Phytoplankton bloom in Shark Bay, Western Australia

Swirls of green and blue color the water of Shark Bay, Australia, in this Moderate Resolution Imaging Spectroradiometer (MODIS) image, taken on October 10, 2005, by NASA’s Terra satellite. The clouds of blue on the north side of the bay are probably phytoplankton, microscopic plants that float on the surface of the water. When phytoplankton multiply rapidly, spreading across a wide area in a dense bloom, they are visible from space because of the color they give the ocean. There are several species of phytoplankton: some color the ocean bright blue by reflecting light off of the white calcium carbonate (chalk) scales that cover them and others produce more of a green color because of chlorophyll. It is possible that many types of phytoplankton were growing in Shark Bay in October 2005.

Phytoplankton are at the base of the marine food chain, so the sites of frequent blooms generally teem with marine life. Shark Bay is no exception: the area supports a wide range of species, many of which are unique to the region. Because of the diversity and uniqueness of the ecosystem at Shark Bay, the bay is a World Heritage Site.

Another example of the diversity of life supported by the sheltered waters of Shark Bay can be seen in the south part of the bay. Within the “”-shaped curve of the land, the water is deep green. The water here is clear and relatively shallow, allowing seagrass to grow on the ocean floor. Of the 13,000 square kilometers that Shark Bay covers, 4,000 square kilometers are blanketed with a meadow of seagrass. It is the world’s largest seagrass meadow. It is probably the seagrass and the limestone reefs near the shore that give the ocean its green color here.

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Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC

Published October 10, 2005
Data acquired October 10, 2005

Source:

Terra > MODIS