Comparative response of Lemnaceae clones to copper(II), chromium(VI), and cadmium(II) toxicity

Abstract

Vascular plants such as aquatic macrophytes have been used as reference organisms in ecotoxicological assessments of environmental toxicants in aquatic systems for more than two decades (Lewis 1995; Wang and Freemark 1995; Lytle and Lytle 2001). Lemnaceae are the most extensively studied family (Wang 1990; Wang 1992; Mohan and Hosetti 1999) and were incorporated to standardized protocols by environmental protection agencies or organizations (USEPA 1996; Environment Canada 1999; OECD 2000). Lemna gibba and Lemna minor were the selected species among the Lemnaceae family for most of the standarized protocols. A limitation in the selection of these reference species is distribution; L. gibba is widely distributed in South America while L. minor is not found in the Neotropical region (Landolt 1986; Landolt 1996). The search for reference organisms to be used in ecotoxicological testing with bioassays in the Pampean Region of Buenos Aires Province (Argentina) comprises the use of fish, amphibians, crustaceans and algae from surface water bodies (Ronco et al. 2000a). Previous local reports using vascular plants aimed at assessing toxicity with seeds (Sobrero et al. 1996; Ronco et al. 2000b). The present study reports data on the comparative response of a local clone of L. gibba with two collection clones of L. gibba and L. minor to three environmentally relevant toxic metals using laboratory toxicity tests.