The relationship between metal concentrations and phenotypes in the Baltic clam Macoma balthica (L.) from the Gulf of Gdansk, southern Baltic

• Published in: Chemosphere (Oxford) 2002-05, Vol.47 (5), p.475-484
• Main Authors: Sokolowski, Adam, Fichet, Denis, Garcia-Meunier, Pascale, Radenac, Gilles, Wolowicz, Maciej, Blanchard, Gerard
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - drug effects; Anaerobiosis; Animal, plant and microbial ecology; Animals; Applied ecology; Baltic Sea, Gdansk Gulf; Biochemistry, Molecular Biology; Biodiversity; Biodiversity and Ecology; Biological and medical sciences; Bivalvia - chemistry; Bivalvia - drug effects; Bivalvia - genetics; Colour; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Environmental Monitoring - methods; Environmental Sciences; Fundamental and applied biological sciences. Psychology; Genomics; Hydrogen Sulfide - metabolism; Life Sciences; Macoma balthica; Metals, Heavy - analysis; Metals, Heavy - pharmacology; Molecular biology; Phenotype; Phenotypes; Pigmentation - drug effects; Poland; polymorphism; Populations and Evolution; Quantitative Methods; Shape; Southern Baltic Sea; Systematics, Phylogenetics and taxonomy; Trace Elements - analysis; Trace Elements - pharmacology; Trace metals; Water Pollutants, Chemical - analysis
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(02)00002-4

Soft tissue accumulated concentrations of nine metals (V, As, Se, Ag, Cd, Pb, Mn, Cu and Zn) were studied in two main phenotypes (1) according to external shell colour (white and pink), and (2) according to shell shape (shell with a rounded posterior end––“regular” and with an elongate posterior end and a notable flexure––“irregular”) of the Baltic clam Macoma balthica from southern Baltic Sea off Poland. No differences in metal concentrations were observed between colour-based phenotypes. By contrast, “irregular” clams exhibited generally higher concentrations of all elements in their tissues than “regular” bivalves. This finding provides the first reference on a potential linkage of shell deformation with tissue metal concentrations within one entire population of clams living in the same habitat. Different ability of metal handling in the shape-based phenotypes is presumably related to different physiological capacity of the bivalves induced by the selection effect of specific environmental conditions. It is suggested that unfavourable conditions in deep waters of the Gulf of Gdansk (e.g. hypoxia/anoxia, hydrogen sulphide, elevated bioavailability of metals) induces, in a certain part of the population, morphological deformation of shell (thereby leading to irregular shape) and in parallel physiological adaptations which result in greater sensitivity to trace metals of “irregular” clams. This hypothesis however, requires further investigation with special focus on genetic divergences between phenotypes because till now we cannot exclude the co-occurrence of two types (semi-species) of clams in the Gulf: an Atlantic type and a Baltic type. Genetic analysis with a use of DALP technique revealed strong intrapopulational polymorphism but no fingerprints or intraspecific polymorphism characterising any of the phenotypes considered (both colour- and shape-based). Since eight polymorphic loci were clearly identified further studies of population genetic structure hold optimistic promise.