『アオウミガメに付着するフジツボ類のj多種共存』 (Hayashi & Tsuji, 2008)

↑漁港での調査風景。乗っているカメがアカウミガメ、抱えているカメがアオウミガメです。この研究ではアオウミガメのみを対象としました。

一方、この一年間の調査で、どんなウミガメにもたいていフジツボ類が付着しているということが明らかになりました。一方で、全く１個体もフジツボをつけていないカメもいました。それは甲長45cm以下の若い個体です。ウミガメ類は卵から孵化し、砂浜から海に入ります。このときは甲長５cm程度です。しかし、その後甲長およそ40cm前後までほとんど野外で観察例がなく、この見つからない時期のカメを「lost age（ロストエイジ）」と呼んでいます。見つからないのでどこでどのように成長しているのか、よくわかっていません。この一年間の調査でフジツボをひとつも付けていないのはロストエイジ直後の小型の個体ばかり、ちょっと大きくなると多かれ少なかれ必ずフジツボを付けている…これらの事実から、ロストエイジのウミガメはフジツボ類の幼生が少ない海域で泳いでいるのではないか、と考えることができます。

ウミガメ自体は見つからないロストエイジですが、カメフジツボ類の幼生の分布を調べればロストエイジの生活海域もわかるかもしれない。

フジツボ類を生きたデータロガー、衛星発信機として使用することで、ウミガメの回遊行動解明ができるかもしれない。

この卒論での思いつきが今もカメフジツボの研究を続ける大きなモチベーションとなっています。

自分の恥を晒すだけですが、この研究ではフジツボは３タイプいる、ということで解析しました。しかし、皮膚に付くタイプはPlatylepas spp.ということで種判別できていませんでした。博士課程に進学し、フジツボの分類を学んでみると、当時３タイプ、と認識していたフジツボ類には全部で７種もいることが判明しました。フジツボ類を用いたウミガメの生態解明にはきちんとした種判別ができないといけない…そんなわけで博士課程に進学し、カメフジツボの仲間を含むオニフジツボ超科の分類学・分子系統学をテーマに研究を続けています。

この研究は毎度元気なウミガメを捕獲し、調査させていただいた沖縄県宜野座村漢那漁港の海人の皆さんの協力を得て実施しました。改めて感謝いたします。

Ryota Hayashi & Kazuki Tsuji

Spatial distribution of turtle barnacles on the green sea turtle, Chelonia mydas.

Ecological Research, 23(1), 121-125. 2008.

Cited by 30 papers (at 2021/1/21):

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Bressan MJ, de Lima TG, de Melo LF, Rigoglio NN, Lopes EQ (2020) The green turtle Chelonia mydas (linnaeus, 1758) (Testudines: Cheloniidae) body’s score from dead specimens in stranding on Cananeia-Iguape-Peruibe environmental protection area, South Sao Paulo Coast. Brazilian Journal of Animal and Environmental Research, 3(3), 1871-1884.

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Cheang CC, Tsang LM, Chu KH, Cheng I-J, Chan BKK (2013) Host-specific phenotypic plasticity of the turtle barnacle Chelonibia testudinaria: a widespread generalist rather than a specialist. PLoS ONE, 8(3), e57592.

Devin ML, Sadeghi P (2010) Barnacles on hawksbill sea turtles, Eretmochelys imbricata, in Hormoz Island, Iran. Zoology in the Middle East, 49(1), 45-48.

Doell SA, Connolly RM, Limpus CJ, Pearson RM, van de Merwe JP (2017) Using growth rates to estimate age of the sea turtle barnacle Chelonibia testudinaria. Marine Biology, 164(12), 222.

Ewers-Saucedo C, Arendt MD, Wares JP, Ritschoff D (2015) Growth, age structure and mating group size in an androdioecious barnacle: Implications for the evolution of dwarf males. Journal of Crustacean Biology, 35(2), 166-176.

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Fernandez-Leborans G (2013) A review of cnidarian epibionts on marine crustacea. Oceanological and Hydrobiological Studies, 42(3), 347-357.

Frick MG, Pfaller JB (2013) Sea turtle epibiosis. In: The Biology of Sea Turtles Volume III, Chapter: 15, CRC Press, Eds. Wyneken J, Lohmann KJ, Musick JA, pp. 399-426.

Fuller WJ, Broderick AC, Enever R, Thorne P, Godley BJ (2010) 'Motile homes: a comparison of the spatial distribution of epibiont communities on Mediterranean sea turtles'. Journal of Natural History, 44(27), 1743-1753.

Hamabata T, Nishizawa H, Kawazu I, Kameda K, Kamezaki N, Hikida T (2018) Stock composition of green turtles Chelonia mydas foraging in the Ryukyu Archipelago differs with size class. Marine Ecology Progress Series, 600, 151-163.

Hayashi R (2009) New host records of the turtle barnacle, Cylindrolepas sinica: a case study of sea turtle's behavior and their epibionts. Marine Biodiversity Records, 2, e165, 1-4.

Hayashi R (2012) Atlas of the barnacles on marine vertebrates in Japanese waters including taxonomical review of superfamily Coronuloidea (Cirripedia: Thoracica). Journal of the Marine Biological Association of the United Kingdom, 92(1), 107-127.

Hayashi R (2013) A checklist of the turtle and whale barnacles (Cirripedia: Thoracica: Coronuloidea). Journal of the Marine Biological Association of the United Kingdom, 93(1), 143-182.

Hayashi R, Nishizawa H (2015) Body size distribution demonstrates flexible habitat shift of green turtle (Chelonia mydas). Global Ecology and Conservation, 3, 115-120.

Ihwan MZ, Joseph J, Jamaan AS, Wahidah W, Marina H (2018) Occurrence of epibiont barnacles Chelonibia testudinaria on green turtle Chelonia mydas at Brunei Bay. International Journal of Zoological Research, 14, 43-48.

Jones TT, Van Houtan KS, Bostrom BL, Ostafichuk P, Mikkelsen J, Tezcan E, Carey M, Imlach B, Seminoff JA (2013) Calculating the ecological impacts of animal-borne instruments on aquatic organisms. Methods in Ecology and Evolution, 4(12), 1178-1186.

Lim KK, Hussein MAS, Palaniappan P (2021) Abundance, placement and sexual identity of the epizoic barnacle Chelonibia testudinaria relative to the size and species of host turtles in Mabul Island, Malaysia. Journal of the Marine Biological Association of the United Kingdom, 1-11. DOI: 10.1017/S0025315420001198.

Miranda EBP (2017) The plight of reptiles as ecological actors in the tropics. Frontiers in Ecology and Evolution, https://doi.org/10.3389/fevo.2017.00159.

Moreno‐Colom P, Ten S, Raga JA, Aznar FJ (2020) Spatial distribution and aggregation of Xenobalanus globicipitis on the flukes of striped dolphins, Stenella coeruleoalba: An indicator of host hydrodynamics? Marine Mammal Science, doi:10.1111/mms.12691

Munroe DM, Noda T (2009) Spatial pattern of rocky intertidal barnacle recruitment: comparison over multiple tidal levels and years. Journal of the Marine Biological Association of the United Kingdom, 89(2), 345-353.

Nájera-Hillman A, Bass JB, Buckham S (2012) Distribution patterns of the barnacle, Chelonibia testudinaria, on juvenile green turtles (Chelonia mydas) in Bahia Magdalena, Mexico. Revista Mexicana de Biodiversidad, 83, 1171-1179.

Nolte CR, Nel R, Pfaff MC (2020) Determining body condition of nesting loggerhead sea turtles (Caretta caretta) in the South-west Indian Ocean. Journal of the Marine Biological Association of the United Kingdom, 1-9. DOI: https://doi.org/10.1017/S0025315420000107

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Razaghian H, Esfandabad BS, Hesni MA, Shoushtari RV, Toranjzar H, Miller J (2019) Distribution patterns of epibiotic barnacles on the hawksbill turtle, Eretmochelys imbricata, nesting in Iran. Regional Studies in Marine Science, 27, 100527. doi:10.1016/j.rsma.2019.100527

Rivera SF, Vasselon V, Ballorain K, Carpentier A, Wetzel CE, Ector L, Bouchez A, Rimet F (2018) DNA metabarcoding and microscopic analyses of sea turtles biofilms: Complementary to understand turtle behavior. PLoS ONE, 13(4), e0195770.

Robinson NJ, Lazo-Wasem EA, Paladino FV, Zardus JD, Pinou T (2017) Assortative epibiosis of leatherback, olive ridley and green sea turtles in the Eastern Tropical Pacific. Journal of the Marine Biological Association of the United Kingdom, 97(6), 1233-1240.

Suárez-Morales E, Morales-Vela B, Padilla-Saldívar J, Silva-Briano M (2010) The copepod Balaenophilus manatorum (Ortíz, Lalana and Torres, 1992) (Harpacticoida), an epibiont of the Caribbean manatee. Journal of Natural History, 44(13-14), 847-859.