Aquatic ecology and Biodiversity

Unit 3- Population ecology

3.4. Population density
The number of individuals of a species present in a defined area is a measure of population density. Population size increases and decreases over time. There are factors such as resource availability, competition, parasitism, predation, climate, etc. that usually operate in an ecosystem to keep populations within certain boundaries. It refers to “The total number of individuals in a unit area or unit volume at a given time”. Eg: No. of bacteria/ litre; No. of plants / acre; No. of benthos / m². The density of population is expressed as, D = N/A/t. Where,D = Population density, N = Number of individuals, T = Time, A = Area