カスタムメイドのバイオロギング装置を用いた実験により、イルカの遊泳とエネルギー要求に関する新たな知見が得られた Experiments with custom-made biologging devices offer new insight into dolphin swimming and energy requirements
2022-10-22 ミシガン大学
A dolphin wearing a biologging tag. The tag is attached to the animal using suction cups, and can measure the sounds the animal hears, sound the animal uses to communicate and echolocate, as well as the motion of the animal. Image credit: Alex Shorter, University of Michigan
ミシガン大学のエンジニアは、ドルフィンクエスト・オアフ島の海洋哺乳類の専門家と共同で、海洋哺乳類の保護活動を強化するために、動きや行動を監視する海洋哺乳類用のウェアラブルセンサーの開発を主導してきました。
イルカやその他の海洋生物は、気候変動、乱獲、船舶、建設、石油探査、海軍のソナー活動などによる騒音汚染など、人間の攪乱によってその生息環境に影響を受けています。このような撹乱は、魚の捕食や社交といった動物の重要な行動を阻害する可能性がありますが、動物は水中で生活しているため、撹乱の測定は困難です。
人間が使用するフィットネストラッカーに非常によく似たデバイス(バイオロギングタグ)が生物学の研究に使用されていますが、水泳のエネルギーコストを見積もることは困難でした。今回、ロガーヘッド社、マサチューセッツ州ウッズホール海洋研究所、デンマークのオーフス大学と共同で製作したカスタムバイオロギングタグにより、ミシガン州のエンジニアは、動物が泳ぐ際の数千回のストロークの動きを測定することができるようになりました。
<関連情報>
- https://news.umich.edu/new-activity-trackers-for-dolphin-conservation/
- https://journals.biologists.com/jeb/article-abstract/225/22/jeb244599/285140/Tag-based-estimates-of-bottlenose-dolphin-swimming
タグを用いたバンドウイルカの遊泳行動とエネルギー代謝の推定 Tag-based estimates of bottlenose dolphin swimming behavior and energetics
Joaquin T. Gabaldon,Ding Zhang,Julie Rocho-Levine,Michael J. Moore,Julie van der Hoop,Kira Barton,K. Alex Shorter
Journal of Experimental Biology Published:30 NOVEMBER 2022
DOI:https://doi.org/10.1242/jeb.244599
ABSTRACT
Current estimates of marine mammal hydrodynamic forces tend to be made using camera-based kinematic data for a limited number of fluke strokes during a prescribed swimming task. In contrast, biologging tag data yield kinematic measurements from thousands of strokes, enabling new insights into swimming behavior and mechanics. However, there have been limited tag-based estimates of mechanical work and power. In this work, we investigated bottlenose dolphin (Tursiops truncatus) swimming behavior using tag-measured kinematics and a hydrodynamic model to estimate propulsive power, work and cost of transport. Movement data were collected from six animals during prescribed straight-line swimming trials to investigate swimming mechanics over a range of sustained speeds (1.9–6.1 m s-1). Propulsive power ranged from 66 W to 3.8 kW over 282 total trials. During the lap trials, the dolphins swam at depths that mitigated wave drag, reducing overall drag throughout these mid- to high-speed tasks. Data were also collected from four individuals during undirected daytime (08:30–18:00 h) swimming to examine how self-selected movement strategies are used to modulate energetic efficiency and effort. Overall, self-selected swimming speeds (individual means ranging from 1.0 to 1.96 m s-1) tended to minimize cost of transport, and were on the lower range of animal-preferred speeds reported in literature. The results indicate that these dolphins moderate propulsive effort and efficiency through a combination of speed and depth regulation. This work provides new insights into dolphin swimming behavior in both prescribed tasks and self-selected swimming, and presents a path forward for continuous estimates of mechanical work and power from wild animals.
