Impact from the ocean/land interface
South-east Regional Marine Plan
National Oceans Office, 2001
About the report
Activities at the ocean/land interface impact significantly on the marine environment. Habitats and biological communities in the South-east Marine Region are affected primarily by urban and agricultural run-off, industrial and sewage effluent discharges and coastal development. Water quality is degraded in many areas by high nutrient and sediment loads, heavy metals, chemical pollutants, faecal bacteria and organic wastes, and periodically does not comply with guidelines for protection of aquatic ecosystems. The largest impacts have been caused by elevated nutrient levels and sedimentation, and include widespread loss of seagrass beds and eutrophication of coastal waters. Parallel losses in invertebrates and fish have been linked to declines in coastal fisheries, while algal blooms include toxic species that have contaminated shellfish and pose human health threats. Saltmarsh and mangroves have also suffered incremental declines in coverage due to habitat loss and smothering, further reducing nursery areas for coastal fish.
Heavy metals and other persistent chemicals are bio-accumulated in a range of marine species, while fish kills and disease have occurred due to oxygen depletion, chemical contaminants and acidic run-off. Organic pollution has also had major impacts on benthic communities near pollution sources, leading to reduced biodiversity. Extensive habitat loss and modification has resulted from drainage and reclamation, port and marina construction, dredging, flow alterations and urban development. Impacts have included loss of seagrass and wetlands flora, local extinctions of fish populations, destruction of natural spawning and nursery grounds and loss of benthic communities.
There have been a number of improvements in approaches to water quality and habitat management at the ocean/land interface, particularly over the past ten years. However, continued losses of seagrass and poorly degraded water resources indicate that the marine environment remains highly disturbed. The impacts on various types of marine biota in the South-east Marine Region are summarised in Table 1.