Seawater Inundation from the 2011 Tohoku Tsunami Continues to Strongly Affect Soil Bacterial Communities 1 Year Later

Abstract

The effects of inundation caused by the 2011 Tohoku tsunami on soil bacterial communities in agricultural fields were evaluated. Bacterial communities were compared across three different types of soil, unflooded field (UF) soil, soil flooded for 2 weeks (short term (ST)), and soil flooded for 2 months (long term (LT)), using polymerase chain reaction-pyrosequencing of 16S rRNA genes. Acidobacteria were dominant in UF, with a relative abundance of approximately 35 %, and Proteobacteria dominated flooded soils (30-67 %). Hierarchical cluster analysis indicated that the community structure of soil bacteria in flooded soils (ST and LT) clearly differed from that in UF. Differences between LT and ST fields were rarely observed in terms of chemical properties and microbial community structure at the phylum level. However, sulfur-oxidizing bacteria (SOB) and nitrite-oxidizing bacteria (NOB) in LT tended to occur at high and low abundances, respectively. Halothiobacillus, a halotolerant SOB, was detected in all LT fields. Unexpectedly, a zeta-Proteobacteria, which had previously only been detected in marine environments, was detected in LT fields only. Our results demonstrate that the effects of the 2011 Tohoku tsunami on soil bacterial communities in agricultural fields may have lasted at least 1 year. Furthermore, SOB, NOB, and zeta-Proteobacteria may serve as indicators of the effects of seawater inundation on microorganisms.

Changes in Bacterial Communities in Seawater-Flooded Soil in the Four Years After the 2011 Tohoku Tsunami in Japan

“…The average air temperatures in the area during April of 2013, 2014 and 2015 were 9.0 • C, 9.3 • C and 10.6 • C, respectively. Soil samples were taken from unflooded field (UF; Field 1 (UF1)), fields flooded for two weeks (short term, ST; Field 2 (ST2)) and fields flooded for two months (long term, LT; Field 3 (LT3)), the same as in our previous study [7]. Sampling fields were continuously cultivated with the same rice variety (Japonica cv.…”

“…1 Details were given in Asano et al [7] 2 Rice bran was supplied for soil amendment a month prior (approximately 0.15 kg/m 2 ). 3 Soil dressing was performed six months prior.…”

“…We performed DNA extraction via the same method as in our previous study [7]. The total DNA was extracted from 500 mg soil using a FastDNA Spin Kit for Soil (MP Biomedicals, Santa Ana, CA, USA) according to the manufacturer's instructions.…”

“…Inundation also greatly affects the soil microbial communities. In our previous study, this effect was evaluated using molecular biological techniques [7]. A year after the Tohoku tsunami, the phyla Acidobacteria and Proteobacteria were dominant in unflooded and flooded soil, respectively.…”

Comparison of Bacterial Communities in Beach Sands along the East Coast of North Gyeongsang Province

“…바다의 쓰나미에 의하여 해수에 오염된 농지는 정상적 인 농지보다 Acidobacteria의 분포가 30% 높아졌다는 자료 해변모래의 미생물군집 비교 379 (Asano et al, 2013) Cyanobacteria 그룹은 하수처리장에서 주로 분포하며, Cyanobacteria 가 분비하는 이차대사산물은 세균의 생장을 저해하는 것으로 알 려져 있다 (Martins et al, 2011). Cyanobacteria의 이차대사산물 때문인지 Cyanobacteria가 93% 이상 우점하고 있는 영덕군 장 사해수욕장의 A4 모래와 포항시 흥환리의 C1 모래는 다른 지역 의 모래와 비교할 때 미생물의 다양도지수(Shannon index)가 감 소하였다 (Fig.…”