Mapping distribution of cysts of recent dinoflagellate and Cochlodinium polykrikoides using next-generation sequencing and morphological approaches in South Sea, Korea

Abstract

The total dinoflagellate cyst community and the cysts of Cochlodinium polykrikoides in the surface sediments of South Sea (Tongyeong coast), South Korea, were analysed using next-generation sequencing (NGS) and morphological approaches. Dinoflagellate cysts can be highly abundant (111–4,087 cysts g−1 dry weight) and have diverse species composition. A total of 35 taxa of dinoflagellate cysts representing 16 genera, 21 species (including four unconfirmed species), and 14 complex species were identified by NGS analysis. Cysts of Scrippsiella spp (mostly Scrippsiella trochoidea) were the most dominant and Polykrikos schwartzii, Pentapharsodinium dalei, Ensiculifera carinata, and Alexandrium catenella/tamarense were common. Thus, a combination of NGS and morphological analysis is effective for studying the cyst communities present in a given environment. Although C. polykrikoides developed massive blooms during 2013–2014, microscopy revealed low density of their cysts, whereas no cysts were detected by NGS. However, the vegetative C. polykrikoides not appeared during 2015–2017 in spite of the observation of C. polykrikoides cysts. This suggests that the C. polykrikoides blooms were not due to development of their cysts but to other factors such as currents transporting them to a marine environment suitable for their growth.

Comparative analysis of morphological and molecular approaches integrated into the study of the dinoflagellate biodiversity within the recently deposited Black Sea sediments – benefits and drawbacks

“…Our findings were in line with those indicated in other studies integrating molecular and morphological approaches, not only for resting cysts, but also for planktonic stages (e.g. Penna et al 2010 , Eiler et al 2013 , Zimmermann et al 2015 , Hirai et al 2017 , Jung et al 2018 , Perini et al 2019 ). It should also be acknowledged that the discrepancy between LM and NGS could be attributed to a number of different methodological biases – from sampling to database biases ( Matsuoka and Fukuyo 2000 , Zimmermann et al 2015 , Danovaro et al 2016 , Dzhembekova et al 2017 , Harvey et al 2017 , Smith et al 2017 ) (Table 3 ).…”

“…This is precisely the reason why the recent molecular methods have appeared to be gaining in popularity when studying microbial diversity in sediment samples, unlocking their potential for more sensitive detection and exact taxonomical identification ( Penna et al 2010 , Forster et al 2016 ). Besides, the morphological analysis applied together with the next-generation sequencing (NGS) tool is likely to generate greater discrimination power giving a better insight into the resting stage communities in a given environment ( Piredda et al 2017 , Jung et al 2018 ). The classical morphological method proves to be particularly effective in estimating the abundance of different morphotypes, whereas the obtained environmental high-throughput sequence data are considered appropriate for a better assessment and re-evaluation of the taxon composition of resting propagules in the benthos.…”

Zooming in on dynamics of marine microbial communities in the phycosphere of Akashiwo sanguinea (Dinophyta) blooms

“…The V4-V5 region of the 18S rDNA gene was targeted using the Illumina tagged forward (TAReuk454FWD1) and reverse (TAReukREV3) primers (Supplementary Table 11). Although we did not perform replicate experiments, we attempted to overcome the experimental bias and obtain more accurate results as follows; 1), intensive daily continuous monitoring in JBTMS, 2), in-door microcosm experiments to verify changes in endoparasitic dinoflagellates and NCLDVs in the field, and 3) three PCRs performed in distinct tubes, and then mixing of the PCR reaction products to obtain more accurate mNGS results [49]. The amplified products from the first PCR were individually purified using a QIAquick PCR purification kit (Qiagen, Hilden, Germany).…”

Study on distribution of Cysts of Harmful Algal Blooms-forming algae at Sohar Industrial Port, Sea of Oman

“…Al-Hashmi, S. Dobrestov & Kim, 2010). Among approximately 2000 dinoflagellates species existing in marine ecosystem, there are around 200 species that form resting cysts as part of their life cycle (Joyce et al, 2005;Jung et al, 2018). These life stages form an important component of the ecology and distribution of dinoflagellates (Ellegaard et al, 1994).…”

“…Cysts are accumulated in the sediments where they remain sustainable for long periods of time until suitable conditions are available to bloom. (Joyce et al, 2005;Jung et al, 2018;Satta et al, 2013).…”