Sargassum muticum - Japanese wireweed
SCIENTIFIC NAME
Sargassum muticum (Yendo) Fensholt, 1955
1991 - 2000
NW Pacific
Aquaculture - importing live animals
Japanese wireweed originates from the Pacific Northwest along the coasts of Japan, Russia, Korea and China [2].
First observation in Belgium
Since 1972-1973, assemblages of Japanese wireweed, swept away by the currents, washed ashore on the Belgian coast [3]. The first specimen growing on-site was found on the 18th of June 1999 in the Port of Zeebrugge (Connection Dock) at three metres depth [4].
Spreading in Belgium
Japanese wireweed washes ashore regularly along our coastline [3]. Of all the floating seaweeds assemblages along our coasts, most are made up of this large brown seaweed [5]. The first attached Japanese wireweed specimen in Belgium was found in Zeebrugge [4], from where it steadily continued to spread throughout the entire port area [6]. In 2000, specimens were sighted in the Sluice Dock of Ostend. Bizarrely, no attached specimens were found in the sluice-dock between 2002 and 2004. However, from 2005 onwards, the species did appear there again [6]. Today, growing specimens of Japanese wireweed have been observed in De Panne, the Port of Ostend, De Haan and Zwin Nature Park. [7].
Spreading in neighbouring countries
On the 17th of February 1973, Japanese wireweed was observed for the first time in Europe. About thirty attached specimens were found in the lagoons around Bembridge on the Isle of Wright (Southern England) [8-10]. In this region, Japanese wireweed has been present for some years as specimens have washed ashore on the English coast since 1971 [10]. In the United Kingdom, this species (along with other non-native species) is monitored by the Marine Aliens Project [11]. In Ireland, the species was observed in 2002. Here, it continued to expand and is considered potentially highly invasive [12].
In France, growing individuals of this type of seaweed were observed in 1976 [13]. The Japanese wireweed continued to spread along the Atlantic Coast – from Norway to Spain – and in the Mediterranean. This spread occurred (mainly) natural, using the prevailing currents, and was probably also facilitated by oyster transport [8-10, 13].
In April-May 1977, the first fragments of Japanese wireweed washed ashore in the Netherlands on the island of Texel [3, 14]. The first attached specimens were not found until 1980. Suddenly, the species was widespread and found all along the island of Texel, in Lake Grevelingen, the Harbour of Goes and the Eastern Scheldt [15, 16]. Today, many individuals grow in Lake Grevelingen and the Europoort (in the Port of Rotterdam) [13].
In Sweden, this species has been spotted at the outflow of cooling water from power stations [17]. In the future, climate change could be the main reason for the northwards expansion of this species [11].
The import of oysters brought the Japanese wireweed to Western Canada, where it was first noticed in 1944. It is believed that this seaweed got similarly introduced to France. From France, the seaweed spread (probably) naturally throughout Europe [8, 13].
Natural dispersal happens primarily via the fertile side branches. These break off and spread with the currents and provide offspring in new areas. Furthermore, the thallus, or body of the seaweed, can float together with the substrate to which it is attached to new areas. Once detached, the seaweed can still reproduce but no longer establish itself in a new place [8, 18].
The Japanese wireweed has a high growth rate [19] and grows up to four centimetres a day in-situ [8]. This non-indigenous weed can grow up to 10 metres [8] tall and produce large amounts of offspring [20].
During summer and autumn, side branches break off, sometimes together with the mature reproductive structures or receptacula. These drift away and can survive for up to three months [21]. The receptacula produce both eggs (up to 300) and sperm and are self-fertilising. One specimen weighs only 15 grams and can produce more than half a million offspring [20], often at a considerable distance from the parent. This nomadic existence contributes significantly to the success of this seaweed species.
Despite these characteristics, Japanese wireweed does not behave like a typical exotic species. Alien species typically have short life cycles, in which they produce a maximum of offspring at the youngest possible age and then die quickly. On the contrary, Japanese wireweed has a long lifecycle, with an average of seven years. In addition, the presence of other specimens helps the young seaweed to establish itself. The latter suggests that this species adapts its environment to its needs [22].
Grazers that feed on algae often have a specific diet and do not readily switch to a new food source. This behaviour might give the non-native seaweed S. muticum a competitive advantage over native seaweeds [23, 24].
S. muticum appears to have better resistance to biofouling [25]. Fewer weeds and algae grow on this species, thus blocking less light, which further enhances the invasiveness of the Sargassum species.
Japanese wireweed can handle a wide range of environmental conditions. However, high temperatures are favourable and accelerate the spread of this species. The seaweed finds ideal growing conditions at 25°C and a salinity of 34 PSU. Moreover, Japanese wireweed can grow in more unfavourable conditions – at temperatures between 10-30°C and salinity fluctuating between 6.8-34 PSU [26]. The species reproduces in warm and cold water, provided the salinity is not below 16 PSU [2]. By comparison, the North Sea has a salt concentration of about 35 PSU.
This brown seaweed species has good buoyancy, allowing it to spread across long distances via the sea currents. For example, it extended its habitat in England by more than 100 kilometres annually in a northeastern direction by hitching a ride on favourable sea currents [13].
It is not yet clear whether global warming will be beneficial for this seaweed or not. Increasing CO2 concentrations in the air (and thus in the sea) will acidify the oceans. The increasing use of pesticides is causing eutrophication, i.e. an excess of nutrients. A study by Xu et al. (2017) [27] showed that increased CO2 levels and increased eutrophication each enhanced the growth of S. muticum, but the combination of the two effects did not.
Japanese wireweed is displacing native species due to its rapid growth. Its large branches block the sunlight for the species of seaweed growing closer to the bottom [28]. As a result, these lower-growing individuals do not get enough sunlight to survive. When Japanese wireweed established itself in Grandcamp-Maisy (Normandy, France) in the early 1990s, the sugar kelp Saccharina latissima disappeared completely [29].
Native seaweed species of the Wadden Sea, such as Vertebrata fucoides, Pterothamnion plumula and Elachista fucicola, also get displaced by Japanese wireweed [30]. These native species grow on recently formed hard substrates created by the invasive Japanese oyster Crassostrea gigas and are outcompeted after the arrival of the Japanese wireweed [29].
These observations make it clear that this alien species competes with the indigenous species of seaweed. However, opinions are divided as to whether it also affects the local communities associated with these seaweeds. One study shows that Japanese wireweed doesn’t cause any notable changes in the associated communities [31]. Other studies emphasise that this species can indeed cause changes throughout the ecosystem [32]. The larger the mass of seaweed, the greater its impact. Although, its impact can fluctuate depending on the season and specific interactions with other species. Thus, the effects of the presence of Japanese wireweed also depends on the area where the research takes place and the species communities found there [33].
The exotic Japanese skeleton shrimp Caprella mutica is often associated with Japanese wireweed, as demonstrated in the port of Zeebrugge [34]. The seaweed forms floating thalli, to which C. mutica can attach itself and, thereby, spread towards new areas [35]. This shows that S. muticum can increase the impact of other invasive species. Japanese wireweed can be a nuisance to humans [28]. Here are some examples (not exhaustive) of problems from areas where the species is present in large numbers:
- Floating seaweed mats get caught in fishing nets and ships' propellers;
- In the event of massive stranding of seaweeds, a (short-lived) odour nuisance may arise after a while due to the decay of the algae [36];
- Japanese wireweed clogs pipes of both ships and industrial installations;
- Vegetation on oyster and mussel beds (e.g. in France) slows down the growth of these molluscs and makes harvesting difficult;
- Dense seaweed packets hinder recreational boats with outboard motors, swimmers, and anglers.
In British waters, several attempts were made to eradicate Japanese wireweed, so far, without success. Commonly used techniques are manual or mechanical removal or spraying herbicides. The herbicides were not selective enough and required too high a dose. The possibility of controlling the species biologically was also investigated. Unfortunately, no species were found that preferred Japanese wireweed over other algae
In Belgian marine waters, S. muticum is reported mainly in port areas and, contrary to expectations, does not seem to cause any economic damage in these places [37]. Therefore, no measures have been implemented in Belgium for the removal of this species.
Analyses show that the bioactive substances in S. muticum could make this species of economic significance in Europe. Therefore, the collection of this species might be of interest in the context of future management plans [38]. Furthermore, this seaweed is capable of biosorption, which means that it can absorb various substances from the water, such as phenol
In its native range (Japanese coast), this wireweed is much smaller than in the United Kingdom [41]. In our regions, a single seaweed thallus can be 5 to 10 metres long.
The seaweed forms long, annually recurring branches that are equipped with countless small floating air bladders. These air bladders ensure that the side branches stay upright in the water column or float on the surface [8]. In summer and autumn, side branches break off together with the mature reproductive structures. These can survive for up to three months while floating in the water [20] and thus travel great distances to colonise new places. Each side branch produces both eggs and sperm and can fertilise itself. Young seaweeds settle on a hard substrate – sometimes at a considerable distance from the parent plants – and grow slowly during the cold winter months. In the following spring and summer, they grow to their adult size. The cycle is completed in late summer and autumn when the side branches break off again. The base of the parent plants remains and sprouts again in spring [4].
Dikes, gravel foundations of dams and piers get colonised up to a depth of about 2.5 metres [4]. The seaweed usually grows close to the surface, although it can occur at greater depths up to 25 metres [8].
[1] World Register of Marine Species (WoRMS) (2020). Sargassum muticum (Yendo) Fensholt, 1955. [http://www.marinespecies.org/aphia.php?p=taxdetails&id=494791] (2020-11-17).
[2] Wallentinus, I. (1999). Sargassum muticum (Yendo) Fensholt, Sargassaceae, Fucales, Phaeophyceae (Japweed, wire weed, strangle weed), in: Gollasch, S. et al. Exotics across the ocean. Case histories on introduced species: their general biology, distribution, range expansion and impact: prepared by Members of the European Union Concerted Action on testing monitoring systems for risk assessment of harmful introductions by ships to European waters (MAS-CT-97-0111). Department of Fishery Biology, Institute for Marine Science, University of Kiel: Germany: pp. 21-30. [http://www.vliz.be/imis/imis.php?module=ref&refid=123813]
[3] Coppejans, E.; Rappé, G.; Podoor, N.; Asperges, M. (1980). Sargassum muticum (Yendo) Fensholt ook langs de Belgische kust aangespoeld. Dumortiera 16: 7-13. [http://www.vliz.be/imis/imis.php?module=ref&refid=3616]
[4] De Blauwe, H. (2000). Japans bessenwier Sargassum muticum gevestigd te Zeebrugge. De Strandvlo 20(1): 33-35. [http://www.vliz.be/imis/imis.php?module=ref&refid=19298]
[5] Vandendriessche, S. (2007). Drijvend zeewier als efemeer neustonisch habitat = Floating seaweed as ephemeral neustonic habitat. PhD Thesis. Universiteit Gent: Gent. 155 pp. [http://www.vliz.be/imis/imis.php?module=ref&refid=106496]
[6] 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]
[7] Waarnemingen afkomstig van Waarnemingen.be: een initiatief van Natuurpunt Studie vzw en de Stichting Natuurinformatie (2011). Japans bessenwier - Sargassum muticum (Yendo) Fensholt. [http://waarnemingen.be/soort/view/20187?from=1900-08-04&to=2011-08-18&species=soort+20187&prov=0&maand=0&os=0&prov_wg=0&page=1] (2018-09-27).
[8] Gollasch, S.; Minchin, D.; Rosenthal, H.; Voigt, M. (Ed.) (1999). Exotics across the ocean. Case histories on introduced species: their general biology, distribution, range expansion and impact: prepared by Members of the European Union Concerted Action on testing monitoring systems for risk assessment of harmful introductions by ships to European waters (MAS-CT-97-0111). Department of Fishery Biology, Institute for Marine Science, University of Kiel: Germany. ISBN 3-89722-248-5. 73 pp. [http://www.vliz.be/imis/imis.php?module=ref&refid=123809]
[9] Farnham, W.F.; Fletcher, R.L.; Irvine, L.M. (1973). Attached Sargassum found in Britain. Nature (Lond.) 243: 231-232. [http://www.vliz.be/imis/imis.php?module=ref&refid=206402]
[10] Critchley, A.T.; Farnham, W.F.; Morrell, S.L. (1983). A chronology of new European sites of attachment for the invasive brown alga, Sargassum muticum, 1973–1981. J. Mar. Biol. Ass. U.K. 63(4): 799-811. [http://www.vliz.be/imis/imis.php?module=ref&refid=206266]
[11] Reid, P.C.; Valdes, L. (Ed.) (2011). ICES status report on climate change in the North Atlantic. ICES Cooperative Research Report, 310. ICES: Copenhagen. ISBN 978-87-7482-096-3. 262 pp. [http://www.vliz.be/nl/catalogus?module=ref&refid=207971]
[12] Rae, M.; Folch, H.; Moniz, M.B.J.; Wolff, C.W.; McCormack, G.P.; Rindi, F.; Johnson, M.P. (2013). Marine bioactivity in Irish waters. Phytochemistry Reviews 12(3): 555-565. [http://www.vliz.be/en/imis?module=ref&refid=226492]
[13] 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]
[14] Prud'homme van Reine, W.F. (1977). Japans bessenwier aan onze kust. Het Zeepaard 37(4): 58-63. [http://www.vliz.be/en/imis?module=ref&refid=116961]
[15] Prud'homme van Reine, W.F.; Nienhuis, P.H. (1982). Occurrence of the brown alga Sargassum muticum (Yendo) Fensholt in The Netherlands. Bot. Mar. 25: 37-39. [http://www.vliz.be/en/imis?module=ref&refid=120967]
[16] Prud'homme van Reine, W.F. (1980). De invasie van het Japans bessenwier in Nederland. Vita Marina Zeebiologische Dokumentatie: zeebiologie, zeeaquariologie, malacologie, in: [s.d.]. Vita Marina Zeebiol. Doc. Mariene Flora, 19. Stichting Biologia Maritima: Den Haag: pp. 35-40. [http://www.vliz.be/imis/imis.php?module=ref&refid=76072]
[17] Fagerholm, B.; Andersson, J.; Florin, A.-B. (2013). Monitoring of alien species at nuclear power plants in Sweden, in: Robbens, J. et al. Non-indigenous species in the North-East Atlantic. Ostend, 20-22 November 2013: Book of abstracts. VLIZ Special Publication, 66. Institute for Agricultural and Fisheries Research (ILVO)/Flanders Marine Institute (VLIZ): Oostende: pp. 22. [http://www.vliz.be/nl/catalogus?module=ref&refid=230688]
[18] Naylor, M. (2006). Alien species in Swedish seas: Japweed (Sargassum muticum). Second update. Alien species in Swedish seas and coastal areas. Informationscentralerna för Bottniska viken, Egentliga Östersjön och Västerhavet: Sweden. 4 pp. [http://www.vliz.be/imis/imis.php?module=ref&refid=207072]
[19] Hales, J.M.; Fletcher, R.L. (1989). Studies on the recently introduced brown alga Sargassum muticum (Yendo) Fensholt: IV. The effect of temperature, irradiance and salinity on germling growth. Bot. Mar. 32(167-176). [http://www.vliz.be/imis/imis.php?module=ref&refid=120970]
[20] Norton, T.A.; Deysher, L.E. (1988). The reproductive ecology of Sargassum muticum at different latitudes, in: Ryland, J.S. et al. Reproduction, Genetics and Distributions of Marine Organisms: 23rd European Marine Biology Symposium, School of Biological Sciences, University of Wales, Swansea, 5-9 September 1988. International Symposium Series, 23. Olsen & Olsen: Swansea: pp. 147-152. [http://www.vliz.be/imis/imis.php?module=ref&refid=27056]
[21] Farnham, W.; Murfin, C.; Critchley, A.T.; Morrell, S. (1980). Distribution and control of the brown alga Sargassum muticum, in: Levring, T. Xth International Seaweed Symposium. Proceedings Göteborg, Sweden, August 11-15, 1980. Walter De Gruyter: Göteborg: pp. 277-282. [http://www.vliz.be/imis/imis.php?module=ref&refid=124106]
[22] Engelen, A.; Santos, R. (2009). Which demographic traits determine population growth in the invasive brown seaweed Sargassum muticum? J. Ecol. 97(4): 675-684. [http://www.vliz.be/imis/imis.php?module=ref&refid=206670]
[23] Engelen, A.H.; Henriques, N.; Monteiro, C.A.; Santos, R. (2011). Mesograzers prefer mostly native seaweeds over the invasive brown seaweed Sargassum muticum. Hydrobiologia 669(1): 157-165. [http://www.vliz.be/nl/catalogus?module=ref&refid=297663]
[24] Monteiro, C.A.; Engelen, A.H.; Santos, R.O.P. (2009). Macro- and mesoherbivores prefer native seaweeds over the invasive brown seaweed Sargassum muticum: a potential regulating role on invasions. Mar. Biol. (Berl.) 156(12): 2505-2515. [http://www.vliz.be/en/imis?module=ref&refid=258590]
[25] Schwartz, N.; Dobretsov, S.; Rohde, S.; Schupp, P.J. (2017). Comparison of antifouling properties of native and invasive Sargassum (Fucales, Phaeophyceae) species. Eur. J. Phycol. 52(1): 116-131. [http://www.vliz.be/nl/catalogus?module=ref&refid=301908]
[26] 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]
[27] Xu, Z.G.; Gao, G.; Xu, J.T.; Wu, H.Y. (2017). Physiological response of a golden tide alga (Sargassum muticum) to the interaction of ocean acidification and phosphorus enrichment. Biogeosciences 14(3): 671-681. [http://www.vliz.be/nl/catalogus?module=ref&refid=301645]
[28] Critchley, A.T.; Farnham, W.F.; Morrell, S.L. (1986). An account of the attempted control of an introduced marine alga, Sargassum muticum, in Southern England. Biol. Conserv. 35: 313-332. [http://www.vliz.be/imis/imis.php?module=ref&refid=120978]
[29] Givernaud, T.; Cosson, J.; Givernaud-Mouradi, A. (1991). Etude des populations de Sargassum muticum (Yendo) Fensholt sur les côtes de Basse-Normandie (France), in: Elliott, M. et al. Estuaries and Coasts: Spatial and Temporal Intercomparisons. ECSA 19 Symposium, University of Caen, France. International Symposium Series, 3. Olsen & Olsen: Fredensborg: pp. 129-132. [http://www.vliz.be/imis/imis.php?module=ref&refid=121303]
[30] Lang, A.C.; Buschbaum, C. (2010). Facilitative effects of introduced Pacific oysters on native macroalgae are limited by a secondary invader, the seaweed Sargassum muticum. J. Sea Res. 63(2): 119-128. [http://www.vliz.be/nl/catalogus?module=ref&refid=297665]
[31] Engelen, A.H.; Primo, A.L.; Cruz, T.; Santos, R. (2013). Faunal differences between the invasive brown macroalga Sargassum muticum and competing native macroalgae. Biological Invasions 15(1): 171-183. [http://www.vliz.be/nl/catalogus?module=ref&refid=297686]
[32] Salvaterra, T.; Green, D.S.; Crowe, T.P.; O'Gorman, E.J. (2013). Impacts of the invasive alga Sargassum muticum on ecosystem functioning and food web structure. Biological Invasions 15: 2563-2576. [http://www.vliz.be/nl/catalogus?module=ref&refid=297687]
[33] Vaz-Pinto, F.; Olabarria, C.; Arenas, F. (2014). Ecosystem functioning impacts of the invasive seaweed Sargassum muticum (Fucales, Phaeophyceae). J. Phycol. 50(1): 108-116. [http://www.vliz.be/nl/catalogus?module=ref&refid=297689]
[34] Boets, P.; Lock, K.; Goethals, P.L.M. (2012). Assessing the importance of alien macro-Crustacea (Malacostraca) within macroinvertebrate assemblages in Belgian coastal harbours. Helgol. Mar. Res. 66(2): 175-187. [http://www.vliz.be/en/imis?module=ref&refid=206987]
[35] Hebbelinck, L. (2010). Monitoring van exotische macro-invertebraten in de Vlaamse havens. MSc Thesis. Universiteit Gent, Faculteit Bio-Ingenieurswetenschappen: Gent. 87 pp. [http://www.vliz.be/en/imis?module=ref&refid=197447]
[36] Global Invasive Species Database (2005). Sargassum muticum. [http://www.issg.org/database/species/ecology.asp?si=727&fr=1&sts=sss&lang=EN] (2008-03-04).
[37] Belgische Staat (2012). Initiële beoordeling voor de Belgische mariene wateren: Kaderrichtlijn Mariene Strategie – Art 8, lid 1a & 1b. BMM/Federale Overheidsdienst Volksgezondheid, Veiligheid van de Voedselketen en Leefmilieu: Brussel. 81 pp. [http://www.vliz.be/en/imis?module=ref&refid=220230]
[38] Tanniou, A.; Vandanjon, L.; Incera, M.; Leon, E.S.; Husa, V.; Le Grand, J.; Stiger-Pouvreau, V. (2014). Assessment of the spatial variability of phenolic contents and associated bioactivities in the invasive alga Sargassum muticum sampled along its European range from Norway to Portugal. J. Appl. Phycol. 26: 1215-1230. [http://www.vliz.be/nl/catalogus?module=ref&refid=297693]
[39] Rubín, E.; Rodriguez, P.; Herrero, R.; de Vicente, M.E.S. (2006). Biosorption of phenolic compounds by the brown alga Sargassum muticum. J. Chem. Technol. Biot. 81(7): 1093-1099. [http://www.vliz.be/nl/catalogus?module=ref&refid=301905]
[40] Vieira, B.R.C.; Pintor, A.M.A.; Boaventura, R.A.R.; Botelho, C.M.S.; Santos, S.C.R. (2017). Arsenic removal from water using iron-coated seaweeds. J. Environ. Manage. 192: 224-233. [http://www.vliz.be/nl/catalogus?module=ref&refid=301644]
[41] Rueness, J. (1989). Sargassum muticum and other introduced Japanese macroalgae: biological pollution of European coasts. Mar. Pollut. Bull. 20(4): 173-176. [http://www.vliz.be/imis/imis.php?module=ref&refid=117886]
VLIZ Alien Species Consortium (2020). Sargassum muticum – Japanese wireweed. Non-native species of the Belgian part of the North Sea and adjacent estuaries anno 2020. Flemish Institute for the Sea (VLIZ). 9 pp.