Delayed Recovery from Declines in the Population Densities and Species Richness of Intertidal Invertebrates Near Fukushima Daiichi Nuclear Power Plant

Toshihiro Horiguchi,Keita Kodama,Ik Joon Kang,Gen Kume

doi:10.1007/978-981-13-8218-5_6

Abstract

In June 2014, May and June 2015, and June 2016, we conducted quantitative quadrat surveys of sessile invertebrates at seven intertidal sites in Ibaraki, Fukushima, and Miyagi Prefectures, including the sites near Fukushima Daiichi Nuclear Power Plant (FNPP), to check whether species richness, population densities, and biomass had recovered from declines after the 2011 Tohoku earthquake, tsunami and nuclear disaster. Additionally, in April, July, August and September from 2012 to 2017, we monitored the population density and spawning behavior of rock shells (Thais clavigera) in the field near FNPP. Increases in species richness and population densities in the intertidal zone near FNPP were not found until at least 4–5 years had passed after the FNPP accident. Densities of and reproductive performance by T. clavigera populations near FNPP in 2017 remained below levels before the accident. Although invertebrate larval recruitment from remote areas to the intertidal zone near FNPP could have been expected, this was not clearly observed until 2016 at the earliest. Thus, it is possible that environmental factors inhibited invertebrate reproduction, recruitment or both in the intertidal zone near FNPP at least for 5 years.

Highlights

After the 2011 Tohoku earthquake (Mw 9.0) and tsunami on 11 March 2011(the Great East Japan Earthquake Disaster), three nuclear reactors melted down at Fukushima Daiichi Nuclear Power Plant (FNPP)
The similarity in species number between Tomioka and Okuma, both of which are located south of FNPP, was not very high and did not significantly differ from that between other sites in 2014, as determined by analysis of similarity (ANOSIM) of the biotic community structure represented by Bray-Curtis similarity among site groups [35] (P = 0.14; Figs. 6.2b and 6.5a)
They reported that the number of intertidal species decreased significantly with proximity to FNPP, and that no rock shell (T. clavigera) specimens were found near FNPP, from Hirono to Futaba Beach in 2012

Summary

Introduction

After the 2011 Tohoku earthquake (Mw 9.0) and tsunami on 11 March 2011(the Great East Japan Earthquake Disaster), three nuclear reactors melted down at Fukushima Daiichi Nuclear Power Plant (FNPP). The amount of radionuclide leakage from the FNPP accident was about one-tenth of that released by the 1986 Chernobyl NPP accident in Ukraine, where the total release of radionuclides was estimated to be 5,300 PBq, excluding radioactive noble gases (e.g., krypton-85, xenon-137 etc) [1]. The Tokyo Electric Power Company (FNPP owner and operator, TEPCO) estimated that 500 PBq of radioactive noble gases, 500 PBq of iodine-131 (131I), 10 PBq of cesium-134 (134Cs) and 10 PBq of 137Cs were released from FNPP to the atmosphere between March 12 and 31, 2011 [2] and that atmospheric fallout and direct leakage from the reactors released an additional 11 PBq of 131I, 3.5 PBq of 134Cs and 3.6 PBq of 137Cs into the marine environment between March 26 and September 30, 2011 [3]. Estimates of direct 137Cs leakage from FNPP into the sea range from 3 to 6 PBq [5–13]

Methods

Results

Conclusion