Marine pests can have a significant impact on our natural coastal environment, and we can all take steps to help prevent them establishing in Hawke’s Bay waters.
Marine pests compete with and prey on native species, modify natural habitats, affect marine industries, and alter ecosystem processes. Once here, they are difficult and expensive to get rid of.
Boat hulls are considered the main way marine pests are spread. A restricted number of harbours and vessels entering Hawke’s Bay presents an opportunity to manage the main domestic vector pathway of marine pests entering Hawke’s Bay waters.
Two marine pests - Mediterranean fanworm (Sabella spallanzanii) and Clubbed tunicate (Styela clava) - are classified as exclusion pests in the Regional Pest Management Plan. Neither of these pests are known to be established in Hawke’s Bay but are established in some other areas of New Zealand. We want to keep our marine environment free of these invasive pests.
The adult Mediterranean fanworm is a tube-dwelling worm. There are many native fanworms that look similar, however, the Mediterranean fanworm is the largest fanworm in New Zealand, with its body measuring up to 20mm wide and from 100 – 800mm long.
It has a prominent single, spiral crown (fan) of feeding tentacles that extend out of the tube and can be 150mm wide. The crown is often banded orange, purple or white. Mediterranean fanworm’s outer tube is leathery, flexible and muddy looking in appearance.
Mediterranean fanworm can live in most artificial and natural habitats in the marine environment but it will not tolerate freshwater. It prefers sheltered, nutrient-enriched waters and is generally found in shallow, subtidal habitats to a depth of 30m. It attaches to a range of solid surfaces including artificial materials (wharf pilings, pontoons, etc.) as well as rocks, wood and benthic organisms (ascidians, mussels, oysters). It is also a common fouling species on moored vessels. Mediterranean fanworm can also be found on soft substrates, generally attached to a small buried fragment of shell or rock.
Mediterranean fanworm can form dense colonies of up to 1000 individuals per square metre that will compete with native species for food and space. As a result, existing species can be squeezed out and new generations prevented from re-establishing. Therefore, Mediterranean fanworm could have a significant impact on our commercial and recreational fisheries, and marine environments such as Pania Reef.
The ability of this species to attach to a wide range of surfaces in varying environmental conditions, its fast rate of growth, and its prolific breeding habits, make it particularly competitive. It has no known predators in New Zealand.
Mediterranean fanworm is spread to new locations primarily through vessel biofouling, although the movement of aquaculture equipment or other marine structures may also contribute to its spread.
photo credit: NRC
The Clubbed tunicate has a long, club-shaped body tapering to a short, tough stalk.
The surface is rumpled and knobbly, and the leathery skin ranges in colour from brownish to white. The Clubbed tunicate can grow up to 160mm in length. By comparison the native species is white to purple with a much longer stalk (two-thirds to three-quarters the overall length of the animal).
The Clubbed tunicate has been found in the low intertidal zone to water up to 40m deep, however, it is most commonly found in water less than 25m deep.
Clubbed tunicate grows on natural and artificial hard marine surfaces, including on rocks, shellfish or shell fragments, wharves, vessel hulls and aquaculture structures.
The Clubbed tunicate is a highly efficient filter feeder which is able colonise a range of hard surfaces and tolerate wide ranges of salinity and temperature. These features enable the clubbed tunicate to form monospecific stands at high densities (up to 500-1000 individuals per square metre) which can outcompete native species. Therefore, Clubbed tunicate could have a significant impact on our commercial and recreational fisheries, and marine environments such as Pania Reef.
Clubbed tunicate is spread to new locations primarily through vessel biofouling, although the movement of aquaculture equipment or other marine structures may also contribute to its spread.
In 2015, 351 non-indigenous species were identified in New Zealand’s coastal waters and 187 had established a breeding population. The table below shows some of the marine pests established in New Zealand and the impacts they can have - some of these could have impacts in Hawke’s Bay coastal waters.
Many other marine pests have already established in New Zealand, and others threaten to invade.
To find out about other marine pests check out the Ministry for Primary Industries' marine pest identification guide.
Impact and History
Asian date (bag) mussel
Small, thin-shelled mussel that lives in estuaries
Asian paddle crab
Large, aggressive swimming crab
Australian droplet tunicate
Sea squirt that forms long, white cylindrical tubes
Greentail (greasyback) prawn
Prawn that grows to about 13cm in length
Very large, fast-growing worm that builds long, flexible tubes up to 1m in length.
Rapid growing sea squirt that forms dense colonies
Small bivalve (shellfish with two hinged shells)
Fast-growing brown kelp
Pyura sea squirt
Sea squirt that inhabits the mid intertidal zone to the shallow intertidal zone
Grows on hard surfaces from the intertidal zone down to 65m
You can help prevent the spread of marine pests by:
Keeping a vigilant eye out for Mediterranean fanworm and clubbed tunicate in Hawke’s Bay waters and reporting them immediately
Ensuring your vessel's hull is clean and free of fouling before you travel to a new area
Regularly cleaning your vessel’s hull – keeping fouling growth to no more than a slime layer and/or goose barnacles
Applying a thorough coating of antifouling paint and keep it in good condition
Cleaning and drying any marine equipment (e.g. ropes, lines and pots) before using in a new area
Inspecting areas on your boat that retain water for signs of marine life
Checking for aquatic weeds tangled around anchors, trailers and other equipment
Keeping your haul out/antifoul receipts onboard to provide as evidence of recent treatment or lift and wash
Make use of haul out facilities in the upper North Island
Under the Biosecurity Act 1993, operators of a vessel must abide by this rule:
The operator of a vessel entering the waters of the Hawke’s Bay Regional Council must ensure the hull (includes hull area, niche areas and wind and water line) or any structure or navigation aid of any origin, is sufficiently cleaned and antifouled so that there is no more than a slime layer and/or goose barnacles.
International commercial shipping is governed by international rules about ballast and hull cleaning.
International vessels that stay in New Zealand waters for up to 20 days and are only visiting approved Places of First Arrival, remain under and must abide by the rules of the Craft Risk Management Standard (CRMS): Biofouling.
International vessels staying for 21 days or more, or visiting non-approved Places of First Arrival, must abide by the Coastal Plan rules of the relevant regional council/unitary authority, following the completion of MPI biosecurity inspections in accordance with CRMS.
International vessels arriving in New Zealand waters have additional obligations under the Craft Risk Management Standard: Biofouling on Vessels Arriving to New Zealand (May 2014).
Hawke’s Bay Regional Council is part of the North Marine Biosecurity Partnership with 6 other regional and unitary councils, sharing knowledge and expertise.
In early 2019 Hawke’s Bay Regional Council commissioned a survey by divers of the underwater structures in Napier’s Inner Harbour to look for Mediterranean fanworm and Clubbed tunicate. This recent survey showed that the harbour is clear of these pests, and the survey will be carried out in another 2 years. The previous diver survey in 2016 also showed these pests were not present.
Also early in 2019 regional council biosecurity staff held a well-attended workshop to discuss marine pest issues with local boating and harbour interests.
In November 2017 Hawke’s Bay Regional Council staff worked with the Mana Ahuriri Trust to remove 219 tonnes of invasive marine tubeworm (Ficopomatus enigmaticus) from Ahuriri estuary. Read more about that project.
Staff have an important advisory role for landowners and work to raise awareness.
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