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Résumé :
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Bryozoans are small, filter-feeding animals that live in colonies attached to all kinds of substrata in a variety of habitats. Some 'moss animals' form slender, chitinous, branching tubules; others produce gelatinous sheets and ribbons, or globular colonies. Several species can cause problems by clogging wastewater treatment systems, and the recent discovery that bryozoans act as hosts for a myxozoan parasite responsible for Proliferative Kidney Disease in salmonid fish has focussed attention on their economic importance. The earlier key by S. P. Mundy (FBA Sci. Pub. 41, 1980) listed 14 species of freshwater bryozoans in the British Isles and Europe. This completely new key by T. S. Wood and B. Okamura recognises 19 species and removes two of the species listed by Mundy. The key for identification to species is based on colony shape and form, and microscopic examination of asexually-produced statoblasts. Key characters are profusely illustrated with line-drawings, supported by micrographs obtained by scanning electron microscopy which show the detailed surface structures of statoblasts. Colony shapes and general features are also illustrated with a series of photographs. Introductory sections deal with the following aspects of bryozoan biology: general structure, life history, feeding, population biology, predation and parasitism, systematics, evolution, historical studies, and methods for collection, preservation and microscopic examination. A later section of taxonomic and ecological notes provides additional information to aid identification with the key, and briefly describes the distribution and relative rarity of each species. Recent literature is thoroughly reviewed and is supported by nearly 150 references.
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