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  • 1
    Electronic Resource
    Electronic Resource
    Protozoan species accrual on artificial islands in differing lentic and wetland systems (1980)
    Springer
    Hydrobiologia 75 (1980), S. 161-178 
    Details
    ISSN: 1573-5117
    Keywords: Artificial substrates ; colonization ; eutrophication ; protozoa ; secondary production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the recently broadened context of insular biogeographic theory, artificial substrates might well be considered as initially barren islands with the surrounding natural community acting as a source pool of potential colonists. In an attempt to relate protozoan communities forming on polyurethane foam (PF) substrates to their environments, a series of field experiments were performed in several aquatic and semi-aquatic (wetlands) systems in Michigan, Virginia, and Colorado. Results were considered in the context of island colonization theory. Given relatively stable environmental conditions and sufficient time to colonize, protozoa formed highly replicable communities on PF substrates; MacArthur & Wilson's equation for noninteractive island colonization, S = Seq ·(l-e−Gt ), accuratelt described the process of species accrual in most cases. Sites were compared using non-linear regression estimates of the parameter, G, which reflects the rate at which substrates attained equilibrium species numbers. In general, the rate of equilibrium acquisition reflected differences in productivity and structure between the protozoan communities from the various habitats and systems studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007429
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluating the hazard of dodecyl alkyl sulphate to natural ecosystems using indigenous protistan communities (1997)
    Springer
    Ecotoxicology 6 (1997), S. 67-85 
    Details
    ISSN: 1573-3017
    Keywords: model stream ; mesocosm ; surfactant ; protozoa ; algae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The effect of the surfactant dodecyl alkyl sulphate (C12AS) on the structure and function of lotic protistan assemblages was examined using the Experimental Stream Facility (ESF) operated by the Procter and Gamble Company. Population- and community-level responses to C12AS were monitored on introduced substrates placed in the channels 28 days prior to dosing (mature communities) as well as those placed in the channels on day 0 of dosing (immature communities), to allow for a broad assessment of the effect of the chemical on processes contributing both to community development and maintenance. C12AS appeared to elicit a subsidy response from the native protistan assemblage which may have resulted from both positive and negative responses at trophic levels above and below the assemblage. Protistan responses to the surfactant tended to occur more rapidly and be more sensitive than those documented for invertebrates and fish. C12AS elicited a modest response (i.e. a 20% change) from several reliable parameters including community respiration (reduced dissolved oxygen at 289 μg per L), protozoan species richness (increased at 63 μg per L) and protozoan community composition (increased dissimilarity at 1254 μg per L). Responses to C12AS exceeded expected exposures in the real world by a factor of six or greater thereby indicating that the hazard of exposure to C12AS to stream communities is low. The results of this study support the use of mesocosms as decisive tools for evaluating the hazard posed by consumer product chemicals to natural communities and ecosystems
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018606206549
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  • 3
    Electronic Resource
    Electronic Resource
    Export of species to islands from sources of differing maturity (1985)
    Springer
    Hydrobiologia 121 (1985), S. 103-109 
    Details
    ISSN: 1573-5117
    Keywords: protozoa ; colonization ; species exchange ; artificial substrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Export of species from sources (epicenters) of differing ages and complexities was examined using laboratory microcosms. Polyurethane foam (PF) artificial substrates were colonized by protozoans for different time periods in a small pond. Substrates were returned to the laboratory and used as epicenters for protozoan colonization of barren PF ‘islands’ in initially sterile microcosms. Islands were exposed to epicenters for either 24 h or continuously for 28 d. Islands from pairs of microcosms exposed to epicenters of identical ages were sampled on 1, 3, 7, 14, 21, 28 and 46 d after initial epicenter exposure. Colonization parameters were estimated by fitting numbers of colonizing species to the MacArthur-Wilson equilibrium model. Islands exposed continuously to epicenters were colonized by significantly more species than those exposed for only 24 h. Islands exposed to immature, species poor epicenters were colonized by a greater proportion of the source community than those exposed to more mature, species rich epicenters. All islands were depauperate compared to epicenters except those exposed to the most immature (1 d old) epicenter. Colonization continued at a reduced rate in spite of the absence of the epicenter. Results from communities with rapid species turnover and rapidly reproducing species suggest that the continuous presence of a species source is less important for colonization of a new habitat. Dispersal of potential colonists occurs rapidly in these communities. Less mature communities dominated by pioneer forms are more effective at producing colonists than more mature communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008712
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