著者

Hiroshi Ueda Hiroshi Itoh Junya Hirai Kiyotaka Hidaka

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.17, no.2, pp.221-230, 2022-05-30 (Released:2022-05-31)

参考文献数

22

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The Paracalanus parvus (Claus, 1863) species complex is a common marine calanoid copepod found in the world’s oceans. Recent genetic analyses of its specimens from the world oceans revealed that the complex in the western North Pacific consists of three species, i.e., P. indicus Wolfenden, 1905, P. tropicus Andronov, 1977 and an undescribed species. We assign the last one to be Paracalanus orientalis n. sp. by comparing it with previous morphological descriptions of related species. Both sexes of the new species are fully described based on genetically identified specimens from the surface layer of the south of Japan. The new species can be reliably distinguished from P. indicus and P. tropicus by the hunchback shape of the female if it is clearly present. Among the three species, the high length:width ratio of the third exopod segment of leg 4 is also characteristic of the new species, which would be identifiable, in most cases, by having a ratio of 5.4 or more.

著者

Yuki Hamaguchi Akane Iida Jun Nishikawa Euichi Hirose

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.3, pp.221-227, 2021-08-06 (Released:2021-07-31)

参考文献数

20

被引用文献数

2

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Mastigias papua, known as the golden (or spotted) jellyfish, is an epipelagic jellyfish widely distributed in the warm waters of the West Pacific. This jellyfish has a brownish body, owing to zooxanthellae, and white spots. We measured the maximum force to pierce the umbrella, which averaged 94–144 mm in diameter, to evaluate the hardness of M. papua, and returned a range of 0.14–0.45 N. Correlation analyses indicate that when the M. papua medusa grows (i.e., becomes heavier), the umbrella becomes larger in diameter, as well as thicker and harder within the size range we examined. However, a significant relationship between the hardness of the umbrellar apex and the thickness of the umbrella was not obtained. White spots are comprised of loose aggregates of mesogleal cells containing reflective granules. Since the white spots and the transparent parts were not significantly different in hardness, the spots were unlikely to strengthen the umbrella. The primary function of the spots may be the shading of solar radiation. Most of the zooxanthellae are located in mesogleal cells, and often beneath the exumbrellar epidermis. Therefore, light shading by white spots may be unnecessary for the zooxanthellae in mesogleal cells.

著者

Takumi Teraoka Kanako Amei Yutaka Fukai Kohei Matsuno Hiroji Onishi Atsushi Ooki Tetsuya Takatsu Atsushi Yamaguchi

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.17, no.4, pp.369-382, 2022-11-30 (Released:2022-11-30)

参考文献数

67

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Knowledge about the taxonomic and size composition of mesozooplankton is of critical importance for both fisheries and oceanography. In this study, we collected an annual time series of mesozooplankton samples in Funka Bay and analysed them using ZooScan to reveal the seasonal changes in taxonomic and size structure. Both zooplankton abundance and biovolume peaked in April and were dominated by an appendicularian Oikopleura labradoriensis which has been reported as being are being important food source for flatfish larvae. Furthermore, Noctiluca scintillans was abundant from September to December. The occurrence of this species may be related to the recent increase in the transport of Tsugaru Warm Current water into the bay. The Normalized Biomass Size Spectra (NBSS) was significant for 16 of 21 sampling dates. Insignificant NBSS, with an extremely flat slope, was observed for January–March. Significant NBSS with a flat slope was observed in April. Then, the relatively steep slopes of the NBSS were the case from mid-May to December. These seasonal changes in the slope of NBSS suggest that the energy transfer efficiency for higher trophic levels varied seasonally. The observed slopes of the NBSS in Funka Bay ranged from −1.09 to −0.30, which was flatter than the theoretical value (−1) and the previously reported values for the oceanic region of the western North Pacific. This suggests that the energy transfer efficiency to organisms at higher trophic levels in the Funka Bay is higher than in the adjacent oceanic region.

著者

Ikuhiko Kin Naoto Jimi Susumu Ohtsuka Gaku Mizuno Toru Nakamura Yoichi Maekawa Yuichi Oba

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.17, no.2, pp.214-220, 2022-05-30 (Released:2022-05-31)

参考文献数

37

被引用文献数

1

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The polychaete genus Tomopteris is an important component of the zooplankton and is also known for its communication using bioluminescence. However, there have been few studies about the species diversity and ecology of Tomopteris because of taxonomic and handling difficulties resulting from the fragility of their bodies. In this study, we performed DNA barcoding and species delimitation analysis to better understand the species diversity of Tomopteris using 17 specimens collected on a research cruise conducted off the eastern Kii Peninsula, Japan. Due to damage to the detailed morphological characteristics necessary for identifications based on the current taxonomy, none of the specimens was morphologically identifiable at the species level. The analyses of the mitochondrial cytochrome c oxidase subunit I (COI) and nuclear large ribosomal subunit (28S) RNA gene sequences revealed 7–8 molecularly delimited species among them, which was greater than the number of species currently recognized in Japan. These results suggest that the traditional morphology-based taxonomy overlooks the taxonomic complexity of Tomopteris, thus a combinatory analysis of both morphology and DNA barcoding will be desirable for assessing the true species biodiversity of Tomopteris.

著者

Miles I Peterson Kei Chloe Tan Allen Collins Satoshi Kitano Yasushi Kusuoka Takahito G Suzuki Masao Migita Iffah Iesa Stacy Pirro Dhugal Lindsay Cheryl Lewis Ames

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.17, no.2, pp.231-248, 2022-05-30 (Released:2022-05-31)

参考文献数

39

被引用文献数

1

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Freshwater jellyfish comprising the genus Craspedacusta are thought to have originated in the Yangtze River, China and have since spread to all continents except Antarctica. In this study, jellyfish were collected from Haruta-ike, an artificial pond in Chikuma City, Nagano (Japan). Medusae were identified as Craspedacusta sowerbii using morphological and molecular techniques. Despite the existence of Haruta-ike since prior to the Edo era (ca. 1603), this work represents the first published record of freshwater jellyfish in this pond. Herein, we report on the novel swimming behavior documented in this population, which includes both male and female C. sowerbii medusae. Additionally, we discuss the life cycle of polyps reared in culture from Machikane-ike, a pond in Osaka for which we have published the first complete mitochondrial genome of C. sowerbii from Japan. Finally, we report on the morphology and life cycle of the rare Japanese freshwater jellyfish Astrohydra japonica in Lake Biwa (Shiga), documented only a few times in the 40 years since its original discovery in Japan. The results of our robust phylogenetic analysis using the 16S rRNA gene and COI markers of C. sowerbii and A. japonica in this study and for C. sowerbii material from Singapore, together with all publicly available sequences for these markers for the two species worldwide, revealed two major C. sowerbii clades suggesting the Nagano and Osaka populations originated from two distinct introduction events. This collaborative research was made possible through international collaborations among multiple research facilities, museums and one wildlife reserve.

著者

Roberta Beltrão Michiko Monde Takayuki Mine Hiroshi Ueda

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.2, pp.63-73, 2023-05-31 (Released:2023-05-30)

参考文献数

45

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Ariake Bay has Japan’s biggest nori seaweed farming field in the innermost part and has suffered from environmental degradation since the late 1990s. To elucidate the seasonal patterns in the copepod community structure in the inner bay, we examined monthly plankton-net samples collected in the top 2-m layer at 11 stations for 5 years from April 2002 to March 2007. Of the 11 stations, 7 were at the high-turbidity site (HTS) representing the nori farming field and 4 in the offshore low-turbidity site (LTS) for comparison. The copepod community in the HTS was dominated almost year round by Oithona davisae, whose 5-year mean abundance of 203 ind. L−1 comprised 84% of copepods and was more than double that in the LTS. O. davisae became extremely abundant in summer with the maximum monthly mean abundance in the HTS of 2756 ind. L−1 and the maximum sample-specific abundance of 10116 ind. L−1. The following predominant copepods in the HTS were Parvocalanus crassirostris in summer–autumn, Microsetella norvegica in summer, Acartia omorii in spring, and Paracalanus parvus s.l. irregularly. Possible causes for high abundance of O. davisae in the HTS are assumed to be sufficient food resources, water temperature over 21°C, and a wide salinity tolerance range of the species.

著者

Karin Inoue Takuya Yahagi Taeko Kimura Yasunori Kano

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.17, no.1, pp.66-75, 2022-02-22 (Released:2022-02-23)

参考文献数

71

被引用文献数

1

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Ellobium chinense is a red-listed snail species of the family Ellobiidae with a geographic distribution from Vietnam and south coast of China to South Korea and mainland Japan. This species is restricted to specialized habitats in a narrow upper-intertidal to lower-supratidal zone of salt marshes and thus particularly sensitive to environmental degradation through land reclamation and other human activities. Here, we first report the genetic diversity and population structure of E. chinense in Japan to evaluate the connectivity and conservation value of its local populations. Specimens were collected from seven localities (Tsu, Okayama, Yamaguchi, Usa, Imari, Saga and Izumi) that cover the species’ present distribution in the country. Analyses of 612-bp sequences of the mitochondrial cytochrome c oxidase subunit I gene showed high genetic diversity within populations and a reasonable level of connectivity among populations. However, significant genetic differentiation was detected among distant geographic regions in Japan and South Korea, due potentially to the disjunct distribution of habitable salt marshes and a short pelagic larval period of the species. The population of the Ise–Mikawa Bay area, representing the eastern limit of the current distribution range, showed the highest level of genetic differentiation and deserve particular conservation efforts to avoid local extinction, which occurred in Tokyo Bay area in the last century.

著者

Mitsuko Hidaka-Umetsu Dhugal J. Lindsay

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.13, no.2, pp.41-45, 2018-05-30 (Released:2018-05-24)

参考文献数

14

被引用文献数

2

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An individual narcomedusa assignable to Solmissus incisa sensu lato was observed having ingested a fish at 573 m depth near the southeast slope of the Kaikata seamount, Japan. Solmissus is a very common deep-sea narcomedusan genus that is widely considered to be a predator specializing on gelatinous plankton. Several cryptic species, with differences in the number of tentacles and form of manubrial pouches, are thought to be included in the nominal species Solmissus incisa. Therefore, the present study gives a short description of the morphotype of Solmissus incisa s.l. observed with a fish in its stomach, as well as several individuals of the same morphotype that had ingested gelatinous prey.

著者

Masayoshi Sano Ryosuke Makabe Ryo Matsuda Norio Kurosawa Masato Moteki

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.17, no.4, pp.349-357, 2022-11-30 (Released:2022-11-30)

参考文献数

37

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Molecular analysis is a common tool for marine ecological and biological research. For genomic analysis of zooplankton, ethanol preservation and freezing are often used to preserve samples until analysis. However, these methods have disadvantages, such as the loss of morphological information. Recently, 10% Lugol’s iodine solution (10% Lugol) has been shown to be an effective preservative of plankton samples for molecular analysis, even after 18 months. However, that study only reported a PCR-based molecular study using copepods. We tested the preservation effectiveness of 10% Lugol on various zooplankton over 33 months by comparing them to samples preserved by freezing or in 5% formalin seawater. The results revealed that the total amounts of DNA extracted from crustacean and gelatinous zooplankton preserved in 10% Lugol were the same or higher than those preserved in formalin or by freezing. Gel electrophoresis of the extracted DNA indicated that the DNA of the samples preserved in 10% Lugol was not fragmented during the preservation period. PCR amplification of a partial 18S rRNA gene using DNA extracted from various zooplankton taxa (siphonophores, copepods, ostracods, doliolids, polychaetes, pteropods, euphausiids, and chaetognaths) was successful. Sequences of morphologically identified species preserved in 10% Lugol had BLAST hits to sequences of these species deposited in Genbank, with a similarity of 100%, which indicated there was no sequence alteration during the preservation period. Thus, we conclude that 10% Lugol is a suitable preservative for molecular analysis of various zooplankton taxonomic groups.

著者

Kazutaka Takahashi Hiroshi Itoh Junya Hirai Kazuaki Tadokoro Koh Nishiuchi

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.17, no.4, pp.358-368, 2022-11-30 (Released:2022-11-30)

参考文献数

31

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A new species of sapphirinid copepod, Sapphirina doliolettae n. sp. was described from the Kuroshio Extension region in the western North Pacific Ocean. The new species is similar to S. nigromaculata and S. scarlata with respect to the following characteristics: 5-segmented antennule, one inner marginal process on caudal rami, and slender endopods with two apical spines on leg 4. However, it can be distinguished from these congeners by a combination of the following characteristics: the relative length of each segment of the antennule and antenna in both sexes, the width of the fourth pedigerous somite in females, the shape of the anterolateral corner of the genital somite in males and terminal process length of 3rd endopodal segment of leg 2 in males. The mitochondrial cytochrome oxidase subunit I sequences of S. doliolettae showed high interspecific variabilities from other Sapphirina species, including S. nigromaculata (20.2%) and S. scarlata (21.6–21.8%).

著者

Yuka Kushida Hiroki Kise Catherine S. McFadden James Davis Reimer

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.15, no.3, pp.259-268, 2020-08-14 (Released:2020-08-04)

参考文献数

48

被引用文献数

1 4

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Sea pens are ecologically important habitats for associated marine organisms, serving as ecosystem engineers in sandy or muddy seafloor environments. In such areas, sea pens can form habitats with high population densities known as “sea pen fields”. However, the presence and importance of sea pen fields have not been well studied in shallow waters in East Asia. Here, we report a sea pen field of Virgularia sp. aff. gustaviana in the shallow waters of Ushibuka Marine Park, in the Amakusa Islands of southern Japan. The average colony numbers of the field across all depths (7–20 m) was 10.3 colonies/m2 (live colonies) to 13.6 colonies/m2 (all: live+dead colonies+holes), and the area of the sea pen field was at least ∼50,000 m2. At a depth of 15 m, the substratum consisted of sand and fallen leaves of terrestrial origin, and the highest sea pen density was observed (averages=17.2 live colonies/m2, =25.8 total (live+dead+holes) colonies/m2). At a depth of 20 m, the substratum consisted of broken shells and rocks and had the lowest density (live colonies: average=0.8 colonies/m2, all: average=1.0 colonies/m2). There were significant differences in colony number of Virgularia sp. aff. gustaviana between the “sand”, “sand+leaves”, and “broken shells/rocks” substrates. We hypothesize that the strength of the water currents caused by local geographic features and tidal movements produce suitable sedimentation and habitat for this species of sea pen. Therefore, we suggest that preserving the natural coastline is crucial to protect this and other sea pen fields in shallow waters and their benthic marine communities.

著者

Yusuke Yamana Taiga Kunishima Masami Obuchi Takuma Fujii

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.15, no.2, pp.168-177, 2020-05-27 (Released:2020-05-30)

参考文献数

11

被引用文献数

3

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With a focus on building an inventory of subtropical species of epifaunal holothurians and completing an environmental assessment, SCUBA surveys were carried out in the Amami Islands of Kagoshima Prefecture in southern Japan. The following 12 nominal species belonging to seven genera (subgenera), as well as two as yet undescribed species belonging to two genera, were observed: Bohadschia argus Jäger, 1833; B. bivittata Mitsukuri, 1912; B. vitiensis (Semper, 1867); Holothuria (Halodeima) atra Jäger, 1833; H.(H.) edulis Lesson, 1830; Holothuria (Microthele) nobilis (Selenka, 1867); Personothuria graeffei (Semper, 1867); Stichopus chloronotus Brandt, 1835; S. hermanni Semper, 1867; S. naso Semper, 1867; Thelenota anax H.L. Clark, 1921; Euapta sp.; Synapta maculata (Chamisso et Eysenhardt, 1821); and Opheodesoma sp. In the semi-closed waters around the Amami Islands, epifaunal holothurians showed what seemed to be species-specific distribution patterns related to topographical features. Furthermore, ignition loss values of feces and sediments suggested that selective deposit feeding may be predominant in at least several of the species sampled.

著者

Yoshinari Endo Yuma Sato Atsushi Yamaguchi Igor Dovgal

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.17, no.4, pp.393-405, 2022-11-30 (Released:2022-11-30)

参考文献数

54

被引用文献数

1

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This study investigated the host-epibiont relationship between calanoid copepods and suctorian ciliates collected widely from the northern North Pacific Ocean. Mid- and deep-water adult female calanoids without dormant stages were found to be infested with suctorians, probably because of their larger size, longer intermolt duration and longevity in comparison to males and surface water species. A total of 259 calanoids belonging to sixteen species were infested with five suctorian species. Among them, Candacia columbiae, Gaetanus minutus, Lucicutia bicornuta, Metridia similis, Pleuromamma scutullata, and Racovitzanus antarcticus were reported to be infested with suctorians for the first time in the present study. Ephelota coronata infested only Metridia pacifica and displayed a strong host preference, whereas the other suctorians displayed a weaker host preference. Any suctorian species that infested Metridia pacifica and M. similis attached almost exclusively to their urosome. Suctorians might avoid or could not stay attached to the anterior parts of these fast-swimming copepods. The attachment sites of Actinocyathula pleuromammae and Paracineta gaetani extended to the anterior part of the copepod body as the number of attached suctorians increased, suggesting they were obliged to attach to suboptimal parts that were exposed to faster flow speed.

著者

Akira Ishikawa Yuta Takei Ken-Ichiro Ishii Mineo Yamaguchi

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.17, no.4, pp.383-392, 2022-11-30 (Released:2022-11-30)

参考文献数

46

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The temporal changes in the behavior of vegetative cells and cysts of the noxious red tide flagellates Chattonella (C. antiqua and C. marina) were investigated in Ago Bay, central Japan, mainly in 2013. In this study, in situ germination flux (cells m−2 day−1) was measured in May, June, and October 2013, using a ‘plankton emergence trap/chamber (PET chamber)’. Vegetative cells occurred in April and increased from May, forming a bloom in July with cyst production, and subsequently decreased thereafter. This change in the occurrence of the vegetative cells was considered to be controlled primarily by temperature and secondarily by nutrients and biotic factors. The PET chamber experiment showed that cyst germination in May contributed largely to forming the initial vegetative population to initiate blooming. An experiment to elucidate the effect of storage temperature on the germinability of cysts in the sediment showed that newly produced cysts (immature dormant cysts) mature (acquire germinability) under low storage temperature (10°C) within at least one month, indicating that cysts need to experience a cold season in the sediment for their maturation. The PET chamber experiment conducted in October before a cold season also confirmed that cysts scarcely germinated from the cyst population, containing many immature dormant cysts, in the in situ sediment. However, these cysts could act as seeds to form the initial population of the subsequent bloom in the next season, since the cysts will mature by then. Consequently, Chattonella cysts were concluded to play crucial roles in the population dynamics.

著者

Akiyuki Kenmochi Hiroyuki Matsuura Takashi Yoshikawa Rumi Sohrin Yumiko Obayashi Jun Nishikawa

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.17, no.1, pp.57-65, 2022-02-22 (Released:2022-02-23)

参考文献数

53

被引用文献数

1

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Seasonal occurrences of marine cladocerans in offshore Suruga Bay, Japan, were studied from 2014 to 2019. Zooplankton samples were collected monthly from a station (depth: ca. 1000 m) located in the offshore area of the bay. Cladocerans appeared each year from February to December, and disappeared in January. Their abundance increased drastically from April to September and comprised a substantial portion of the offshore mesozooplankton community during this period. Maximum cladoceran abundance occurred from June to August, ranging from 65.9–1341.9 individuals m−3. These patterns in cladoceran abundances were basically repeated each year throughout the study period. This result suggests that mass occurrences of cladocerans in offshore regions of the bay during the spring-summer are regular events rather than sporadic. Seven species, which have previously been reported from Japanese waters, were identified, and successional changes in the dominant species were observed. The most abundant species, Penilia avirostris, carried parthenogenetic embryos in brood pouches, suggesting that they were not simply transported from coastal areas, but that they also reproduce in the offshore waters. Regular mass occurrences of marine cladocerans in offshore Suruga Bay could have an important impact on the offshore ecosystem of the bay, and factors enabling these population cycles need to be determined.

著者

Yuki Ishikawa-Ishiwata Yuichi Nosaka Toshinori Usui Hiroshi Sasaki

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.2, pp.74-83, 2023-05-31 (Released:2023-05-30)

参考文献数

58

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We investigated the growth, thermotolerance, and fatty acid composition of the green alga Desmodesmus sp., which was isolated from a freshwater puddle in Ibaraki, Japan. Incubation experiments on the isolated strain were performed at a range of temperatures (20–40°C) with continuous illumination (110 µmol photons m−2 s−1) and nutrient-replete medium. High specific growth rates of 1.14–1.62 day−1 were observed at 20–35°C, but growth rates declined to 0.59 day−1 at 40°C. Lipid contents were 13.2%–14.4% (% dry weight) at 20–35°C and increased to 21.3% at 40°C. Some microalgae are known to regulate membrane fluidity by changing their fatty acid compositions in response to changes in ambient temperature. We found that the major polyunsaturated fatty acid (PUFA; C18:3 ω3) of Desmodesmus sp. was negatively correlated with water temperature. By contrast, no significant relationship was identified between temperature and the ratio of saturated to unsaturated fatty acids. The negative relationship between ω3 PUFA composition and temperature was stronger among thermotolerant as opposed to non-thermotolerant microalgae. This suggests that thermotolerant Desmodesmus sp. can grow at high temperatures by altering its fatty acid composition to affect membrane fluidity.

著者

Shinji Shimode Takafumi Yamaguchi Kiyotaka Hidaka

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.17, no.3, pp.301-311, 2022-08-30 (Released:2022-08-30)

参考文献数

41

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Calanus sinicus is one of the most dominant planktonic copepods and plays a key role as a secondary producer in the mid-latitude coastal shelf areas of the Northwestern Pacific. In this study, we investigated seasonal changes in in situ egg production rate (EPR) of C. sinicus collected from March 2014 to February 2015 in Sagami Bay, Japan. Simultaneously, we collected formalin-preserved samples to measure reproductive index (RI), which was calculated as the proportion of individuals with matured gonad to total females in each sample. Monthly averages of EPR and RI varied from 2.4 to 44.9 eggs female−1 day−1 and 0% to 75.9%, respectively. RI showed a significant positive effect on EPR. Moreover, EPR decreased with increasing temperature, which was the inverse of the effect of temperature on EPR reported in a previous study in the Seto Inland Sea. The difference between the studies suggests that the local population may adapt to different temperature environments in each location. Using a stepwise multiple regression model, EPR estimates for C. sinicus in Sagami Bay were explained by the average water temperature and RI with high probability (R2=0.71). Although local water temperature ranges must be considered before applying our model to other areas, the model would be useful to reconstruct past secondary production of C. sinicus from preserved samples collected in other neighboring coastal areas.

著者

Susumu Ohtsuka Kazuhiko Koike Dhugal Lindsay Jun Nishikawa Hiroshi Miyake Masato Kawahara Nova Mujiono Juro Hiromi Hironori Komatsu

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.4, no.1, pp.1-13, 2009-02-25 (Released:2009-04-20)

参考文献数

91

被引用文献数

45 53

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Since marine medusae and ctenophores harbor a wide variety of symbionts, from protists to fish, they constitute a unique community in pelagic ecosystems. Their symbiotic relationships broadly range from simple, facultative phoresy through parasitisim to complex mutualism, although it is sometimes difficult to define these associations strictly. Phoresy and/or commensalism are found in symbionts such as pycnogonids, decapod larvae and fish juveniles. Parasitism and/or parasitoidism are common in the following symbionts: dinoflagellates, ciliates, anthozoan larvae, pedunculate barnacles, anuropid isopods, and hyperiid amphipods. Mutualism is established between ctenophores and gymnamoebae, and between rhizostome medusae and endosymbiotic dinoflagellates. More information on symbiotic apostome ciliates, anthozoan larvae and hyperiid amphipods is definitely needed for further studies in consideration of their high prevalence and serious damage they can inflict on their hosts. The present paper briefly reviews previously published data on symbionts on these gelatinous predators and introduces new information in the form of our unpublished data.

著者

Akane Iida Kenji Nohara Fatimah Md. Yusoff Khwanruan Srinui Tran Manh Ha Susumu Ohtsuka Ephrime B. Metillo Honorio B. Pagliawan Jun Nishikawa

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.308-317, 2021-11-17 (Released:2021-11-18)

参考文献数

63

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The rhizostome jellyfishes, Rhopilema hispidum and Lobonemoides robustus, are two of the most abundant and commercially important species in Southeast Asia. However, information on genetic diversity and continuities among local populations remains totally unknown. We explored the genetic structure and population continuities of R. hispidum and L. robustus using genetic markers (COI & ITS1 regions) at 11 locations in four countries in Southeast Asia where fisheries were conducted. Rhopilema populations showed genetic distances (ΦST) among locations correlated positively with geographic distances, suggesting that they are in the isolation-by-distance (IBD). In Lobonemoides, molecular analysis revealed three distinct clades corresponding to sampling locations. Genetic distances among locations in L. robustus suggested that all populations maintain significant isolation. Our study reveals that these two blooming species have different phylogeographic patterns and differ in genetic diversity and continuities. Eustatic sea level changes during the Pleistocene and present ocean current systems, as well as differences in biological characteristics of these two species may explain these phylogeographic differences. Our results also suggest that jellyfish fisheries need to be carefully managed to avoid extinction of local populations and maintain the genetic diversity of these species, especially for L. robustus, which exhibits considerable genetic diversity in each location.

著者

Hiromi Kayama Watanabe Chong Chen Eijiroh Nishi Yasuhiko Ohara

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.1, pp.73-77, 2021-02-19 (Released:2021-02-19)

参考文献数

19

被引用文献数

3

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Phyllochaetopterus (Annelida: Chaetopteridae) is a diverse genus of tube-dwelling polychaetes found in a wide range of marine environments from subtidal to abyssal depths, including chemosynthesis-based ecosystems. The Shinkai Seep Field (SSF) is a serpentinite-hosted system in the Mariana Trench, where the deepest-known Phyllochaetopterus polychaetes inhabit the surfaces of brucite/carbonate chimneys. Despite all specimens collected from SSF being morphologically consistent with P. polus originally described from a deep-sea hot vent on the Mid-Atlantic Ridge, molecular barcoding using the mitochondrial cytochrome c oxidase subunit I (COI) gene revealed at least three cryptic lineages, none of which corresponded to P. polus. Phylogenetic reconstruction recovered P. polus embedded among the three SSF lineages, confirming their close relationship. These results warrant careful examination of Phyllochaetopterus from other regions using integrative taxonomy in order to understand its true diversity and pinpoint further taxonomically informative morphological characters.