Document Type



Western Australian Marine Science Institution


School of Science


Lavery P, McMahon K, Statton J, Vanderklift M, Strydom S, Kendrick G. (2019). Synthesis Report: Defining thresholds and indicators of primary producer response to dredging-related pressures. Report of Theme 5 prepared for the Dredging Science Node, Western Australian Marine Science Institution, Perth, Western Australia, 32 pp.


Seagrasses form a small component of a diverse group of organisms termed ‘benthic primary producers’. Benthic primary producers are organisms that grow on the sea-bed that obtain some or all of their energy needs from photosynthesis. This includes animals such as scleractinian corals and some sponges that host microscopic intercellular algae, coralline and turf algae, and the larger seaweeds such as the kelps and sargassum. Seagrasses are marine flowering plants, more closely related to land plants than seaweeds and algae. Seagrasses live mostly in soft sediments, and can be found from the shallow intertidal zone through to a depth of 60 m when waters are exceptionally clear allowing sufficient sunlight to reach the seafloor. Some species form persistent underwater meadows, while others form transitory meadows, and occur in low-density patches or as understorey species. Seagrasses typically require more light than algae to survive because of the respiratory demand of the underground roots and rhizomes. Seagrasses provide many important services. As primary producers, they contribute to the base of the marine foodweb and the habitats they form are important nursery areas for commercially-important prawns and provide shelter and foraging grounds for many species of fish. Seagrasses also play an important role in recycling nutrients, filtering water, sequestering carbon from the atmosphere and protecting the coastline from erosion. Because they are sensitive to change, they make useful indicators of environmental health. Furthermore, tropical seagrasses are essential food sources for dugong which is a marine mammal of particular conservation and Indigenous cultural interest...

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Creative Commons Attribution 3.0 License
This work is licensed under a Creative Commons Attribution 3.0 License.