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Gut passage and insect grazer selectivity of lotic diatoms
Author(s) -
PETERSON CHRISTOPHER G.
Publication year - 1987
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1987.tb01330.x
Subject(s) - diatom , biology , caddisfly , taxon , dominance (genetics) , ecology , algae , botany , larva , biochemistry , gene
SUMMARY 1. Grazing experiments were conducted in a small Kentucky stream to determine if epilithic diatom taxa differed in susceptibility to grazing by the larval caddisfly, Neophylax autumnus , and whether ingested taxa varied in digestibility. Live/dead ratios of diatom cells from N. autumnus faecal material were compared with live/dead ratios of cells taken from adjacent epilithic habitats to determine diatom digestibility. Selectivity was studied by comparing relative abundances of diatom taxa on substrata with the relative abundances of these taxa in grazer faecal material. 2. 73% of the diatoms collected from epilithic habitats contained intact chloroplasts and were characterized as live cells. Only 42% of diatoms eliminated in caddisfly faeces were living. The five dominant diatom taxa did not differ in digestibility. Elimination of viable diatoms in grazer faecal material may contribute to diatom drift in streams, and thus supply individuals for downstream recolonization. Failure to document live/dead ratios of diatoms from grazed substrata can lead to overestimation of the digestibility of taxa and misinterpretation of results. 3. Grazers in this investigation were more successful at ingesting large, high‐profile diatom taxa (i.e. Cymbella, Meridion and Gomphonema ) and less able to remove small, adnate forms ( Achnanthes minutissima ). Such 'selectivity’may be one mechanism by which A. minutissima maintains dominance in this system.