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Tanaka K.,Kuroshio Biological Research Foundation | Taino S.,Kochi Prefectural Fishery Experiment Station | Haraguchi H.,Coastal Branch of Tottori Prefectural Museum | Prendergast G.,Education Board of Shimanto City | Hiraoka M.,Kochi University
Ecology and Evolution | Year: 2012

To assess distributional shifts of species in response to recent warming, historical distribution records are the most requisite information. The surface seawater temperature (SST) of Kochi Prefecture, southwestern Japan on the western North Pacific, has significantly risen, being warmed by the Kuroshio Current. Past distributional records of subtidal canopy-forming seaweeds (Laminariales and Fucales) exist at about 10-year intervals from the 1970s, along with detailed SST datasets at several sites along Kochi's >700 km coastline. In order to provide a clear picture of distributional shifts of coastal marine organisms in response to warming SST, we observed the present distribution of seaweeds and analyzed the SST datasets to estimate spatiotemporal SST trends in this coastal region. We present a large increase of 0.3°C/decade in the annual mean SST of this area over the past 40 years. Furthermore, a comparison of the previous and present distributions clearly showed the contraction of temperate species' distributional ranges and expansion of tropical species' distributional ranges in the seaweeds. Although the main temperate kelp Ecklonia (Laminariales) had expanded their distribution during periods of cooler SST, they subsequently declined as the SST warmed. Notably, the warmest SST of the 1997-98 El Niño Southern Oscillation event was the most likely cause of a widespread destruction of the kelp populations; no recovery was found even in the present survey at the formerly habitable sites where warm SSTs have been maintained. Temperate Sargassum spp. (Fucales) that dominated widely in the 1970s also declined in accordance with recent warming SSTs. In contrast, the tropical species, S. ilicifolium, has gradually expanded its distribution to become the most conspicuously dominant among the present observations. Thermal gradients, mainly driven by the warming Kuroshio Current, are presented as an explanation for the successive changes in both temperate and tropical species' distributions. © 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.


Denis V.,Academia Sinica, Taiwan | Mezaki T.,Kuroshio Biological Research Foundation | Tanaka K.,Kuroshio Biological Research Foundation | Kuo C.-Y.,Academia Sinica, Taiwan | And 4 more authors.
PLoS ONE | Year: 2013

Background: Seawater temperature is the main factor restricting shallow-water zooxanthellate coral reefs to low latitudes. As temperatures increase, coral species and perhaps reefs may move into higher-latitude waters, increasing the chances of coral reef ecosystems surviving despite global warming. However, there is a growing need to understand the structure of these high-latitude coral communities in order to analyze their future dynamics and to detect any potential changes. Methodology/Principal Findings: The high-latitude (32.75°N) community surveyed was located at Tatsukushi, Shikoku Island, Japan. Coral cover was 60±2% and was composed of 73 scleractinian species partitioned into 7 functional groups. Although only 6% of species belonged to the 'plate-like' functional group, it was the major contributor to species coverage. This was explained by the dominance of plate-like species such as Acropora hyacinthus and A. solitaryensis. Comparison with historical data suggests a relatively recent colonization/development of A. hyacinthus in this region and a potential increase in coral diversity over the last century. Low coverage of macroalgae (2% of the benthic cover) contrasted with the low abundance of herbivorous fishes, but may be reasonably explained by the high density of sea urchins (12.9±3.3 individuals m-2). Conclusions/Significance: The structure and composition of this benthic community are relatively remarkable for a site where winter temperature can durably fall below the accepted limit for coral reef development. Despite limited functionalities and functional redundancy, the current benthic structure might provide a base upon which a reef could eventually develop, as characterized by opportunistic and pioneer frame-building species. In addition to increasing seawater temperatures, on-going management actions and sea urchin density might also explain the observed state of this community. A focus on such 'marginal' communities should be a priority, as they can provide important insights into how tropical corals might cope with environmental changes. © 2013 Denis et al.


Toshino S.,Kitasato University | Toshino S.,Kuroshio Biological Research Foundation | Miyake H.,Kitasato University | Ohtsuka S.,Hiroshima University | And 5 more authors.
Evolution and Development | Year: 2015

Both sexes of the Japanese giant box jellyfish Morbakka virulenta were collected from the Seto Inland Sea, western Japan in December 2011, in order to observe the developmental processes from polyps to medusae. The medusa production in M. virulenta is up to now a unique process in cubozoans in that it exhibits a form of monodisc strobilation where the polyp is regenerated before the medusa detaches. This mode of medusa production was previously thought to be exclusive to scyphozoans. The general shape of young medusae resembles that of other cubozoans such as Alatina moseri and Copula sivickisi, but is differentiated from these by the short capitate tentacles and the lack of gastric filaments in the stomach. The unique medusa production of M. virulenta highly implies a phylogenetic similarity between cubozoans and scyphozoans. © 2015 Wiley Periodicals, Inc.


Toshino S.,Kitasato University | Toshino S.,Kuroshio Biological Research Foundation | Miyake H.,Kitasato University | Srinui K.,Burapha University | And 5 more authors.
Hydrobiologia | Year: 2016

Box jellyfishes are considered among the most dangerous sea creatures due to the lethal poisonous stings to humans. In order to predict the occurrences of box jellyfishes, it is necessary to understand their ecology and life cycle. The small box jellyfish Tripedalia binata was collected from eastern Thailand, in order to observe its life history, to compare its morphological characters with other cubozoans, and to discuss ecology and phylogeny in the class Cubozoa. Fertilization occurred internally, blastulae developed into planulae. Planulae were bred in the gastral pocket of the female medusa and released into the water. Free swimming planulae settled and metamorphosed into polyps. Adult polyps formed cysts at temperatures below 20°C water deterioration or starvation. Budding occurred in adult polyps, and buds were released after commencement of budding. Complete metamorphosis of a whole polyp into a single medusa occurred. Newly detached medusae were distinguished from those of other cubozoans by the pattern of nematocyst warts on the exumbrella and red chromatophores. The developmental features of T. binata resemble most closely those of T. cystophora and Copula sivickisi. The similarities in all early life cycle stages of those species support the close relationship of these species in the family Tripedaliidae. © 2016 Springer International Publishing Switzerland


Maoka T.,Research Institute for Production Development | Akimoto N.,Kyoto University | Tsushima M.,Kyoto Pharmaceutical University | Komemushi S.,Osaka City University | And 6 more authors.
Marine Drugs | Year: 2011

Carotenoids of the corals Acropora japonica, A. secale, and A. hyacinthus, the tridacnid clam Tridacna squamosa, the crown-of-thorns starfish Acanthaster planci, and the small sea snail Drupella fragum were investigated. The corals and the tridacnid clam are filter feeders and are associated with symbiotic zooxanthellae. Peridinin and pyrrhoxanthin, which originated from symbiotic zooxanthellae, were found to be major carotenoids in corals and the tridacnid clam. The crown-of-thorns starfish and the sea snail D. fragum are carnivorous and mainly feed on corals. Peridinin-3-acyl esters were major carotenoids in the sea snail D. fragum. On the other hand, ketocarotenoids such as 7,8-didehydroastaxanthin and astaxanthin were major carotenoids in the crown-of-thorns starfish. Carotenoids found in these marine animals closely reflected not only their metabolism but also their food chains. © 2011 by the authors; licensee MDPI.


Okubo N.,Keio University | Okubo N.,Kyoto University | Okubo N.,Australian National University | Okubo N.,Tokyo Keizai University | And 7 more authors.
PLoS ONE | Year: 2013

A comprehensive understanding of coral reproduction and development is needed because corals are threatened in many ways by human activity. Major threats include the loss of their photosynthetic symbionts (Symbiodinium) caused by rising temperatures (bleaching), reduced ability to calcify caused by ocean acidification, increased storm severity associated with global climate change and an increase in predators caused by runoff from human agricultural activity. In spite of these threats, detailed descriptions of embryonic development are not available for many coral species. The current consensus is that there are two major groups of stony corals, the "complex" and the "robust". In this paper we describe the embryonic development of four "complex" species, Pseudosiderastrea tayamai, Galaxea fascicularis, Montipora hispida, and Pavona Decussata, and seven "robust" species, Oulastrea crispata, Platygyra contorta, Favites abdita, Echinophyllia aspera, Goniastrea favulus, Dipsastraea speciosa (previously Favia speciosa), and Phymastrea valenciennesi (previously Montastrea valenciennesi). Data from both histologically sectioned embryos and whole mounts are presented. One apparent difference between these two major groups is that before gastrulation the cells of the complex corals thus far described (mainly Acropora species) spread and flatten to produce the so-called prawn chip, which lacks a blastocoel. Our present broad survey of robust and complex corals reveals that prawn chip formation is not a synapomorphy of complex corals, as Pavona Decussata does not form a prawn chip and has a well-developed blastocoel. Although prawn chip formation cannot be used to separate the two clades, none of the robust corals which we surveyed has such a stage. Many robust coral embryos pass through two periods of invagination, separated by a return to a spherical shape. However, only the second of these periods is associated with endoderm formation. We have therefore termed the first invagination a pseudo-blastopore. © 2013 Okubo et al.


PubMed | University of Miyazaki, Kuroshio Biological Research Foundation, Australian National University, The University of Okinawa and 2 more.
Type: Comparative Study | Journal: PloS one | Year: 2013

A comprehensive understanding of coral reproduction and development is needed because corals are threatened in many ways by human activity. Major threats include the loss of their photosynthetic symbionts (Symbiodinium) caused by rising temperatures (bleaching), reduced ability to calcify caused by ocean acidification, increased storm severity associated with global climate change and an increase in predators caused by runoff from human agricultural activity. In spite of these threats, detailed descriptions of embryonic development are not available for many coral species. The current consensus is that there are two major groups of stony corals, the complex and the robust. In this paper we describe the embryonic development of four complex species, Pseudosiderastrea tayamai, Galaxea fascicularis, Montipora hispida, and Pavona Decussata, and seven robust species, Oulastrea crispata, Platygyra contorta, Favites abdita, Echinophyllia aspera, Goniastrea favulus, Dipsastraea speciosa (previously Favia speciosa), and Phymastrea valenciennesi (previously Montastrea valenciennesi). Data from both histologically sectioned embryos and whole mounts are presented. One apparent difference between these two major groups is that before gastrulation the cells of the complex corals thus far described (mainly Acropora species) spread and flatten to produce the so-called prawn chip, which lacks a blastocoel. Our present broad survey of robust and complex corals reveals that prawn chip formation is not a synapomorphy of complex corals, as Pavona Decussata does not form a prawn chip and has a well-developed blastocoel. Although prawn chip formation cannot be used to separate the two clades, none of the robust corals which we surveyed has such a stage. Many robust coral embryos pass through two periods of invagination, separated by a return to a spherical shape. However, only the second of these periods is associated with endoderm formation. We have therefore termed the first invagination a pseudo-blastopore.


Shibata H.,Kitasato University | Miyake H.,Kitasato University | Goto T.,Iwate Fisheries Technology Center | Adachi A.,Enoshima Aquarium | And 2 more authors.
Plankton and Benthos Research | Year: 2015

Mass aggregations of Aurelia limbata have been reported along the Pacific coast of northern Japan, from spring to fall. The polyp stage is important for understanding the factors leading to mass occurrences of jellyfish, because polyps reproduce asexually and are responsible for the release of many ephyrae. Until the present report, the polyps of A. limbata had not been found in the wild and their ecology remained unknown. We found 18 polyps of A. limbata attached to two pieces of deep-sea debris, an aluminum beverage can and a plastic bottle, collected by bottom trawl at depths of 296 m and 392 m, respectively. Strobilation of the polyps was observed at 4°C without temperature change stimulation. This raises the possibility that strobilation occurs in low-temperature environments throughout the year. A large quantity of debris had sunk to the seafloor off the coast because of the tsunami tidal wave after the Great East Japan Earthquake, increasing the available substrate for A. limbata polyps. Additional ecological research on polyps and medusae in deep waters is necessary to predict future blooms of A. limbata. © The Plankton Society of Japan.


Nakano R.,Kuroshio Biological Research Foundation
Molluscan Research | Year: 2016

Stomach contents of Kalinga ornata and Plocamopherus tilesii (Nudibranchia: Doridacea: Polyceridae) were investigated using a light microscope to reveal their natural diets. Ossicles of ophiuroids were found in the stomachs of four out of 29 specimens of K. ornata. In contrast, both zooecia of Bryozoa and ossicles of ophiuroids were found in the stomachs of P. tilesii specimens. This is only the second record of a nudibranch species feeding on ophiuroids. © 2016 The Malacological Society of Australasia and the Society for the Study of Molluscan Diversity


Karyotype analysis was performed on the scleractinian coral Coelastrea aspera Verrill, 1866, commonly found along temperate coasts in Japan (30-35N) and in coastal waters in the Indian and Pacific oceans. G-banding of Coelastrea aspera was successfully performed, although the banding pattern was not as clear as that in mammals. The karyogram clearly revealed that this coral had a homogeneously staining region (hsr) in chromosome 11. This hsr consisted of ribosomal RNA (rRNA) related genes, which was demonstrated by fluorescence in situ hybridization (FISH) with probes generated using 28S ribosomal DNA (rDNA) primers and those generated through chromosome microdissection. In addition, we conducted silver-stained nucleolus organizer region (Ag-NOR) analysis and found Ag depositions in the interphase nuclei but not on rRNA gene loci and hsr(s) in the mitotic stage. The hsr of this coral was observed in approximately 50% of the metaphase spreads analyzed. This may explain the diversity of coral rDNA based on the molecular study of sequence analysis. Furthermore, it was discovered that human telomere and Alu repeated sequences were present in this Coelastrea aspera. Probes derived from human Alu sequences are expected to play an important role in the classification of corals. Overall, our data can be of great value in discriminating among scleractinian coral species and understanding their genetics, including chromosomal evolution.

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