Retrospective analysis of phytoplankton assemblages on the Iwate coast before and after the 2011 tsunami using cryopreserved DNA samples
2017; Wiley; Volume: 26; Issue: 2 Linguagem: Inglês
10.1111/fog.12203
ISSN1365-2419
AutoresYutaka Okumura, Shinnosuke Kaga,
Tópico(s)Isotope Analysis in Ecology
ResumoAbstract We assessed the feasibility of retrospectively reconstructing phytoplankton assemblages using next‐generation sequencing of the Psb A gene from cryopreserved DNA sampled from Ofunato and Yamada bays during the bloom season before (May–August 2010) and after (June–July 2011) the tsunami. The total number of phytoplankton species detected was >280 when the operational taxonomic unit ( OTU ) similarity threshold was set at 0.95. During the investigation, the sequences of Bacillariophyta, which are considered a suitable food for oysters, comprised >50% of the phytoplankton composition in both bays. Chlorophyta, mainly pico‐Prasinophyceae, which are too small for oysters, comprised 30%. Chroomonas sp. (ex Dinophysis acuminata ), Geminigera cryophila , Teleaulax amphioxeia , and Cryptophyta sp. ( CR ‐ MAL 11), which have relation to diarrhetic shellfish poisoning, were predominant in the Cryptophyta. Dinophysis spp. were the predominant Dinophyceae species, and cause diarrhetic shellfish poisoning. Because these phytoplankton species are unsuitable oyster food, we think that continuous monitoring of species is necessary. After the tsunami, the beta diversity using unweighted UniFrac in Ofunato Bay tended to differ from those before the tsunami. The ratio of predominant of Bacillariophyta species tended to decrease after the tsunami, the number of minor species detected in each taxon tended to increase. We infer that the temporary change was caused by the multiple environmental changes, such as the resuspension of cysts and phytoplankton deposited in the seabed, destroyed local sewage infrastructure, breakwater, and many oyster rafts.
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