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THE ROLE OF INDIVIDUAL VARIABILITY IN POPULATION DYNAMICS UNDER CHANGING ENVIRONMENTAL CONDITIONS
Citation:
Richmond, C. E. AND K. A. Rose. THE ROLE OF INDIVIDUAL VARIABILITY IN POPULATION DYNAMICS UNDER CHANGING ENVIRONMENTAL CONDITIONS. Presented at Ecological Society Of America Meeting, Spokane, WA, August 12, 1999.
Description:
Environmental variability can influence species distributions through changes in
survival, fecundity, behavior, and metabolic activities. As worldwide coastal populations rise, the associated deforestation and development can increase both quantities and variability in runoff, sediment loads, terrestrial nutrients and pollutants which are transported into estuaries, adding to the environmental variability faced by organisms in this dynamic habitat. Individual variability in to)erance can determine a species' ability to persist despite these unstable environmental conditions. We constructed an individual-based model (IBM) to study how nutrient inputs influence two ubiquitous estuarine copepods, Acarlia hudsonica and Acarlia tonsa. The IBM format incorporates information on resources, abiotic and biotic conditions, and individual variability into predictions of population response to environmental change. The model describes individual copepod growth and molting through the naupliar, copepodite, and adult life stages, as influenced by the availability of their primary food source, phytoplankton. Phytoplankton abundances are modeled as a function of abiotic conditions including nutrient inputs, water temperature, day length and solar irradiance. Phytoplankton abundances and copepod growth rates, molting rates, and fecundities are influenced by the quantity, variability, and timing of nutrient inputs. The model quantitatively and qualitatively explores to what extent individual variability enables species persistence in an unpredictable or deteriorating environment.