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Short‐term (24–48 h) colonization dynamics of periphytic diatoms on artificial (styrofoam) substrata were examined using fast‐flushing, continuous‐flow troughs located on the North Thompson River, British Columbia. Two parallel troughs, one exposed to natural light and the other completely darkened, showed significant differences in periphyton biomass, chlorophyll a, and algal taxonomic composition with 24 h. Experiments which commenced at the onset of natural darkness demonstrated that rates of algal immigration during the night were the same in both troughs. Within 2–3 h of sunrise, however, certain diatom species (most notably Hannaea arcus (Ehr.) Pair, and Diatoma tenue Ag.) selectively emigrated from the artificially darkened trough but remained in the trough exposed to natural light. More closely adhering species such as Achnanthes minutissima Kütz, also showed significant emigration from the darkened trough after light deprivation for two photoperiods. Data from adhesion, emigration, and sinking rate experiments indicate that differential egress of cells from the darkened versus the lighted environments is the result of cellular regulation of buoyancy or form resistance.

SUMMARY.Libraries are generally organized by function in order to carry out their mission efficiently. Academic librarians who are faculty also have a collegial organization that exists apart from any functional arrangement. Public and technical services librarians in this sort of organization are colleagues who have responsibility for the library in the way that teaching faculty are responsible for the programs in their departments. This article discusses the characteristics of the successful collegial organization and the relationship of technical and public services librarians in a collegial library.