Marine pest and disease impacts

South Australia prevents the introduction and spread of aquatic pests through marine management.

Marine pests can have the following impacts on our state.

Damage to the marine environment

Marine pests compete for space and food supply. This results in changes to the native habitat that may threaten the local food chain.

For example, an exotic seaweed smothering native seagrass beds can affect the abundance of fish and other species that sheltered among the seagrass. Such changes may also reduce the area’s recreational and cultural value to the community.

Depleted fishing grounds and aquaculture stock

Some marine pests are voracious predators, capable of depleting aquaculture stock or fishing grounds.

Reduced seafood availability may:

  • increase the cost of seafood to consumers
  • impact the viability of the state’s seafood industries.

Unattractive coastal areas

Some pests can damage the aesthetic value of shorelines and coastal areas, affecting recreation and tourism.

Common examples include:

  • fouling of coastal structures
  • overabundance of sharp or unattractive shells
  • erosion resulting from crabs burrowing into shorelines.

Damage to marine and industrial infrastructure

Introduced species can settle on marine structures, potentially causing damage. High risk structures include:

  • jetties
  • industrial water intake pipes
  • longlines used in aquaculture.

The costs of repairing or replacing these can be significant and present an ongoing maintenance expense.

Reduced vessel performance

A build-up of marine biofouling on vessel hulls affects vessel speed, which can impact fuel efficiencies. Although antifouling coating helps prevent biofouling, if the coating is not applied correctly or reapplied in a timely manner, it is less effective.

Biofouling can also clog a vessel’s internal water pipes, causing:

  • engine damage
  • ineffective firefighting ability
  • damage to other water-reliant systems.

Reduced vessel performance increases operating costs, which in turn increases freight costs.

Potential human illness

Some marine pests can accumulate or carry harmful organisms, including toxic algae, bacteria and flukes. Consumption of affected shellfish or crustaceans can lead to serious illness.

Apart from human health consequences, a loss of public confidence in local supply can significantly impact Australia’s seafood industries.

Spread of fish and shellfish diseases

Aquatic pests can be hosts for infectious and notifiable diseases which impact our seafood industries.

An example is the viral pathogen that causes Pacific Oyster Mortality Syndrome (POMS), a virus affecting Pacific oysters (Crassostrea gigas). It can cause rapid and high mortalities in farmed oysters (up to 100% within days of being detected).

To safeguard South Australia’s $32 million oyster growing industry, general restrictions are in place on importing oysters into South Australia to prevent disease introduction.

However, the risk of POMS can also be spread via oysters that attach themselves to vessels (biofouling) and carry the virus. Vessel owners can help prevent the spread of established marine pest species and disease through vessel cleaning and biosecurity practices:

More information

Page last reviewed: 28 Nov 2022

 


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