Soft sediment environments include gravelly, sandy, silty and muddy areas of the seafloor and are home to a wide variety of organisms including invertebrates (e.g. worms, crabs, shellfish), bottom-dwelling fish and bacteria. The majority of salmon farms in Tasmania are located over soft sediment environments.
The release of uneaten salmon feed, salmon faeces and other nutrient-rich organic matter (e.g. biofouling debris) into the water column occurs as a result of current marine salmon farming practices in Tasmania. Some of this organic matter dissolves in the water column (dissolved waste), while some of it is released in the form of particles (particulate waste) which float in the water column, sinking to the seafloor at varying rates depending on particle size and water current speeds. The release of dissolved and particulate waste has the ability to interact with soft sediment environments in a number of ways, including through:
The impacts of these interactions tend to be greatest immediately below actively farmed salmon cages, decreasing with distance from the farm. The magnitude of interactions depends on the intensity and management practices of farming, the environmental conditions at the farm site (e.g. depth of water below cages, the energy of the environment) and the sensitivity of the soft sediment ecosystem.
How can extra organic matter and sedimentation interact with soft sediment ecosystems?
For more detailed information on the interactions between salmon farming and soft sediment environments, browse through our research outputs on our publications page.
