A detailed observation of a whale carcass deployed in Sagami Bay, Japan

The deep sea is generally considered an oligotrophic environment with an average total organic carbon content in sediments of 0.5% by weight. Massive sporadic inputs of organic material into the deep sea, such as the recent oil spill in the Gulf of Mexico or the influx of terrigenous products transported by the tsunami in Japan, must have had a significant impact on the surrounding environments.
Deadfalls of large nektonic animals are the more typical manner by which pulses of organic material reach the deep-sea floor. Whales contribute a large amount of organic material posthumously. The sediments directly underlying a sunken whale carcass experience an initial pulse of labile organic material equivalent to 2,000 years of background organic carbon flux. Little is known, however, about the decomposition process of sunken whale carcasses. Rare examples include two whale carcasses deployed off California. Aggregations of hagfish and some other scavengers have removed whale soft tissue at high rates (40–60 kg d-1).
Here we conducted an in situ deployment of a stranded sperm whale carcass in the bathyal zone at a depth of 489 m in Sagami Bay, Japan. Three diving cruises were conducted using two human occupied vehicles (HOVs) Triton and Deep Rover or the remotely operated vehicle (ROV) Hyper-Dolphin. Two time-lapse video cameras, one time-lapse still camera, two sediment traps, three current profilers, 5 thermometers and one REDOX sensor were deployed around the carcass for three month. More than 90% of soft tissues of the whale were consumed within three months of deployment and the estimated consumption rate was comparable to that shown in the previous studies. Results of time-lapse image analyses and physico-chemical measurements will be shown.

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First Name: 
Yoshihiro
Last Name: 
Fujiwara
Telephone: 
+81 46 867 9561
Affiliation: 
JAMSTEC
First Name: 
Masaru
Last Name: 
Kawato
Affiliation: 
JAMSTEC
First Name: 
Yasuo
Last Name: 
Furushima
Affiliation: 
JAMSTEC
First Name: 
Jacopo
Last Name: 
Aguzzi
Affiliation: 
ICM-CSIC
First Name: 
Adrian
Last Name: 
Bodenmann
Affiliation: 
Institute of Industrial Science, the University of Tokyo
First Name: 
Blair
Last Name: 
Thornton
Affiliation: 
Institute of Industrial Science, the University of Tokyo
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Ecological Interactions
Abstract ID: 
CBE5-188