) were photographed, and the slide images digitized and analyzed. All L. rubellus showed reddish-purple pigmentation of the body wall that declined in intensity posteriorly. The metal- and metalloid-resistant earthworms, whether mature or immature, showed yellowing in the posterior half of the body. The source of the coloration was intense yellow pigmentation of the chloragogenous tissue surrounding the alimentary canal. The yellow pigmentation is masked by reddish-purple body wall pigmentation anteriorly. Total As concentrations in tissues were determined for the anterior, middle and posterior sections of resistant and non-resistant L. rubellus. Highest concentrations were in the middle sections of the mature and immature resistant L. rubellus (36.17+/-19.77 and 27.77+/-9.02 mgAs kg-1, respectively). Resistant immature L. rubellus lost condition over 28 days in soil treated with 750 mgAs kg-1, possibly due to a higher metabolism, whilst there was no loss in condition for resistant mature L. rubellus in the treated soil. As far as the authors are aware, this is the first report of yellow pigmentation of this kind in earthworms. The pigmentation may provide a useful indicator of exposure/resistance to soil contamination.