New Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa

South African coelacanths, Latimeria chalumnae, were intensively studied using submersibles in the Comoros Islands before recent progress in deep-diving techniques led to the discovery of coelacanths living at shallower depths off Sodwana Bay, South Africa, which were then studied by divers in close...

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Autores principales:	Jiro Sakaue, Kazuhiko Maeda, Michael J. Miller, Ryuichi Sakai, Koh-ichi Tahara, Hideki Abe, Kazuya Maeda, Hitoshi Ida
Formato:	article
Lenguaje:	EN
Publicado:	Frontiers Media S.A. 2021
Materias:	coelacanth Latimeria chalumnae dorsal fin Sodwana Bay set cameras trimix-diving Science Q General. Including nature conservation, geographical distribution QH1-199.5
Acceso en línea:	https://doaj.org/article/7fe484596f6e4cd3a31d5f5db900664a
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spelling	oai:doaj.org-article:7fe484596f6e4cd3a31d5f5db900664a2021-11-10T08:34:25ZNew Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa2296-774510.3389/fmars.2021.755275https://doaj.org/article/7fe484596f6e4cd3a31d5f5db900664a2021-11-01T00:00:00Zhttps://www.frontiersin.org/articles/10.3389/fmars.2021.755275/fullhttps://doaj.org/toc/2296-7745South African coelacanths, Latimeria chalumnae, were intensively studied using submersibles in the Comoros Islands before recent progress in deep-diving techniques led to the discovery of coelacanths living at shallower depths off Sodwana Bay, South Africa, which were then studied by divers in close encounters or from underwater vehicles. However, all previous observations were made under intense human influence, so the “natural” behaviors of coelacanths have never been observed. Here we sought to record the natural behaviors of coelacanths by minimizing anthropogenic influences using trimix-gas diving and remote recording techniques. We thus set fixed camera and current/temperature recorders at 98 and 113 m to monitor the behaviors of fishes and oceanographic parameters over a 6-day period. Time-lapse video observations succeeded to record one coelacanth that entered the cave during the coldest-water period, two sand tiger sharks, and many other smaller fishes entering a cave. An extensive analysis of the footage led to an interesting discovery that the first dorsal fin angle of the coelacanth corelated with the presence-or-absence of a large shark that frequently passed through the cave. When no shark was present, the coelacanth’s dorsal fin was folded ∼3/4 of the time, but when the shark entered the cave, its dorsal fin was unfolded > 95% of the time, while no such reactions were observed with other observed fishes. The erected coelacanth first dorsal fin posture is an important part of the iconic symbol of these ancient fish, but it may be reflecting stressful situations such as responses to potential predators. Our observation clearly showed that the dorsal fin is in a folded position during a steady relaxed state of the fish and it can be unfolded in response to external stimuli. Use of non-biased observation systems is strongly recommended when observing the natural behavior of coelacanths.Jiro SakaueKazuhiko MaedaMichael J. MillerRyuichi SakaiKoh-ichi TaharaHideki AbeKazuya MaedaHitoshi IdaFrontiers Media S.A.articlecoelacanthLatimeria chalumnaedorsal finSodwana Bayset camerastrimix-divingScienceQGeneral. Including nature conservation, geographical distributionQH1-199.5ENFrontiers in Marine Science, Vol 8 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	coelacanth Latimeria chalumnae dorsal fin Sodwana Bay set cameras trimix-diving Science Q General. Including nature conservation, geographical distribution QH1-199.5
spellingShingle	coelacanth Latimeria chalumnae dorsal fin Sodwana Bay set cameras trimix-diving Science Q General. Including nature conservation, geographical distribution QH1-199.5 Jiro Sakaue Kazuhiko Maeda Michael J. Miller Ryuichi Sakai Koh-ichi Tahara Hideki Abe Kazuya Maeda Hitoshi Ida New Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa
description	South African coelacanths, Latimeria chalumnae, were intensively studied using submersibles in the Comoros Islands before recent progress in deep-diving techniques led to the discovery of coelacanths living at shallower depths off Sodwana Bay, South Africa, which were then studied by divers in close encounters or from underwater vehicles. However, all previous observations were made under intense human influence, so the “natural” behaviors of coelacanths have never been observed. Here we sought to record the natural behaviors of coelacanths by minimizing anthropogenic influences using trimix-gas diving and remote recording techniques. We thus set fixed camera and current/temperature recorders at 98 and 113 m to monitor the behaviors of fishes and oceanographic parameters over a 6-day period. Time-lapse video observations succeeded to record one coelacanth that entered the cave during the coldest-water period, two sand tiger sharks, and many other smaller fishes entering a cave. An extensive analysis of the footage led to an interesting discovery that the first dorsal fin angle of the coelacanth corelated with the presence-or-absence of a large shark that frequently passed through the cave. When no shark was present, the coelacanth’s dorsal fin was folded ∼3/4 of the time, but when the shark entered the cave, its dorsal fin was unfolded > 95% of the time, while no such reactions were observed with other observed fishes. The erected coelacanth first dorsal fin posture is an important part of the iconic symbol of these ancient fish, but it may be reflecting stressful situations such as responses to potential predators. Our observation clearly showed that the dorsal fin is in a folded position during a steady relaxed state of the fish and it can be unfolded in response to external stimuli. Use of non-biased observation systems is strongly recommended when observing the natural behavior of coelacanths.
format	article
author	Jiro Sakaue Kazuhiko Maeda Michael J. Miller Ryuichi Sakai Koh-ichi Tahara Hideki Abe Kazuya Maeda Hitoshi Ida
author_facet	Jiro Sakaue Kazuhiko Maeda Michael J. Miller Ryuichi Sakai Koh-ichi Tahara Hideki Abe Kazuya Maeda Hitoshi Ida
author_sort	Jiro Sakaue
title	New Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa
title_short	New Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa
title_full	New Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa
title_fullStr	New Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa
title_full_unstemmed	New Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa
title_sort	new insights about the behavioral ecology of the coelacanth latimeria chalumnae video recorded in the absence of humans off south africa
publisher	Frontiers Media S.A.
publishDate	2021
url	https://doaj.org/article/7fe484596f6e4cd3a31d5f5db900664a
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New Insights About the Behavioral Ecology of the Coelacanth Latimeria chalumnae Video Recorded in the Absence of Humans Off South Africa

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