Details of a Researcher

Published Papers - HARII Saki

Division display >> ／ All the affair displays1 - 73 of about 73

A method for detecting acid phosphatase activity in corals

Tomohiro Sasamoto, Kento Muta, Kanae Koike, Yuuki Kodama, Masahiro Fujishima, Seiya Kitanobo, Tomihiko Higuchi, Masaya Morita, Saki Harii, and Ikuko Yuyama

Galaxea, J Coral Reef Stud ( JCRS ) 2025 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Shallow corals acclimate to mesophotic depths while maintaining their heat tolerance against ongoing climate change

Parviz Tavakoli-Kolour, Frederic Sinniger, Masaya Morita, Sanaz Hazraty-Kari, Takashi Nakamura, Saki Harii

Marine Pollution Bulletin ( Elsevier BV ) 209 117277 - 117277 2024.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI

Using underwater mini-ROV for coral eDNA survey: a case study in Okinawan mesophotic ecosystems

Noriyuki Satoh, Frederic Sinniger, Haruhi Narisoko, Shinichiro Nagahama, Nobuhiro Okada, Yuki Shimizu, Yuki Yoshioka, Kanako Hisata, Saki Harii

Coral Reefs ( Springer Science and Business Media LLC ) 2024.11 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Abstract Mesophotic coral ecosystems (MCEs) are light-dependent communities occurring at depths of 30–150 m. They have been suggested to serve as refuge against thermal stress during heat waves for some coral species. Recent studies on MCEs have revealed a high diversity of communities, some unique, and that these ecosystems are far from being immune to anthropogenic threats. However, the depths at which these ecosystems are found make their exploration and study challenging. Consequently, most suitable environments for MCEs remain unexplored. To facilitate the detection and characterization of MCEs, we improved the methodology for mesophotic scleractinian survey by environmental DNA (eDNA) metabarcoding analysis using seawater collected by underwater mini-Remote Operated Vehicle (mini-ROV). We tested this improved approach at upper mesophotic sites in Okinawa, Japan, with different corals dominating the communities (i.e., Alveopora-dominated, Seriatopora-dominated, and Acropora-dominated communities). Despite the proximity of the different sites, our eDNA metabarcoding analyses detected the dominant coral genera specific to each site. In addition, this study detected numerous other genera present at these sites, including Acropora, Pachyseris, Galaxea, Lobophyllia, Montipora, Pocillopora, Porites, and others. Therefore, this study might support a new technical gate for comprehensive survey of MCEs using eDNA samples collected by underwater mini-ROV, although further technical improvement is required for quantitative estimation.

Access this article

DOI

Presence of coral-killing sponges in Okinawan mesophotic coral ecosystems

Ritzelle L Albelda, Frederic Sinniger, Yuji Ise, Saki Harii

Bulletin of Marine Science ( Bulletin of Marine Science ) 100 ( 3 ) 503 - 518 2024.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Shallow reefs worldwide are degrading due to multiple threats. Mesophotic coral ecosystems (MCEs; 30– 150 m depth) have been investigated for their diversity and potential to serve as a coral refuge and re-seed shallow reefs. However, recent studies showed that MCEs are also disturbed by various factors, including diseases, pollution, storms, and thermal-induced bleaching. Among the disturbances, coral-killing sponges are also known to decimate many Indo-Pacific shallow reefs but are rarely reported at mesophotic depths. Here, we report the first comprehensive assessment of the coral-killing sponges Chalinula nematifera (de Laubenfels, 1954) and Terpios hoshinota Rützler and Muzik, 1993 in MCEs. Specifically, we investigated (1) their prevalence, (2) sponge-affected corals, and (3) coral-sponge interaction types at 40 m depth in Okinawa, southern Japan. We found that C. nematifera and T. hoshinota were present but at low prevalences, with the highest mean cover of 3.8% and 1.8%, respectively. Although both species appeared to be substrate- generalists, they mainly affected the dominant coral taxa, such as branching corals Acropora tenella and Seriatopora sp. Both sponges mainly interacted with corals by overgrowth, followed by tissue and peripheral contact. Due to lack of prior knowledge, it is unclear whether the current observation of the coral-killing sponges captured their expansion, decline, or steady state in Okinawan MCEs. Thus, this study provides unprecedented insights about coral-killing sponges at mesophotic depths which highlights the need to monitor more MCEs globally, prioritizing regions with shallow reefs that are already threatened by these sponges.

Access this article

DOI

Acoustic Distribution Maps of Phonating Species in Coral Reefs

Tomonari Akamatsu 1, Frederic Sinniger, Saki Harii

Marine Research 4 ( 1 ) 27 - 36 2024.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI

Plasticity of shallow reef corals across a depth gradient

Parviz Tavakoli-Kolour, Frederic Sinniger, Masaya Morita, Sanaz Hazraty-Kari, Takashi Nakamura, Saki Harii

Marine Pollution Bulletin ( Elsevier BV ) 197 115792 - 115792 2023.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI

Variability in thermal stress thresholds of corals across depths

Parviz Tavakoli-Kolour, Frederic Sinniger, Masaya Morita, Takashi Nakamura, Saki Harii

Frontiers in Marine Science ( Frontiers Media SA ) 10 2023.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Mesophotic habitats are potential refugia for corals in the context of climate change. The seawater temperature in a mesophotic habitat is generally lower than in a shallow habitat. However, the susceptibility and threshold temperatures of mesophotic corals are not well understood. We compared 11 mesophotic and shallow species to understand their thermal stress thresholds using physiological parameters. Coral fragments were exposed to two thermal stress treatments, with temperatures set at ~30°C and ~31°C, and a low-temperature treatment set at ~28°C as the “no stress” condition for 14 days. We found that the threshold temperature of coral species at mesophotic depths is slightly lower or equal to that of corals in shallow depths. The results suggest that species in the mesophotic coral ecosystems can survive low (&lt;4 degree heating weeks) thermal stress. However, mass bleaching and high mortality can be expected when temperatures rise above 4 degree heating weeks.

Access this article

DOI

A tenuis relationship: traditional taxonomy obscures systematics and biogeography of the ‘Acropora tenuis’ (Scleractinia: Acroporidae) species complex

Tom C L Bridge, Peter F Cowman, Andrea M Quattrini, Victor E Bonito, Frederic Sinniger, Saki Harii, Catherine E I Head, Julia Y Hung, Tuikolongahau Halafihi, Teina Rongo, Andrew H Baird

Zoological Journal of the Linnean Society ( Oxford University Press (OUP) ) 2023.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Abstract Molecular phylogenetics has fundamentally altered our understanding of the taxonomy, systematics and biogeography of corals. Recently developed phylogenomic techniques have started to resolve species-level relationships in the diverse and ecologically important genus Acropora, providing a path to resolve the taxonomy of this notoriously problematic group. We used a targeted capture dataset (2032 loci) to investigate systematic relationships within an Acropora clade containing the putatively widespread species Acropora tenuis and its relatives. Using maximum likelihood phylogenies and genetic clustering of single nucleotide polymorphisms from specimens, including topotypes, collected across the Indo-Pacific, we show ≥ 11 distinct lineages in the clade, only four of which correspond to currently accepted species. Based on molecular, morphological and geographical evidence, we describe two new species; Acropora rongoi n. sp. and Acropora tenuissima n. sp. and remove five additional nominal species from synonymy. Systematic relationships revealed by our molecular phylogeny are incongruent with traditional morphological taxonomy and demonstrate that characters traditionally used to delineate species boundaries and infer evolutionary history are homoplasies. Furthermore, we show that species within this clade have much smaller geographical ranges and, consequently, population sizes than currently thought, a finding with profound implications for conservation and management of reef corals.

Access this article

DOI

Response of resistant larvae of the coral Acropora tenuis to future thermal stress

Sanaz Hazraty-Kari, Masaya Morita, Parviz Tavakoli-Kolour, Saki Harii

Marine Pollution Bulletin ( Elsevier BV ) 192 115060 - 115060 2023.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI

Energy allocation trade-offs as a function of age in fungiid corals

Grinblat M, Eyal-Shaham L, Eyal G, Ben-Zvi O, Harii S, Morita M, Sakai K, Hirose M, Miller DJ and Loya Y

Frontiers in Marine Science 10 ( 1113987 ) 1 - 13 2023.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI

Daily temporal homeostasis in the coral Acropora digitifera

Rosenberg Y, Doniger T, Lampert S, Sinniger F, Harii S, Levy O

Frontiers in Marine Science 10 ( 1149490 ) 2023.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI

Daily temporal homeostasis in the coral Acropora digitifera

Yaeli Rosenberg, Tirza Doniger, Sarit Lampert, Frederic Sinniger, Saki Harii, Oren Levy

Frontiers in Marine Science ( Frontiers Media SA ) 10 1149490 2023.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The study aimed to gain a deeper understanding of the daily fluctuations in gene expression at a transcript level in the coral Acropora digitifera and create a comprehensive map of the biological processes that occur under natural environmental conditions. The coral is a key organism in marine ecosystems, and understanding its physiology and the adaptation mechanisms it uses to cope with daily environmental changes is vital for its survival and the preservation of coral reefs. The study’s results showed that certain genes in the coral exhibit specific patterns of expression at different times of the day. These genes play critical roles in regulating a wide range of physiological and behavioral processes, such as metabolism, development, and DNA damage repair. During the day, the coral expends energy on growth and development, and these genes are actively involved in these processes. On the other hand, at night, the coral’s focus shifts toward repair and recovery. The genes that are active during this period are involved in processes like DNA repair, hypoxia response, and transcription. This is a crucial time for the coral, as it’s exposed to a range of environmental stressors that can damage its DNA and impact its overall health. In conclusion, this study provides valuable insights into the cyclic regulatory processes that help the coral adapt to daily external variations and sustain its physiology. It highlights the importance of understanding the daily rhythms of gene expression in marine organisms and the role they play in maintaining the health of coral reefs. This research can be used to develop strategies to preserve coral reefs and mitigate the effects of environmental changes on coral physiology.

Access this article

DOI

Reactions of juvenile coral to three years of consecutive thermal stress.

Hazraty-Kari S, Morita M, Tavakoli-Kolour P, Nakamura T, Harii S

The Science of the total environment ( Science of the Total Environment ) 863 161227 - 161227 2023.03 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

PubMed

Acclimation potential of Acropora to mesophotic environment

Parviz Tavakoli-Kolour, Frederic Sinniger, Masaya Morita, Saki Harii

Marine Pollution Bulletin ( Elsevier BV ) 188 114698 - 114698 2023.03 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI

Using Soundscapes to Assess Changes in Coral Reef Social-Ecological Systems

Tzu-Hao Lin, Frederic Sinniger, Saki Harii, Tomonari Akamatsu

Oceanography 2023.02 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

Coral larvae suppress heat stress response during the onset of symbiosis decreasing their odds of survival.

Kitchen SA, Jiang D, Harii S, Satoh N, Weis VM, Shinzato C

Molecular ecology ( Molecular Ecology ) 31 ( 22 ) 5813 - 5830 2022.11 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The endosymbiosis between most corals and their photosynthetic dinoflagellate partners begins early in the host life history, when corals are larvae or juvenile polyps. The capacity of coral larvae to buffer climate-induced stress while in the process of symbiont acquisition could come with physiological trade-offs that alter behaviour, development, settlement and survivorship. Here we examined the joint effects of thermal stress and symbiosis onset on colonization dynamics, survival, metamorphosis and host gene expression of Acropora digitifera larvae. We found that thermal stress decreased symbiont colonization of hosts by 50% and symbiont density by 98.5% over 2 weeks. Temperature and colonization also influenced larval survival and metamorphosis in an additive manner, where colonized larvae fared worse or prematurely metamorphosed more often than noncolonized larvae under thermal stress. Transcriptomic responses to colonization and thermal stress treatments were largely independent, while the interaction of these treatments revealed contrasting expression profiles of genes that function in the stress response, immunity, inflammation and cell cycle regulation. The combined treatment either cancelled or lowered the magnitude of expression of heat-stress responsive genes in the presence of symbionts, revealing a physiological cost to acquiring symbionts at the larval stage with elevated temperatures. In addition, host immune suppression, a hallmark of symbiosis onset under ambient temperature, turned to immune activation under heat stress. Thus, by integrating the physical environment and biotic pressures that mediate presettlement event in corals, our results suggest that colonization may hinder larval survival and recruitment under projected climate scenarios.

Access this article

DOI
Search related information

PubMed

Quantitative three-dimensional morphological analysis supports species discrimination in complex-shaped and taxonomically challenging corals

Catalina Ramírez-Portilla, Inge M. Bieger, Robert G. Belleman, Thomas Wilke, Jean-François Flot, Andrew H. Baird, Saki Harii, Frederic Sinniger, Jaap A. Kaandorp

Frontiers in Marine Science ( Frontiers Media SA ) 9 2022.09 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Morphological characters play an important role in species descriptions and are essential for a better understanding of the function, evolution and plasticity of an organism's shape. However, in complex-shaped organisms lacking characteristic features that can be used as landmarks, quantifying morphological traits, assessing their intra- and interspecific variation, and subsequently delineating phenotypically distinct groups continue to be problematic. For such organisms, three-dimensional morphological analysis might be a promising approach to differentiate morphogroups and potentially aid the delineation of species boundaries, though identifying informative features remains a challenge. Here, we assessed the potential of 3D-based quantitative morphology to delineate a priori and/or to discriminate a posteriori morphogroups of complex-shaped and taxonomically challenging organisms, such as corals from the morphologically diverse genus Acropora. Using three closely related coral taxa previously delimited using other lines of evidence, we extracted a set of variables derived from triangulated polygon meshes and medial axis skeletons of the 3D models. From the resulting data set, univariate and multivariate analyses of 3D-based variables quantifying overall shape including curvature, branching, and complexity were conducted. Finally, informative feature selection was performed to assess the discriminative power of the selected variables. Results revealed significant interspecific differences in the means of a set of 3D-based variables, highlighting potentially informative characters that provide sufficient resolution to discriminate morphogroups congruent with independent species identification based on other lines of evidence. A combination of representative features, remarkably represented by curvature, yielded measures that assisted in differentiating closely related species despite the overall morphospaces overlap. This study shows that a well-justified combination of 3D-based variables can aid species discrimination in complex-shaped organisms such as corals and that feature screening and selection is useful for achieving sufficient resolution to validate species boundaries. Yet, the significant discriminative power displayed by curvature-related variables and their potential link to functional significance need to be explored further. Integrating informative morphological features with other independent lines of evidence appears therefore a promising way to advance not only taxonomy but also our understanding of morphological variation in complex-shaped organisms.

Access this article

DOI

Limited acclimation of early life stages of the coral Seriatopora hystrix from mesophotic depth to shallow reefs.

Prasetia R, Sinniger F, Nakamura T, Harii S

Scientific reports ( Scientific Reports ) 12 ( 1 ) 12836 - 12836 2022.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Mesophotic coral ecosystems (MCEs, reefs between 30 and 150 m depth) have been hypothesized to contribute to shallow reef recovery through the recruitment of larvae. However, few studies have directly examined this. Here we used mesophotic colonies of Seriatopora hystrix, a depth generalist coral, to investigate the effect of light intensity on larval behavior and settlement through ex situ experiments. We also investigated juvenile survival, growth, and physiological acclimation in situ. Bleached larvae and a significant reduction in settlement rates were found when the mesophotic larvae were exposed to light conditions corresponding to shallow depths (5 and 10 m) ex situ. The in situ experiments showed that mesophotic juveniles survived well at 20 and 40 m, with juveniles in shaded areas surviving longer than three months at 3-5 m during a year of mass bleaching in 2016. Juvenile transplants at 20 m showed a sign of physiological acclimation, which was reflected by a significant decline in maximum quantum yield. These results suggest that light is a significant factor for successful recolonization of depth-generalist corals to shallow reefs. Further, recolonization of shallow reefs may only occur in shaded habitats or potentially through multigenerational recruitments with intermediate depths acting as stepping stones.

Access this article

DOI
Search related information

PubMed

The early acquisition of symbiotic algae benefits larval survival and juvenile growth in the coral Acropora tenuis.

Hazraty-Kari S, Masaya M, Kawachi M, Harii S

Journal of experimental zoology. Part A, Ecological and integrative physiology ( Journal of Experimental Zoology Part A: Ecological and Integrative Physiology ) 337 ( 5 ) 559 - 565 2022.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Larval dispersal and postsettlement survival of corals play significant roles in the maintenance of coral populations. Most corals acquire their symbiotic algae (Symbiodiniaceae) from the environment in each generation (horizontal transmission). For horizontal transmitters, the quick establishment of symbiosis is important for their survival, since the photosynthetic activity of symbiotic algae provides energy. However, recent studies have indicated that oxidative stress resulting from photosynthesis might also harm coral larvae. Therefore, it remains unclear whether symbionts contribute energy sources along with intrinsic lipids from eggs and assist in settlement/metamorphosis in early life stages. In the present study, we show that symbiotic algae contribute supplemental energy and are also associated with settlement. Furthermore, although juveniles acquired symbiotic algae after settlement, the acquisition of symbiotic algae in the larval stages caused higher growth (number of polyps and size) and low mortality in the juvenile stage. Our data suggest that symbiotic larvae potentially have longer dispersal periods due to their lower lipid consumption rates, which make them better able to retain buoyancy and motility, increasing the ability of symbiotic larvae to settle in favored locations compared with aposymbiotic larvae. Moreover, postsettlement juveniles may continue to benefit from symbiotic relationships formed during the larval stage. Overall, these findings reveal that the effects of symbiotic algae on Acropora tenuis coral larvae are beneficial, particularly under normal seawater temperature conditions.

Access this article

DOI
Search related information

PubMed

Solving the Coral Species Delimitation Conundrum.

Ramírez-Portilla C, Baird AH, Cowman PF, Quattrini AM, Harii S, Sinniger F, Flot JF

Systematic biology ( Systematic Biology ) 71 ( 2 ) 461 - 475 2022.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Distinguishing coral species is not only crucial for physiological, ecological, and evolutionary studies but also to enable effective management of threatened reef ecosystems. However, traditional hypotheses that delineate coral species based on morphological traits from the coral skeleton are frequently at odds with tree-based molecular approaches. Additionally, a dearth of species-level molecular markers has made species delimitation particularly challenging in species-rich coral genera, leading to the widespread assumption that interspecific hybridization might be responsible for this apparent conundrum. Here, we used three lines of evidence-morphology, breeding trials, and molecular approaches-to identify species boundaries in a group of ecologically important tabular Acropora corals. In contrast to previous studies, our morphological analysis yielded groups that were congruent with experimental crosses as well as with coalescent-based and allele sharing-based multilocus approaches to species delimitation. Our results suggest that species of the genus Acropora are reproductively isolated and independently evolving units that can be distinguished morphologically. These findings not only pave the way for a taxonomic revision of coral species but also outline an approach that can provide a solid basis to address species delimitation and provide conservation support to a wide variety of keystone organisms. [Acropora; coral reefs; hybridization; reproductive isolation; taxonomy.]

Access this article

DOI
Search related information

PubMed

Mineral Components of Scleractinian Coral Skeletons Cultured Without Symbionts

Motai S.

Journal of Geophysical Research: Biogeosciences ( Journal of Geophysical Research: Biogeosciences ) 127 ( 2 ) 2022.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Skeletons of contemporary reef-building scleractinian corals are formed of aragonite, a polymorph of the calcium carbonate (CaCO3), notwithstanding calcite being a more stable phase under the condition of coral habitats. Circumstances developing aragonite in coral calcification have been addressed currently. Considering that the symbiotic relationship between the coral host and dinoflagellate algae (zooxanthellae) is perhaps relevant to coral calcification, we studied the impact of these symbiotic relationships on CaCO3 polymorph selection. Juvenile scleractinian corals (Acropora tenuis and Acropora digitifera) absent symbionts were cultured in seawaters with varied Mg/Ca molar ratios (mMg/Ca), and the mineral phases of the skeletons were detected employing X-ray diffraction. The findings revealed that diminutive quantities of calcite precipitated as coral skeleton in Acropora digitifera surprisingly in pseudo-present seawater (mMg/Ca similar to 5). Additionally, coral developed skeletons from only calcite in seawater with an mMg/Ca < 1. The evidence gathered in this investigation suggests that the symbiotic relationship affects the establishment of aragonite skeletons in the course of coral calcification.

Access this article

DOI

A coral spawning calendar for Sesoko Station, Okinawa, Japan

Baird Andrew H., Edwards Alasdair J., Guest James R., Harii Saki, Hatta Masayuki, Lachs Liam, Mera Hanaka, Sinniger Frederic, Abrego David, Ben-Zvi Or, Bronstein Omri, Cabaitan Patrick C., Cumbo Vivian R., Eyal Gal, Eyal-Shaham Lee, Feldman Bar, Figueiredo Joana, Flot Jean-François, Grinblat Mila, Heyward Andrew, Hidaka Michio, Hirose Mamiko, Iguchi Akira, Isomura Naoko, Kinzie Robert A., Kitanobo Seiya, Kuba Alyson, Levy Oren, Loya Yossi, Mezaki Takuma, Mohamed Amin R., Morita Masaya, Nojima Satoshi, Nozawa Yoko, Prasetia Rian, Puill-Stephan Eneour, Ramirez-Portilla Catalina, Rapuano Hanna, Rosenberg Yaeli, Sakai Yusuke, Sakai Kazuhiko, Shlesinger Tom, Terraneo Tullia I., Yakovleva Irina, Yamamoto Hiromi H., Yamazato Kiyoshi

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 41 - 49 2022.01

Type of publication: Research paper (scientific journal)

Sesoko Station, Okinawa, has been the site of many significant advances in coral reproductive research and it continues to be a preferred destination for both Japanese and international researchers. Consequently, there are decades of spawning observations, which we present and explore here with the aim of making it easier to predict when species spawn at Sesoko Station. The data include over 700 spawning observations from 87 species of reef-building hermatypic corals. Almost all spawning occurred between dusk and dawn, with most spawning activity concentrated in the 2 to 4 hours after sunset. Some phylogenetic patterns were evident: most Acropora species spawn on or around the 6th full moon after December 21st (the northern hemisphere winter solstice); spawning in common species of merulinids and Porites appears to be concentrated around the 7th full moon and spawning in the fungiids around the 8th and subsequent full moons. The night of peak spawning with respect to the night of the full moon varied considerably among years in common Acropora species, but was dependent on the calendar date of the full moon in May or June. Therefore, despite an extended spawning season of over three months and considerable variation in the calendar date of spawning in many species among years, the month and night of spawning are reasonably predictable for many species enhancing the value of Sesoko Station as a site for coral reproductive research.

Access this article

DOI
Search related information

CiNii Research

Overview of the mesophotic coral ecosystems around Sesoko Island, Okinawa, Japan

Sinniger Frederic, Albelda Ritzelle L., Prasetia Rian, Rouzé Héloïse, Sitorus Erlangga D., Harii Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 69 - 76 2022.01

Type of publication: Research paper (scientific journal)

Coral reef ecosystems extend beyond the standard SCUBA diving depth. These ecosystems found between approximately 30 and over 150 m are referred to as mesophotic coral ecosystems (MCEs). Mesophotic coral communities have already been reported from Okinawa over 50 years ago. However, since then little additional knowledge has been obtained on the distribution and diversity of mesophotic corals in the region. Here, we provide an overview of the coral communities observed at selected sites in the region around Sesoko Island. Using photo-quadrats, we surveyed coral communities and specifically the contribution of the dominant coral genera to the total coral cover between different sites at depths ranging from 30 to 80 m. We found that deep coral communities around Sesoko Island hold a high potential biodiversity and need to be taken into account into coastal management plans.

Access this article

DOI
Search related information

CiNii Research

Long-term trends and seasonal variations in environmental conditions in Sesoko Island, Okinawa, Japan

Singh Tanya, Sinniger Frederic, Nakano Yoshikatsu, Nakamura Shigeo, Kadena Shouhei, Jinza Mori, Fujimura Hiroyuki, Harii Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 121 - 133 2022.01

Type of publication: Research paper (scientific journal)

Knowledge of environmental factors is crucial in understanding biological and ecological processes. Yet information on the environment around Sesoko Island, Okinawa, Japan, one of the main locations for coral reef research in Japan, remains scarce. Data of air and sea surface temperature (SST), wind velocity, wave height, and frequency of typhoons have been manually recorded at Sesoko Station, Tropical Biosphere Research Station, the University of the Ryukyus from September 1990 to November 2021. Here we describe the seasonal and long-term trends in these environmental variables at Sesoko Island. Some of the key findings were that the air temperature and SST fluctuated by ~9-12°C throughout the year. A rise in air temperature and SST between 1990 and 2021 was observed in the winter and autumn season, respectively. The Degree Heating Week (DHW) based on the in-situ data reflected the bleaching observations around Sesoko Station. The DHW exceeded the critical bleaching level of 8°C-week in 1998 and the significant bleaching level of 4°C-week in 2001, 2016, and 2017. Weak southerly winds were dominant in summers, while stronger northeasterly winds were dominant in winters. The frequency of winds between 3.4 to 7.9 m/s and northeastern winds have increased through time. Typhoons generally occur between May and October, and the frequency of typhoons has not increased over the past 30 years. Wave heights never exceeded 0.5 m and were highest between July and September. These findings will provide a reliable baseline of the environment at Sesoko Island for further ecological studies.

Access this article

DOI
Search related information

CiNii Research

Deepest observation of the butterflyfish Coradion altivelis (Perciformes: Chaetodontidae) in Japan

Sinniger Frederic, Akamatsu Tomonari, Harii Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 39 - 40 2022.01

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Coral reef research in Sesoko Island -50 years anniversary of Sesoko Station, University of the Ryukyus-

Harii Saki, Morita Masaya, Sakai Kazuhiko, Sinniger Frederic, Takemura Akihiro, Yamashiro Hideyuki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 1 - 4 2022.01

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

A coral spawning calendar for Sesoko Station, Okinawa, Japan

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 41 - 49 2022.01

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Overview of the mesophotic coral ecosystems around Sesoko Island, Okinawa, Japan

Sinniger Frederic, Albelda Ritzelle L., Prasetia Rian, Rouzé Héloïse, Sitorus Erlangga D., Harii Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 69 - 76 2022.01

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Long-term trends and seasonal variations in environmental conditions in Sesoko Island, Okinawa, Japan

Singh Tanya, Sinniger Frederic, Nakano Yoshikatsu, Nakamura Shigeo, Kadena Shouhei, Jinza Mori, Fujimura Hiroyuki, Harii Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 121 - 133 2022.01

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Deepest observation of the butterflyfish Coradion altivelis (Perciformes: Chaetodontidae) in Japan

Sinniger Frederic, Akamatsu Tomonari, Harii Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 39 - 40 2022.01

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Coral reef research in Sesoko Island -50 years anniversary of Sesoko Station, University of the Ryukyus-

Harii Saki, Morita Masaya, Sakai Kazuhiko, Sinniger Frederic, Takemura Akihiro, Yamashiro Hideyuki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 24 ( 1 ) 1 - 4 2022.01

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Unique environmental Symbiodiniaceae diversity at an isolated island in the northwestern Pacific.

Yorifuji M, Yamashita H, Suzuki G, Kawasaki T, Tsukamoto T, Okada W, Tamura K, Nakamura R, Inoue M, Yamazaki M, Harii S

Molecular phylogenetics and evolution ( Molecular Phylogenetics and Evolution ) 161 107158 - 107158 2021.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Dinoflagellates in the family Symbiodiniaceae are intensively investigated as algal symbionts of corals and other invertebrates, underpinning coral reef ecosystems as primary producers. Diversity, including regional diversification, of free-living communities is less studied. In this study, an environmental Symbiodiniaceae community at an isolated island, Okinotori Island, Japan, was investigated to determine whether the community is endemic or common with other locations near continents and major ocean currents. Symbiotic algae in common corals at the island were the same type as those of the corals from other Japanese waters. In the environmental samples, genera Symbiodinium (formerly clade A), Cladocopium (clade C), Durusdinium (clade D), and clades F (including Freudenthalidium), G, and I, were identified through analysis of internal transcribed spacer region 2 of nuclear ribosomal RNA gene (ITS2) sequences. Interestingly, some sequences found were genetically different from those of previously reported genera/clades. These unknown sequences were genetically included in the Symbiodiniaceae linage, but they were differentiated from the previously known nine clades. The sequences formed a cluster in the phylogenetic tree based on 28S nrDNA. These sequences were thus considered members of a novel clade in the family (clade J). In total, 120 kinds of ITS2 sequences were produced; while 10 were identical to previously reported sequences, the majority were highly divergent. These genetically unique Symbiodiniaceae types, including novel clade J, may have evolved in isolation and reflect the environmental characteristics of the Okinotori Island.

Access this article

DOI
Search related information

PubMed

Morphological stasis masks ecologically divergent coral species on tropical reefs.

Bongaerts P, Cooke IR, Ying H, Wels D, den Haan S, Hernandez-Agreda A, Brunner CA, Dove S, Englebert N, Eyal G, Forêt S, Grinblat M, Hay KB, Harii S, Hayward DC, Lin Y, Mihaljević M, Moya A, Muir P, Sinniger F, Smallhorn-West P, Torda G, Ragan MA, van Oppen MJH, Hoegh-Guldberg O

Current biology : CB ( Current Biology ) 31 ( 11 ) 2286 - 2298.e8 2021.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Coral reefs are the epitome of species diversity, yet the number of described scleractinian coral species, the framework-builders of coral reefs, remains moderate by comparison. DNA sequencing studies are rapidly challenging this notion by exposing a wealth of undescribed diversity, but the evolutionary and ecological significance of this diversity remains largely unclear. Here, we present an annotated genome for one of the most ubiquitous corals in the Indo-Pacific (Pachyseris speciosa) and uncover, through a comprehensive genomic and phenotypic assessment, that it comprises morphologically indistinguishable but ecologically divergent lineages. Demographic modeling based on whole-genome resequencing indicated that morphological crypsis (across micro- and macromorphological traits) was due to ancient morphological stasis rather than recent divergence. Although the lineages occur sympatrically across shallow and mesophotic habitats, extensive genotyping using a rapid molecular assay revealed differentiation of their ecological distributions. Leveraging "common garden'' conditions facilitated by the overlapping distributions, we assessed physiological and quantitative skeletal traits and demonstrated concurrent phenotypic differentiation. Lastly, spawning observations of genotyped colonies highlighted the potential role of temporal reproductive isolation in the limited admixture, with consistent genomic signatures in genes related to morphogenesis and reproduction. Overall, our findings demonstrate the presence of ecologically and phenotypically divergent coral species without substantial morphological differentiation and provide new leads into the potential mechanisms facilitating such divergence. More broadly, they indicate that our current taxonomic framework for reef-building corals may be scratching the surface of the ecologically relevant diversity on coral reefs, consequently limiting our ability to protect or restore this diversity effectively.

Access this article

DOI
Search related information

PubMed

Environmental constraints on the mode of symbiont transmission in corals

Baird Andrew H., Yakovleva Irina M., Harii Saki, Harii Saki, Sinniger Frederic, Hidaka Michio

Journal of Experimental Marine Biology and Ecology ( ELSEVIER ) 538 2021.05 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

Theory predicts that passing symbionts directly from parent to offspring should benefit the host by reducing conflict between diverse symbionts and benefit the symbiont by guaranteeing transmission. However, in some symbiotic associations, such as those between corals and algae of the family Symbiodiniaceae, vertical transmission is rare, suggesting a substantial cost. Here, we show that coral larvae which contained symbionts had lower survivorship than larvae of the same species that lacked symbionts when exposed to natural sunlight. Higher activity of antioxidant defenses and higher levels of oxidative cellular damage observed in symbiotic larvae suggest that reactive oxygen species, produced by stress on the photosynthetic apparatus of the symbionts, are responsible for these higher rates of mortality under solar radiation. We hypothesize that symbionts are a burden in the early life history of broadcast spawning corals under conditions typically experienced on the ocean surface during dispersal. This is one possible reason why species with an obligate pre-motile period of between 12 and 36 h very rarely have vertical transmission of symbionts, in contrast to species whose larvae are small or swim on release that often have vertical transmission of symbionts.

Access this article

DOI
Search related information

J-GLOBAL

N-Acetyl-d-Glucosamine-Binding Lectin in Acropora tenuis Attracts Specific Symbiodiniaceae Cell Culture Strains.

Takeuchi R, Jimbo M, Tanimoto F, Iijima M, Yamashita H, Suzuki G, Harii S, Nakano Y, Yasumoto K, Watabe S

Marine drugs ( Marine Drugs ) 19 ( 3 ) 2021.03 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Many corals establish symbiosis with Symbiodiniaceae cells from surrounding environments, but very few Symbiodiniaceae cells exist in the water column. Given that the N-acetyl-d-glucosamine-binding lectin ActL attracts Symbiodiniaceae cells, we hypothesized that corals must attract Symbiodiniaceae cells using ActL to acquire them. Anti-ActL antibody inhibited acquisition of Symbiodiniaceae cells, and rearing seawater for juvenile Acropora tenuis contained ActL, suggesting that juvenile A. tenuis discharge ActL to attract these cells. Among eight Symbiodiniaceae cultured strains, ActL attracted NBRC102920 (Symbiodinium tridacnidorum) most strongly followed by CS-161 (Symbiodinium tridacnidorum), CCMP2556 (Durusdinium trenchii), and CCMP1633 (Breviolum sp.); however, it did not attract GTP-A6-Sy (Symbiodinium natans), CCMP421 (Effrenium voratum), FKM0207 (Fugacium sp.), and CS-156 (Fugacium sp.). Juvenile polyps of A. tenuis acquired limited Symbiodiniaceae cell strains, and the number of acquired Symbiodiniaceae cells in a polyp also differed from each other. The number of Symbiodiniaceae cells acquired by juvenile polyps of A. tenuis was correlated with the ActL chemotactic activity. Thus, ActL could be used to attract select Symbiodiniaceae cells and help Symbiodiniaceae cell acquisition in juvenile polyps of A. tenuis, facilitating establishment of symbiosis between A. tenuis and Symbiodiniaceae cells.

Access this article

DOI
Search related information

PubMed

An Indo-Pacific coral spawning database.

Baird AH, Guest JR, Edwards AJ, Bauman AG, Bouwmeester J, Mera H, Abrego D, Alvarez-Noriega M, Babcock RC, Barbosa MB, Bonito V, Burt J, Cabaitan PC, Chang CF, Chavanich S, Chen CA, Chen CJ, Chen WJ, Chung FC, Connolly SR, Cumbo VR, Dornelas M, Doropoulos C, Eyal G, Eyal-Shaham L, Fadli N, Figueiredo J, Flot JF, Gan SH, Gomez E, Graham EM, Grinblat M, Gutiérrez-Isaza N, Harii S, Harrison PL, Hatta M, Ho NAJ, Hoarau G, Hoogenboom M, Howells EJ, Iguchi A, Isomura N, Jamodiong EA, Jandang S, Keyse J, Kitanobo S, Kongjandtre N, Kuo CY, Ligson C, Lin CH, Low J, Loya Y, Maboloc EA, Madin JS, Mezaki T, Min C, Morita M, Moya A, Neo SH, Nitschke MR, Nojima S, Nozawa Y, Piromvaragorn S, Plathong S, Puill-Stephan E, Quigley K, Ramirez-Portilla C, Ricardo G, Sakai K, Sampayo E, Shlesinger T, Sikim L, Simpson C, Sims CA, Sinniger F, Spiji DA, Tabalanza T, Tan CH, Terraneo TI, Torda G, True J, Tun K, Vicentuan K, Viyakarn V, Waheed Z, Ward S, Willis B, Woods RM, Woolsey ES, Yamamoto HH, Yusuf S

Scientific data 8 ( 1 ) 35 - 35 2021.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The discovery of multi-species synchronous spawning of scleractinian corals on the Great Barrier Reef in the 1980s stimulated an extraordinary effort to document spawning times in other parts of the globe. Unfortunately, most of these data remain unpublished which limits our understanding of regional and global reproductive patterns. The Coral Spawning Database (CSD) collates much of these disparate data into a single place. The CSD includes 6178 observations (3085 of which were unpublished) of the time or day of spawning for over 300 scleractinian species in 61 genera from 101 sites in the Indo-Pacific. The goal of the CSD is to provide open access to coral spawning data to accelerate our understanding of coral reproductive biology and to provide a baseline against which to evaluate any future changes in reproductive phenology.

Access this article

DOI
Search related information

PubMed

Effects of light on the Ba/Ca ratios in coral skeletons

Yamazaki A.

Chemical Geology ( Chemical Geology ) 559 2021.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The ratios of barium to calcium (Ba/Ca) in reef coral skeletons have been used as a proxy to reconstruct temporal change in barium concentration in surface ocean. To reduce the uncertainty of the coral Ba/Ca proxy, the Ba distribution coefficients between seawater and coral skeletons were determined under different light conditions. Coral planulae (Acropora tenuis) were metamorphosed and settled in dishes with commercial peptide Hym-248 in the laboratory. Juvenile corals were infected with symbiotic algae (Durusdinium sp.) and cultured in 5 Ba concentrations (5, 10, 20, 35, and 150 mol/mol) for 2 months. Half of the dishes were placed under low light conditions (10-33 mu mol m(-2) s(-1)), and another half of the dishes were placed under high light conditions (67-84 mu mol m(-2) s(-1)). The Ba/Ca ratios in the coral skeletons were highly correlated with those in ambient seawater under both high and low conditions (R-2 > 0.8). The Ba distribution coefficients between seawater with 5-35 mol/mol of Ba concentration and coral skeletons were 0.72 and 2.83 under high and low light conditions, respectively. These results suggest that biological processes related to light availability could influence to Ba/Ca-coral.

Access this article

DOI

Exploring coral reef biodiversity via underwater soundscapes

Tzu-Hao Lin, Tomonari Akamatsu, Frederic Sinniger, Saki Harii

Biological Conservation ( Elsevier BV ) 253 108901 - 108901 2021.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI

Exploring coral reef biodiversity via underwater soundscapes

Tzu-Hao Lin, Tomonari Akamatsu, Frederic Sinniger, Saki Harii

in press 2021 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Coral-spawn slicks: Reflectance spectra and detection using optical satellite data

Yamano H., Sakuma A., Harii S.

Remote Sensing of Environment ( Remote Sensing of Environment ) 251 2020.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI Repository

Development of an automated transportable continuous system to measure the total alkalinity of seawater

Yamamoto S., Kayanne H., Fujita N., Sato Y. Kurihara H., Harii S., Hemmi A., Dickson A.G.

Talanta ( Talanta ) 221 121666 2020.10 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Anthropogenic CO2 emissions are contributing to global warming and ocean acidification. Rapid and accurate measurements of seawater carbonate chemistry are critical to understand current changes in the ocean and to predict future effects of such changes on marine organisms and ecosystems. Total alkalinity (A(T)) measurements can be used to directly determine the calcification rate, but they are time-consuming and require large sample volumes. Herein, we describe an automated and transportable flow-through system that can conduct continuous A(T) measurement using an ion sensitive field effect transistor (ISFET) - Ag/AgCl sensor and three different reference materials. The response time, stability, and uncertainty of our system were evaluated by comparing A(T) values of calibrated reference materials to those calculated by our system. Our system requires only small amounts of seawater (<10 mL) and a short time per sample (<5 min) to produce results with a relative uncertainty of less than 0.1% (approx. 2.2 mu mol kg(-1)). This system is expected to facilitate easy and rapid in-situ measurement of A(T). Continuous A(T) measurements would enable us to determine short-term calcification responses to changes in light or temperature and improve our understanding of the metabolic mechanisms of creatures such as corals.

Access this article

DOI
Search related information

PubMed

A unique reproductive strategy in the mushroom coral Fungia fungites

Eyal-Shaham L. Eyal G, Ben-Zvi O, Sakai K, Harii S, Sinniger F, Hirose M, Cabaitan P, Bronstein O, Feldman B, Shlesinger T, Levy O, Loya Y

Coral Reefs ( Coral Reefs ) 39 ( 6 ) 1793 - 1804 2020 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The vast majority of scleractinian corals are either simultaneous hermaphrodites or gonochoric. Exceptions to these are rare. Nevertheless, species belonging to the family Fungiidae are known to exhibit a wide variety of reproductive strategies. We examined the reproductive ecology of the mushroom coral Fungia fungites in Okinawa. Our study was conducted as part of a long-term, wide-ranging project (2009-2010 and 2013-2017) which explored the unique reproductive strategies of several species belonging to the family Fungiidae. Here we report the co-occurrence of males, females, and hermaphrodite individuals in a long-term monitored population of the reproductively atypical brooder coralF. fungites within the family Fungiidae.F. fungitesstatus as a single-polyped solitary coral, was used to perform manipulative experiments to determine the degree of dependence of an individual coral on its conspecific neighbors for reproduction, and examined whether a constant sperm supply is obligatory for the continuous production of planulae. Isolated females ofF. fungitesexhibited a distinctive reproductive strategy, expressed in continuously releasing planulae also in the absence of males. Observations conducted on a daily basis for 2.5 months (throughout the reproductive season of 2015) revealed that some of these individuals released planulae continuously, often between tens and hundreds every day. In an effort to explain this phenomenon, three hypotheses are discussed: (1) Self-fertilization; (2) Asexual production of planulae (i.e., parthenogenetic larvae); and (3) Extended storage of sperm. Finally, we emphasize the importance of continuous and long-term monitoring of studies of coral reproduction; through further genetic studies of coral populations representing a broad range of species and their larval origin.

Access this article

DOI

Coral-spawn slicks: Reflectance spectra and detection using optical satellite data

Yamano H, Sakuma A, Harii S

Remote Sensing of Environment in press 2020 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

Demystifying Circalunar and diel rhythmicity in Acropora digitifera under constant dim light

Rosenberg Y, Doniger T, Harii S, Sinniger F, Levy O

iScience 22 477 - 488 2019.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

Repository

Demystifying Circalunar and diel rhythmicity in Acropora digitifera under constant dim light

Rosenberg Y, Doniger T, Harii S, Sinniger F, Levy O

iScience 22 477 - 488 2019.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The challenges of the deep should not preclude robust ecological analysis

TE Roberts, TCL Bridge, MJ Caley, S Rowley, F Sinniger, S Harii, M Lesser, M Slattery, AH Baird

Science 2019.08

Type of publication: Research paper (other science council materials etc.)

Global biogeography of coral recruitment: tropical decline and subtropical increase.

Price NN, Muko S, Legendre L, Steneck R, Van Oppen MJH, Albright R, Ang Jr P, Carpenter RC, Chui APY, Fan T-Y, Gates RD, Harii S, Kitano H, Kurihara H, Mitarai S, Padilla-Gamiño JL, Sakai K, Suzuki G, Edmunds PJ

Marine Ecology Progress Series 621 1 - 17 2019.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

Repository

Repetitive sex change in the stony coral Herpolitha limax across a wide geographic range.

Eyal-Shaham L, Eyal G, Sakai K, Nozawa Y, Harii S, Sinniger F, Bronstein O, Ben-Zvi O, Shlesinger T, Loya Y

Scientific reports ( Scientific Reports ) 9 ( 1 ) 2936 2019.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI Repository
Search related information

PubMed

Onset of symbiosis between Tetralia crabs and Acropora corals revealing the smallest host habitat size

ROUZÉ Héloïse, SINNIGER Frederic, HARII Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 21 ( 1 ) 1 - 2 2019 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Deciphering the nature of the coral-Chromera association.

Mohamed AR, Cumbo VR, Harii S, Shinzato C, Chan CX, Ragan MA, Satoh N, Ball EE, Miller DJ

The ISME journal ( ISME Journal ) 12 ( 3 ) 776 - 790 2018.03 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Since the discovery of Chromera velia as a novel coral-associated microalga, this organism has attracted interest because of its unique evolutionary position between the photosynthetic dinoflagellates and the parasitic apicomplexans. The nature of the relationship between Chromera and its coral host is controversial. Is it a mutualism, from which both participants benefit, a parasitic relationship, or a chance association? To better understand the interaction, larvae of the common Indo-Pacific reef-building coral Acropora digitifera were experimentally infected with Chromera, and the impact on the host transcriptome was assessed at 4, 12, and 48 h post-infection using Illumina RNA-Seq technology. The transcriptomic response of the coral to Chromera was complex and implies that host immunity is strongly suppressed, and both phagosome maturation and the apoptotic machinery is modified. These responses differ markedly from those described for infection with a competent strain of the coral mutualist Symbiodinium, instead resembling those of vertebrate hosts to parasites and/or pathogens such as Mycobacterium tuberculosis. Consistent with ecological studies suggesting that the association may be accidental, the transcriptional response of A. digitifera larvae leads us to conclude that Chromera could be a coral parasite, commensal, or accidental bystander, but certainly not a beneficial mutualist.

Access this article

DOI Repository
Search related information

PubMed

Behavior of brooded coral larvae in response to elevated pCO2

Bergman JL, Harii S, Kurihara H, Edmunds PJ

Frontier Marine Science ( Frontiers in Marine Science ) 5 ( 51 ) 1 - 11 2018.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Elevated pCO2 threatens coral reefs through impaired calcification. However, the extent to which elevated pCO2 affects the distribution of the pelagic larvae of scleractinian corals, and how this may be interpreted in the context of ocean acidification (OA), remains unknown. We tested the hypothesis that elevated pCO2 affects one aspect of the behavior (i.e., motility) of brooded larvae from Pocillopora damicornis in Okinawa (Japan), and used UV-transparent tubes that were 68-cm long (45 mm ID) to incubate larvae on a shallow fringing reef. Replicate tubes were filled with seawater at ~400 μatm or ~1,000 μatm pCO2, stocked with 50 larvae each, and incubated vertically for 12 h with their midpoints at 0.3-m (shallow) or 3.3-m (deep) depth over a reef at 4-m depth. Larval behavior was assayed through their position in the tubes, which was scored in situ every 4 h beginning at 08:00 h. Lipid content was measured at the end of the experiment as a potential driver of behavior through its effects on larval buoyancy. Larval position in the tubes varied between depths and time of day at ~400 μatm pCO2 and ~1,000 μatm pCO2. At ~400 μatm, larvae moved toward the top (0.1-m) of shallow tubes throughout the day, but in the deep tubes they aggregated at the bottom of the tubes from 08:00 to 20:00 h. In contrast, larvae incubated at ~1,000 μatm pCO2 aggregated at the bottom of shallow tubes at 08:00 and 20:00 h, however in the deep tubes they were found in the bottom throughout the day. As lipid content of the larvae declined 23-25% at ~1,000 vs. ~400 μatm pCO2, loss of lipid may be a cause of modified larval behavior at high pCO2. If the pCO2-mediated changes in behavior and lipid content during this short experiment occur during longer exposures to high pCO2, our results suggest OA could alter the dispersal capacity of brooded coral larvae.

Access this article

DOI Repository

Journal publication of the Japanese Coral Reef Society: Past, present and future

FUJITA Kazuhiko, HARII Saki, HIDAKA Michio, YAMASHIRO Hideyuki

Journal of the Japanese Coral Reef Society ( The Japanese Coral Reef Society ) 20 ( 1 ) 89 - 97 2018

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Estimation of the reproductive timing of two genetically different lineages of the blue coral Heliopora coerulea (Pallas, 1766) around Sekisei Lagoon

TANINAKA Hiroki, HARII Saki, KAGAWA Hirohiko, UENO Mitsuhiro, F. KITANO Yuko, SAITO Yuta, NAGAI Satoshi, YASUDA Nina

Journal of the Japanese Coral Reef Society ( The Japanese Coral Reef Society ) 20 ( 1 ) 39 - 51 2018

Type of publication: Research paper (scientific journal)

The blue coral (Heliopora coerulea, Pallas 1766) is a reef-building coral, which is recently been classified as a threatened species. Recent population genetic analyses have found two genetically distinct, cryptic lineages of this coral (types A and B). However, the ecological differences between them, as well as the drivers of this speciation, are still unclear. The aim of this study was to examine the possible differentiation in the reproductive timing of the two lineages, as a plausible cause of speciation. We subjected both formalin- and ethanol-preserved samples of the coral, collected from sympatric H. coerulea populations, for tissue and genetic analyses. Samples were collected every one or two months, from June 2014 to September 2017, around Sekisei Lagoon, southwest Okinawa, Japan. We also conducted field observations of the coral's reproductive behavior (larval brooding) in mid-June and July. As a result we could observe larval brooding behavior from mid- to late-July in type B; however no such behavior was observed in type A during the observation and sampling period. After examining a total of 468 histological samples, we found that the diameters of the oocytes and spermaries peaked from May to June in type A, whereas in type B they peaked from June to July, after which the spermaries disappeared or diminished. Our study demonstrates that the two H. coerulea lineages, under the same environmental conditions, exhibit different reproductive timings. This gap in reproductive timing, which possibly stemmed from endogenous differences, might have promoted their genetic differentiation and speciation into two distinct lineages.

Access this article

DOI
Search related information

CiNii Research

石西礁湖周辺における遺伝的に異なる2タイプのアオサンゴHeliopora coerulea(Pallas, 1766)の生殖時期推定

谷中絢貴, 波利井佐紀, 香川浩彦, 上野光弘, 北野裕子, 斎藤佑太, 長井敏, 安田仁奈

日本サンゴ礁学会誌 20 39 - 51 2018 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Seriatopora diversity preserved in upper mesophotic coral ecosystems in Southern Japan

Frederic Sinniger, Rian Prasetia, Makiko Yorifuji, Pim Bongaerts, Saki Harii

Frontiers in Marine Science ( Frontiers Media S. A ) 4 ( MAY ) 2017.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Coral reefs worldwide are facing increasing stress due to drastic changes in their environment. Mesophotic coral ecosystems (MCEs) have been considered as a potential refuge from several major stressors, such as warm-water bleaching events. However, their role as a subsequent source of larvae remains unclear for many species, particularly as genetic differentiation of corals over depth has frequently been observed. In 1998 and 2001, two severe bleaching events around Okinawa Island in Japan resulted in major changes to the shallow reefs, including the local "extinction" of species such as Seriatopora hystrix at Sesoko Island. However, recently this species was found to be present in abundance at mesophotic depths in the area, despite no clear signs of recovery being observed in the adjacent shallow waters. Here, we assessed the genetic diversity of Seriatopora from this deep population and provide a comparison with populations from shallow to mesophotic depths in other parts of the Ryukyu archipelago, to understand their depth specificity and their importance in genetic diversity conservation of affected shallow populations. High levels of genetic diversity were observed in both shallow and mesophotic Seriatopora populations for both the nuclear (internal transcribed spacer 2, ITS2) and the mitochondrial (hypervariable open reading frame, ORF) markers, with no clear partitioning of haplotypes over depth or across locations in the archipelago. Both ITS2 and ORF suggest the presence of potential cryptic species and the discrepancy between the markers could reflect hybridization or incomplete lineage sorting. Although associated endosymbionts (Symbiodinium spp.) all shared the same mitochondrial haplotype (cytochrome oxidase subunit 1, COI), the nuclear ribosomal ITS2 revealed slight potential habitat partitioning between the genotypes, with a small decrease of C59 Symbiodinium types below 10 m depth and a mirrored increase in C1/C78a-related types. The relative absence of depth-specific host lineages and the substantial overlap between shallow and deep Symbiodinium types indicate that Okinawan MCEs may act as a refuge preserving genotypic diversity of bleaching-sensitive coral such as Seriatopora, and on the long-term may have the potential to contribute to shallow-water recolonization of this species.

Access this article

DOI Repository

Coral larvae are poor swimmers and require fine-scale reef structure to settle.

Hata T, Madin JS, Cumbo VR, Denny M, Figueiredo J, Harii S, Thomas CJ, Baird AH

Scientific reports ( NATURE PUBLISHING GROUP ) 7 ( 1 ) 2249 2017.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Reef coral assemblages are highly dynamic and subject to repeated disturbances, which are predicted to increase in response to climate change. Consequently there is an urgent need to improve our understanding of the mechanisms underlying different recovery scenarios. Recent work has demonstrated that reef structural complexity can facilitate coral recovery, but the mechanism remains unclear. Similarly, experiments suggest that coral larvae can distinguish between the water from healthy and degraded reefs, however, whether or not they can use these cues to navigate to healthy reefs is an open question. Here, we use a meta-analytic approach to document that coral larval swimming speeds are orders of magnitude lower than measurements of water flow both on and off reefs. Therefore, the ability of coral larvae to navigate to reefs while in the open-ocean, or to settlement sites while on reefs is extremely limited. We then show experimentally that turbulence generated by fine scale structure is required to deliver larvae to the substratum even in conditions mimicking calm back-reef flow environments. We conclude that structural complexity at a number of scales assists coral recovery by facilitating both the delivery of coral larvae to the substratum and settlement.

Access this article

DOI Repository
Search related information

PubMed

Canonical and cellular pathways timing gamete release in Acropora digitifera, Okinawa, Japan

Y. Rosenberg, T. Doniger, S. Harii, F. Sinniger, O. Levy

MOLECULAR ECOLOGY ( WILEY ) 26 ( 10 ) 2698 - 2710 2017.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Natural light cycles are important for synchronizing behavioural and physiological rhythms over varying time periods in both plants and animals. An endogenous clock, regulated by positive and negative elements, interacting in feedback loops controls these rhythms. Many corals exhibit diel cycles of polyp expansion and contraction entrained by solar light patterns and monthly cycles of spawning or planulation that correspond to nocturnal lunar light cycles. However, despite considerable interest in studies of coral reproduction, there is currently not enough molecular information about the cellular pathways involved with synchronizing spawning/planulation in broadcast spawners and brooders. To determine whether the endogenous clock is implicated in the regulation of reproductive behaviour in corals, we characterized the transcriptome of Acropora digitifera colonies at twelve time points over a 2-month period of full and new moons, starting with the day of spawning in June 2014. We identified 608 transcripts with differential expression only on the spawning night during the coral setting phase and gamete release. Our data revealed an upregulation of light-sensing molecules and rhodopsin-like receptors that initiate signalling cascades, including the glutamate, SMAD signalling and WNT signalling pathways, neuroactive ligand-receptor interactions and calcium signalling. These are all involved in cell cycling, cell movement, tissue polarity, focal adhesion and cytoskeleton reorganization and together lead to gamete release. These findings can improve the understanding of many time-based cycles and extend our knowledge of the interplay between exogenous signals and the endogenous clock in cnidarians.

Access this article

DOI
Search related information

PubMed

Establishment of a model for chemoattraction of Symbiodinium and characterization of chemotactic compounds in Acropora tenuis

Ryota Takeuchi, Mitsuru Jimbo, Fumika Tanimoto, Chiaki Tanaka, Saki Harii, Yoshikatsu Nakano, Ko Yasumoto, Shugo Watabe

FISHERIES SCIENCE ( SPRINGER JAPAN KK ) 83 ( 3 ) 479 - 487 2017.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Corals harbor symbiotic dinoflagellates, Symbiodinium spp., acquired from surrounding environments. Because Symbiodinium are present at low densities in the water column, corals may attract these symbionts using chemotactic compounds. To examine whether corals contain chemotactic compounds, we established an assay to measure the chemotactic activity for Symbiodinium using an extract of the coral Acropora tenuis, a major reef-building coral in Japan. Our assay revealed that Symbiodinium strain NBRC102920 (clade A), which is taken up by juvenile A. tenuis polyps, is attracted to crude A. tenuis extracts. We found that the chemotactic compounds are water-soluble, heat-labile macromolecules and that the chemotactic activity was inhibited by N-acetyl-D-glucosamine (GlcNAc). We separated the GlcNAc-binding fraction (Fr-ActL) and identified it as the most plausible candidate for the chemoattractant, since the chemotactic activity of the crude A. tenuis extract appeared to be mainly attributable to the activity of Fr-ActL and was also inhibited by the addition of GlcNAc. These results indicate that chemoattraction is mediated via the binding of Symbiodinium to Fr-ActL.

Access this article

DOI

First record of spawning in the mesophotic Acropora tenella in Okinawa, Japan

PRASETIA Rian, SINNIGER Frederic, HARII Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 ) 19 ( 1 ) 5 - 6 2017 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Access this article

DOI
Search related information

CiNii Research

Reproductive biology of the deep brooding coral Seriatopora hystrix: Implications for shallow reef recovery.

Prasetia R, Sinniger F, Hashizume K, Harii S

PloS one ( PUBLIC LIBRARY SCIENCE ) 12 ( 5 ) e0177034 2017 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Mesophotic coral ecosystems (MCEs, between 30 and 150 m depth) are hypothesized to contribute to the recovery of degraded shallow reefs through sexually produced larvae (referred to as Deep Reef Refuge Hypothesis). In Okinawa, Japan, the brooder coral Seriatopora hystrix was reported to be locally extinct in a shallow reef while it was found abundant at a MCE nearby. In this context, S. hystrix represents a key model to test the Deep Reef Refuge Hypothesis and to understand the potential contribution of mesophotic corals to shallow coral reef recovery. However, the reproductive biology of mesophotic S. hystrix and its potential to recolonize shallow reefs is currently unknown. This study reports for the first time, different temporal scales of reproductive periodicity and larval settlement of S. hystrix from an upper mesophotic reef (40 m depth) in Okinawa. We examined reproductive seasonality, lunar, and circadian periodicity (based on polyp dissection, histology, and ex situ planula release observations) and larval settlement rates in the laboratory. Mesophotic S. hystrix reproduced mainly in July and early August, with a small number of planulae being released at the end of May, June and August. Compared to shallow colonies in the same region, mesophotic S. hystrix has a 4-month shorter reproductive season, similar circadian periodicity, and smaller planula size. In addition, most of the planulae settled rapidly, limiting larval dispersal potential. The shorter reproductive season and smaller planula size may result from limited energy available for reproduction at deeper depths, while the similar circadian periodicity suggests that this reproductive aspect is not affected by environmental conditions differing with depth. Overall, contribution of mesophotic S. hystrix to shallow reef rapid recovery appears limited, although they may recruit to shallow reefs through a multi-step process over a few generations or through random extreme mixing such as typhoons.

Access this article

DOI Repository
Search related information

PubMed

Shift of symbiont communities in Acropora tenuis juveniles under heat stress.

Yorifuji M, Harii S, Nakamura R, Fudo M

PeerJ ( PEERJ INC ) 5 ( 12 ) e4055 2017 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Ocean warming is a major threat to coral reefs, leading to an increasing frequency and amplitude of coral bleaching events, where the coral and its algal symbiont associations breakdown. Long-term change'and resilience of a symbiont community in coral juveniles is l thought to be one of the most important aspects for determining therma tolerance of the coral holobionts; however, despite its importance, they are not well documented in both under elevated temperature and even under natural condition. Here we investigated changes in symbiont communities in juveniles of the coral Acropora tenuis under controlled heat stress conditions (30 degrees C, 31/32 degrees C) and natural variations in seawater temperatures (19-30 degrees C) for up to four months. Compared with the ambient temperature conditions, coral survival rates were higher when exposed to 30 degrees C, but survival rates decreased when exposed to 31/32 degrees C. Symbiodinium types A3, Cl, sand D1-4 were detected in the juveniles under all thermal conditions; however, in higher water temperatures (31/32 degrees C), both the prevalence of D1-4 Symbiodinium and the number of juveniles harboring only this type of symbiont increased after two to four months later. In contrast, colonies at lower temperatures (30 degrees C and ambient) harbored multiple clades of symbionts over the same experimental period. These results highlight.. the flexibility of the coral Symbiodinium symbiosis for juvenile A. terms under variable thermal conditions. In particular, the benefit of the preferential association with type D1-4 can be considered as a response when under heat-stress conditions, and that could help corals to cope with ocean warming.

Access this article

DOI Repository
Search related information

PubMed

Effect of elevated temperature on fecundity and reproductive timing in the coral Acropora digitifera.

Paxton CW, Baria MV, Weis VM, Harii S

Zygote (Cambridge, England) ( CAMBRIDGE UNIV PRESS ) 24 ( 4 ) 511 - 6 2016.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The synchrony of spawning is of paramount importance to successful coral reproduction. The precise timing of spawning is thought to be controlled by a set of interacting environmental factors, including regional wind field patterns, timing of the sunset, and sea surface temperatures (SST). Climate change is resulting in increased SST, which is causing physiological stress in corals and could also be altering spawning synchrony and timing. In this study, we examined the effect of increasing seawater temperature by 2 degrees C for 1 month prior to the predicted spawning time on reproduction in the coral Acropora digitifera. This short period of elevated temperature caused spawning to advance by 1 day. In animals incubated at elevated temperature, egg number per egg bundle did not change, however, egg volume significantly decreased as did sperm number. Our results indicate that temperature is acting both as a proximate cue to accelerate timing and as a stressor on gametogenesis to reduce fecundity. This finding suggests that increasing SSTs could play a dramatic role in altering reproductive timing and the success of corals in an era of climate change.

Access this article

DOI
Search related information

PubMed

The transcriptomic response of the coral Acropora digitifera to a competent Symbiodinium strain: the symbiosome as an arrested early phagosome

A. R. Mohamed, V. Cumbo, S. Harii, C. Shinzato, C. X. Chan, M. A. Ragan, D. G. Bourne, B. L. Willis, E. E. Ball, N. Satoh, D. J. Miller

MOLECULAR ECOLOGY ( WILEY ) 25 ( 13 ) 3127 - 3141 2016.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Despite the ecological significance of the relationship between reef-building corals and intracellular photosynthetic dinoflagellates of the genus Symbiodinium, very little is known about the molecular mechanisms involved in its establishment. Indeed, microarray-based analyses point to the conclusion that host gene expression is largely or completely unresponsive during the establishment of symbiosis with a competent strain of Symbiodinium. In this study, the use of Illumina RNA-Seq technology allowed detection of a transient period of differential expression involving a small number of genes (1073 transcripts; <3% of the transcriptome) 4 h after the exposure of Acropora digitifera planulae to a competent strain of Symbiodinium (a clade B strain). This phenomenon has not previously been detected as a consequence of both the lower sensitivity of the microarray approaches used and the sampling times used. The results indicate that complex changes occur, including transient suppression of mitochondrial metabolism and protein synthesis, but are also consistent with the hypothesis that the symbiosome is a phagosome that has undergone early arrest, raising the possibility of common mechanisms in the symbiotic interactions of corals and symbiotic sea anemones with their endosymbionts.

Access this article

DOI
Search related information

PubMed

Gametogenesis and fecundity of Acropora tenella (Brook 1892) in a mesophotic coral ecosystem in Okinawa, Japan

Rian Prasetia, Frederic Sinniger, Saki Harii

CORAL REEFS ( SPRINGER ) 35 ( 1 ) 53 - 62 2016.03 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Mesophotic coral ecosystems (below 30-40 m depth) host a large diversity of zooxanthellate coral communities and may play an important role in the ecology and conservation of coral reefs. Investigating the reproductive biology of mesophotic corals is important to understand their life history traits. Despite an increase in research on mesophotic corals in the last decade, their reproductive biology is still poorly understood. Here, gametogenesis and fecundity of the Indo-Pacific mesophotic coral, Acropora tenella, were examined in an upper mesophotic reef (40 m depth) in Okinawa, Japan for the first time. Acropora tenella is a hermaphrodite with a single annual gametogenic cycle, and both oogenesis and spermatogenesis occurring for 11-12 and 5-6 months, respectively. Timing of spawning of this species was similar to other shallow Acropora spp. in the region. However, colonies had longer gametogenic cycles and less synchronous gamete maturation compared to shallow acroporids with spawning extended over consecutive months. Both the polyp fecundity (number of eggs per polyp) and gonad index (defined as the number of eggs per square centimeter) of A. tenella were lower than most acroporids. Our findings contribute to understanding of the life history of corals on mesophotic reefs and suggest that the reproductive biology of upper mesophotic corals is similar to that of shallow-water corals.

Access this article

DOI

Worldwide analysis of sedimentary DNA reveals major gaps in taxonomic knowledge of deep-sea benthos

Frédéric Sinniger, Jan Pawlowski, Saki Harii, Andrew J. Gooday, Hiroyuki Yamamoto, Pierre Chevaldonné, Tomas Cedhagen, Gary Carvalho, Simon Creer

Frontiers in Marine Science ( Frontiers Media S. A ) 3 ( 92 ) 1 - 14 2016 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Deep-sea sediments represent the largest but least known ecosystem on earth. With increasing anthropogenic pressure, it is now a matter of urgency to improve our understanding of deep-sea biodiversity. Traditional morpho-taxonomic studies suggest that the ocean floor hosts extraordinarily diverse benthic communities. However, due to both its remoteness and a lack of expert taxonomists, assessing deep-sea diversity is a very challenging task. Environmental DNA (eDNA) metabarcoding offers a powerful tool to complement morpho-taxonomic studies. Here we use eDNA to assess benthic metazoan diversity in 39 deep-sea sediment samples from bathyal and abyssal depths worldwide. The eDNA dataset was dominated by meiobenthic taxa and we identified all animal phyla commonly found in the deep-sea benthos yet, the diversity within these phyla remains largely unknown. The large numbers of taxonomically unassigned molecular operational taxonomic units (OTUs) were not equally distributed among phyla, with nematodes and platyhelminthes being the most poorly characterized from a taxonomic perspective. While the data obtained here reveal pronounced heterogeneity and vast amounts of unknown biodiversity in the deep sea, they also expose the difficulties in exploiting metabarcoding datasets resulting from the lack of taxonomic knowledge and appropriate reference databases. Overall, our study demonstrates the promising potential of eDNA metabarcoding to accelerate the assessment of deep-sea biodiversity for pure and applied deep-sea environmental research but also emphasizes the necessity to integrate such new approaches with traditional morphology-based examination of deep-sea organisms.

Access this article

DOI Repository

Genetic diversity, paraphyly and incomplete lineage sorting of mtDNA, ITS2 and microsatellite flanking region in closely related Heliopora species (Octocorallia).

Yasuda N, Taquet C, Nagai S, Fortes M, Fan TY, Harii S, Yoshida T, Sito Y, Nadaoka K

Molecular phylogenetics and evolution ( ACADEMIC PRESS INC ELSEVIER SCIENCE ) 93 161 - 71 2015.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Examining genetic diversity and lineage sorting of different genes in closely related species provide useful information for phylogenetic analyses and ultimately for understanding the origins of biodiversity. In this study, we examined inter- and intraspecific genetic variation in internal transcribed spacer 2 (ITS2), partial mitochondrial gene (mtMutS), and nuclear microsatellite flanking region in two closely related octocoral species (Heliopora coerulea, HC-A and HC-B). These species were recently identified in a population genetic study using microsatellite markers. The two species have different reproductive timing, which ecologically promotes lineage sorting. In this study, we examined whether species boundaries could be detected by the commonly used nuclear ITS2 and mtMutS, as well as by possibly neutral microsatellite flanking sequences. Haplotype network analysis of microsatellite flanking region revealed that a possible ancestral haplotype was still shared between the two species, indicating on-going lineage sorting. Haplotype network analysis of ITS2 and microsatellite flanking region revealed shared haplotypes between the two lineages. The two species shared fewer ITS2 sequences than microsatellite flanking region sequences. The almost fixed point mutation at the tip of helix 3 of ITS2 was not associated with the secondary structure or compensatory base changes (CBCs). The phylogenetic tree of ITS2 showed paraphyly and that of the microsatellite flanking region indicated that lineage sorting for the two species may be incomplete. Much higher intra-and inter-individual variation of ITS2 was observed in HC-B than that in HC-A, highlighting the importance of examining ITS2 from multiple individuals to estimate genetic diversity. The mitochondrial mtMutS gene sequences from 39 individuals, including both species collected from Japan and Taiwan, showed no variation because of slow rates of mitochondrial nucleotide substitution. This study suggests caution is warranted when reciprocal monophyly in a phylogenetic tree is used as the criterion for delimiting closely related octocoral species based on ITS2 or mtMtuS sequences. Detection of boundaries between closely related species requires multi-locus analysis, such as genetic admixture analysis using multiple individuals. (C) 2015 The Authors. Published by Elsevier Inc.

Access this article

DOI Repository
Search related information

PubMed

Tolerance to Elevated Temperature and Ocean Acidification of the Larvae of the Solitary Corals Fungia fungites (Linnaues, 1758) and Lithophyllon repanda (Dana, 1846).

Baria MV, Kurihara H, Harii S

Zoological science ( ZOOLOGICAL SOC JAPAN ) 32 ( 5 ) 447 - 54 2015.10 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Increase in atmospheric CO2 is the main driver of global climate change and is projected to elevate sea surface temperature by at least 2 degrees C and to decrease oceanic pH by 0.3 to 0.4 units by the end of the century. These factors seriously threaten coral reef ecosystems worldwide. In Okinawa, solitary corals are an important feature of the coral community structure. While previous studies on the effects of ocean warming (OW), ocean acidification (OA) and its combination on larval survival focused on colonial coral species, the present study assessed the effect of high temperature on larvae from solitary corals. In this study, we examined the influence of OW (control = 28 degrees C; control + 3 = 31 degrees C; control + 6 = 34 degrees C) and OA (control, pCO(2) = 400 to 500 mu atm; medium, pCO(2) = 1000 to 1300 mu atm; high, pCO(2) = 1700 to 2200 mu atm) on the larval survival of two solitary corals, Fungia fungites and Lithophyllon repanda for eight days. Results showed that F. fungites was neither affected by OW, OA, nor its combination. Similarly, survival of L. repanda was not affected by OA however it was significantly affected by temperature. Temperature tolerance varies between species; L. repanda (+3 degrees C above ambient) has lower tolerance than F. fungites (+6 degrees C above ambient). This observation suggests that fungiid larvae had higher tolerance to elevated temperature stress relative to other scleractinian corals. With the projected increase in OW and OA in the future, fungiids may retain good potential to widely disperse and successfully recruit to natal and other neighbouring reefs.

Access this article

DOI
Search related information

PubMed

Cues from the reef: olfactory preferences of a symbiotically luminous cardinalfish

Alison L. Gould, Saki Harii, Paul V. Dunlap

CORAL REEFS ( SPRINGER ) 34 ( 2 ) 673 - 677 2015.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The symbiotically luminous, reef-dwelling cardinalfish, Siphamia tubifer (Perciformes: Apogonidae), exhibits daily site fidelity, homing behavior, and a preference for the long-spined urchin, Diadema setosum, as its daytime host. The fish acquires its symbiont during larval development and releases large numbers of the bacteria with its feces daily at a host urchin. To examine the role of olfaction in site fidelity and homing by S. tubifer, juvenile and adult fish were tested in a two-channel choice flume for their olfactory preferences. Neither juveniles nor adults showed a preference for seawater conditioned by D. setosum. Juvenile fish, but not adults, preferred seawater conditioned by conspecific fish versus unconditioned seawater. Both juveniles and adults preferred seawater conditioned by their luminous symbiont and also preferred home site water to foreign reef water. These results suggest that S. tubifer uses chemical cues for homing and possibly settlement and symbiont acquisition, but not for host urchin recognition.

Access this article

DOI

Possible involvement of Tachylectin-2-like lectin from Acropora tenuis in the process of Symbiodinium acquisition

Nami Kuniya, Mitsuru Jimbo, Fumika Tanimoto, Hiroshi Yamashita, Kazuhiko Koike, Saki Harii, Yoshikatsu Nakano, Kenji Iwao, Ko Yasumoto, Shugo Watabe

FISHERIES SCIENCE ( SPRINGER JAPAN KK ) 81 ( 3 ) 473 - 483 2015.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Most reef-building corals in tropical and subtropical areas symbiose with microalgae from the genus Symbiodinium (dinoflagellate) and depend on the photosynthate produced by the microalgae. The majority of corals acquire Symbiodinium from the surrounding environment through horizontal transfer, but the molecular mechanisms involved in the acquisition of Symbiodinium remain unknown. It has been hypothesized that carbohydrate-binding proteins, or lectins, of the host coral recognize cell surface carbohydrates of Symbiodinium in the process of acquiring symbionts. Thus, we examined the molecular mechanisms involving lectins and carbohydrates using model organism Acropora tenuis, a common reef-building coral, and Symbiodinium culture strains. Juvenile polyps acquire more cells of Symbiodinium strain NBRC102920 at 72-96 h of metamorphosis induction than in any other period. Glycosidase treatment of Symbiodinium inhibited the acquisition of Symbiodinium by juvenile coral polyps. The presence of carbohydrates D-galactose, N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine at 10 mM also tended to decrease Symbiodinium acquisition. We isolated two N-acetyl-D-galactosamine binding lectins with apparent molecular masses of 14.6 and 29.0 kDa from A. tenuis, and de novo sequencing and cDNA cloning showed that the 29.0 kDa protein is Tachylectin-2-like lectin (AtTL-2). The anti-Tachylectin-2 antibody is suggested to bind specifically to AtTL-2. The antibody also inhibited binding of AtTL-2 to N-acetyl-D-galactosamine-resin and the acquisition of Symbiodinium by juvenile A. tenuis polyps. Based on these results, AtTL-2 is likely involved in the process of Symbiodinium acquisition.

Access this article

DOI Repository

Geographic variation in long-term trajectories of change in coral recruitment: a global-to-local perspective

P. J. Edmunds, R. Steneck, R. Albright, R. C. Carpenter, A. P. Y. Chui, T. -Y. Fan, S. Harii, H. Kitano, H. Kurihara, L. Legendre, S. Mitarai, S. Muko, Y. Nozawa, J. Padilla-Gamino, N. N. Price, K. Sakai, G. Suzuki, M. J. H. van Oppen, A. Yarid, R. D. Gates

MARINE AND FRESHWATER RESEARCH ( CSIRO PUBLISHING ) 66 ( 7 ) 609 - 622 2015 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Compiled abundances of juvenile corals revealed no change over time in the Pacific, but a decline in the Caribbean. Using these analyses as a rationale, we explored recruitment and post-settlement success in determining coral cover using studies in the Caribbean (St John, Bonaire) and Pacific (Moorea, Okinawa). Juvenile corals, coral recruits, and coral cover have been censused in these locations for years, and the ratio of juvenile (J) to recruiting (R) corals was used to measure post-settlement success. In St John and Bonaire, coral cover was stable but different between studies, with the ratio of the density of juveniles to density of recruits (J:R) 0.10; in Moorea, declines in coral cover were followed by recovery that was related to the density of juvenile corals 3 years before, with J:R 0.40; and in Okinawa, a decline in coral cover in 1998 was followed by a slow recovery with J/R 0.01. Coral cover was associated positively with juvenile corals in St John, and in Okinawa, the density of juvenile corals was associated positively with recruits the year before. J:R varied among studies, and standardised densities of juvenile corals declined in the Caribbean, but increased in the Pacific. These results suggest that differences in the post-settlement success may drive variation in coral community structure.

Access this article

DOI

High tolerance of symbiotic larvae of Pocillopora damicornis to thermal stress.

Haryanti D, Yasuda N, Harii S, Hidaka M

Zoological studies ( SPRINGER HEIDELBERG ) 54 ( JULY ) e52 2015 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Background: When coral planulae, which use a horizontal mode of symbiont transmission, are inoculated with Symbiodinium, they suffer greater oxidative stress under strong light or high-temperature stress than non-symbiotic counterparts. Thus, dinoflagellate symbionts may become a source of reactive oxygen species (ROS) under stress. However, it remains unknown whether vertically transmitted symbionts negatively affect coral larvae under stress. We investigated the thermal tolerance of symbiotic planulae of a vertical transmitter coral, Pocillopora damicornis. Results: P. damicornis larvae, which have a large number of symbionts, survived the high-temperature treatment (32 degrees C) for 2 weeks. Significant reductions in Symbiodinium cell density were observed, but these did not lead to increased mortality of planulae during the 2-week experimental period. Although no significant difference was detected in the percentage of apoptotic cells between temperature treatment groups, pre-bleaching larvae exposed to 31 degrees C tended to exhibit higher percentages of apoptotic (TUNEL-positive) cells in the gastrodermis than 32 degrees C-treated larvae, which contained reduced numbers of Symbiodinium cells. Conclusions: Symbiotic larvae of P. damicornis survived well under high-temperature conditions, although their Symbiodinium cell density decreased. This suggests that P. damicornis larvae have the capacity to reduce the symbiont cell density without a harmful effect on their survivorship under thermal stress. Further studies on antioxidant systems and possible suppression of apoptotic pathways are necessary to elucidate the mechanism underlying the high thermal tolerance of symbiotic larvae of P. damicornis.

Access this article

DOI Repository
Search related information

PubMed

Spectral Diversity and Regulation of Coral Fluorescence in a Mesophotic Reef Habitat in the Red Sea.

Eyal G, Wiedenmann J, Grinblat M, D'Angelo C, Kramarsky-Winter E, Treibitz T, Ben-Zvi O, Shaked Y, Smith TB, Harii S, Denis V, Noyes T, Tamir R, Loya Y

PloS one ( PUBLIC LIBRARY SCIENCE ) 10 ( 6 ) e0128697 2015 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

The phenomenon of coral fluorescence in mesophotic reefs, although well described for shallow waters, remains largely unstudied. We found that representatives of many scleractinian species are brightly fluorescent at depths of 50-60 m at the Interuniversity Institute for Marine Sciences (IUI) reef in Eilat, Israel. Some of these fluorescent species have distribution maxima at mesophotic depths (40-100 m). Several individuals from these depths displayed yellow or orange-red fluorescence, the latter being essentially absent in corals from the shallowest parts of this reef. We demonstrate experimentally that in some cases the production of fluorescent pigments is independent of the exposure to light; while in others, the fluorescence signature is altered or lost when the animals are kept in darkness. Furthermore, we show that green-to-red photoconversion of fluorescent pigments mediated by short-wavelength light can occur also at depths where ultraviolet wavelengths are absent from the underwater light field. Intraspecific colour polymorphisms regarding the colour of the tissue fluorescence, common among shallow water corals, were also observed for mesophotic species. Our results suggest that fluorescent pigments in mesophotic reefs fulfil a distinct biological function and offer promising application potential for coral-reef monitoring and biomedical imaging.

Access this article

DOI Repository
Search related information

PubMed

Onset and flexibility of symbiosis and effect of symbiotic dinoflagellate on energy source in scleractinian coral larvae

Yasuda　Naoko,Rodriguez-Lanetty　Mauricio,Hidaka　Michio,

COE報告書（平成19年度） ( 琉球大学21世紀COEプログラム ) 2008.03

Type of publication: Research paper (other science council materials etc.)

Access this article

DOI

　PREV-NEXT　

<HARII Saki>

Published Papers - HARII Saki