|
Seagrass provides a critical part of the coastal and marine landscape. It is a vital part of the ecosystem and plays an important role in maintaining the ecological processes and protecting the range of beneficial uses that can be supported in areas such as Cockburn Sound. Seagrass communities maintain water clarity through stabilising coastal zones and mud banks and preventing erosion, and assist in the recycling of nutrients.
Seagrasses are not algae, like kelp, but are true flowering plants that live underwater. They get their energy from sunlight through photosynthesis like most algae and terrestrial plants. Seagrass meadows provide food, shelter, and breeding and nursery grounds for many species of fish.
In estuaries and coastal areas, seagrasses are important habitat for marine invertebrates, such as Blue Manna crabs, worms, molluscs and small crustaceans, which play an important role in food chains. Seagrasses also shelter the larval stages of many fish and other sea creatures. Among the fish that live in seagrasses are leatherjackets, mullet and whiting, as well as juvenile Tailor, Bream and flathead, and seadragons.
Many seabirds, such as terns, Fairy Penguins and cormorants, and sea mammals, like sea lions and dolphins, feed on fish, therefore seagrasses may be important for the long term survival of these animals.
Without seagrasses many populations of fish and crustaceans would probably collapse. The loss of seagrasses in coastal sites may have far reaching effects because juvenile fish, crabs and prawns need them as nursery grounds and for protection.
Seagrasses are important not only for their role in maintaining biodiversity in the marine environment, but also for their value in supporting human activities such as commercial and recreational fishing.
Seagrass populations near Rous Head have declined over the past century. The causes for the seagrass loss in the Rous Head area are likely to be attributed to a number of factors including increased sedimentation and nutrients from catchment activities, the dredging of shipping channels and dredging in the Fremantle inner harbour.
The loss of seagrass cover is likely to have resulted in long-term changes to the physical and biological characteristics of marine environments. Where seagrass is lost, sediment is frequently suspended, creating poor water quality which in turn inhibits seagrass re-establishment and the return of seagrass-reliant communities.
While there has been some very limited recovery of seagrass, the conditions outlined above make it particularly difficult for seagrass to regenerate. At NPQ it is proposed to generate new seagrass cover both outside the seawall and in the internal waters using the latest regeneration techniques.
† BACK TO QUESTIONS
|
