Austrominius modestus - New-Zealand barnacle

Originally, the New Zealand barnacle Austrominius modestus was found only in Australia and Asia. The species was introduced to Europe from Australia or New Zealand. Today, the New Zealand barnacle has a worldwide distribution in tropical and temperate seas ^{[2, 3]}.

First observation in Belgium

In Belgium, the New Zealand barnacle was observed for the first time in 1950, attached to the hull of a ship ^[4]. However, there is a very large chance that the New Zealand barnacle was already present in our area before this time and only noticed later ^[5].

Spreading in Belgium

At present, the New Zealand barnacle is the most common barnacle along the Belgian coast. The species can be found on all kinds of hard surfaces, where it competes with other species for space. This barnacle is also well represented on the buoys off the coast ^{[5, 6]}. The New Zealand barnacle can be found from the high intertidal (high on the beach) to the far sea. The depth limit is set at approximately five metres below the mean water level at low tide ^[2], although individuals are occasionally observed at greater depths.

Spreading in neighbouring countries

In 1945, the New Zealand barnacle was found for the first time in Europe, in Chichester harbour (Hampshire, England). Probably, this species was already introduced before 1945, between 1940 and 1943 ^[7]. During World War II, the species was a veritable plague on war- and merchant ships ^[2]. Reports on the distribution patterns of the New Zealand barnacle around the coasts of Britain ^[2] show that between 1940 and 1960 it spread from Southampton to the Scottish Borders and from Chichester Harbour to the Shetland Islands. This broad distribution got accomplished in only 38 years. Such dispersal rates have rarely or never been seen for native species. Today, the New Zealand barnacle is a common species along the entire coastline of the British Isles ^[8].

Apart from Great Britain, the species also occurs along the Atlantic coasts of Europe: from Germany to the Netherlands, Belgium and France to Spain (Gibraltar) and Portugal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{[2, 9]}. No permanent populations are found in the Mediterranean yet.

In the Netherlands, this barnacle was observed for the first time in 1946 at Wassenaar (province of South Holland) ^{[10, 11]}. The species had probably already settled at Hoek of Holland by 1945. In 1951, this exotic species had colonised almost the entire Dutch coastline and this has not changed since ^[12-14]. In Germany, Denmark and the Netherlands, the species is considered invasive ^[15].

Since the New Zealand barnacle attaches itself to a hard surface, it belongs to the biofouling community. This species has likely reached our regions by attaching itself to the hulls of ships. Alternatively, larvae of this barnacle got transported with the ballast water of ships ^{[2, 3, 7]}.

The New Zealand barnacle is a fast-growing species resistant to low salinity and turbid water. Adults can survive both in the open sea and near freshwater ^[5]. Furthermore, this barnacle has a wide temperature gradient: it withstands colder water temperatures better than the European barnacle species Chthamalus spp. and can thrive better in warmer water temperatures – up to more than 20 °C - than barnacles belonging to the genus Balanus.

The initial growth rate is fast. For example, the New Zealand barnacle can reach adult size (6-7 mm) after only eight weeks and reaches sexual maturity already in its first year of life. These barnacles can produce several broods per year if the temperature is high enough. In comparison, the native acorn barnacle Semibalanus balanoides spawns only once a year ^[2]. By producing several broods per year, the New Zealand barnacle can successfully colonise empty spaces in autumn, e.g. after a boat has rubbed against the quay ^[6]. The New Zealand barnacle can be found all across the tidal zone; from the sublittoral - which is permanently submerged even at low tide – to high upon the beach. All these features make the New Zealand barnacle a most efficient “invader”.

The New Zealand barnacle needs solid substrates to establish itself. Examples include coastal defence works, port infrastructure, ship hulls, mussel and oyster beds, etc.

In recent decades, transoceanic maritime traffic has increased dramatically and in combination with a reduction in navigation time, due to ships becoming faster, these factors have resulted in a much higher survival chance of the fouling organisms and those present in the ballast water ^{[2, 3]}.

Locally, this species can expand its habitat through the release of larvae, which can travel up to 70 km per year with the help of the sea currents ^[2].

Colder water temperatures prevent further expansion to more northerly coasts, such as those of Scandinavia. On the other hand, scientists have described how the New Zealand barnacle was able to expand its area northwards during the warm summer of 1959 ^[9]. During hot summers there is often a larger bloom of phytoplankton. This higher food supply allows the barnacles to take up more food and therefore grow and reproduce faster ^[2].

The New Zealand barnacle competes with native barnacle species, oysters and mussels for food and available space, and can therefore threaten local native fauna. In northern areas, it competes with the acorn barnacle Semibalanus balanoides, while in southern Europe it competes with the barnacle species Chthamalus spp. The native common rock barnacle has almost completely disappeared in some places after the appearance of its New Zealand ‘cousin’. This is a clear example of a change in the faunal community present after the introduction of an exotic species ^{[3, 4, 14]}. Further north, on the island of Cumbrae in Scotland, the New Zealand barnacle suffers from colder temperatures. Here, it is established, but it cannot compete with the native Semibalanus balanoides, so both species can remain present in the community ^[8].

In the shipping industry, the New Zealand barnacle is well known. The species is a permanent member of the biofouling community and may cause economic problems. For example, ships experience a less efficient use of fuel and the fouling also entails increased maintenance costs. Attachment of barnacles can be prevented by treatment of ship hulls with antifouling paint, which is, however, an expensive undertaking ^[16]. In addition, many of these paints damage the ecosystem. Some toxic substances from antifouling paints cause long-term environmental damage long after they have been withdrawn from circulation, such as tributyltin (TBT), the use of which has been banned since 2003 ^[17].

A special feature of this species is that the shell consists of only four calcareous plates (instead of six, like in our other barnacles) in addition to the four plates of the operculum. The New Zealand barnacle is a small, low cone-shaped barnacle, with a 0.5 to 1 cm diameter. Solitary specimens are star-shaped. Juveniles are almost translucently grey-white and have smooth sides with folds, while older animals are brown to grey coloured and have noticeably coarser and vertically ribbed sides. The opening in the middle is relatively large and diamond-shaped. The plates of the operculum have a greyish tint ^{[18, 19]}.

This barnacle can be a real nuisance to mussel and oyster farmers: they cover the oyster and mussel shells, slowing their growth. Moreover, they compete with them for space ^{[4, 20]}. This competition disappears closer to the northern distribution limit of the New Zealand barnacle, where the native bivalves occur in an equally high abundance ^[8].

The New Zealand barnacle is a suspension feeder, feeding by means of a protruding cirral apparatus ^[21], which is more or less reminiscent of a sieve with which they strike through the water. Food particles in the water column stick to the cirral fan and are thus absorbed. The flapping frequency of the New Zealand barnacle with this device is much higher (up to 18 times per 10 seconds) than in native species (5-10 times per 10 seconds) ^[2], which gives this barnacle another advantage.

The New Zealand barnacle can store metals such as copper (Cu), lead (Pb) or zinc (Zn), which are normally toxic inside of the body. By measuring the concentration of these substances in certain tissues of the body, scientists can get an idea of the state and evolution of the water quality over time, and how this has affected the present fauna ^[22].

[1]         World Register of Marine Species (WoRMS) (2020). Austrominius modestus (Darwin, 1854). [http://www.marinespecies.org/Berms/aphia.php?p=taxdetails&id=712167] (2020-11-17).

[2]         Crisp, D.J. (1958). The spread of Elminius modestus Dawin in north-east Europe. J. Mar. Biol. Ass. U.K. 37: 483-520. [http://www.vliz.be/en/imis?module=ref&refid=27239]

[3]         Eno, N.C.; Clark, R.A.; Sanderson, W.G. (Ed.) (1997). Non-native marine species in British waters: a review and directory. Joint Nature Conservation Committee: Peterborough. ISBN 1-86107-442-5. 152 pp. [http://www.vliz.be/nl/imis?module=ref&refid=24400]

[4]         Leloup, E.; Lefevere, S. (1952). Sur la présence dans les eaux de la côte belge du cirripède, Elminius modestus Darwin, 1854, du copépode parasite, Mytilicola intestinalis Steuer, 1902, et du polychète, Mercierella enigmatica Fauvel, 1922. Med. K. Belg. Inst. Nat. Wet. 28(48): 1-12. [http://www.vliz.be/en/imis?module=ref&refid=20621]

[5]         Kerckhof, F. (2002). Barnacles (Cirripedia, Balanomorpha) in Belgian waters, an overview of the species and recent evolutions, with emphasis on exotic species. Bull. Kon. Belg. Inst. Natuurwet. Biologie 72(Suppl.): 93-104. [http://www.vliz.be/en/imis?module=ref&refid=66768]

[6]         Kerckhof, F.; Cattrijsse, A. (2001). Exotic Cirripedia (Balanomorpha) from buoys off the Belgian coast. Senckenb. Marit. 31(2): 245-254. [http://www.vliz.be/en/imis?module=ref&refid=25318]

[7]         Bishop, M.W.H. (1947). Establishment of an immigrant barnacle in British coastal waters. Nature (Lond.) 159(4041): 501-502. [http://www.vliz.be/en/imis?module=ref&refid=120621]

[8]         Gallagher, M.C.; Davenport, J.; Gregory, S.; McAllen, R.; O'Riordan, R. (2015). The invasive barnacle species, Austrominius modestus: Its status and competition with indigenous barnacles on the Isle of Cumbrae, Scotland. Est., Coast. and Shelf Sci. 152: 134-141. [http://www.vliz.be/nl/catalogus?module=ref&refid=296693]

[9]         Barnes, H.B.; Barnes, M. (1968). Elminius modestus Darwin, a recent extension of the distribution and its present status on the southern part of the French Atlantic coast. Cah. Biol. Mar. 9(3): 261-268. [http://www.vliz.be/en/imis?module=ref&refid=58478]

[10]       Boschma, H. (1948). Elminius modestus in The Netherlands. Nature (Lond.) 161(4089): 403-404. [http://www.vliz.be/en/imis?module=ref&refid=119232]

[11]       Leenhouts, P. (1948). De vondsten van Elminius modestus. Het Zeepaard 8(3-4): 26-27. [www.vliz.be/en/imis?module=ref&refid=113835]

[12]       Den Hartog, K. (1953). Elminius modestus in 1952. Het Zeepaard 13(1): 12-13. [http://www.vliz.be/en/imis?module=ref&refid=114313]

[13]       Den Hartog, C. (1955). Sublitorale vondsten van Elminius modestus. Het Zeepaard 15(6): 83-84. [http://www.vliz.be/en/imis?module=ref&refid=114441]

[14]       Wolff, W.J. (2005). Non-indigenous marine and estuarine species in the Netherlands. Zool. Meded. 79(1): 3-116. [http://www.vliz.be/en/imis?module=ref&refid=101200]

[15]       ICES Advisory Committee on the Marine Environment (2006). Report of the Working Group on Introductions and Transfers of Marine Organisms (WGITMO) 16-17 March 2006 Oostende, Belgium. CM Documents - ICES. CM 2006(ACME:05). ICES: Copenhagen. 330 pp. [http://www.vliz.be/en/imis?module=ref&refid=111237]

[16]       Schultz, M.P.; Bendick, J.A.; Holm, E.R.; Hertel, W.M. (2010). Economic impact of biofouling on a naval surface ship. Biofouling 27(1): 87-98. [http://www.vliz.be/en/imis?module=ref&refid=206434]

[17]       Thomas, K.V.; Brooks, S. (2010). The environmental fate and effects of antifouling paint biocides. Biofouling 26(1): 73-88. [http://www.vliz.be/nl/catalogus?module=ref&refid=298933]

[18]       Southward, A.J. (2008). Barnacles: keys and notes for the identification of British species. Synopses of the British Fauna, N.S. 57. Field Studies Council: Shrewsbury. ISBN 978-1-85153-270-4. viii, 140 pp. [http://www.vliz.be/en/imis?module=ref&refid=119980]

[19]       Huwae, P.H.M. (1985). De Rankpotigen (Crustacea - Cirripedia) van de Nederlandse kust. Tabellenserie van de Strandwerkgemeenschap (SWG), 28. Strandwerkgemeenschap: Leiden. 44 pp. [http://www.vliz.be/en/imis?module=ref&refid=197223]

[20]       Polk, P. (1976). Nog iets over Zeepokken. De tuimelaar 3(1): 6-7. [http://www.vliz.be/en/imis?module=ref&refid=70536]

[21]       Labarbera, M. (1984). Feeding currents and particle capture mechanisms in suspension feeding animals. Am. Zool. 24: 71-84. [http://www.vliz.be/en/imis?module=ref&refid=120624]

[22]       Reis, P.A.; Salgado, M.A.; Vasconcelos, V. (2011). Barnacles as biomonitors of metal contamination in coastal waters. Est., Coast. and Shelf Sci. 93(4): 269-278. [http://www.vliz.be/nl/catalogus?module=ref&refid=296694]

VLIZ Alien Species Consortium (2020). Austrominius modestus – New Zealand barnacle. Non-native species of the Belgian part of the North Sea and adjacent estuaries anno 2020. Flemish Institute for the Sea (VLIZ). 6 pp.