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Seagrass ‘fairy circles’ on the Isles of Scilly

Published online by Cambridge University Press:  13 June 2022

Richard M. Warwick Open the ORCID record for Richard M. Warwick [Opens in a new window]
Richard M. Warwick*
Affiliation:
Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth PL1 3DH, UK Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, 90 South St, Murdoch, Western Australia 6150, Australia
*
Author for correspondence: Richard M. Warwick, E-mail: rmw@pml.ac.uk
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Abstract

Perfectly circular patches bare of vegetation in otherwise continuous swards of seagrass, and perfect circles of seagrass with lush fringes of shoots on the outer margins but with virtually bare centres, have both attracted popular attention as ‘fairy circles’ or ‘fairy rings’ in view of the folklore surrounding the supernatural origins of their terrestrial fungal counterparts. Aerial photographic and satellite surveys show that, on the Isles of Scilly, circles of Zostera marina of the second type occur sporadically, with exceptionally prolific clusters in specific localities associated with the colonization of bare substratum after disturbance, gradually disappearing over the period of this study at one site and appearing at another. Their abundance is the highest recorded anywhere in the world. Early suggestions that they represent seaweed growth on the stones of ancient hut-circles, submerged for centuries as a result of sea-level rise, are refuted. It is argued that they result from the unrestricted clonal growth of genets arising from individual Zostera seedlings, expanding equally in two dimensions and colonizing vacant habitat, with the older central shoots senescing and dying. Diameters of the circles constitute a stepwise increase in size, and the growth increments may represent a similar rate of seasonal growth in consecutive years, implying a linear rhizome growth rate of ~2.5 m year−1, which would be exceptional for Zostera marina, but which is supported by an observation on circles exposed on a low spring tide and would be an evolutionary adaptation for rapid recolonization in such a physically disturbed environment.

Keywords

Circle sizeclonal rhizome growthgenet ageIsles of Scillyphysical disturbancerecolonizationseedling productionZostera marina
Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 102 , Issue 1-2 , March 2022 , pp. 63 - 68
Copyright
Copyright © The Author(s), 2022. Published by Cambridge University Press on behalf of Marine Biological Association of the United Kingdom

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References

Bell, SS, Fonseca, MS and Stafford, NB (2006) Seagrass ecology: new contributions from a landscape perspective. In Larkum, AWD, Orth, RJ and Duarte, CM (eds), Seagrasses: Biology, Ecology and Conservation. Dordrecht: Springer, pp. 625‒645.Google Scholar
Boese, BL, Kaldy, JE, Clinton, PJ, Eldridge, PM and Folger, CL (2009) Recolonization of intertidal Zostera marina L. (eelgrass) following experimental shoot removal. Journal of Experimental Marine Biology and Ecology 374, 69–77.CrossRefGoogle Scholar
Borum, J, Raun, AL, Hasler-Sheetal, H, Pedersen, MO, Pedersen, O and Holmer, M (2014) Eelgrass fairy rings: sulfide as inhibiting agent. Marine Biology 161, 351–358.CrossRefGoogle Scholar
Boudouresque, CF, Ballesteros, E, Ben Maiz, N, Boisset, F, Bouladier, E, Cinelli, F, Cirik, S, Cormaci, M, Jeudy De Grissac, A, Laborel, J, Lanfranco, E, Lundberg, B, Mayhoub, H, Meinesz, A, Panayotidis, P, Semroud, R, Sinnassamy, JM, Span, A and Vuignier, G (1990) Livre rouge “Gérard Vuignier” des végétaux, peuplements et paysages marins menacés de Méditerranée. Programme des Nations Unies pour l'Environnement publ, 250 pp.Google Scholar
Boudouresque, CF, Bernard, G, Bonhomme, P, Charbonnel, E, Diviacco, G, Meinesz, A, Pergent, G, Pergent-Martini, C, Ruitton, S and Tunesi, L (2006) Préservation et conservation des herbiers à Posidonia oceanica. RAMOGE pub, 202 pp.Google Scholar
Bull, J and Kenyon, E (2020) LIFE Recreation ReMEDIES – Isles of Scilly Seagrass Survey: 2020 LIFE Recreation ReMEDIES Report. Report to Natural England, 45 pp.Google Scholar
Duarte, CM, Fourqurean, JW, Krause-Jensen, D and Olesen, B (2006) Dynamics of seagrass stability and change. In Larkum, AWD, Orth, RJ and Duarte, CM (eds), Seagrasses: Biology, Ecology and Conservation. Dordrecht: Springer, pp. 271–294.Google Scholar
Duarte, CM and Sand-Jensen, K (1990) Seagrass colonization: patch formation and patch growth in Cymodocea nodosa. Marine Ecology Progress Series 65, 193–200.CrossRefGoogle Scholar
Fonseca, MS and Kenworthy, WJ (1987) Effects of current on photosynthesis and distribution of seagrasses. Aquatic Botany 27, 59–78.CrossRefGoogle Scholar
Fonseca, MS, Zieman, JC, Thayer, GW and Fisher, JS (1983) The role of current velocity in structuring eelgrass (Zostera marina L.) meadows. Estuarine Coastal and Shelf Science 17, 367–380.CrossRefGoogle Scholar
Frederiksen, M, Krause-Jensen, D, Holmer, M and Laursen, JS (2004) Spatial and temporal variation in eelgrass (Zostera marina) landscapes: influence of physical setting. Aquatic Botany 78, 147–165.CrossRefGoogle Scholar
Jackson, EL, Higgs, S, Allsop, T, Cawthray, A, Evans, J and Langmead, O (2011) Isles of Scilly Seagrass Mapping. Natural England Commissioned Reports, Number 087, 68 pp.Google Scholar
Kendrick, GA, Orth, RJ, Statton, J, Hovey, R, Ruiz-Montoya, L, Lowe, RJ, Krauss, SL and Sinclair, EA (2017) Demographic and genetic connectivity: the role and consequences of reproduction, dispersal and recruitment in seagrasses. Biological Reviews 92, 921–938.CrossRefGoogle ScholarPubMed
Kendrick, GA, Waycott, M, Carruthers, TJB, Cambridge, ML, Hovey, R, Krauss, SL, Lavery, PS, Les, DH, Lowe, RJ, Vidal, OMI, Ooi, JLS, Orth, RJ, Rivers, DO, Ruiz-Montoya, L, Sinclair, EA, Statton, J, van Dijk, JK and Verduin, JJ (2012) The central role of dispersal in the maintenance and persistence of seagrass populations. BioScience 62, 56–65.CrossRefGoogle Scholar
Marbà, N and Duarte, CM (1998) Rhizome elongation and seagrass clonal growth. Marine Ecology Progress Series 174, 269–280.CrossRefGoogle Scholar
Marine Ecological Surveys Limited (2017) Isles of Scilly Complex SAC Seagrass Survey 2016. Technical Report-March 2017, 44 pp.Google Scholar
Meinesz, A and Lefèvre, JR (1984). Régénération d'un herbier de Posidonia oceanica, quarante années après sa destruction par une bombe dans la rade de Villefranche (Alpes-Maritimes, France). In Boudouresque, CF, Jeudy de Grissac, A and Olivier, J (eds), 1st. International Workshop on Posidonia oceanica Beds. Marseille: GIS Posidonie publ, pp. 22–36.Google Scholar
Olesen, B and Sand-Jensen, K (1994) Patch dynamics of eelgrass Zostera marina. Marine Ecology Progress Series 106, 147–156.CrossRefGoogle Scholar
Pasqualini, V, Pergent-Martini, C and Pergent, G (1999) Environmental impact identification along the Corsican coast (Mediterranean Sea) using image processing. Aquatic Botany 65, 311–320.CrossRefGoogle Scholar
Pergent, G, Djellouli, A, Hamza, AA, Ettayeb, KS, Alkekli, A, Talha, M and Alkunti, E (2007). Structure of Posidonia oceanica meadows in the vicinity of Ain Al Ghazala lagoon (Libya): the “macroatoll” ecomorphosis. In Pergent-Martini, C, El Asmi, S and Le Ravallec, C (eds), Proceedings of the Third Mediterranean Symposium on Marine Vegetation (Marseilles, 27–29 March 2007), Tunis: RAC/SPA publ, pp. 135–140.Google Scholar
Pergent, G and Pergent-Martini, C (1995) Dynamique et évolution de l'herbier à Posidonia oceanica en Méditerranée. Gionale Botanico Italiano 129, 303–317.Google Scholar
Phillips, RC and Menez, EG (1988). Seagrasses. Smithsonian Contribution to the Marine Sciences No. 34. Washington, DC: Smithsonian Institution Press, 104 pp.Google Scholar
Potouroglou, M, Kenyon, EJ, Gall, A, Cook, KJ and Bull, JC (2014) The roles of flowering, overwinter survival and sea surface temperature in the long-term population dynamics of Zostera marina around the Isles of Scilly, UK. Marine Pollution Bulletin 83, 500–507.Google ScholarPubMed
Reusch, TBH, Stam, WT and Olsen, JC (1998) Size and estimated age of genets in eelgrass, Zostera marina, assessed with microsatellite markers. Marine Biology 133, 519–525.CrossRefGoogle Scholar
Ruiz-Reynés, D, Gomila, D, Sintes, T, Hernández-García, E, Marbà, N and Duarte, CM (2017) Fairy circle landscapes under the sea. Science Advances 3, e1603262.CrossRefGoogle ScholarPubMed
Thomas, C (1985) Exploration of a Drowned Landscape: Archaeology and History of the Isles of Scilly. London: BT Batsford.Google Scholar
Tomasello, A, Di Maida, G, Calvo, S, Pirrotta, M, Borra, M and Procaccini, G (2009) Seagrass meadows at the extreme of environmental tolerance: the case of Posidonia oceanica in a semi-enclosed coastal lagoon. Marine Ecology 30, 288–300.CrossRefGoogle Scholar
Verhagen, JHG and Nienhuis, PH (1983) A simulation model of production, seasonal changes in biomass and distribution of eelgrass (Zostera marina) in Lake Grevelingen. Marine Ecology Progress Series 10, 187–195.CrossRefGoogle Scholar
Vidondo, B, Duarte, CM, Middelboe, AL, Stefansen, K, Lützen, T and Nielsen, SL (1997) Dynamics of a landscape mosaic: size and age distributions, growth and demography of seagrass Cymodocea nodosa patches. Marine Ecology Progress Series 158, 131–138.Google Scholar
Warwick, RM (2014). The Isles of Scilly: sustaining biodiversity. In Ray, GC and McCormick-Ray, J (eds), Marine Conservation: Science, Policy, and Management. Chichester: Wiley–Blackwell, pp. 234‒261.Google Scholar