Transport of diatom frustules by copepod fecal pellets to the sediments of Lake Michigan1

摘要: Zooplankton fecal pellets cxpellcd near the surface of lakes provide a mechanism for removal diatoms to deeper water. Scanning electron micrographs show that copepod pellets, collected from Lake Michigan, contained fractured specimens 21 species diatoms. Few intact were observed and many frustules reduced small fragments during ingestion by copepods. The peritrophic membrane surrounding is composed polysaccharides, one which chitin. This broken down bacterial decomposition in 6-14 days as settle at an average velocity 4.7 m d”. As result, released water more than 70 deep do not transport diatom directly sediment. In large proportion Michigan sediments via originating unlikely, since about 60% lake >70 deep. Recent studies have indicated potential importance planktonic crustacean downward marine waters (Osterberg et al. 1963; Lowman 1971; Cherry 1975; Schrader 1971). A similar has been described freshwater systems. purpose our study was determine fate zooplankton their role sedimentation dissolution Michigan. Forster (1953) showed feces crustaceans Gould (1957) suggested Calanoid copepods may also be chitinous; using method developed Campbell ( 1929)) he found no evidence chitin but thought this probably due amount material used test. length time pellet remains depends on rate decomposed. We therefore investigated chemical nature, mode, degradation pellets. acknowledge assistance P. 1 Work performed uader auspices U.S. Energy Research Development Administration. Harris analysis G. Chubb aid Biology Electron Microscope Center.