Durvillaea antarctica, also known ascochayuyo andrimurapa,[1] is a large, robust species ofsouthern bull kelp found on the coasts ofChile, southernNew Zealand, andMacquarie Island.[2][3][4][5]D. antarctica, analga, does not have air bladders, but floats due to a unique honeycomb structure within the alga's blades, which also helps thekelp avoid being damaged by the strong waves.[6][7]
The species was first described in 1822,[8] asFucus antarcticus, and revised in 1892 asDurvillaea antarctica.[9] The genus nameDurvillaea was given in memory of the French explorerJules Dumont d'Urville, while theLatin derived epithet refers toantarctic.[10]
In 2012, a taxonomic revision led to the recognition of a new species,Durvillaea poha, based on genetic, morphological and ecological evidence,[3] which was previously recognised as the 'cape' lineage ofDurvillaea antarctica.[3][11][12]D. poha is the only other species in the genus to share the honeycombed structure and buoyancy ofD. antarctica.D. poha occurs only in southern New Zealand and on subantarctic islands (includingSnares andAuckland Islands), whereasD. antarctica has a wider distribution, and is found around New Zealand, Chile and other subantarctic islands. In southern New Zealand,D. poha andD. antarctica can be found growing together, althoughD. poha normally grows higher up or further back on the rock platforms, or in more sheltered bays, where wave force is weaker.D. poha generally has wider fronds thanD. antarctica, and can appear more 'orange' across the frond area.[3][5] Mitochondrialintrogression has been observed between the two species, where some plants in Wellington exhibited the nuclear DNA ofD. poha but also mitochondrial DNA belonging toD. antarctica.[13]
Further diversity, with additional unclassified lineages have been identified within the species.[5][12]
The blades ofDurvillaea antarctica are green to golden brown with a leathery texture. The honeycomb structure of the blade gives strength and buoyancy.[6][7] This novel structure is thought to be responsible for the wide distribution of this genus, as the kelp is able to float when its holdfast fails. It can colonise other coastlines in this manner, and has been shown to carry communities of invertebrates across vast ocean distances from one shore to another.[14] Specimens ofD. antarctica have been found to float for up to 210 days, during which time high wind speeds transport kelp rafts up to 10,000 km.[15] Environmental factors such as temperature, solar radiation and surface winds (all of which vary with latitude) affect buoyancy of rafts and their rate of travel.[15] Rafts ofD. antarctica are more likely to disperse offshore if plants detach during outgoing tides during autumn and winter.[16] It is thought that this 'rafting' withDurvillaea antarctica and other floating seaweeds allowed a wide range of species to recolonise sub-Antarctic shores scoured clean by ice during the last Ice Age.[17]
The holdfast ofD. antarctica is large and is very difficult to remove.D. antarctica has to resist forces equivalent to 1100 km/h on land.[18][clarification needed] The holdfast failing is usually the result of worms and molluscs which feed on the tissue because of the sheltered habitat it creates.[19] It is also common for its host rock to be broken off without the holdfast losing its grip, with this contributing significantly to erosion in some areas.[2] Recruitment rates of this species is very low, therefore the ecological impact of harvesting this species is too great.[19]
Morphology ofD. antarctica
Cross-section revealing the honeycomb structure of blades
Durvillaea antarctica reproduces sexually by producing egg and sperm that are released into the water. Eggs and sperm are produced on specific sites of the frond. A large individual can produce 100 million eggs in twelve hours.[19] The season when reproduction occurs varies with location, but is generally during winter months.[20] Eggs are small and disperse over short distances, and they generally require calm or moderate wave action in order to settle and successfully attach to substrates.[21]
Durvillaea antarctica has a circumpolar distribution between the latitudes of 29°S and 55°S, found in Chile, southern New Zealand, and Macquarie Island.[2][3][4][5][22][23][24] The type locality is Cape Horn, Chile.[6][20]
It is found on exposed shores, especially in the northern parts of its range, and attaches itself with a strong holdfast.[2][3]
Plants ofD. antarctica can detach from substrates, particularly during storms. The kelp floats as a raft and can travel vast distances at sea, driven by ocean currents. Kelp-associated invertebrates can be transported inside of drifting holdfasts, potentially leading to long-distance dispersal and a significant impact upon the population genetic structure of those species.[26][27][28][29]
Fronds ofD. antarctica can be infected by an endophytic, phaeophycean algal parasiteHerpodiscus durvillaeae(Lindauer) G. R. South.[32][33] Fronds can also be infectedMaullinia, a genus of intracellular,protistan parasites.[34][35][36] Based on genetic evidence, bothH. durvillaeae andMaullinia have likely been dispersed across the Southern Hemisphere via rafting bull kelp.[33][34][36][37]
Stems and holdfasts ofD. antarctica andD. incurvata are harvested from the coast of Chile and is used inChilean cuisine for various recipes, includingsalads andstews.[5] InQuechua the species is called:cochayuyo (cocha: lake, andyuyo: weed), andhulte.[5] TheMapuche indigenous people refer to it ascollofe orkollof.[5][38]
The expressionremojar el cochayuyo (literally: to soak the cochayuyo) is used inChilean Spanish to refer tosexual intercourse.[39] The expression derives from the fact that harvestedD. antarctica is preserved by being sun-dried and then softened by soaking in a dish of water.
Along withD. poha, blades ofD. antarctica are used to make traditionalpōhā bags, which are used to carry and store food and fresh water, to propagate liveshellfish, and to make clothing and equipment for sports.[40][41][42] Pōhā are especially associated withNgāi Tahu and are often used to carry and storemuttonbird (tītī) chicks.[40][41] The species is calledrimurapa inMāori.[1][40][41]
^ab"rimurapa".māoridictionary.co.nz. Retrieved21 November 2019.
^abcdSmith, J.M.B. and Bayliss-Smith, T.P. (1998). Kelp-plucking: coastal erosion facilitated by bull-kelpDurvillaea antarctica at subantarctic Macquarie Island,Antarctic Science 10 (4), 431–438.doi:10.1017/S0954102098000522.
^abcdefFraser, Ceridwen I.; Spencer, Hamish G.; Waters, Jonathan M. (2012). "Durvillaea poha sp. nov. (Fucales, Phaeophyceae): a buoyant southern bull-kelp species endemic to New Zealand".Phycologia.51 (2):151–156.Bibcode:2012Phyco..51..151F.doi:10.2216/11-47.1.S2CID86386681.
^abMaggy Wassilieff.Seaweed - Bull kelp’s honeycombed structure,Te Ara - the Encyclopedia of New Zealand, Ministry of Culture and Heritage. Updated 2 March 2009. Retrieved 9 March 2010.
^Choris, L. (1822). Voyage pittoresque autour du monde. Part I. pp. vi + 17, 12 plates. Paris
^Hariot, P. (1892). Complément à la flore algologique de la Terre de Feu. Notarisia 7: 1427-1435.
^Fraser, Ceridwen I.; Hay, Cameron H.; Spencer, Hamish G.; Waters, Jonathan M. (2009). "Genetic and morphological analyses of the southern bull kelpDurvillaea antarctica (Phaeophyceae: Durvillaeales) in New Zealand reveal cryptic species".Journal of Phycology.45 (2):436–443.Bibcode:2009JPcgy..45..436F.doi:10.1111/j.1529-8817.2009.00658.x.PMID27033822.S2CID18309093.
^abFraser, C.I.; Winter, D.J.; Spencer, H.G.; Waters, J.M. (2010). "Multigene phylogeny of the southern bull-kelp genusDurvillaea (Phaeophyceae: Fucales)".Molecular Phylogenetics and Evolution.57 (3):1301–11.Bibcode:2010MolPE..57.1301F.doi:10.1016/j.ympev.2010.10.011.PMID20971197.
^Fraser CI, Nikula R & Waters JM (2011) Oceanic rafting of a coastal community.Proceedings of the Royal Society, B, 278:649-655.
^abTala, Fadia; López, Boris A.; Velásquez, Marcel; Jeldres, Ricardo; Macaya, Erasmo C.; Mansilla, Andrés; Ojeda, Jaime; Thiel, Martin (2019). "Long-term persistence of the floating bull kelpDurvillaea antarctica from the South-East Pacific: Potential contribution to local and transoceanic connectivity".Marine Environmental Research.149:67–79.Bibcode:2019MarER.149...67T.doi:10.1016/j.marenvres.2019.05.013.PMID31154063.S2CID173993590.
^Hawes, Nicola A.; Taylor, David I.; Schiel, David R. (2019). "Transport of drifting fucoid algae: Nearshore transport and potential for long distance dispersal".Journal of Experimental Marine Biology and Ecology.490:634–41.doi:10.1016/j.jembe.2017.02.001.
^Fraser CI, Nikula R, Spencer HG & Waters JM (2009) Kelp genes reveal effects of subantarctic sea ice during the Last Glacial Maximum.Proceedings of the National Academy of Sciences, USA, 106:3249-3253.
^Hurd, C (2003).The Living Reef. Nelson, New Zealand: Craig Potton Publishing.
^abcBradstock, M (1989).Between the Tides. New Zealand: David Bateman Limited.
^abcParvizi, Elahe; Dutoit, Ludovic; Fraser, Ceridwen I.; Craw, Dave; Waters, Jonathan M. (2022). "Concordant phylogeographic responses to large-scale coastal disturbance in intertidal macroalgae and their epibiota".Molecular Ecology.31 (2):646–657.Bibcode:2022MolEc..31..646P.doi:10.1111/mec.16245.PMID34695264.S2CID239888553.
^abCumming, Rebecca A.; Nikula, Raisa; Spencer, Hamish G.; Waters, Jonathan M. (2014). "Transoceanic genetic similarities of kelp-associated sea slug populations: long-distance dispersal via rafting?".Journal of Biogeography.41 (12):2357–2370.Bibcode:2014JBiog..41.2357C.doi:10.1111/jbi.12376.S2CID84574097.
^abFraser, Ceridwen I.; Waters, Jonathan M. (2013). "Algal parasiteHerpodiscus durvillaea (Phaeophyceae: Sphacelariales) inferred to have traversed the Pacific Ocean with its buoyant host".Journal of Phycology.49 (1):202–206.Bibcode:2013JPcgy..49..202F.doi:10.1111/jpy.12017.PMID27008401.S2CID21397549.
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