Copepod Biodiversity in Japan: Recent Advances in Japanese Copepodology

Ohtsuka, Susumu; Nishida, Shuhei

doi:10.1007/978-4-431-56432-4_22

Cited by 7 publications

(2 citation statements)

References 173 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The assumption that O. davisae has been transferred from the Black Sea to the Sea of Marmara can be confirmed by the coincidence of morphological and physiological characteristics of females; in addition, the same population structure of this species was synchronically studied in both seas (Isinibilir et al, 2016). Since O. davisae did not occur in European seas until 2003 (Saiz et al, 2003), one can suggest that the species was transported into the Black Sea with ship ballast waters, probably from southeastern Asia (Gubanova et al, 2014), where this copepod is prevalent (Ohtsuka and Nishida, 2017). Despite the fact that O. davisae is a warm-water species (Uye and Sano, 1995), it has successfully acclimatized in the cold Black Sea due to its ability to survive low temperatures in the state of fertilized quasi-diapausing females (Hubareva and Svetlichny, 2013;Svetlichny et al, 2016), which can produce a new generation after the spring rise in temperature.…”

Section: Introductionmentioning

confidence: 74%

Population dynamics of the copepod invader Oithona davisae in the Black Sea

Svetlichny¹,

Hubareva²,

İşinibilir³

2018

Turk J Zool

View full text Add to dashboard Cite

During 2013-2016 in Sevastopol Bay, seasonal and interannual dynamics of the population density, age and sex composition, fecundity, and mortality of males and females of O. davisae were studied. A maximum population number (up to 554 ind × 10 3 m-3) was registered at the end of summer-end of autumn. In this period, the nauplii and early copepodite stages constituted up to 95% of the O. davisae population. During 1-2.5 cold winter-spring months, the population consisted only of females, who were not numerous. The phase of latent population development was recorded from April until July-August, with a high share of ovigerous females, maximum clutch size, and high egg production rate but low population density, which may be due to predator pressure from lobate ctenophores. The average share of adult males amounted to 32% at the end of spring and 27% at the beginning of winter, while the share of dead males reached maximum values (20.7%) during the winter degradation period for the population. On the basis of the studied successions of the population's developmental stages, from ovigerous females through nauplii and early copepodites to adults, the number of generations produced by O. davisae during the reproductive period (10-11) was determined.

show abstract

Section: Introductionmentioning

confidence: 74%

Population dynamics of the copepod invader Oithona davisae in the Black Sea

Svetlichny¹,

Hubareva²,

İşinibilir³

2018

Turk J Zool

View full text Add to dashboard Cite

show abstract

“…The variable ocean environment is one of the main factors supporting marine diversity including zooplankton in Japanese waters, and the molecular approach is a useful tool to solve difficulties in species identification ( Fujikura et al, 2010 ; Ohtsuka & Nishida, 2017 ). In this study, we focused on dominant zooplankton species collected from six areas around Japan covering subarctic to subtropical regions.…”

Section: Discussionmentioning

confidence: 99%

Improving taxonomic classification of marine zooplankton by molecular approach: registration of taxonomically verified 18S and 28S rRNA gene sequences

Watanabe

Hirai

Sildever

et al. 2023

PeerJ

View full text Add to dashboard Cite

Background Zooplankton plays an important role in the marine ecosystem. A high level of taxonomic expertise is necessary for accurate species identification based on morphological characteristics. As an alternative method to morphological classification, we focused on a molecular approach using 18S and 28S ribosomal RNA (rRNA) gene sequences. This study investigates how the accuracy of species identification by metabarcoding improves when taxonomically verified sequences of dominant zooplankton species are added to the public database. The improvement was tested by using natural zooplankton samples. Methods rRNA gene sequences were obtained from dominant zooplankton species from six sea areas around Japan and registered in the public database for improving the accuracy of taxonomic classifications. Two reference databases with and without newly registered sequences were created. Comparison of detected OTUs associated with single species between the two references was done using field-collected zooplankton samples from the Sea of Okhotsk for metabarcoding analysis to verify whether or not the newly registered sequences improved the accuracy of taxonomic classifications. Results A total of 166 sequences in 96 species based on the 18S marker and 165 sequences in 95 species based on the 28S marker belonging to Arthropoda (mostly Copepoda) and Chaetognatha were registered in the public database. The newly registered sequences were mainly composed of small non-calanoid copepods, such as species belonging to Oithona and Oncaea. Based on the metabarcoding analysis of field samples, a total of 18 out of 92 OTUs were identified at the species level based on newly registered sequences in the data obtained by the 18S marker. Based on the 28S marker, 42 out of 89 OTUs were classified at the species level based on taxonomically verified sequences. Thanks to the newly registered sequences, the number of OTUs associated with a single species based on the 18S marker increased by 16% in total and by 10% per sample. Based on the 28S marker, the number of OTUs associated with a single species increased by 39% in total and by 15% per sample. The improved accuracy of species identification was confirmed by comparing different sequences obtained from the same species. The newly registered sequences had higher similarity values (mean >0.003) than the pre-existing sequences based on both rRNA genes. These OTUs were identified at the species level based on sequences not only present in the Sea of Okhotsk but also in other areas. Discussion The results of the registration of new taxonomically verified sequences and the subsequent comparison of databases based on metabarcoding data of natural zooplankton samples clearly showed an increase in accuracy in species identification. Continuous registration of sequence data covering various environmental conditions is necessary for further improvement of metabarcoding analysis of zooplankton for monitoring marine ecosystems.

show abstract