Ecology
D
Density Dependence
Quick Definition
Population regulation in which vital rates (birth, death, growth) change in response to population density, providing a self-correcting mechanism for population size.
📖 Full Definition
Density-dependent regulation occurs when population vital rates (survival, growth, reproduction) are influenced by population size itself. At high densities, competition for food and space intensifies, mortality increases, and growth slows — reducing population growth rate. At low densities, resource availability is high, survival and growth improve, and the population rebounds. This negative feedback stabilises population size around the carrying capacity (K). In fish, density-dependent effects are strongest in early life stages (larval and juvenile competition for food and settlement sites). Compensation for fishing mortality through density-dependent mechanisms is the theoretical basis of sustainable harvesting.
🧪 Scientific Usage
The Beverton-Holt stock-recruitment model assumes a hyperbolic, purely density-dependent relationship between spawning stock biomass and recruitment.