Marine Pests

Kangaroo Island is one of Australia’s premier wildlife destinations, and most people understand the importance of keeping Kangaroo Island (KI) free of rabbits and foxes, and of keeping our precious honey and potato industries free of diseases. However, threats to KI’s industries and environment are not solely land-based. Marine pests also pose a significant threat to marine biodiversity as well as our commercial fishing and aquaculture industries. 

A marine pest is a marine organism that is introduced to an area outside of its natural range, generally by human activity. Marine pests are of great concern as they can have detrimental impacts on our coastal habitats, by predating on or out-competing native species for food or space, and altering community structures and food webs. In addition to impacts on biodiversity, marine pests can significantly reduce the economic value of our coastal environment, by altering the recreational appeal of coastal ecosystems or productivity of aquaculture industries, which has potentially damaging economic and social implications.

Recently, isolated populations of marine pests have been turning up at several popular anchorages on KI. Luckily, these populations have been detected early enough for them to be eradicated. Currently there are two main marine pest species that pose a threat to KI’s marine environment and industries, the European Fan Worm (Sabella spallanzanii) and European Sea Squirt (Ciona intestinalis). Both of these species have widely infested Adelaide metropolitan waters, as well as many other marinas and anchorages throughout Gulf St Vincent. 

History of marine pests on Kangaroo Island  

Marine pests were first discovered on KI in 2008, when a single European fan worm (Sabella spallanzanii) was removed from Kingscote Jetty. Surveys undertaken in 2008/09 detected more European fan worm, as well as European sea squirt (Ciona intestinalis) at Kingscote Wharf, the Bay of Shoals anchorage and American River anchorage. See report here. These discoveries have been directly linked to vessel traffic from infected mainland ports. In particular, vessels such as yachts and motor cruisers have been identified as the main method of dispersal of these pests, as they are carried as hull fouling from one port to another. 

In 2017, project staff analysed vessel voyages using Volunteer Marine Radio records to identify high-risk marine pest dispersal nodes and entry points. Adelaide metropolitan marinas, and to a lesser extent, Marina St Vincent (Wirrina), were the most common origins of vessels travelling to KI, and also represent high-risk dispersal nodes for marine pests, as these marinas are known to be heavily infested with several marine pest species. Emu Bay, American River and Kingscote were the most visited destinations on the island, and therefore also the highest-risk entry points for marine pests. The results of this risk assessment have been used to prioritise marine pest survey locations. 

Monitoring program 

To protect the Kangaroo Island marine environment and associated marine industries, the Coast and Marine Program undertakes regular surveillance activities across the island to detect early infestations of marine pests. Surveys largely focus on identified high-risk entry points for marine pests, and consist of underwater visual searches conducted either by SCUBA divers or snorkelers. Searches cover all suitable habitats that marine pests can colonise including jetty pylons, floating pontoons, vessel hulls, wharf and aquaculture infrastructure and natural substrates. Any marine pests that are detected, are recorded, removed and destroyed.

By focusing on marine biosecurity and detecting and eradicating marine pest infestations before they can become a serious problem, the Coast and Marine Program is helping to safeguard KI's rich marine biodiversity and important marine industries for future generations. 

Education and awareness 

Natural Resources KI has also initiated an education program to improve community awareness. This includes:

  • installing signs at boating facilities at Kangaroo Island, and mainland ports
  • distributing fact sheets, brochures and stickers
  • providing training in marine pest identification to local industry and community groups such as Friends of the Sea and local aquaculture businesses
  • engaging with vessel owners to educate them about the problems associated with marine pests and how to identify them. 

What marine pest species to look out for 

Aquarium Caulerpa

Common name: Aquarium Caulerpa
Scientific name: Caulerpa taxifolia
Transferred by: Regenerating from fragments left on fishing or boat gear
Impacts: Smothers native algae and seagrass. Can establish vast beds degrading fish habitat and reducing species diversity.


Asian Date Mussel, Asian Bag Mussel

Common name: Asian Date Mussel, Asian Bag Mussel
Scientific name: Musculista senhousia
Transferred by: Ballast water and biofouling
Impacts: Can outcompete filter-feeding aquaculture species for food, forms dense mats which smother seagrass and can significantly alter habitat.


European Fan Worm

Common name: European Fan Worm
Scientific name: Sabella spallanzanii
Transferred by: Biofouling and ballast water Impacts: vigorous coloniser causing nuisance fouling on aquaculture, infrastructure and vessels, competes with aquaculture species for food, forms vast, dense colonies which outcompete native species and is known to alter food webs.
Impacts:


European Sea Squirt

Common name: European Sea Squirt
Scientific name: Ciona intestinalis
Transferred by: Biofouling
Impacts: Nuisance fouling of aquaculture infrastructure, can out-compete native species


European Shore Crab

Common name: European Shore Crab
Scientific name: Carcinus maenas
Transferred by: Ballast water and biofouling
Impacts: Outcompetes native crabs for food and habitat. Has been implicated in the decline of native shellfish populations.


Northern Pacific Seastar

Common name: Northern Pacific Seastar
Scientific name: Asterias amurensis
Transferred by: Ballast water and biofouling
Impacts: Responsible for killing large numbers of many native species. Can have major impacts on aquaculture, particularly oyster and mussel farms.

 

How can you help? 

Recreational vessels such as yachts and motor cruisers, have been identified as the main method of introducing marine pests to KI, as they are carried as hull fouling from one port to another. Surveys of vessels visiting KI during 2014, revealed that approximately 30 per cent of vessels had unintentionally transported marine pests from Adelaide metropolitan marinas to KI. Surveys of vessels moored at several Adelaide metropolitan marinas during 2016 also revealed that on average 45 per cent of vessels had marine pests fouling their hulls to various degrees. 

NRKI want to ensure that KI’s waters are kept in a pristine condition, and free of marine pests. Every vessel owner can help to achieve this goal by taking some simple actions: 

  1. check and clean your vessel hull and equipment carefully before departing for Kangaroo Island. This includes flushing internal seawater systems in clean, open water to expel any stowaways,
  2. apply and maintain antifouling paint regularly. Preventing biofouling from building up on your hull will also maintain the performance of your vessel. 

Help NRKI protect and secure KI’s pristine marine environment and fabulous fishing for everyone to enjoy. If you see a suspicious sea creature while on KI, please contact the Fishwatch hotline on 1800 065 522. If you think you may have accidentally brought a marine pest with you, or would like more information on marine pests in general, please contact Natural Resources KI on (08) 8553 4444.


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