- 著者
- Justus O. Omweri Keita W. Suzuki Shouji Houki Edouard Lavergne Hiroshi Inoue Hisashi Yokoyama Yoh Yamashita
- 出版者
- The Plankton Society of Japan, The Japanese Association of Benthology
- 雑誌
- Plankton and Benthos Research (ISSN:18808247)
- 巻号頁・発行日
- vol.16, no.4, pp.278-291, 2021-11-17 (Released:2021-11-18)
- 参考文献数
- 64
The euryhaline mysid Neomysis awatschensis occurs widely in estuaries and brackish lakes in Japan. Although N. awatschensis may serve as an essential energy channel to higher trophic levels, its feeding ecology has been studied only in sheltered and desalinated Lake Kasumigaura. To determine major food sources for N. awatschensis, monthly sampling was conducted during the day along the microtidal Yura River estuary from March 2014 to July 2015. Additional sampling was conducted in May 2019 to assess diel vertical migration in relation to feeding. Microscopic examinations revealed that benthic diatoms (e.g. Bacillaria paxillifer and Navicula spp.) dominated in the stomach irrespective of developmental stage, diel cycle, or season. Stable carbon and nitrogen isotope ratios in N. awatschensis and its potential food sources indicated great contributions to the diet of N. awatschensis from benthic microalgae (mainly benthic diatoms) in 2014 and from particulate organic matter (mainly phytoplankton) in 2015. Although N. awatschensis always concentrated close to the bottom in 2019, diel vertical migration might have happened in 2015, when fresh water occupied the whole estuary possibly due to river mouth clogging. Under the stagnant and oligohaline conditions, N. awatschensis could have swum up into the water column and fed on phytoplankton at night in 2015. This hypothesis may resolve the apparent contradiction between the microscopy and stable isotope analysis in 2015. In the Yura River estuary, N. awatschensis feeds primarily on benthic diatoms, although it can utilize phytoplankton flexibly in response to prevailing environmental conditions.
- 著者
- Ryoji Suzuki Shouji Houki Kenji Ito Hiroyuki Shibaike
- 出版者
- The Plankton Society of Japan, The Japanese Association of Benthology
- 雑誌
- Plankton and Benthos Research (ISSN:18808247)
- 巻号頁・発行日
- vol.18, no.4, pp.206-213, 2023-11-27 (Released:2023-11-30)
- 参考文献数
- 21
An environmental DNA (eDNA) detection technique using TaqMan qPCR and LAMP analysis was developed for the Asian clam Corbicula fluminea, which is causing alarm in Japan and worldwide as an invasive alien species. The qPCR primer and probe designed in this study specifically amplified C. fluminea DNA, but did not amplify C. sandai or C. japonica DNA, both native Japanese species. In contrast, LAMP analysis showed that C. sandai DNA also reacted, but with a delay after the amplification of C. fluminea DNA, and it was possible to specifically detect C. fluminea DNA by setting the LAMP analysis time to 30 min. Field surveys at three study sites with different habitat conditions for C. fluminea showed that eDNA detection using qPCR/LAMP analyses were consistent with C. fluminea distribution. The applicability of a simple filtration and concentration method for eDNA using glass fibers in suspension (SGF method) was verified, and the SGF method had a higher eDNA recovery capacity than the conventional aspiration method using glass fiber filter paper. eDNA extraction using the SGF method and eDNA analysis using qPCR/LAMP may be useful for qualitative and simple habitat estimation of C. fluminea in poor water quality environments.