IB Environmental systems and societies Topic 4: Water Key Definitions

Adhesion is the attraction between unlike substances, often involving polar or charged surfaces.

Advection is the wind-blown transport of water vapour or condensed/frozen droplets from one region to another, helping connect local hydrological cycles globally.

Anoxia is the complete absence of dissolved oxygen.

Aquaculture is the controlled farming of aquatic organisms like salmon, tilapia, catfish, oysters and mussels.

Biochemical Oxygen Demand (BOD) is a key water quality parameter that measures the amount of dissolved oxygen required by microorganisms to break down organic material in water.

Biodiversity refers to the variety of life in an ecosystem, encompassing different levels of biological organization.

Biomagnification refers to the process by which the concentration of non-biodegradable pollutants increases as you move up trophic levels in a food chain or food web.

A biotic index is a quantitative score representing the health of an aquatic system, derived from the composition and abundance of pollution-sensitive and pollution-tolerant organisms.

Bottom trawling is an industrial fishing method that drags heavy nets along the seabed, capturing bottom-dwelling species but causing severe damage to habitats and high bycatch rates.

Carbon sequestration is the process of capturing atmospheric carbon dioxide (CO₂) and storing it in solid or liquid form.

A carbon sink is any natural or artificial system that absorbs more carbon than it releases, thus removing CO₂ from the atmosphere.

Carrying capacity is the maximum number of individuals of a species that an environment can sustainably support over time.

Citizen science is the involvement of the general public in scientific research, particularly in collecting, analyzing, and reporting data on environmental systems.

The force of attraction between molecules of the same substance (in this case, water).

Coral bleaching is when corals expel the symbiotic algae living within their tissues due to stress from heat, pollution, or acidification, causing them to turn white.

An area in a water body where oxygen levels are too low to sustain most marine life

Desalination is the process of removing salt and other impurities from seawater to produce freshwater.

Endocrine disruptor is a chemical that interferes with the hormonal system, causing developmental, reproductive, or immune problems.

Eutrophication is a process where excess nutrients, primarily nitrates and phosphates, enter aquatic ecosystems, triggering a cascade of ecological changes.

Evaporation is the transformation of liquid water into vapour due to solar heating.

An oceanic area extending 200 nautical miles from a country’s coastline where that nation has exclusive rights over marine resource use.

A fish stock refers to a population of a particular species of fish that is managed as a unit. It may include all individuals in a defined geographical area.

A flow is the movement of water between stores either as a transfer or a transformation.

Ghost fishing is the unintended capture and death of marine organisms caused by lost or abandoned fishing gear that continues to function passively in the environment.