講演・口頭発表等

国際会議
2019年11月23日

STUDIES ON ECOLOGICAL ROLE AND EFFECT OF LABYRINTHULIDS IN MARINE ENVIRONMENT (LABYRINTHULEA, STRAMENOPILES)

International Symposium on Aquatic Metagenomics 2019
  • Yoko Hamamoto
  • ,
  • Takanori Shono
  • ,
  • Ryosuke Nakai
  • ,
  • Mayumi Ueda
  • ,
  • Satoshi Nagai
  • ,
  • Daiske Honda

記述言語
英語
会議種別
ポスター発表
主催者
International Symposium on Aquatic Metagenomics 2019 Secretariat
開催地
Kitasato University

Thraustochytrids inhabit the ocean all over the world and they have been recognized as important eukaryotic decomposers in the marine ecosystem. Our recent studies revealed a newly recognized pathway in the grazing food chain in the marine ecosystem for thraustochytrids, especially in Aplanochytrium. For example, Aplanochytrium strains obtain nutrients by consuming living diatoms (Hamamoto & Honda, 2019, PLoS ONE 14: e0208941). Also, Aplanochytrium is detected in the gut of zooplankton copepods, suggesting undetected predator–prey relationships in marine ecosystems (Hirai, Hamamoto et al., 2018, Plankton & Benthos Research, 13: 75–82). Here, we investigate their biomass to understand the ecological impact of Aplanochytrium and also thraustochytrids. First, we collected the environmental sample at Osaka Bay, Japan and cell number of Aplanochytrium in the seawater were estimated by quantitative PCR (qPCR) method. We next evaluated Illumina MiSeq-based metagenomic analyses using these samples. In these results, the number of the Aplanochytrium cells was estimated to be larger than in the previous quantitative methods and were particularly abundant among the taxa identified as thraustochytrids. Finally, we considered the carbon flow among major components of food web in Osaka Bay to assess the trophic roles of thraustochytrids. Based on the biomass of thraustochytrids, we evaluated the effect of thraustochytrids on phytoplankton and the effect on zooplankton. Compared with the previous studies on copepod diets (Yang et al., 2009, Journal of Plankton Research, 31: 647–659), it is speculated that thraustochytrids may also supply almost equal amount of the carbon to copepods which is known for nanoflagelates.