Historical and Current Applications

Microcosms have been used in almost every area of terrestrial and aquatic ecology. They have long been used as a classroom teaching tool, bringing aspects of nature into the laboratory. The first ecological experiments using microcosms appear to be those of L. L. Woodruff in 1912 investigating protozoan succession in hay infusions. However, the majority of research with microcosms has been conducted since the 1960s. Early use of microcosms by prominent ecologists including G. F. Gause, H. T. Odum, R. Margalef, R. H. Whittaker, R. J. Beyers, G. D. Cooke, and E. P. Odum has contributed to the development of important concepts in ecology including the competitive exclusion principle, succession, self-organization, and the maximum power principle.

Microcosms continue to be widely used for general ecological studies. However, in recent times, they have also become popular tools to study the fate and effects of contaminants (e.g., heavy metals), pesticides and herbicides, stressors (e.g., high temperatures), novel compounds, and genetically engineered organisms (Figure 1). They provide a comparatively safe means of assessing likely effects on ecosystems without direct exposure to the natural environment. Microcosms are not yet routinely used in ecotoxicological testing despite a strong argument from proponents that single-species tests are inadequate for full evaluation of ecosystem-level impacts. The problems with microcosm use relative to ecotoxico-logical single species tests include the higher costs, time involved, complexity, variability and difficulty in evaluating endpoints. Despite these issues, F. B. Taub and colleagues have worked to develop a standardized (nearly gnotobiotic) aquatic microcosm. This is now registered with the American Society for Testing and Materials as a standard method.

Wheat seedlings

HDPE cylinder Organic material plug

Soil

15 cm

Earthworm

Figure 1 A homogenous integrated soil microcosm, designed as a model terrestrial ecosystem to assess the effects of single pesticides on soil ecosystems. Reproduced from Burrows LA and Edwards CA (2002) The use of integrated soil microcosms to predict effects of pesticides on soil ecosystems. European Journal of Soil Biology 38: 245-249.

Figure 1 A homogenous integrated soil microcosm, designed as a model terrestrial ecosystem to assess the effects of single pesticides on soil ecosystems. Reproduced from Burrows LA and Edwards CA (2002) The use of integrated soil microcosms to predict effects of pesticides on soil ecosystems. European Journal of Soil Biology 38: 245-249.

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