Population control

Factors influencing population control

• Food – both the quantity and the quality of food are important. The population growth and decline of species depends on the amount of their food availability. The more available food, the more the population grows to meet it. The less food, the less fertile a species of reproductive age becomes. Snails, for example, cannot reproduce successfully in an environment low in calcium, no matter how much food there is because they need this mineral for shell growth.
• Predators – as a prey population becomes larger, it becomes easier for predators to find prey. If the number of predators suddenly falls, the prey species might increase in number extremely quickly.
• Competitors – other organisms may require the same resources from the environment, and so reduce the growth of a population. For instance, all plants compete for light. Competition for territory and for mates can drastically reduce the growth of individual organisms.
• Parasites – These may cause disease, and slow down the growth and reproductive rate of organisms within a population.

• Temperature – Higher temperatures speed up enzyme-catalyzed reactions and increase growth.
• Oxygen availability – affects the rate of energy production by respiration.
• Light availability – for photosynthesis. light may also control breeding cycles in animals and plants.
• Toxins and pollutants – tissue growth can be reduced by the presence of, for example, sulphur dioxide, and reproductive success may be affected by pollutants such as estrogen like substances.

  Methods for active population control

Examples