Sandy soft sediments and seagrass

Seagrasses are grass-like plants adapted for life underwater in coastal environments. These highly productive plants provide food and shelter for many fish, birds and other animals and are a critical link in the marine food web. Seagrasses are usually found in shallow water and are very sensitive to water pollution by sediments and nutrients.

A conceptual diagram illustrating some typical plants and animals often found in Derwent estuary seagrass beds and wetlands is provided here.

There are a few small seagrass beds in the bays and coves of the middle and lower Derwent estuary, but the largest areas are found in the region between Cadburys Point and the Granton/Bridgewater area. The Habitat Atlas indicates that there are 6.6 square kilometres of brackish seagrass beds (macrophtyes) and 0.2 square kilometres of marine seagrasses remaining in the Derwent estuary. In some areas, where nutrient levels are high, seagrass beds may become overgrown by thick mats of slimy, green algae.

Did you know?

  • You can often see hundreds of black swans and native ducks feeding on seagrass on both sides of the Bridgewater Causeway, particularly during dry summer months.
  • Seagrasses can be seen from the air and monitoring seagrass in the Derwent estuary involved collecting aerial imagery. See report for more details.

Things to explore

  • Learn more about seagrass at Seagrass Watch and consider how seagrasses in Tasmania may differ from tropical areas.

Fairy or Little Penguin (Eudyptula minor)

Restoring and promoting the Derwent estuary