Biological Institute on Kuroshio

Ōtsuki, Japan

Biological Institute on Kuroshio

Ōtsuki, Japan

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Keshavmurthy S.,Academia Sinica, Taiwan | Fontana S.,Academia Sinica, Taiwan | Fontana S.,National Taiwan Normal University | Mezaki T.,Biological Institute on Kuroshio | And 4 more authors.
Scientific Reports | Year: 2014

Marine invertebrates are particularly vulnerable to climatic anomalies in early life history stages because of the time spent in the water column. Studies have focused on the effect of seawater temperature on fertilization, development, and larval stages in corals; however, none of them show comparative results along an environmental gradient. In this study, we show that temperatures in the range of 15-33°C have strong effects on fertilization rates and embryonic stages of two coral species, Acropora muricata in the subtropical environment and Acropora hyacinthus in subtropical and temperate environments. Deformations after the first cleavage stages were observed at low (15°C) and high (33°C) temperatures. Development was delayed by 6-7 h in the slightly non-optimal temperature of 20°C. We found significant differences in fertilization rates and responses of embryos from different latitudes, with temperate corals being more sensitive to extremely hot temperatures and vice versa. We hypothesize that the coral development is restricted to a narrow temperature range and deviation outside this window could inhibit a species' continuance and ecological success. Thus, it would have significant negative effects on adult populations and communities, playing a role in future of coral reef survival.


PubMed | National Taiwan University, Biological Institute on Kuroshio, National Taiwan Normal University, Academia Sinica, Taiwan and University Pierre and Marie Curie
Type: | Journal: Scientific reports | Year: 2014

Marine invertebrates are particularly vulnerable to climatic anomalies in early life history stages because of the time spent in the water column. Studies have focused on the effect of seawater temperature on fertilization, development, and larval stages in corals; however, none of them show comparative results along an environmental gradient. In this study, we show that temperatures in the range of 15-33 C have strong effects on fertilization rates and embryonic stages of two coral species, Acropora muricata in the subtropical environment and Acropora hyacinthus in subtropical and temperate environments. Deformations after the first cleavage stages were observed at low (15 C) and high (33 C) temperatures. Development was delayed by 6-7 h in the slightly non-optimal temperature of 20 C. We found significant differences in fertilization rates and responses of embryos from different latitudes, with temperate corals being more sensitive to extremely hot temperatures and vice versa. We hypothesize that the coral development is restricted to a narrow temperature range and deviation outside this window could inhibit a species continuance and ecological success. Thus, it would have significant negative effects on adult populations and communities, playing a role in future of coral reef survival.


Nozawa Y.,Academia Sinica, Taiwan | Tanaka K.,Biological Institute on Kuroshio | Reimer J.D.,University of Ryukyus | Reimer J.D.,Japan Agency for Marine - Earth Science and Technology
Zoological Studies | Year: 2011

Plain-surface settlement plates are widely used in coral recruitment research to the almost complete exclusion of plates with other surface types. This study examined whether the surface structure of settlement plates used in coral recruitment studies influences the resultant coral recruits observed on the plate surfaces. Settlement plates with artificially produced micro-crevices (MCs) on the plate surfaces were examined and compared to settlement plates without MCs (plain surfaces). Replicates of the 2 types of settlement plates were deployed side by side at 3 replicate locations for 4 mo during the coral recruitment period, and the number and taxonomic composition of coral recruits on the plate surfaces were compared. Settlement plates with MCs had significantly more coral recruits with a higher variety of species than those without MCs at all 3 locations. There was approximately an order of magnitude difference in the total number of coral recruits between settlement plates with (59-144 recruits/location) and without MCs (1-6 recruits/location). Pocilloporids dominated coral recruits on both types of settlement plates (86%-100%). These results indicate the need to consider the surface structure of settlement plates as a significant factor, along with plate materials and methods of deployment, that influences the resultant coral recruit assemblies observed on settlement plates in coral recruitment studies.


Fujita Y.,University of Ryukyus | Fujita Y.,Marine Learning Center | Obuchi M.,Biological Institute on Kuroshio
Zootaxa | Year: 2012

A new species of the genus Comanthus A.H. Clark, 1908, is described on the basis of specimens collected from Kume Island and Okinawa Island, the Ryukyu Islands, Japan. Comanthus kumi n. sp. is distinguished from all ten congeners by having extremely elongate arms exceeding 300 mm in length and the colouration in life. The new species concealed its whole body in a crevice or small hole on coral reefs during the day and protruded only several elongate arms on the reef surface at night. This habit suggests that the new species is nocturnal. Copyright © 2012. Magnolia Press.


Kitano Y.F.,Kyoto University | Obuchi M.,Biological Institute on Kuroshio | Uyeno D.,University of Ryukyus | Miyazaki K.,Kyoto University | Fukami H.,University of Miyazaki
Zoological Studies | Year: 2013

Background: Goniopora stokesi is an uncommon species mainly found in tropical and subtropical regions but was also reported in temperate regions of Japan. This species has two unique characteristics. First, it does not typically attach to hard substrates, i.e., it is free-living. Although non-free-living colonies were reported, it is unclear whether their morphologies exhibit intraspecific or interspecific differences. Second, they can asexually form daughter colonies, which are secondary colonies that grow on the surface (coenosac) of a parent colony and subsequently detach. To date, this specific characteristic has not been reported in Japan, and it is not clear whether this species occurs in Japan. Results: To clarify the taxonomic status of this species, we investigated its reproductive mechanism in Japan and morphologically and genetically analyzed specimens collected from both subtropical and temperate regions. We found that this species forms daughter colonies in Okinawa, Japan and that free-living colonies in the temperate region, which were formerly recognized as G. stokesi, likely constitute a morphological variation of a separate species. In addition, all non-free-living colonies with G. stokesi-like morphologies were also morphological variations of other species. Conclusions: Overall, free-living colonies with large, deep calices, thin walls, and well-developed epitheca on the underside were G. stokesi, whereas other free-living and all non-free-living G. stokesi-like colonies belonged to other species, such as Goniopora djiboutiensis. © 2013 Kitano et al.; licensee Springer.


Obuchi M.,Biological Institute on Kuroshio | Obuchi M.,University of Ryukyus | Omori A.,University of Tokyo
Zootaxa | Year: 2015

A new genus and new species of antedonid comatulid is described from southern Japan. Belonometra n. gen. has a unique appearance with ten long arms, numerous cirri, and remarkably long and crowded pinnules. The new genus shares some characters with subfamily Heliometrinae. However, the comparative length of pinnules, which is a diagnostic character to determine subfamily Antedonidae, is different. The subfamily into which the new genus should be placed is unclear. Copyright © 2015 Magnolia Press.


Reimer J.D.,University of Ryukyus | Reimer J.D.,Japan Agency for Marine - Earth Science and Technology | Nakachi S.,Biological Institute on Kuroshio | Hirose M.,University of Ryukyus | And 2 more authors.
Marine Biotechnology | Year: 2010

Zoanthids comprise an order of benthic, generally colonial cnidarians, which can usually be distinguished from other hexacorallians by embedded sand and detritus in their mesoglea to help strengthen their structure. These animals are becoming increasingly important research subjects in biochemistry and other research fields. Their inclusion of both calcium and silica results in the need for both decalcification and desilification for internal morphological examinations. Since the methodology of hydrofluoric acid (HF) desilification has rarely been documented in zoanthids, histological surveys for zoanthid taxonomy have often been abandoned and their taxonomy is often problematic. Recent investigations utilizing molecular methods have brought a clearer understanding of zoanthid diversity, but standardization of HF treatments are still needed to provide a link between molecular and more traditional techniques, and to properly examine specimens for which molecular methods may not be an option (e. g., formalin-preserved specimens, etc.). Here, we use both "straight" HF and, for the first time with zoanthids, buffered HF (BHF) treatments at different treatment lengths (1-48 h) on polyps from three different species of zoanthids for histological examination. Section conditions were judged based on the presence/absence of embedded detritus, drag marks, and tissue condition. Results show that the BHF treatment resulted in slightly better tissue conditions for all specimens, and suggest that desilification works well regardless of treatment time for species with smaller (polyp diameter <0.5 cm), less heavily encrusted polyps. Desilification of heavily encrusted Palythoa mutuki polyps were still problematic, with at least 24 h treatment needed. To aid future research, we provide guidelines for HF treatments of zoanthid specimens. © 2009 Springer Science+Business Media, LLC.


Imahara Y.,Biological Institute on Kuroshio
Zootaxa | Year: 2013

Two new species of paralcyoniid octocorals are described from Japan. One of them, Ceeceenus retractus n. sp., is the fifth species of the genus, and the other, Nanalcyon sagamiense n. gen. n. sp., is proposed as a new genus. Nanalcyon is similar to the Mediterranean and Atlantic genera Maasella Poche, 1914 and Paralcyonium Milne Edwards and Haime, 1850, but the new genus clearly differs from these in having independent colonies not joined by stolons. The ultrastructure of the sclerites is compared among the new genus, Ceeceenus and Paralcyonium by means of SEM. All three genera display the same three main types of sclerites, flat platelets, rods and spindles, the ultrastructure of all consisting of non-branching fibrous crystals. In addition to these, two genera, Ceeceenus and Paralcyonium, have flat oval platelets with the ultrastructure showing branching dendritic crystals, lacking in Nanalcyon. Copyright © 2013 Magnolia Press.


Yamazaki A.,Hokkaido University | Yamazaki A.,KIKAI Institute for Coral Reef science | Yamazaki A.,University of Tokyo | Watanabe T.,Hokkaido University | And 5 more authors.
Paleoceanography | Year: 2016

The Kuroshio Current is a major global ocean current that drives the physical ocean-atmosphere system with heat transport from tropical to temperate zones in the North Pacific Ocean. We reconstructed the variability of the Kuroshio transport over the past 150 years using coral skeletal nitrogen isotopic composition (δ15Ncoral). A 150 year δ15Ncoral record (1859–2008 A.D.) is 4 times the length of the observational record (1971 to present) and could provide a direct comparison with global climate change, such as the Pacific Decadal Oscillation (PDO) index and El-Niño–Southern Oscillation (ENSO), through recent global warming. Coral cores from Porites were collected from Tatsukushi Bay in 2008 on the Pacific coast of Japan, which is located on the northern front of the Kuroshio Current. δ15Ncoral was used as a proxy to record the δ15N of nitrate (δ15Nnitrate) controlled by the upwelling of subtropical subsurface water (δ15Nnitrate; ~ +2 − +3‰), and δ15Ncoral was negatively correlated with observations of the Kuroshio transport (R = −0.69, P < 0.001) and the 2 year lagged PDO index (R = −0.63, P < 0.005) from 1972 to 2007. The 150 year record of δ15Ncoral suggested that the Kuroshio transport varied with ~25 year cycle, and the amplitude became more stable, and the volume was intensified through the twentieth century. The Kuroshio transport was intensified by the La Niña state in the early 1900s and by the El Niño-PDO state after the 1920s. Our results suggested that the Kuroshio transport was influenced by the combined climate modes of ENSO and PDO during the last century. © 2016. American Geophysical Union. All Rights Reserved.


Straehler-Pohl I.,Evolutionary Biology and Life Cycle Research | Toshino S.,Kitasato University | Toshino S.,Biological Institute on Kuroshio
Plankton and Benthos Research | Year: 2016

The name Carybdea morandinii Straehler-Pohl & Jarms, 2011 was applied to unknown cubopolyps found on dead coral rock at the Hagenbeck Zoo, Hamburg, Germany, during 1999, and a description was given of its early life history. Although included in Carybdeidae Lesson, 1843, its familial affinities remained uncertain. In 2006, a population of unidentified cubopolyps was discovered on the walls of a saltwater tank at the Umikirara Aquarium, Nagasaki, Japan. In addition, an immature cubomedusa and polyps were collected at Ginowan and Ishigaki, Okinawa, Japan, in 2002 and 2012. Genetic analysis established that these polyps and the medusa belonged to the same species as the polyps found in Nagasaki. Comparisons of the anatomy and asexual propagation methods of Japanese polyps, and their newly detached medusae, with early life stages of cubozoans cultured in Germany, revealed that the Japanese populations were likely conspecific with Carybdea morandinii. Subsequent genetic analysis confirmed this identification. Morphology of Japanese medusae revealed that they were referable to the family Alatinidae Gershwin, 2005, and within that family to the genus Alatina Gershwin, 2005, rather than to the family Carybdeidae. © The Plankton Society of Japan.

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