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December 13, 2019
The University of Tokyo

Applying Ocean Observation Data from Sea Turtles to Seasonal Climate Predictions — Potential Development of an Ocean/Atmospheric Observation System using biologging

1. Key Points

To predict seasonal climate variations, it is important to capture variations in the sea surface temperatures of tropical oceans/seas, which greatly affect global/regional climate variations; however, there is a shortage of subsurface ocean observation data from marginal seas with complex topography.
In this study, we used subsurface ocean observation data from sea turtles tagged with devices to measure depth and temperature to improve the predictive accuracy of variations in sea surface temperatures a few months ahead.
This is the first time that observation data from animals, which are traditionally used for ecological surveys, have been utilized to improve seasonal climate predictions in the tropics.
Our results show the potential of this method for not only understanding the migration patterns of wild animals, but also for constructing an ocean/atmospheric observation system using biologging.


In a collaborative effort, Takeshi Doi, of the Application Laboratory of the Research Institute for Value-Added-Information Generation, Japan Agency for Marine–Earth Science and Technology (JAMSTEC), and researchers in the Behavior, Ecology and Observation Systems Group of the Atmosphere and Ocean Research Institute, University of Tokyo, have succeeded in increasing the accuracy of a new system that predicts sea surface temperatures a few months in advance by applying subsurface ocean observation data from sea turtles. Variations in tropical sea temperatures often lead to unusual seasonal climate variations (e.g. heat waves, warm winters, etc.) and marine resources. Thus, high-precision predictions are very important from both social and economic viewpoints, as they enable preemptive measures to me taken.

In order to generate high-precision predictions, it is crucial to accurately determine ocean surface/subsurface temperatures at the start of a simulation. However, there are currently not enough observation data from marginal seas, which are surrounded by landmasses and islands and often have complex bathymetry (i.e., seafloor topography). Therefore, scientists released five sea turtles after attaching devices which can record and transmit depth and water temperature data via satellite (Figure 1). Using these loggers (Satellite Relay Data Logger), they succeeded in recording the water temperature structure of the Arafura Sea, which is a tropical marginal sea for which observational data have been lacking (Figure 2). By incorporating this water temperature data into a seasonal prediction system, it was found that the predictive simulations of variations in water temperatures in nearby marine regions a few months later were greatly improved (Figure 3).

This study is the first in which the seasonal temperature structure of a tropical sea has been predicted by use of observational data from logger-tagged animals. This success could trigger new developments in ocean/climate simulation technologies and their predictions, as observation data from animals could become integrated into international observation systems, advancing our understanding of the complex interactions between large oceanic bodies and marginal seas. The results of this study were published in Frontiers in Marine Science on December 13 (JST).

Title: Impacts of temperature measurements from sea turtles on seasonal prediction around the Arafura Sea
Authors: Takeshi Doi 1*, Andrea Storto 2,3, Takuya Fukuoka 4, Hiroyuki Suganuma 5 and Katsufumi Sato 4
1. Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
2. Centre for Maritime Research and Experimentation (CMRE), La Spezia, Italy
3. Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna, Italy
4. Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
5. Everlasting Nature of Asia (ELNA), Yokohama, Japan

Figure 1

A olive ridley turtle is returning into the sea. A devices which can record and transmit depth-temperature profiles via satellite was deployed on the carapace. After device transmits data for several months, the device will be detached from the carapace within two years. A photo was taken in June 2019 at a nesting beach in West Papua, Indonesia. The fieldwork was conducted with permission from Dinas Perikanan, Pemerinta Kabupaten Tambrauw.

Figure 1

Fig 1. (a) Migration routes of the five olive ridley turtles from June to October 2017. Each color indicates each individual, and color circles indicate the position where depth-temperature profiles were transmitted.
Fig 2. (b) Depth-temperature profiles obtained from turtles in the region of (133°–138°E, 10°–5°S) during the period from July 27 to August 6, 2017. The colors are the same as (a).

Figure 2

Fig 3. SST anomaly in November 2017 from (a) the observations, (b) the original forecast issued on August 1, 2017, and (c) the forecast after assimilating the sea turtles’ measurements issued on the same date (℃)


(For this study)
Takeshi Doi, Scientist, Application Laboratory, JAMSTEC
Katsufumi Sato, Professor, Atmosphere and Ocean Research Institute, The University of Tokyo
(For press release)
Public Relations Section, Marine Science and Technology Strategy Department , JAMSTEC
Public Relations Office, Atmosphere and Ocean Research Institute, The University of Tokyo
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