factors affecting growth of plankton-systematic/unsystematic

• The changing of seasons (systematic variation)


  1. During spring and summer months, more sunlight reaches the earth's surface as days get longer and nights get shorter

  2. Provides energy for phytoplankton to grow and reproduce

  3. Phytoplankton populations bloom

  4. During autumn and winter months, days get shorter and nights get longer

  5. Less sunlight reaches phytoplankton, causing their populations to decline
• Diurnal (day-night) cycles (systematic variation)


  1. During the day, sun shines upon the earth, providing energy to the phytoplankton to grow

  2. At night, no energy reaches the phytoplankton, meaning they cannot grow
• systematic variations change over the course of a year in a predictable fashion
• Unsystematic variations

  • Cloud cover: clouds blocking the sun reduce the amount of energy reaching the phytoplankton
  • Ice cover: cover by ice reflects the sunlight shining on earth
  • Cover by organisms: other larger organisms may temporarily block out sunlight
  • Particulate cover: particles for example detritus / POM (particulate organic matter) or sedimentation suspended in the water, may block or reflect away sunlight away from phytoplankton
  • Domination of phytoplankton species: different phytoplankton species may dominate at different times due to them being able to exploit a niche no other species can. This niche may sit at a unique spot on the temperature, light, pH axis, giving the phytoplankton species little competition during the time when these variables are perfectly lined up
• unsystematic variations occur throughout the course of the year in a non-predictable way
• both systematic and unsystematic variations can impact the PAR (photosynthetic active radiation) range of wavelengths. These wavelengths span from 400 nm to 70 nm and may be reduced or blocked completely by any of the variations mentioned.