Impacts of Intensive Food Production

• What is eutrophication?

  Nutrient enrichment of water bodies
• What causes algal blooms?

  Nutrient-enriched water conditions
• What happens during algal blooms?

  Light and oxygen are blocked from water
• What is bioaccumulation?

  Pollutants stored in organism tissues
• What is biomagnification?

  Increase of pollutant concentration up food chain
• What is a consequence of biomagnification?

  Impairment of immune and reproductive systems
• Nitrates and phosphates absorbed by plants are used for growth. The use of chemical fertilisers and phosphate-based detergents has greatly increased the levels of nitrates and phosphates entering waterbodies. These cause nutrient enrichment of the water, known as eutrophication, which enhances aquatic plant growth.
• Algae in nutrient-enriched water undergo a population explosion, which is referred to as an algal bloom. As the bloom spreads across the water surface, light and oxygen are prevented from penetrating the water, which affects aquatic life. When the algae and aquatic organisms die, they are decomposed by bacteria, increasing the BOD of the waterbody. At the same time, the decomposition process releases more nitrates and phosphates into the water, causing further eutrophication.
• Pesticides belong to a group of chemicals known as persistent organic pollutants (POP) which are compounds that are resistant to environmental degradation. Pesticides applied in fields can enter waterbodies, where they are absorbed by aquatic invertebrates through their skin, gills and lungs. The pollutant is stored in the tissues of the organism at a rate faster than it can be metabolised or excreted, a process known as bioaccumulation. This doesn't cause damage at lower levels.
• As a consumer eats more contaminated prey, the level of pollutant gradually builds up in its tissues. This predator will in turn be consumed as prey, and the concentration of the pollutant will increase as it's passed up the food chain, eventually reaching toxic levels. The dietary uptake of the pollutant and its movement through trophic levels is known as biomagnification. This causes significant harm to organisms in the higher trophic levels, such as impairment of the immune and reproductive system.