Some Comparative Perspectives on the Ecology and Habitats of Sarcodina
The attached sarcodines, living on terrestrial or aquatic surfaces, are especially favorable subjects for the study of ecological niches. The organisms are sufficiently restricted in their movement, and the environmental surfaces are adequately stable to permit periodic observations of the same group of organisms and their response to changes in the environment. Planktonic organisms, carried by currents, are less easily periodically examined due to their constantly changing location. Moreover, the possibility of mixing with other groups of planktonic organisms due to changes in current and turbulence effects must be taken into account when analyzing niches. The concept of niche is widely used by ecologists, but not always with the same meaning. We will use niche to mean the biological response and accommodation of an organism to the range of environmental and biotic factors that determine its distribution within an ecosystem. In broader perspective, the niche of an organism includes its biological activity (eg, diversity of prey, efficiency of food assimilation, tolerance to variations in temperature, salinity, pH, and E h ) in response to environmental constraints and potentials that determine the geographical range and success of an organism in space and time. In practical terms, one can seldom assess all potential parameters that define a species’ niche. Typically, several key factors are identified (as for example, temperature, pH, salinity, oxygen abundance, and available carbon for nourishment) and their range for a species is determined.
KeywordsPhytoplankton Lignin Silt Turbidity Gravel
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