Published Papers - HARII Saki

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)

　View Summary

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)

　View Summary

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 <I>Acropora digitifera</I> 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.)

　View Summary

eLetter addressing major methodological issues published in Rocha et al. 108, Science

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)

　View Summary

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)

　View Summary

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 <i>Heliopora coerulea</i> (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)

　View Summary

<p>The blue coral (<i>Heliopora coerulea</i>, 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 <i>H. coerulea</i> 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 <i>H. coerulea</i> 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.</p>

• 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)

　View Summary

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)

　View Summary

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)

　View Summary

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)

　View Summary

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 <i>Acropora tenella</i> 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)

　View Summary

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