| General Information: |
| Title: | Acoustic monitoring data of anuran species inside and outside the evacuation zone of the Fukushima Daiichi power plant accident |
| Identifier: | ERDP-2020-12.1.2 |
| Abstract: |
The Fukushima Daiichi power plant accident led to large-scale and long-term evacuation zones in which usual land-use activities such as farming have been stopped. In particular, the loss of irrigated rice paddies is hypothesized to have seriously impacted freshwater biodiversity. In 2014, we started acoustic monitoring of frogs by using digital voice recorders in and around the evacuation zone. For the monitoring project, 52 and 57 monitoring sites were located within schoolyards (including those that had been converted into community centers) to examine the frog assemblages in the urban and rural landscapes of the region in 2014 and 2015, respectively. At each site, a digital voice recorder was installed during the period from May to July, and we recorded 10 min a day at night using a timed-recording mode. We divided the audio data into 20-sec segments and identified species recorded in segments sampled from late May to late June (partly in early July). We identified eight frog species from 1,962 audio segments in total (correspond to four days per year in principal). For each species, intensity of calling at four levels was also recorded as an index of abundance. We are continuing to monitor and intend to update the dataset with new observations hereafter. Our dataset will support scientists and experts in recognizing the status and dynamics of anuran assemblages in and around the evacuation zone and will contribute to the promotion of open science.
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| Keywords: |
- Agricultural landscape
- Satoyama
- Depopulation
- Rice paddy field
- Amphibian
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Involved Parties
| Data Set Owners: |
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Individual: | Akira Yoshioka |
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Organization: | Fukushima Branch, National Institute for Environmental Studies |
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Address: |
| 10-2 Fukasaku, |
| Miharu, Fukushima 963-7700 Japan |
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Email Address:
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Individual: | NIES Fukushima Terrestrial Ecosystem Monitoring Team |
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Organization: | National Institute for Environmental Studies |
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Address: |
| 16-2 Onogawa, |
| Tsukuba, Ibaraki 305-8506 Japan |
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Email Address:
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| Data Set Contacts: |
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Individual: | Akira Yoshioka |
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Organization: | Fukushima Branch, National Institute for Environmental Studies |
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Email Address:
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Individual: | Akira Yoshioka |
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Organization: | Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies |
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| Associated Parties: |
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Individual: | Akira Yoshioka |
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Organization: | Fukushima Branch, National Institute for Environmental Studies |
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Phone:
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Phone:
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Email Address:
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Individual: | Akira Yoshioka |
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Organization: | Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies |
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Email Address:
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Individual: | Noe Matsushima |
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Organization: | Faculty of Science, Toho University |
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Individual: | Shoma Jingu |
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Organization: | Graduate School of Life and Environmental Sciences, University of Tsukuba |
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Individual: | Nao Kumada |
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Organization: | Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies 3: Faculty of Science, Toho University |
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Individual: | Ryoko Yokota |
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Organization: | Freelance |
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Individual: | Ryoko Yokota |
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Organization: | Freelance |
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Individual: | Keita Fukasawa |
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Organization: | Fukushima Branch, National Institute for Environmental Studies |
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Individual: | Keita Fukasawa |
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Organization: | Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies |
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Data Set Characteristics
| Geographic Region: |
| Geographic Description: | the eastern part of Fukushima Prefecture, northeastern Japan |
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Bounding Coordinates:
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| West: | 141.00048 degrees
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| East: | 140.53747 degrees
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| North: | 37.80137 degrees
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| South: | 36.99588 degrees
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Sampling, Processing and Quality Control Methods
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Step by Step Procedures
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| Step 1: |
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Description:
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Study area
The study area and sampling sites are the same as those examined by Yoshioka et al. (2015) and Fukasawa et al. (2017). The area is located in the eastern part of Fukushima Prefecture, northeastern Japan and is enclosed within the following four sets of coordinates: (37.80137°N, 140.53747°E), (37.80136°N, 141.00048°E), (36.99588°N, 141.00048°E), and (36.99588°N, 140.53747°E). The study area contains the evacuation zone, which has been divided into three subzones since October 2013: a zone designated in preparation for lifting the evacuation order (≤20 mSv/year; Zone 1), a restricted residence area (20–50 mSv/year; Zone 2), and a difficult-to-return-to zone (>50 mSv/year; after five years, the air dose rate will be >20 mSv/year; Zone 3). Note that the areas of these subzones have been reviewed annually, and the evacuation order has been partly canceled. In 2014, we set up 52 monitoring sites inside and outside the evacuation zone (33 sites outside the evacuation zone, six sites in Zone 1, seven sites in Zone 2, and six sites in Zone 3). In 2015, we added new five monitoring sites to the sites in 2014 and set up 57 monitoring sites in total (33 sites outside the evacuation zone, eight sites in Zone 1, ten sites in Zone 2, and six sites in Zone 3). All monitoring sites were located within schoolyards (including those that had been converted into community centers) to minimize differences in the local site conditions and to examine the frog assemblages in the urban and rural landscapes that were heavily altered by the sudden halt in usual land management owing to the evacuation.
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| Step 2: |
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Description:
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Sampling
A digital voice recorder (DS-850, Olympus, Tokyo, Japan) was installed at each monitoring site during the period from May to July each year to record the songs of birds and the calls of frogs (see Fukasawa et al. [2017] for further details). In 2014, the recorders were set up at the sites until 21st May and collected after 8th July. In 2015, they were set up until 14th May and collected after 5th July. To record the calls of frogs at night according to the methods of Fukuyama et al. (2009), the recorders were used in a timed-recording mode from 20:00 to 20:10 (total 10 min) daily until the batteries were depleted. The recorders were fixed to tripod stands at a height of about 0.9 m. The recorded data were split into 20-sec segments in MP3 (124 kbps) format, which was treated as the minimum sample unit.
We manually identified frog species from the acoustic data. Because the number of segments was very large, we chose a subset of segments evenly spaced throughout the recording period: four segments per day for four days (May 25th, and June 5th, 15th, and 25th) per site per year, in principle. A total of 1,059 of the 76,020 recorded segments and 903 of the 73,260 recorded segments were chosen in 2014 and 2015, respectively (due to battery depletion of recorders, considerable amount of data could not be obtained on 25th June in 2015). Note that other checked segments were also added to the sample set; for example, segments from June 20th were sometimes checked when no acoustic files were obtained on June 25th as a result of dead batteries at some sites.
Frog species that appeared in each segment were identified and recorded as follows. First, authors experienced with ecological field work screened the segments in which frogs other than Japanese tree frogs (Hyla japonica) or bullfrogs (Lithobates catesbeiana) were calling. The calls of these species can be easily identified by field ecologists without expertise in frogs because their calls are simple, common, and conspicuous in eastern Japan. Then, the segments with calls of other frog species (including sounds judged to be possible frog calls) were checked and identified by frog experts, namely Dr. N. Matsushima, who is one of the authors and who has conducted research on frogs in the evacuation zones in 2012 (Matsushima et al., 2015), or employees of Regional Environmental Planning Inc. (Note that a part of segments was firstly checked by these experts without screening). For the segments that included calls that were difficult to identify at the species level, the authors, including Dr. Matsushima, made the final determination. The occurrence status of each frog species in each segment was ranked at one of four levels: multiple individuals chorusing (level A), a single individual or a few individuals calling conspicuously (level B), obscure or uncertain calling (level C), no discernable calling (level D). Note that levels A–C correspond to “present” and level D corresponds to “absent.” In addition, level C indicates an “uncertain” status.
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| Step 3: |
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Description:
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Potential confounding factors
Because weather condition can affect frog activities, the summary of the weather data on May 25th, and June 5th, 15th, 20th, and 25th at the Fukushima Local Meteorological Observatory was shown in Table 1. This data was obtained from website of Japan Meteorological Agency (http://www.data.jma.go.jp/obd/stats/etrn/index.php, accessed January 22, 2020).
In addition, to support considering confounding factors within schoolyards, information on spatial relationships between conspicuous water bodies (swimming pools and ponds) within schoolyards and exact locations of the digital recorders were listed in Supporting Information Table S1. This information was based on GSI tiles (https://maps.gsi.go.jp/development/ichiran.html) and Aerial photographs compiled by NTT GEOSPACE Corporation in addition to on-site confirmation around the recorders in 2014 and 2015. Note that representative locations of the schools were chosen for decimal latitude and longitude in “NIES_FTEM_ acousticfrog_pa.txt” following Fukasawa et al. (2017).
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| Step 4: |
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Description:
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Taxonomy and systematics
All species were identified by the authors or by professional experts as mentioned above. The scientific nomenclature used was in accordance with the Herpetological Society of Japan (2019).
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Data Set Usage Rights
| A License and usage rights
Users can download the datasets online under a Creative Commons attribution license, CC-BY 4.0 International (https://creativecommons.org/licenses/by/4.0/legalcode). |
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