Effects of metal exposures on juvenile clams, Mercenaria mercenaria

• Published in: Bulletin of environmental contamination and toxicology 2002, Vol.68 (1), p.43-48
• Main Authors: KEPPLER, C. J, RINGWOOD, A. H
• Format: Article
• Language: English
• Subjects: Acute toxicity; Animal, plant and microbial ecology; Animals; Anthropogenic factors; Applied ecology; Bioavailability; Biological and medical sciences; Biological Availability; Bivalvia; Bivalvia - drug effects; Bivalvia - growth & development; Cadmium; Chronic toxicity; Coastal zone; Copper; Developmental stages; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Environmental Exposure; Fundamental and applied biological sciences. Psychology; Larva - drug effects; Larva - growth & development; Lead; Life history; Marine; Mercenaria mercenaria; Metal concentrations; Metals; Metals, Heavy - pharmacokinetics; Metals, Heavy - toxicity; Micronutrients; Mollusca; Mollusks; Nickel; Toxicants; Toxicity; Urbanization; Water Pollutants - pharmacokinetics; Water Pollutants - toxicity; Zinc
• ISSN: 0007-4861; 1432-0800
• DOI: 10.1007/s00128-001-0217-5

Elevated metal concentrations occur throughout the coastal zone due to urbanization and various anthropogenic activities. The lethal concentrations (i.e. LC values based on acute toxicity) for many metals are available for various mollusc species in the literature (Calabrese et al. 1973, Eisler 1977, Chung 1980, Harrison et al. 1984, Ringwood 1990). However, short term exposure studies and lethal tests may not provide an adequate appreciation of the potential chronic toxicity of metals. The concentrations of toxicants required for short term lethal tests are usually much higher than those typically observed in polluted systems. - In part, this is a function of the fact that many metals function as important micronutrients and co-factors (copper, zinc, nickel), whereas others are always considered toxic (cadmium, lead). Regardless, at high enough concentrations, all metals are toxic. It is important that the potential effects of lower sublethal, environmentally realistic concentrations of metals, particularly on sensitive life history stages, are realized. The effects of sublethal concentrations of five common pollutant metals (Cd, Cu, Pb, Ni, Zn) on 7 day growth of juvenile (i.e. seed) clams, Mercenaria mercenaria, were evaluated. Growth was significantly decreased by the 7 day exposures to Cd, Cu, Ni, Pb, and Zn in a dose-dependent manner. When the data are reported as metal concentrations in ug/L, the order of metal toxicity, from most toxic to least toxic, was: Cu > Cd > Zn > Pb > Ni. However, if these results are expressed in molar units, the 7 day growth EC^sub 50^ values would then be Cu = 0.46, Cd = 0.77, Pb = 2.19, Zn = 4.72, Ni = 24.52 uM/L, so Zn and Pb would reverse. The results from these studies are compared to other bivalve metal exposure studies evaluating sublethal endpoints. The data generated from this study are appropriate for use in the calculation of interstitial water toxic units (IWTUs) and the determination of various bioavailability indices. These studies serve to highlight the toxicity of metals, especially Cu, to the various developmental stages of bivalves.[PUBLICATION ABSTRACT]