著者

Sijun Chen Victor S. Kuwahara Tomoyo Katayama Fuminori Hashihama Kazuo Yabe Satoru Taguchi Kazutaka Takahashi

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.214-224, 2023-11-27 (Released:2023-11-30)

参考文献数

53

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We measured the concentrations of photoprotective compounds, carotenoids and mycosporine-like amino acids (MAAs), in surface-dwelling copepods in relation to their vertical distribution patterns along a zonal transect in the subtropical North Pacific to better understand their adaptation to strong ultraviolet (UV) radiation. All the dominant copepod groups analysed had detectable levels of both photoprotective compounds, while the concentrations differed among taxonomic groups. Farranula spp. had high carotenoid and MAA content (mean carotenoids: 0.0656; mean MAAs: 0.0230 µg mg dry wt−1) and the accumulation of MAAs correlated positively with in-situ UV penetration, explaining their constant occurrence in the surface layer throughout the transect. Oncaea spp. and Acrocalanus spp. had higher levels of carotenoids than MAAs and showed variable vertical distribution patterns regardless of UV penetration, suggesting that carotenoids are used only temporally to mitigate the effect of UV radiation. In contrast, Clausocalanus spp. and Calocalanus spp. had the lowest concentrations of both photoprotective compounds (mean carotenoids: 0.0148 and 0.0209; mean MAAs: 0.0015 and 0.0029 µg mg dry wt−1). The mean weighted depth of Clausocalanus spp. showed a significant negative relationship with UV penetration, suggesting that they mitigated the harmful effects of UV radiation through behavioural responses. Calocalanus spp. may have adapted to subtropical surface waters with relatively low photoprotective compound concentrations. Our study demonstrated that surface-dwelling subtropical copepods exhibit taxon-specific patterns in photoprotective compound concentrations that are adaptations to intense UV radiation, which is crucial for understanding the high species diversity of copepod communities in subtropical open waters.

著者

Naoto Jimi Natsumi Hookabe Shinta Fujimoto Hiroki Kise Akito Ogawa Masashi Tsuchiya

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.178-184, 2023-11-27 (Released:2023-11-30)

参考文献数

18

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Three distinct species of fauveliopsid polychaetes were collected from deep-sea sediments in the northwestern Pacific Ocean off Japan. Two of these species were obtained from bathyal and abyssal depths in the Shikoku Basin and were identified as Fauveliopsis levensteinae and Laubieriopsis hartmanae, which have been previously reported from the abyssal plains of the North Pacific Ocean. The third species collected from bathyal depths off Yakushima is new to science and described as Laubieriopsis verrucosa sp. nov. This new species can be distinguished from its congeners by having numerous body papillae across the whole body, 21 chaetigers, and an unpaired genital papilla on the right side of the posterior margin of chaetiger 8. A key to identify Japanese species of Fauveliopsidae is also included.

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

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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.

著者

Yoshino Ishizaki Masaya Ogura Chihiro Takahashi Maya Kaneko Akari Imura Yuta Shiino

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.1, pp.1-12, 2023-02-28 (Released:2023-03-02)

参考文献数

31

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Lack of evidence prevents an understanding of how ghost crabs create burrows underground. For the reconstruction of ichnogenetic stages in the burrows of ghost crabs, we report on how the burrows of the ghost crab Ocypode stimpsoni from the foreshore and backshore on Ikarashi beach, Niigata, Japan are created. Plaster casting of the burrows reveals detailed morphology with bioglyphs on the burrow wall. The casts of burrows show a variety of morphologies, such as J- and Y-shapes. Based on the burrow ichnogeny, J-shaped burrows were well constructed at a shallower level of the waterline underneath the beach, occasionally creating a second opening of the burrow. In turn, Y-shaped burrows were constructed at a deeper waterline, thereby recycling and reburrowing the deepest part of the J-shaped burrow. As a result, the total depth of Y-shaped burrows tends to be larger than that of J-shaped burrows. The depth and mean diameter of the burrows range from 3.3–37.6 cm and 9.28–31.54 mm, respectively, and the depths are apparently shorter than those on a Pacific beach. The lines of evidence suggest that the morphological features of burrows in Ikarashi beach are attributed to a smaller difference in tidal level in the Sea of Japan, where the available space for burrows ought to be limited by the waterline under the ground.

著者

Genki Kobayashi Hajime Itoh Gen Kanaya Hirokazu Abe Shigeaki Kojima

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.1, pp.13-20, 2023-02-28 (Released:2023-03-02)

参考文献数

57

被引用文献数

1

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Genetic homogeneity among populations of marine organisms with high dispersal potential is maintained by high gene flow whereas genetic differentiation is often formed under the presence of dispersal barriers. One of the possible dispersal barriers for intertidal species in Japan is the Sea of Japan because several tidal-flat species are absent in the region due to the small tidal range. In this study, we aimed to validate this possibility by examining the population genetic structure of the intertidal crab Macrophthalmus japonicus, which possesses a long planktonic larval period indicating high dispersal potential but is absent on the Sea of Japan side in Honshu Island. In total, 83 haplotypes of the mitochondrial cytochrome c oxidase subunit I were recovered from 154 specimens collected from 10 Japanese sampling sites and three GenBank sequences from China and Korea. All populations showed high genetic diversity except for the northernmost population at Asadokoro site in Mutsu Bay. The ΦST values among populations were low, even between populations with great distances such as the Pacific side of northeastern Honshu and Kyushu Islands (ca. 1500 km). On the other hand, the ΦST values between Asadokoro site and the other Japan sites were high. The isolation of the northernmost population despite the high dispersal potential of M. japonicus is probably because of the absence of neighboring populations that can supply larvae to the northernmost population and the invasion of larvae from the Pacific side is blocked by ocean currents.

著者

Taiga Kunishima Katsunori Tachihara

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.1, pp.21-24, 2018-02-28 (Released:2018-03-14)

参考文献数

11

被引用文献数

2 2

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Accurately determining the species richness and/or abundance using quantitative sampling methods is important for understanding community structures. The quadrat method has been one of the most commonly used quantitative methods for estimating benthic animals in tidal flats. However, it is difficult to implement this method in biodiversity surveys of benthic fishes, as they can move across the quadrat, thus altering the observations. In the present study, we introduced the quantitative sampling method for benthic fishes in tide-pools located in tidal flats by employing an improved quadrat with a net and sinkers. This setup prevented the movement of fishes across quadrats, unlike the conventional quadrat method which allowed the easy movement of fishes. This improved quadrat method can be useful in surveying fish biodiversity in tide-pools in a wide range of tidal flats. The potential advantages of this method include 1) determining the accurate biodiversity of fishes in a tidal flat tide-pool, 2) easily comparing the biodiversity per unit area among multi-sampling sites, and 3) easily increasing the number of quadrats in field surveys. We believe that our improved quadrat method will simplify and promote the study of fishes in tidal flats.

著者

Kenji Ito Akihiro Inoue Taeko Kimura

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.3, pp.104-115, 2018-08-27 (Released:2018-08-29)

参考文献数

45

被引用文献数

1 3

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The study was conducted to identify the effect of different types of tube traps on the sampling efficacy and accuracy for invasive golden mussels, Limnoperna fortunei (Dunker, 1857), at four sites in Japan. The traps consisted of PVC tubes (diameter: 5.5 cm; length: 20 cm) inside which a PVC plate was fixed horizontally as settlement substrate, and we examined two trap characteristics: mesh covering at the tube ends (present or not) and substrate texture (even or uneven). Mesh covering had a negative effect (P<0.001) and uneven substrate had a marginally positive effect (P=0.08) on mussel settlement density. A positive relationship was found between larval and settlement density in traps without mesh. These results imply that the most effective type of tube trap had no mesh covering and used uneven substrate. The settlement density of the mussels was also examined on several surfaces of the tube trap and the rope used to suspend the trap. The mussel density on the rope was higher than that on the PVC plates and tubes. The best correlation between settlement density and larval density occurred on the outside of the PVC tubes.

著者

B. A. Venmathi Maran Susumu Ohtsuka

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.3, no.4, pp.202-215, 2008-11-25 (Released:2009-02-25)

参考文献数

41

被引用文献数

13 21

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Parasitic copepods usually have one or more free-swimming larval/juvenile stages for dispersal or infection. However the present study has revealed that adults and chalimus stages of caligiform copepods have often been discovered in plankton samples collected from East Asia. This is the first report on free-swimming adults of caligiform copepods from Japanese and Korean waters. Adults of the following species have been discovered in this study. In Japanese waters: Caligus coryphaenae (4♂♂), Caligus sp. (1♂), Pandarus sp. (4♂♂, 16 chalimi) off Nansei Islands in May 2003 and 2006; C. sclerotinosus (1♀) near a fish farm, Ehime Prefecture in December 2006; C. undulatus (1♀) off Ube, the Seto Inland Sea in July 2006; and C. undulatus (1♂) in the Ariake Sea in June 2007. In Korean waters: C. orientalis (1♀, 1♂) from brackish waters of the Mankyong River and C. undulatus (1♂) from the Seomjin River in October 2006. It is interesting to point out that C. undulatus has never been recorded as a parasite infecting any host, but has been collected from plankton samples in East Asia, India and Brazil. It is also noteworthy to mention that males (80%) were found more frequently than females (20%) in this study. We considered the following possibilities for the occurrences of caligiform adults originally infecting fish: (1) escaping from irritation or diseases in the host, (2) looking for an opportunity to switch hosts, (3) change in their life mode, and (4) accidental detachment. In the case of chalimi, it could be accidental, because they would be tightly attached to the host using a special organ called the “frontal filament”, and cannot grow up to the adult stage without nutrient supply from the host.

著者

Hiroshi Itoh Shuhei Nishida

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.3, no.4, pp.189-201, 2008-11-25 (Released:2009-02-25)

参考文献数

33

被引用文献数

6 8

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A 25-month field survey was conducted to investigate the life cycle and seasonal population fluctuations in the poecilostomatoid copepod Hemicyclops spinulosus in the burrows of the ocypodid crab Macrophthalmus japonicus in the mud-flats of the Tama-River estuary, central Japan. On the basis of sample collections in the water column and from the crab burrows, it was confirmed that H. spinulosus is planktonic during the naupliar stages and settles on the bottom during the first copepodid stage to inhabit the burrows. Furthermore, the copepods' reproduction took place mainly during early summer to autumn with a successive decrease from autumn to winter. A supplementary observation on the burrows of the polychaete Tylorrhynchus heterochaetus suggested that these burrows are another important habitat of H. spinulosus. There were additional discoveries of male polymorphism and precopulatory mate guarding behavior by males, suggesting an adaptation in the reproductive strategy of this copepod to their narrow habitat spaces and low population densities, in contrast to the congeneric species H. gomsoensis, which co-occurs in the estuary but attains much larger population sizes and is associated with hosts having much larger burrow spaces.

著者

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.16, no.2, pp.100-108, 2021-05-27 (Released:2021-06-11)

参考文献数

36

被引用文献数

8

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The golden mussel Limnoperna fortunei (Dunker, 1857) is an invasive freshwater bivalve species that exerts harmful effects on the environment, as well as man-made structures, such as water-treatment systems. By using conventional sampling methods, it is difficult to detect mussels under low-density conditions; however, environmental DNA (eDNA) analysis may be a rapid and efficient method for monitoring this aquatic organism. In this study, we conducted surveys based on the eDNA analysis of L. fortunei in 15 farm ponds in Japan and compared the results with those of two conventional survey methods, visual census and plankton larval survey, to clarify the effectiveness of eDNA analysis for field surveys of L. fortunei. Primers and a probe specific to L. fortunei were developed, and a method for analysis was established. In the laboratory experiments, the species eDNA was detected in all water tanks containing the mussels, and the concentration of eDNA was high in the experimental tank that had high density of L. fortunei. In the field survey, L. fortunei eDNA was detected in all ponds where the mussels were found by conventional survey, and low concentrations of eDNA were also detected in several ponds where no L. fortunei were found by traditional methods. These results suggest that eDNA analysis has greater sensitivity for the detection of L. fortunei in farm ponds than that of conventional methods. Environmental DNA surveys have little impact on water management and are suitable for surveys at water facilities that have not yet been damaged by the mussels.

著者

Junya Hirai Yoko Hamamoto Daiske Honda 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.13, no.2, pp.75-82, 2018-05-30 (Released:2018-05-24)

参考文献数

38

被引用文献数

3 11

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Metagenetic diet analyses of the 18S V9 region were conducted in 40 adult female Calanus sinicus during winter in Tosa Bay (Japan). The majority of prey items were small crustaceans (of Copepoda and Cirripedia) and diatoms, taxa that are dominant in the environment and have been previously reported as important prey items of Calanus. The abundance of sequences attributable to Dinophyta and Chlorophyta was significantly lower in C. sinicus gut contents than in environmental plankton communities, suggesting that C. sinicus avoids prey from these groups. Hydrozoans were also observed, and aplanochytrids (Labyrinthulea) were detected for the first time as a major prey of C. sinicus. Additionally, high proportions of unclassified eukaryote material were observed, suggesting undetected predator–prey relationships in key copepod species in marine ecosystems. The dietary importance of aplanochytrids, heterotrophic protists that accumulate unsaturated fatty acids such as docosahexaenoic acid, has been overlooked in previous research. Calanus sinicus is a key copepod species in the subtropical coastal regions of the western North Pacific, and a major food source for the larvae of commercially important fish; therefore, further investigation into novel prey items such as aplanochytrids is recommended to understand the complex food web structures in marine ecosystems.

著者

TAKASHI TAKAHASHI ISAMU UCHIYAMA

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.2, no.1, pp.12-27, 2007 (Released:2008-05-09)

参考文献数

57

被引用文献数

8 8

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Adults of Oithona atlantica, Oithona plumifera and Oithona similis occurred throughout the year in Toyama Bay (0-500 m), but in the surface layers (0-50 m), the adults of O. atlantica and O. plumifera were observed in Toyama Bay during different seasons. Based on the differences in adult distribution, O. atlantica nauplii were found in samples collected during spring (April to May) while O. plumifera were found in samples collected during autumn (September to October). Identification of O. atlantica and O. plumifera nauplii and comparisons of their morphological differences were based on this temporal separation. Nauplii of O. atlantica, O. plumifera and O. similis differed in their ratio of body height (maximum length of dorsal-ventral axis) to length (H/L). This characteristic ratio was common to all naupliar developmental stages and is therefore useful as a basis for distinguishing between naupliar stages of the three species. The population and community structure and densities of these species of Oithona were investigated in the surface water layer (0-50 m depth) of Toyama Bay from 1997 to 1999. Major population structural changes occurred in different sampling seasons, and may have been influenced by changes in hydrographic conditions, including temperature and water current. In winter and spring (from February to June), many O. similis and O. atlantica nauplii appeared, and the former nauplii were more dominant. Oithona similis nauplii are suggested to may be the most important species as prey for fish larvae.

著者

Ilka Straehler-Pohl

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.189-206, 2020-08-14 (Released:2020-08-04)

参考文献数

31

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In 1934, Stiasny described cubomedusan specimens from Station 279 of the Discovery Expedition 1925–27 in the Gulf of Guinea, West Africa as Tamoya haplonema. He also presented line drawings of the habitus that raised some doubts on the identification of the species. In the collections of the Natural History Museum of London, the described specimens were still available and in good condition due to their storage in formalin. More specimens could be found in other European museums. The formalin made a genetic analysis impossible but as all anatomical structures were excellently preserved, a direct comparison was possible with the structures in Tamoya haplonema and Tamoya ohboya from the Americas. Due to the morphological comparison with the American Tamoya species it could be confirmed that the African Tamoya specimens are an up-to-now undescribed new Tamoya species, Tamoya anacamori sp. nov., described herein.

著者

Kenji Tsuchiya Tomoko Yoshiki Ryota Nakajima Hideo Miyaguchi Victor S. Kuwahara Satoru Taguchi Tomohiko Kikuchi Tatsuki Toda

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.8, no.2, pp.74-87, 2013-05-25 (Released:2014-08-30)

参考文献数

74

被引用文献数

17 29

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Climate change has the potential for intensification of typhoons, which will cause stronger effects on aquatic ecosystems in the future. The effect of typhoon Mawar (T0511), passing Manazuru Port located in the western part of Sagami Bay, Japan, was investigated from August to September 2005. Immediately after the passage of Mawar, photosynthetically available radiation showed high values, salinity decreased dramatically and nutrient concentrations (NO2+NO3, PO4 and Si(OH)4) increased. Skeletonema spp. and Leptocylindrus spp. were dominant after the passage of Mawar, and their succession was linked to the variability of the N/P ratio. Primary production was highest at 349 mg C m−3 day−1 three days after Mawar, and high assimilation numbers lasted for nine days. The integrated primary production during the nine days after Mawar was 2.1×103 mg C m−3, which accounted for 7.2–9.1% of the annual primary production in the upper waters of Sagami Bay. The study confirms that enhanced primary production induced by episodic typhoon events in temperate coastal regions are significant, and should be considered in annual primary production estimates.

著者

Jean-Paul Ducrotoy

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.5, no.Supplement, pp.174-184, 2010-12-25 (Released:2011-03-30)

参考文献数

67

被引用文献数

7 15

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Estuaries are subject to increasing pressures due to local human activities. In addition, global change is affecting coastal habitats. Such disturbances impinge on goods and services provided by these ecosystems. The paper is devoted to efforts to restore environmental quality in some industrialised estuaries during the few past decades. It then compares strategies to recover damaged habitats and methods to restore lost ecological functionalities. Case studies are taken from the Seine in France, the Humber in England, the Scheldt in Belgium and the Netherlands and the Elbe in Germany. The article retraces briefly the morphological and ecological changes which have been inflicted on the estuaries over the last century. It puts into light actions which have been successful in improving their ecological functioning. Through comparing the various restoration schemes, policies are assessed. Details are given on efforts made lately in the Seine estuary which has lost more than 90% of its intertidal areas in about 150 years. Recently, losses due to an extension of harbour facilities in le Havre (“Port 2000”) have been compensated by the rehabilitation of a former mud flat and various constructions such as an artificial island for birds.The discussion confronts the present management of tidal estuaries to future challenges, including global changes. Such changes will not only include global warming and its consequences (sea level rise, biogeochemical cycles alteration...), but also socio-economic adjustments and a possible geo-political reorganization expected to take place in relation to increased harbour activities and the increasing need for more space dedicated to natural habitats and leisure activities (sports, tourism...).The conclusion puts together the various approaches from the considered European estuaries. Resting on a rigorous scientific approach, it proposes a synthetic approach to restoration: 1. Efficient procedures of socio-ecological evaluation, 2. A methodology to assess the ecological quality of systems considered, 3. Rigorous monitoring programs, resting on a relevant choice of indicators, and 4. Participation of local communities, in order to define strategies compatible with conservation and sustainable development at the local, regional and European levels.

著者

Hiroyuki Takasu Haruka Inomata Koji Uchino Saki Tahara Koichiro Mori Yuna Hirano Kana Harada Masahiro Yamaguchi Yuichi Nozoe Hisashi Akiyama

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.14, no.4, pp.320-323, 2019-11-27 (Released:2019-11-25)

参考文献数

19

被引用文献数

9

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We surveyed the spatial and temporal distribution of Japanese sea nettle jellyfish Chrysaora pacifica in Omura Bay, Japan, using an environmental DNA (eDNA) method. In 2018, the C. pacifica eDNA concentration increased from March–May at all depths. The seasonal pattern of C. pacifica eDNA was consistent with previous reports based on visual observations along the Japanese coast. Thus, the eDNA method might have advantages to follow the seasonal pattern of C. pacifica while being less time-consuming and less laborious compared with traditional methods. The eDNA concentrations tended to reach a maximum near and/or below the pycnocline throughout this study. Therefore, the vertical distribution of C. pacifica medusae may have been restricted by strong pycnocline formation in July and August 2018. However, even with a weak pycnocline, which C. pacifica should be able to swim across, the apparent distribution of C. pacifica eDNA seems to be restricted by the pycnocline. Therefore, the eDNA method cannot, currently, accurately assess the absolute vertical distribution pattern of C. pacifica, especially when a pycnocline is formed.

著者

Mattia Ghilardi

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.14, no.3, pp.206-209, 2019-08-26 (Released:2019-08-17)

参考文献数

28

被引用文献数

1

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Velella velella widely occurs in the tropical and temperate oceans of the world and the number of mass strandings of colonies is increasing. Although its historical presence in the south-western Indian Ocean is known, recent observations are limited to Tanzania, Mauritius and South Africa. This is the first record of V. velella from Madagascar and the Mozambique Channel since 1964. Given the perceived increase in gelatinous zooplankton abundance, the lack of recent reports from this area highlights the need to monitor its presence to help coastal communities face the negative consequences of potential blooms.

著者

YAMAMORI LUNA KATO MAKOTO

出版者

日本プランクトン学会、日本ベントス学会

雑誌

Plankton and Benthos Research (ISSN:18808247)

巻号頁・発行日

vol.14, no.2, pp.131-134, 2019

被引用文献数

2

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<p>The rock-boring sea urchin, <i>Echinostrephus molaris</i>, excavates soft rocks, and the pits are later used by non-boring sea urchins such as <i>Echinometra mathaei</i> and <i>Anthocidaris crassispina</i>. The pits used by these non-boring sea urchins are also characteristically inhabited by a limpet-like algivorous trochid snail, <i>Broderipia iridescens</i> (Gastropoda, Trochidae). To determine how this unique symbiotic association is maintained, we observed reproduction and larval development of the snail, and performed assays to detect what induced settlement in the snail larvae. As candidates of settlement inducers, a habitat biofilm plate, the host and the non-host sea urchins, and conspecific snails were kept in separate glass bowls, and newly hatched <i>B. iridescens</i> veliger larvae were introduced to each bowl. Sixty to 80% of larvae settled in bowls that contained the non-boring host sea urchins and conspecific snails. On the other hand, only approximately 8% of the larvae settled in bowls containing the boring non-host sea urchins. This is the first report demonstrating that larval settlement of an algivore is induced not by the habitat biofilms, but by the symbiotic hosts.</p>

著者

Takeo Kurihara Reiko Fuseya Masaya Katoh Ken Inoue

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.5, no.1, pp.11-16, 2010-02-25 (Released:2010-06-25)

参考文献数

19

被引用文献数

5 7

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Giant clams are simultaneous hermaphrodites and are assumed to ejaculate first and, after completely stopping ejaculation, release eggs. In the seed production method aimed at preventing self-fertilization, each adult clam is induced to ejaculate in a tank and then release eggs in another tank. Giant clams, however, have recently been suggested to continue ejaculation for a period after the beginning of egg release. The overlap between ejaculation and egg release might lead to self-fertilization in the tank used for egg release, especially for the eggs released just at the beginning of spawning. We examined the possibility of such self-fertilization for the giant clam Tridacna crocea and obtained three results. (1) In observations with the naked eye in a laboratory, 2 of 38 T. crocea simultaneously ejaculated and released eggs. (2) In a laboratory experiment, 1.5 to 80.0% of eggs released from each adult clam developed into D-shaped larvae without artificial cross-fertilization. Such development occurred more frequently for the eggs released earlier from each adult clam than for the eggs released later from the clam. (3) In observations at a hatchery, 2 to 94% of the eggs released from 4 of 5 adults were found to develop into D-shaped larvae without artificial cross-fertilization. The three results suggest that at least some T. crocea adults continue ejaculation for a period after starting spawning eggs, which causes self-fertilization.

著者

Mikako Gushi Akira Iguchi Ichiro Takeuchi

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.1, pp.17-20, 2018-02-28 (Released:2018-03-14)

参考文献数

18

被引用文献数

3

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An advanced underwater camera was used for recording coral spawning at a flow-through seawater aquarium. A colony of Acropora digitifera from the reef flat of Sesoko Island, Okinawa, Japan was transferred to a flow-through aquarium and photographed continuously for 5 days at 10 min intervals using an underwater digital camera equipped with a lens wiper. LED lighting was provided. The number of gamete bundle-like particles between the coral and seawater surface was counted on the photographs obtained. The gamete bundle release started around 22:00 pm on 31 May, 2015 (2 h and 50 min after sunset and 3 days before full moon). Spawning was estimated to continue for < 2 hours. The present study indicates that an underwater camera with a lens wiper system will help elucidate the details of coral spawning.