Telmatogeton japonicus - Marine splash midge

T. japonicus is native to Japan and Hawaii. Other parts of the Pacific Ocean – such as Australia – may also belong to its natural range ^[2-4].

First observation in Belgium

In Belgium, the presence of T. japonicus was reported for the first time in 2004. At the time, this non-native species was already very common on buoys off our coast ^[5].

Spreading in Belgium

The marine splash midge is present in high densities on buoys, both near the coast and at sea ^[5]. Shortly after the building of wind turbines in the Belgian part of the North Sea, these constructions were colonized by T. japonicus  ^[6]. Nowadays, this species is abundant in the splash zone around wind turbines ^[7]. Furthermore, the marine splash midge can be found on ship hulls. Exceptionally, it occurs on hard substrates in Belgian harbours (e.g. Port of Antwerp) and on beach groynes or dikes ^[8].

Spreading in neighbouring countries

In 1963, the marine splash midge was observed for the first time in Europe, near Kiel in northern Germany. The specimen was considered a new species to science and given the name T. remanei ^[9]. The same mistake occurred in 1977 in Gdańsk Bay (Poland). This time the species was named T. gedanensis ^[10].

In 1999, traces of the marine splash midge (mainly pupae moults, but also adult remains) were retrieved from the water along the rocky west coast of Ireland ^[11]. Later, in 2003, the species was observed at the Danish offshore wind farm ‘Horns Rev’, where it has been prominently present since 2004. At some locations, more than 4,000 individuals can be observed per m² ^[12]. The populations of this species are following the advance of the European wind farms. As a result, the species was found in 2018 along the British, Irish, Belgian, Dutch, German, Polish, Swedish, Finnish, Norwegian and Icelandic coasts ^{[4, 12, 13]}.

Given the location of the first observation in Europe (Kiel Canal), the suspicion arose that shipping must be responsible for the introduction of the marine splash midge to Europe. Because the larvae can attach themselves to ship hulls with their tubes, they can spread easily. On a more local scale (secondary dispersal), the mobility of adult individuals and the sea currents (transport of eggs) play an important role  ^{[2, 6, 8, 14]}.

When new artificial habitats – such as wind turbines or buoys – are placed at sea, indigenous species are not necessarily present to efficiently colonize these new substrates. In these habitats, it is more likely that an invasive species will turn out to be more competitive than the native species ^[15].

In their new habitat, the larvae of the marine splash midge dominate the upper part of the intertidal area and the supralittoral (splash) zone ^{[4, 15]}. In Belgian waters, green algae grow in these zones ^[15], which appear to be a good food source for these larvae ^{[16, 17]}. Since the number of artificial habitats in the future will most likely increase, these can serve as ‘stepping stones’ for T. japonicus. These ‘stepping stones’ make it easier for non-native animals, including the marine splash midge, to expand their habitat ^[7].

Additionally, T. japonicus is well-adapted to widely varying conditions and intense eutrophication (an excess of nutrients in the seawater). This latter trait would have facilitated the colonization of the eutrophic Baltic Sea ^[4]

The marine splash midge requires a hard substrate in the supralittoral zone to attach its eggs. These include ship hulls, buoys, pylons of offshore platforms and wind farms, rocky coasts and dikes ^{[2, 18]}. Therefore, artificial constructions contribute significantly to the spreading of this species ^{[2, 4]}. In the Netherlands, the construction of beach groynes promotes the spreading of the marine splash midge ^[18].

The species is mainly found in the marine environment, although it also occurs in the brackish water environment of the Gulf of Finland with salinity below 4 PSU ^[13]. For comparison: the seawater of the North Sea has a salinity of approximately 35 PSU. It seems unlikely that the species will also colonize freshwater habitats ^[19]

In the Netherlands, this non-indigenous midge is an important food source for sandpipers and turnstones ^[18]. Especially during the winter, when other food is scarce, the contribution of this non-native species to their diet is important. Migratory birds have also been observed foraging for the marine splash midge ^[4].

Although T. japonicus occurs in large numbers in its specific habitat (vertical walls in the supralittoral zone), the species poses little danger to other indigenous species, since they do not inhabit this type of habitat. As a result, the marine splash midge will not compete with indigenous species and, hence, not outcompete them ^[20].

Along with many other attaching organisms, the marine splash midge is part of the so-called biofouling community ^[6]. Fouling can affect various substrates and even cause economic damage. The prevention of fouling on ship hulls by treatment with antifouling paints is very expensive ^[21]. In addition, many of these paints damage the ecosystem long after their use has been stopped. An example is tributyltin (TBT), which is banned since 2003 ^[22].

The marine splash midge belongs to the marine chironomids (nonbiting midges). The larvae (Figure 1) live in tubes attached to solid substrates in the upper intertidal and supralittoral zone. They feed on, among other things, green and blue algae (cyanobacteria) ^{[4, 17]}. The larvae grow to 10 mm in size. Later, a pupa of max. 6.5 mm is formed. After 2-3 days, the adult midge emerges ^{[10, 17]} and lives for only four days ^[13].

Adults can fly, but like other related chironomids, it is better adapted to walking. This species folds its wings towards each other at rest, allowing the legs to move freely ^[23]. Adults mainly occur on hard substrates along the supralittoral zone, where the waves’ splashing water does not seem to harm them, not even during mating ^[14]. The species does not bite – unlike mosquitoes (Culicidae) – since it does not require blood to be able to reproduce.

The pupal exuviae (moults) of the marine splash midge – left behind after the adults emerge from their pupae – can be distinguished from other species by being translucent and having only eight (instead of nine) posterior segments ^[13].

Figure 1: (Left) Tubes with larvae of Telmatogeton japonicus in the splash zone on a buoy off the Belgian coast (© Bob Rumes); (Middle) T. japonicus larva (© Francis Kerckhof); (Right) Characteristic larval mouthparts (mentum and mandibles) of T. japonicus (© Bob Rumes).

[1]          World Register of Marine Species (WoRMS) (2020). Telmatogeton japonicus Tokunaga, 1933. [http://www.marinespecies.org/aphia.php?p=taxdetails&id=118154] (2020-11-17).

[2]          Kerckhof, F.; Haelters, J.; Gollasch, S. (2007). Alien species in the marine and brackish ecosystem: the situation in Belgian waters. Aquat. Invasions 2(3): 243-257. [http://www.vliz.be/en/imis?module=ref&refid=114365]

[3]          Newman, L.J. (1988). Evolutionary relationships of the Hawaiian and North American Telmatogeton (Insecta; Diptera: Chironomidae). Pac. Sci. 42(1-2): 56-64. [http://www.vliz.be/en/imis?module=ref&refid=206246]

[4]          Brodin, Y.; Andersson, M.H. (2009). The marine splash midge Telmatogon japonicus, Diptera; Chironomidae) - extreme and alien? Biological Invasions 11(6): 1311-1317. [http://www.vliz.be/en/imis?module=ref&refid=141707]

[5]          Kerckhof, F. (2005). National Report Belgium, 2004, in: ICES Advisory Committee on the Marine Environment. Report of the Working Group on Introductions and Transfers of Marine Organisms (WGITMO): By Correspondence. CM Documents - ICES. CM 2005(ACME:05). ICES: Copenhagen: pp. 23-25. [http://www.vliz.be/en/imis?module=ref&refid=208325]

[6]          Kerckhof, F.; Degraer, S.; Norro, A.; Rumes, B. (2011). Offshore intertidal hard substrata: a new habitat promoting non-indigenous species in the Southern North Sea: an exploratory study., in: Degraer, S. et al. Offshore wind farms in the Belgian part of the North Sea: Selected findings from the baseline and targeted monitoring. pp. 27-37. [http://www.vliz.be/en/imis?module=ref&refid=207279]

[7]          De Mesel, I.; Kerckhof, F.; Norro, A.; Rumes, B.; Degraer, S. (2015). Succession and seasonal dynamics of the epifauna community on offshore wind farm foundations and their role as stepping stones for non-indigenous species. Hydrobiologia 756(1): 37-50. [http://www.vliz.be/en/imis?module=ref&refid=245077]

[8]          Rumes, B.; Kerckhof, F. (2011). On the occurrence and habitat of Telmatogeton japonicus Tokunaga (Diptera; Chironomidae) in the Southern Bight of the North Sea., in: Mees, J. et al. VLIZ Young Marine Scientists' Day, Brugge, Belgium 25 February 2011: book of abstracts. pp. 74. [http://www.vliz.be/en/imis?module=ref&refid=202856]

[9]          Remmert, H. (1963). Telmatogeton remanei n. sp., eine neue marine Chironomide aus der Kieler Förde. Zool. Anz. 171(5-8): 165-178. [http://www.vliz.be/en/imis?module=ref&refid=208397]

[10]        Szadziewski, R. (1977). Telmatogeton gedanensis sp. n. (Clunioninae, Chironomidae, Diptera) - new marine chironomid from the Polish Baltic coast. Pol. Pismo Entomol. 47: 175-184. [http://www.vliz.be/en/imis?module=ref&refid=206247]

[11]        Murray, D.A. (2000). First record of Telmatogeton japonicus Tokunaga (Dipt., Chironomidae) from the British Isles and additional records of halobiontic Chironomidae from Ireland. Entomol. Mon. Mag. 136: 157-160. [http://www.vliz.be/en/imis?module=ref&refid=206129]

[12]        Elsam Engineering A/S (2005). Elsam offshore wind turbines: Horns Rev annual status report for the environmental monitoring programme 1 January 2004 - 31 December 2004. Elsam Engineering A/S: Fredericia, Denmark. 96 pp. [http://www.vliz.be/en/imis?module=ref&refid=206242]

[13]        Raunio, J.; Paasivirta, L.; Brodin, Y. (2009). Marine midge Telmatogeton japonicus Tokunaga (Diptera: Chironomidae) exploiting brackish water in Finland. Aquat. Invasions 4(2): 405-408. [http://www.vliz.be/en/imis?module=ref&refid=206249]

[14]        Cranston, P.S. (1989). The adult males of Telmatogetoninae (Diptera: Chironomidae) of the Holarctic region – keys and diagnosis. Entomol. Scand. Suppl. 34: 17-21. [http://www.vliz.be/en/imis?module=ref&refid=206241]

[15]        Kerckhof, F.; Norro, A.; Jacques, T.; Degraer, S. (2009). Early colonisation of a concrete offshore windmill foundation by marine biofouling on the Thornton Bank (southern North Sea), in: Degraer, S. et al. Offshore wind farms in the Belgian part of the North Sea: State of the art after two years of environmental monitoring. Management Unit of the North Sea Mathematical Models, Marine Ecosystem Management Unit/Royal Belgian Institute of Natural Sciences: Brussel: pp. 39-51. [http://www.vliz.be/en/imis?module=ref&refid=142997]

[16]        Tokunaga, M. (1935). Chironomidae from Japan (Diptera): IV. On the early stages of a marine midge, Telmatogeton japonicus Tokunaga. Philipp J. Sci. 57: 491-511. [http://www.vliz.be/en/imis?module=ref&refid=208354&printversion=1&dropIMIStitle=1]

[17]        Sunose, T.; Fujisawa, T. (1982). Ecological studies of the intertidal chironomid Telmatogeton japonicus Tokunaga in Hokkaido. Res. Popul. Ecol. 24: 70-84. [http://www.vliz.be/en/imis?module=ref&refid=206607]

[18]        Boudewijn, T.J.; Meijer, A.J.M. (2007). De kolonisatie door flora en fauna van betonblokken op het zuidelijk havenhoofd te Ijmuiden. Betonblokken als foerageergebied voor paarse strandlopers en steenlopers: eindrapport. Bureau Waardenburg Rapport, 07-051. Bureau Waardenburg. Culemborg. 108 pp. [http://www.vliz.be/en/imis?module=ref&refid=198236]

[19]        Failla, A.; Vasquez, A.V.; Fujimoto, M.; Ram, J.L. (2015). The ecological, economic and public health impacts of nuisance chironomids and their potential as aquatic invaders. Aquat. Invasions 10(1): 1-15. [http://www.vliz.be/en/imis?module=ref&refid=296690]

[20]        Degraer, S.; Kerckhof, F.; Reubens, J.; Vanermen, N.; De Mesel, I.; Rumes, B.; Stienen, E.W.M.; Vandendriessche, S.; Vincx, M. (2013). Not necessarily all gold that shines: appropriate ecological context setting needed!, in: Degraer, S. et al. Environmental impacts of offshore wind farms in the Belgian part of the North Sea: Learning from the past to optimise future monitoring programmes. pp. 175-181. [http://www.vliz.be/nl/imis?module=ref&refid=231908]

[21]        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]

[22]        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]

[23]        Cheng, L. (Ed.) (1976). Marine insects. XII. North-Holland: Amsterdam. ISBN 0-444-11213-8. 581 pp. [http://www.vliz.be/en/imis?module=ref&refid=39162]

VLIZ Alien Species Consortium (2020). Telmatogeton japonicus – Marine splash midge. Non-indigenous species in the Belgian part of the North Sea and adjacent estuaries anno 2020. Flanders Marine Institute (VLIZ). 6 pp.