Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help
Researched by | Nicola White | Refereed by | Dr Dagmar Stengel |
Authority | (Linnaeus) S.F.Gray, 1821 | ||
Other common names | - | Synonyms | - |
A common brown seaweed, which has a two stage morphology. Small button-like thalli are first produced, from which long strap-like reproductive fronds (receptacles) are formed in autumn. The strap-like reproductive fronds grow quickly between February and May, reaching a length of up to 2 m. The plant releases gametes from June until the winter when it starts to decay. Plants commonly live for 2-3 years and reproduce once before dying.
Also commonly known as sea thong.
- none -
Phylum | Ochrophyta | Brown and yellow-green seaweeds |
Class | Phaeophyceae | |
Order | Fucales | |
Family | Himanthaliaceae | |
Genus | Himanthalia | |
Authority | (Linnaeus) S.F.Gray, 1821 | |
Recent Synonyms |
Typical abundance | Moderate density | ||
Male size range | Up to 2m | ||
Male size at maturity | 15mm | ||
Female size range | 15mm | ||
Female size at maturity | |||
Growth form | Capitate / Clubbed | ||
Growth rate | max. 16mm/day | ||
Body flexibility | |||
Mobility | |||
Characteristic feeding method | Autotroph | ||
Diet/food source | |||
Typically feeds on | Not relevant | ||
Sociability | |||
Environmental position | Epifloral | ||
Dependency | Independent. | ||
Supports | None | ||
Is the species harmful? | No |
Physiographic preferences | Open coast, Strait / sound, Sea loch / Sea lough, Ria / Voe |
Biological zone preferences | Lower eulittoral, Sublittoral fringe |
Substratum / habitat preferences | Bedrock, Large to very large boulders |
Tidal strength preferences | Moderately Strong 1 to 3 knots (0.5-1.5 m/sec.), Strong 3 to 6 knots (1.5-3 m/sec.), Weak < 1 knot (<0.5 m/sec.) |
Wave exposure preferences | Moderately exposed, Sheltered |
Salinity preferences | Full (30-40 psu) |
Depth range | Not relevant |
Other preferences | No text entered |
Migration Pattern | Non-migratory / resident |
Reproductive type | Gonochoristic (dioecious) | |
Reproductive frequency | Semelparous / monotely | |
Fecundity (number of eggs) | No information | |
Generation time | 2-5 years | |
Age at maturity | 2 year | |
Season | June - December | |
Life span | 2-5 years |
Larval/propagule type | - |
Larval/juvenile development | Not relevant |
Duration of larval stage | No information |
Larval dispersal potential | No information |
Larval settlement period | Insufficient information |
The MarLIN sensitivity assessment approach used below has been superseded by the MarESA (Marine Evidence-based Sensitivity Assessment) approach (see menu). The MarLIN approach was used for assessments from 1999-2010. The MarESA approach reflects the recent conservation imperatives and terminology and is used for sensitivity assessments from 2014 onwards.
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
High | High | Moderate | Moderate | |
Himanthalia elongata is permanently attached to the substratum, so it would be removed upon substratum loss. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
High | High | Moderate | Low | |
Smothering would cover and probably kill the button-like vegetative bodies of Himanthalia elongata. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
High | High | Moderate | Moderate | |
Silt may settle out on the fronds of Himanthalia elongata, reducing light available for photosynthesis and lowering growth rates. Young stages of the species are very intolerant of siltation (Moss et al., 1973) so the impact of the factor would depend on the time of year when it happened. If siltation occurred from June to December, when gametes are released, the population would be highly intolerant because zygotes cannot grow on silt (Moss et al., 1973). The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
No information | ||||
High | High | Moderate | Moderate | |
Himanthalia elongata can tolerate some increase in desiccation because the upper limit of the algae is controlled by biological interactions rather than physiological tolerance. After the Torrey Canyon oil spill, which killed limpets, Himanthalia elongata extended temporarily 2m vertically up the shore (Southward & Southward, 1978). The species also suffered no damage during the unusually hot summer of 1983 (Hawkins & Hartnoll, 1985), when it suffered increased desiccation. However, vegetative and reproductive plants died during hot weather during spring tides in Co. Clare (Stengel, pers. comm.). Therefore intolerance to desiccation is reported as high. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
Intermediate | High | Low | Moderate | |
Himanthalia elongata may physiologically tolerate an increase in the period of emergence because it has been found to grow 2m vertically further up the shore in the absence of limpets (Southward & Southward, 1978). However, an increase in the period of emergence would probably result in a depression of the species upper limit on the shore. A reduction in the period of emersion would conversely allow the upper limit of the species to extend further up the shore. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
No information | ||||
Intermediate | High | Low | Low | |
Himanthalia elongata can tolerate fairly strong currents, as evidenced by its presence in tidal rapids in Lough Ine, Ireland. An increase in tidal strength may lead to plants being torn off the substratum resulting in poor settlement of germlings. Alternatively the substratum with plants attached may be mobilised. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
No information | ||||
Intermediate | High | Low | Low | |
Germination and vegetative growth in Himanthalia elongata are highly intolerant of reductions in temperature and are limited at temperatures below 15 degrees C (Stengel, 2000 in prep.). This species is less intolerant of increases in temperature as plants survived the unusually hot summer of 1983 apart from a slight bleaching of buttons (Hawkins & Hartnoll, 1985). | ||||
No information | ||||
Low | Very high | Very Low | Moderate | |
An increase in turbidity would reduce the light available for photosynthesis and therefore lower growth rates. A prolonged occurrence of increased turbidity will delay vegetative growth and may result in a failure to become fertile in autumn (Stengel, pers. comm.) On return to normal turbidity levels the growth rate would be quickly restored. | ||||
No information | ||||
High | High | Moderate | Moderate | |
Himanthalia elongata is mostly found on moderately exposed shores. An increase in wave action would result in plants and germlings being torn off the substratum and cause a shift in the community to barnacles. A decrease in the level of wave action would result in the species being displaced by faster growing fucoids such as Fucus serratus. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
No information | ||||
Tolerant | Not relevant | Not sensitive | Moderate | |
Seaweeds have no known mechanism for the perception of noise. | ||||
Tolerant | Not relevant | Not sensitive | Moderate | |
Seaweeds have no known mechanism for visual perception. | ||||
Intermediate | High | Low | Low | |
Physical disturbance by anchors or a passing scallop dredge may damage fronds of established seaweeds and kill germlings. Abrasion may be caused by human trampling, which has been shown to reduce algal cover on shores (Holt et al., 1997). However, Himanthalia elongata is unlikely to be subject to heavy trampling because it only occurs near the low water springs mark. Therefore, intolerance has been assessed as intermediate. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
High | High | Moderate | Moderate | |
Himanthalia elongata is permanently attached to the substratum and once removed it cannot survive. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. |
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
Low | High | Low | Low | |
Himanthalia elongata was not affected by dispersants used after the 'Torrey Canyon' oil spill. Indeed the species increased its vertical range as a result of the loss of grazing gastropods (Southward & Southward, 1978). | ||||
No information | Not relevant | No information | Not relevant | |
Insufficient information | ||||
Intermediate | High | Low | Low | |
Himanthalia elongata survived the 'Torrey Canyon' oil spill and indeed extended 2 m vertically up the shore, due to the absence of grazers (Southward & Southward, 1978). The species lives in the lower eulittoral and sublittoral fringe, which means that oil will rapidly be washed off the fronds. It also usually occurs in areas with strong currents, so oil would be dispersed more quickly. Therefore, it is predicted that oil does not have a substantial impact on the species. | ||||
No information | Not relevant | No information | Not relevant | |
Insufficient information | ||||
Intermediate | High | Low | Low | |
Nutrients are required for algal growth. A small increase in nutrient levels may enhance growth rates but large increases have a detrimental effect by leading to overgrowth of brown seaweeds by green algae (Fletcher, 1996). Decreases in nutrient levels may slow down algal growth. The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
High | High | Moderate | Moderate | |
Himanthalia elongata is intolerant of salinity because reduced salinity has an adverse effect on zygote development. When salinity is below 21 psu few eggs survive (Moss et al., 1973). The species recruited to concrete blocks placed in the intertidal zone (within an existent population of Himanthalia elongata) at an average level of 45 buttons per block (968 sq. cm in area) in March of the first year, dropping to only 4 or 5 buttons per block by early summer, but rising to 1500 buttons per block by March of the second year (Stengel et al., 1999). However, the zygotes are relatively large, heavy and settle out rapidly (Moss et al. 1973) and probably have limited dispersal capability. Subsequent survival of early germlings is dependant on the presence of adult thalli or other foliose algae providing protection from desiccation, wave action and high irradiances, although shading probably limits growth rates of the germlings (Stengel et al., 1999; Stengel pers. comm.). Dispersal of gametes is probably very limited (Stengel pers. comm.). Although the above suggests that recovery may take 1-2 years in the vicinity of populations of this species (depending on the time of year); recovery by recruitment from other populations may take longer. Therefore, recovery is reported as high; populations may take up to 5 years to re-establish. | ||||
No information | ||||
No information | Not relevant | No information | Not relevant | |
Insufficient information |
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
No information | Not relevant | No information | Not relevant | |
Insufficient information | ||||
No information | Not relevant | No information | Not relevant | |
Insufficient information | ||||
Intermediate | High | Low | Low | |
Himanthalia elongata rapidly recruits to cleared areas of the shore (Stengel et al., 1999), so provided not too much of the shore is harvested the species would be able to recover relatively quickly. | ||||
Tolerant* | Not relevant | Not sensitive* | Low | |
Extraction of grazers from semi-exposed shores, such as limpets and littorinids, could cause the upper limit of Himanthalia elongata to extend up the shore. This species could also be affected by trampling from humans harvesting red algae in the vicinity. |
- no data -
National (GB) importance | - | Global red list (IUCN) category | - |
Native | - | ||
Origin | - | Date Arrived | Not relevant |
Fletcher, R.L., 1996. The occurrence of 'green tides' - a review. In Marine Benthic Vegetation. Recent changes and the Effects of Eutrophication (ed. W. Schramm & P.H. Nienhuis). Berlin Heidelberg: Springer-Verlag. [Ecological Studies, vol. 123].
Guiry, M.D. & Blunden, G., 1991. Seaweed Resources in Europe: Uses and Potential. Chicester: John Wiley & Sons.
Hardy, F.G. & Guiry, M.D., 2003. A check-list and atlas of the seaweeds of Britain and Ireland. London: British Phycological Society
Hawkins, S.J. & Hartnoll, R.G., 1985. Factors determining the upper limits of intertidal canopy-forming algae. Marine Ecology Progress Series, 20, 265-271.
Kitching, J.A., 1987. The fauna and flora associated with Himanthalia elongata (L) S. F. Gray in relation to water current and wave action in the Lough Hyne Marine Nature Reserve. Estuarine, Coastal and Shelf Science, 25, 663-676.
Moss, B., Mercer, S., & Sheader, A., 1973. Factors Affecting the Distribution of Himanthalia elongata (L.) S.F. Gray on the North-east Coast of England. Estuarine and Coastal Marine Science, 1, 233-243.
Southward, A.J. & Southward, E.C., 1978. Recolonisation of rocky shores in Cornwall after use of toxic dispersants to clean up the Torrey Canyon spill. Journal of the Fisheries Research Board of Canada, 35, 682-706.
Stengel, D.B., Wilkes, R.J. & Guiry, M.D., 1999. Seasonal growth and recruitment of Himanthalia elongata (Fucales, Phaeophycota) in different habitats on the Irish west coasts. European Journal of Phycology, 34, 213-221.
Centre for Environmental Data and Recording, 2018. Ulster Museum Marine Surveys of Northern Ireland Coastal Waters. Occurrence dataset https://www.nmni.com/CEDaR/CEDaR-Centre-for-Environmental-Data-and-Recording.aspx accessed via NBNAtlas.org on 2018-09-25.
Cofnod – North Wales Environmental Information Service, 2018. Miscellaneous records held on the Cofnod database. Occurrence dataset: https://doi.org/10.15468/hcgqsi accessed via GBIF.org on 2018-09-25.
Environmental Records Information Centre North East, 2018. ERIC NE Combined dataset to 2017. Occurrence dataset: http://www.ericnortheast.org.ukl accessed via NBNAtlas.org on 2018-09-38
Fenwick, 2018. Aphotomarine. Occurrence dataset http://www.aphotomarine.com/index.html Accessed via NBNAtlas.org on 2018-10-01
Fife Nature Records Centre, 2018. St Andrews BioBlitz 2014. Occurrence dataset: https://doi.org/10.15468/erweal accessed via GBIF.org on 2018-09-27.
Fife Nature Records Centre, 2018. St Andrews BioBlitz 2015. Occurrence dataset: https://doi.org/10.15468/xtrbvy accessed via GBIF.org on 2018-09-27.
Fife Nature Records Centre, 2018. St Andrews BioBlitz 2016. Occurrence dataset: https://doi.org/10.15468/146yiz accessed via GBIF.org on 2018-09-27.
Kent Wildlife Trust, 2018. Kent Wildlife Trust Shoresearch Intertidal Survey 2004 onwards. Occurrence dataset: https://www.kentwildlifetrust.org.uk/ accessed via NBNAtlas.org on 2018-10-01.
Manx Biological Recording Partnership, 2017. Isle of Man wildlife records from 01/01/2000 to 13/02/2017. Occurrence dataset: https://doi.org/10.15468/mopwow accessed via GBIF.org on 2018-10-01.
Manx Biological Recording Partnership, 2018. Isle of Man historical wildlife records 1995 to 1999. Occurrence dataset: https://doi.org/10.15468/lo2tge accessed via GBIF.org on 2018-10-01.
National Trust, 2017. National Trust Species Records. Occurrence dataset: https://doi.org/10.15468/opc6g1 accessed via GBIF.org on 2018-10-01.
NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.
OBIS (Ocean Biodiversity Information System), 2023. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2023-03-24
Outer Hebrides Biological Recording, 2018. Non-vascular Plants, Outer Hebrides. Occurrence dataset: https://doi.org/10.15468/goidos accessed via GBIF.org on 2018-10-01.
Royal Botanic Garden Edinburgh, 2018. Royal Botanic Garden Edinburgh Herbarium (E). Occurrence dataset: https://doi.org/10.15468/ypoair accessed via GBIF.org on 2018-10-02.
South East Wales Biodiversity Records Centre, 2018. SEWBReC Algae and allied species (South East Wales). Occurrence dataset: https://doi.org/10.15468/55albd accessed via GBIF.org on 2018-10-02.
The Wildlife Information Centre, 2018. TWIC Biodiversity Field Trip Data (1995-present). Occurrence dataset: https://doi.org/10.15468/ljc0ke accessed via GBIF.org on 2018-10-02.
This review can be cited as:
Last Updated: 29/05/2008