Bibliographie der Flussperlmuschel Margaritifera Margaritifera (Linnaeus, 1758) [Mollusca: Pelecypoda]

Bibliography of the freshwater Pearlmussel Margaritifera margaritifera (Linnaeus, 1758) [Mollusca: Pelecypoda] The freshwater pearlmussel, described by Linnaeus as Mya margaritifera is one of the most important molluscs existing. It belongs with only a few congeneric fossil and recent species to the distinct family Margaritiferidae. The distribution of the species is Holarctic (figs. 1-2), being known from western, northern and central Europe, and via Siberia to Japan. In North America it is found at the northeast coast of the United States and East Canada. The habitat requires clean, cold and streaming freshwater. The life cycle of Margaritifera margaritifera and its reproduction are unique within the bivalves (fig. 3). From the fertilized eggs grows a glochidium, which is kept in the marsupium of the female mussel for about 4 weeks. Then follows a parasitic stage on, and later encysted in, the gills of a host fish (Salmo trutta fario) for up to 10 months. The glochidium was discovered by Anthony van Leeuwenhoek in 1665, and later described as Glochidium parasiticum by Rathke in 1797. It was recognized the juvenile stage of a freshwater mussel in the 19th century. After leaving its host trout the young mussel grows very slowly for two to three years, deep in the substrate, untill the shell has reached a length of 15-20 mm. Then it starts living in the surface layers of the substrate, where the animal becomes mature at the age of 20 years. Due to water pollution and destroying its natural habitat, the populations of M. margaritifera have decreased rapidly during this century (figs. 4 and 5). The species has become extinct in many places (fig. 1) and is rare in others. For these reasons the freshwater pearlmussel belongs now to the endangered molluscs, and is placed on the preliminary list of protected animals ( the IUCN Invertebrate Red Data Book, 1983). The shell was collected for its mother-of-pearl. Being also a producer of pearls, the animal has played a role in the cultural history, having supplied royalty and nobility of the European courts for centuries with freshwater pearls. Because of the value of pearls, scientists were stimulated to produce cultivated ones. It is known that Linnaeus (1707-1778) experimented with the species to cultivate pearls. During the 19th century pearl formation was studied by European malacologists (Pagenstecher, Möbius, von Hessling, de Fllippi, and Küchenmeister). At the turn of the century Japanese zoologists worked with the marine pearloyster (Pinctada) in the Ago Bay, and finally Mikimoto and Nishikawa were able to produce round cultivated pearls with a nucleus of mother-ofpearl. Next to the cultivation of pearls in marine bivalves, the Japanese also grow non-nucleated pearls in the freshwater mussel Hyriopsis, at Lake Biwa. Several techniques have been developed to distinct natural pearls from cultivated ones and from glass imitations. During the first half of the 20th century European scientists (Dubois, Boutan, Alverdes, Wellmann) experimented on M. margaritifera. In the United States freshwater pearlmussels of the family Unionidae, living in the Mississippi River, were investigated, mainly for the production of buttons. During the last decades the study of Margaritifera margaritifera is concentraded in Germany (Jungbluth c.s., Baer, Bishoff, Utermark), Austria (Grohs), Great Britain (Young, Williams) and the USA (Johnson, Smith). The literature on Margaritology (= the science of pearl molluscs and pearls) is very extensive. The three authors have published here a specialized bibliography on all aspects of the family Margaritiferidae. The present work contains the titles from preliminary lists prepared by Jungbluth and coworkers in 1977 and 1980. To these were added many titles about the freshwater pearlmussel from the bibliographies on margaritology compiled through the years by Grohs and Coomans. Several colleagues kindly supplied obscure titles not known to us before. The Bibliography (p. 1-191) is followed by an Index of Subjects (p. 192- 203), divided into eleven main Key words, with subdivisions (p. xxviii-xxix). On ten graphs (p. xxi-xxv) the number of titles per subject are plotted, from which is shown that most titles are about Distribution, Pearls, and Ecology. An Index of Authors (p. 204-213) is added, whereas in an Appendix (p. 214-218) the latest available literature is mentioned. The authors gladly will be informed about any omissions in this Bibliography. The chapters preceding the Bibliography were written by Jungbluth (“Distribution and biology of the freshwater pearlmussel”, and “Evaluation of the titles”), and by Grohs (“History of Margaritology”). Coomans wrote the “Introduction” and this “Summary”. The work is published by the Zoological Museum at Amsterdam.