Seagrasses of Shark Bay

What are seagrasses?

Seagrasses are marine plants with the same basic structure as land plants. They produce flowers; have strap-like or oval leaves and a root system. They grow in shallow coastal waters with sandy or muddy bottoms. They are not seaweeds (a type of algae) but are most closely related to lilies. They thrive in waters with low wave energy such as Shark Bay.

Link to seagrass video

Watch an underwater video of seagrass in Shark Bay here

Seagrass in Shark Bay

Seagrass is probably the most dominant organism in Shark Bay, greatly modifying the physical, chemical and biological environment. Even the local geology of the bay has been influenced by seagrass which slows water flow, traps sediment and helps build massive sand banks that alter current patterns and modify salinity in large areas of Shark Bay. Visit our geology pages to see how seagrass has helped shape Shark Bay.

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Wireweed (Amphibolis antarctica) is the most common seagrass in Shark Bay, making up about 85% of total seagrass area.

Seagrass aerial photo

When seen from the air, seagrass in Shark Bay often takes on a banded appearance. Seagrass grows in bands that form perpendicular to the water flow.

Map of seagrass distribution in Shark Bay

Seagrass also has an important role in the local ecology. Around 4000 square kilometres of sea floor are colonised by seagrass, making these the biggest seagrass banks in the world. Shark Bay’s large dugong population rely on these seagrass banks for food, moving between different meadows during the year to feed.

The stromatolites of Hamelin Pool probably owe their existence to seagrass. The large banks of sand built up by the seagrass meadow have restricted water flow into Hamelin Pool, causing the salinity level to rise and create an environment perfect for stromatolites. Read more about this World Heritage phenomenon here.

For more information on the biology of seagrasses check out our seagrass fact sheet.

What seagrasses live in Shark Bay?

Link to seagrasses ID page