Haematococcus pluvialis is a freshwater species of green algae, or Chlorophyte.
This species can produce high concentrations of the antioxidant astaxanthin, which is important in aquaculture, and cosmetics. The high amount of astaxanthin is present in the resting cells, which are produced and rapidly accumulated when the environmental conditions become unfavorable for normal cell growth.
The astaxanthin can be elicited under conditions of: bright light, high salinity, and low availability of nutrients.
Haematococcus pluvialis is usually found in temperate regions globally. Astaxanthin is believed to protect the cysts from UV-radiation.