Effects of predation and disturbance on the population growth and dynamics of the polychaete Capitella capitata (Type I)

Abstract

Populations of the polychaete Capitella capitata (Type I) were cultured in the laboratory under constant conditions and subjected to two intensities of density-independent exploitation (12 and 23% of the population removed per week) over an 81- to 85-week period (September 1981 to May 1983). Density-independent exploitation reduced the amplitude of the oscillations but did not stabilize the populations. An additional pair of populations were cultured in a similar manner except that they were subjected to a daily physical disturbance of their sediment habitat. In these trays C. capitata established moderately stable low level populations in spite of the continuous disturbance of their habitat. The data suggest that C. capitata are unlikely to maintain an equilibrium population, except for short periods of time or when subjected to intense density-dependent effects. Exploitation by a predator may not stabilize its prey population unless the prey can respond in a density-dependent fashion to prey population growth.