APES Topic 1.8: Primary Productivity

Photosynthesis

The process by which plants use light energy to convert water and carbon dioxide into oxygen and carbohydrates.

Primary Productivity

The rate at which solar energy is converted into organic compounds via photosynthesis over a unit of time.

Net Primary Productivity (NPP)

The rate of energy storage by photosynthesizes in a given area, after subtracting the energy lost to respiration.

Gross Primary Productivity (GPP)

The total rate of photosynthesis in a given area.

Aphotic Zone

The water column depth at which there is no light available for photosynthesis (>200 m).

Euphotic Zone

The water column depth to where both red and blue light penetrate and photosynthesis occurs (0-100 m).

Dysphotic Zone

The water column depth where sunlight decreases rapidly and cannot support photosynthesis (100-200 m).