Marine pest and disease impacts

South Australia’s marine pest focus is on preventing the introduction and spread of aquatic pests. Below are some of the impacts marine pests have.

Damage to the marine environment

Marine pests compete for space and food supply, resulting in changes to the native habitat that may threaten the local food chain. For example, an exotic seaweed smothering native seagrass beds may affect the abundance of fish and other species that previously sheltered among the seagrass. Such changes may also reduce the area’s recreational and cultural value to the community.

Depletion of 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 and reduce the viability of the state’s seafood industries.

Reducing the attractiveness of coastal areas

Some pests can extensively damage the aesthetic and amenity value of shorelines and coastal areas, affecting recreation and tourism. Common examples include fouling of coastal structures, overabundance of sharp or unattractive shells and erosion resulting from crabs burrowing into shorelines.

Damaging marine and industrial infrastructure

Introduced species can settle on marine structures such as jetties, industrial water intake pipes or longlines used in aquaculture, and potentially cause damage. The costs of repairing or replacing these structures can be significant and present an ongoing maintenance expense.

Reducing vessel performance

A build-up of marine biofouling on vessel hulls affects vessel speed, which can impact fuel efficiencies. Although antifouling coating can help prevent biofouling, if the coating is not applied correctly or reapplied in a timely manner, its effectiveness can be greatly reduced. Biofouling can also clog a vessel’s internal water pipes, causing engine damage, ineffective firefighting ability and damage to other water-reliant systems. Reduced vessel performance increases operating costs, which in turn increases freight costs.

Potentially causing 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.

Potentially hosting fish and shellfish diseases

Aquatic pests can be hosts for infectious and notifiable diseases which can impact our seafood industries. An example is the viral pathogen that causes Pacific Oyster Mortality Syndrome (POMS), a virus which affects Pacific Oysters (Crassostrea gigas) and 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 that causes POMS.

Vessel owners can help prevent the spread of established marine pest species and disease by having good vessel cleaning practices in place. Get more information on the biofouling and ballast water page.

More information

Page Last Reviewed: 26 Feb 2018
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