Yoron Island Research Articles

Distinct patterns of coral lesion composition from national/quasi-national marine parks of Kerama and Yoron Islands, Ryukyu Archipelago

A wide variety of coral communities are found in the Ryukyu Archipelago in southern Japan. Although reports of coral diseases and lesions in this region have increased since the 2000's, the variations of coral diseases among islands are somewhat limited. In this study, we conducted surveys to reveal the coral lesion assemblage and patterns in the marine national park area of Kerama Island and the quasi-national park on Yoron Island. Both sites are located 150 km away apart in the Ryukyu Archipelago. In total, 12 gross lesions were found in 30 coral genera. Corals in Yoron Island had 22% greater gross lesion abundance than Kerama Island (13.40 ± 1.36%) with an overall mean lesion abundance of 16.83 ± 1.66% (mean ± SE). Each Island shows a distinct pattern and group of coral lesion compositions. The disease lesion group of 7.21 ± 1.37% was dominated by White Syndrome (WS) and Black Band Disease (BBD), which severely infected various coral genera in Yoron Island. Corals in Kerama Island were predominantly affected by non-disease group lesion (9.76 ± 1.33%), such as Chalinula nematifera (CN) sponge overgrowing on the coral surface. Corals in the genus Pachyseris were highly susceptible (17.79%) to the diseases on Yoron Island, while Acroporid corals were the most susceptible (8.32%) to the diseases on Kerama Island. In addition, Porites were affected by disease and non-disease lesions from all sites in both Kerama and Yoron. These findings highlight the emergence of potential threats to coral communities in these national/quasi-national marine parks in Kerama and Yoron Island, which may be a factor limiting the survival and growth of key Scleractinian coral taxa. In addition, immediate consideration of environmental monitoring may be required to prevent coral disease outbreaks in the future.

First Japanese Records of the Indo-Pacific Scorpionfish (Scorpaenidae) <i>Scorpaenodes corallinus</i>, with a Re-evaluation of Coronal Spines as a Diagnostic Character

Fifteen specimens (70.9–95.5 mm standard length) of the Indo-Pacific species Scorpaenodes corallinus Smith, 1957, previously recorded from Mozambique, Tanzania, Kenya, the Seychelles, Indonesia, Australia, the Hawaiian Islands, New Caledonia and French Polynesia, and recently collected from Okinawa Island (Okinawa Islands) and Yoron Island (Amami Islands), represent the first Japanese records of the species. Examination of a wide range of specimens indicated that the presence of coronal spines (formerly considered diagnostic of the species) was inconsistent. The new standard Japanese name “Ichigo-isokasago” is proposed for the species.

Placeholders in Yoron Ryukyuan: A view from Functional Discourse Grammar

Placeholders (PHs) are employed by the speaker who encounters a word-formulation problem in interaction due to “communicative” or “social” factors. PHs have been studied for a number of languages, but no single study has been presented for Ryukyuan varieties. Our first aim is to bridge this gap by describing several types of PH in Yoron Ryukyuan (spoken on Yoron island, Kagoshima, Japan) in comparison with some other languages. Another outstanding issue in the past literature is that little attention has been paid to the theoretical modelling of PHs, with a few exceptions such as the structural-functional account of PHs within Functional Discourse Grammar (FDG). Our second aim is to provide a theoretical treatment of Yoron Ryukyuan data by extending the previous FDG account. Our analysis relies on distinctive features of the FDG architecture. To give a specific example, the basic theoretical unit is a Discourse Act, rather than a sentence; this enables us to account for the presence of the target word (which may be uttered after a PH, and which is usually sub-sentential) as a full-fledged Discourse Act within the Move structure. The proposed analysis thus lends support to cross-linguistic applicability of the FDG model.

A new wrasse, Novaculops compressus n. sp. (Perciformes: Labridae),from the western Pacific Ocean.

A new sandy, Novaculops compressus n. sp. is described on the basis of two specimens collected from Yoron Island, Japan and Panay Island, the Philippines. The new species is characterized by IX, 12 dorsal-fin rays, III, 12 anal-fin rays, 12 or 13 pectoral-fin rays, interrupted lateral line, 12 + 5 pored lateral-line scales, 4 scale rows above lateral line, 9 scale rows below lateral line, 16 total gill rakers, snout length 11.1% of standard length (SL), orbit diameter 10.0-10.1% SL, body depth 30.9% SL, anal-fin base length 36.2-37.6% SL, first dorsal-fin spine length 6.4-7.0% SL, pectoral-fin axil black, and first two dorsal-fin membranes black. This species is sympatric with N. sciistius in Kagoshima, Japan.

East Asian Passiflora distortion virus: a novel potyvirus species causing deformation of passionfruits in Japan

Viruses assumed to belong to a new Potyvirus were detected in passionfruit plants with foliar mosaic, leaf curl and fruit malformation that were collected from Akita City, Akita Prefecture in 2013, Nago City, Okinawa Prefecture in 2014, and Satsuma Town and Yoron Island, Kagoshima Prefecture in 2015. The isolates of this virus species were not detected by ELISA and RT-PCR targeting East Asian Passiflora virus (EAPV)-AO (Amami Oshima strain), which induces woodiness disease of passionfruit in Japan. The isolates were designated PV-AK (Akita), PV-OK (Okinawa), PV-YO (Yoron), and PV-SA (Satsuma). In a host-range test of 13 cultivars of French bean, four were systemically infected with the PV isolates and two with EAPV-AO. Cowpea cv. Kurodane sanjaku was systemically infected with PV isolates and induced mosaic symptoms on non-inoculated leaves distant from the inoculated leaves but was immune to EAPV-AO. The complete genomic sequences of the PV isolates consisted of 9973 nucleotides (nt) excluding the poly(A) tail, and encoded 3217 amino acids of polyprotein, flanked by 129–130 nt of the 5′-noncoding region and 193 nt of the 3′-noncoding region. Whole-genome nucleotide and amino acid sequences indicated that they belong to identical species. The potyvirus with the highest whole-genome nucleotide identity to the PV isolates is watermelon mosaic virus, which shares 68.1% identity, versus 65.3% for EAPV-AO. On the basis of ICTV-naming regulations, these PV isolates belong to a new species in the Potyvirus genus, but are distantly related to EAPV. Here, we propose East Asian Passiflora distortion virus as the new species name.

Topographic Anaglyphs from Detailed Digital Elevation Models Covering Inland and Seafloor for the Tectonic Geomorphology Studies in and around Yoron Island, Ryukyu Arc, Japan

Anaglyphs produced using a digital elevation model (DEM) are effective to identify the characteristic tectono–geomorphic features. The objective of this study is to reinvestigate the tectonic geomorphology and to present novel tectonic maps of the late Quaternary in and around the Yoron island based on the interpretation of extensive topographical anaglyphs along the map areas that cover the inland and seafloor. Vintage aerial photographs are used to produce the 3-m mesh inland digital surface model (DSM); further, the 0.6-s to 2-s-mesh seafloor DEM is processed using the cloud point data generated through previous surveys. Thus, we identify anticlinal deformation on both the Pleistocene marine terrace and the seafloor to the north of the island. The deformation axis extends in a line and is parallel to the general trend of the island shelf. The Tsujimiya fault cuts the marine terraces, which extend to the Yoron basin’s seafloor. If we assume that the horizontal compressive stress axis is perpendicular to the island shelf, these properties can easily explain the distribution and style of the active faults and deformation. This study presents an effective methodology to understand the island arc tectonics, especially in case of small isolated islands.

Background factors contributing to over-consumption of alcohol and risk of lifestyle related diseases among middle-aged women on an isolated island

Objectives This study aimed to identify social factors that contribute to harmful alcohol use, defined as consuming more than 20 g of ethanol per day and raising the risk of lifestyle-related diseases, among women living on an isolated island, which has a culture that tolerates heavy drinking.Methods The participants were residents of Yoron Island, Kagoshima prefecture, aged 20-64 years (393 women and 419 men). A survey that included general questions about health was conducted as part of the Health Yoron 21 (second term) survey in July 2016. The outcome was presence or absence of harmful alcohol use, and the predictors were social factors. Multiple logistic regression analysis was conducted to assess the association between harmful alcohol use and social factors. Age, presence or absence of child, and the length of time living on the island were also entered into the model as control variables.Results Analysis of data from 309 women showed that 46 women (14.8%) engaged in harmful alcohol use, and five significant factors were identified: restaurant and tourist industry workers (OR 6.73, 95%CI 1.13-39.98); smoking (OR 4.47, 95%CI 1.36-14.63); participation in recreational activities (OR 4.47, 95%CI 1.93-10.39); depressed within the past 2 weeks (OR 2.47, 95%CI 1.08-5.68); and drinking at home (OR 16.52, 95%CI 6.77-40.29).Conclusion This study identified negative aspects of social interactions in women engaged in harmful alcohol use. Additionally, depression within the previous 2 weeks was associated with harmful alcohol use. Given the island culture, drinking is expected to contribute to forming and maintaining better human relationships. However, drinking should be moderated in the interest of health. The results of this study will be used for Health Yoron 21 (second term).

漂砂の指標としての『星砂』の砕屑過程 : 与論島北東部現成サンゴ礁を例として

漂砂の指標としての『星砂』の砕屑過程 : 与論島北東部現成サンゴ礁を例として

Preliminary report on the geology of Richo formation in Yoron Island, Ryukyu Islands, Japan

Preliminary report on the geology of Richo formation in Yoron Island, Ryukyu Islands, Japan

Two new dwarfgobies (Teleostei: Gobiidae) from the Ryukyu Islands, Japan: Eviota flavipinnata and Eviota rubrimaculata.

Two new species of Eviota from Yoron Island, the Ryukyu Islands, Japan, are described. Both species belong to the cephalic sensory-canal pore system pattern 2 (lacking only the H [IT] pore); have some pectoral-fin rays branched; have a dorsal/anal-fin formula of 9/8; no dark spot over the ural centrum; no prominent distinct dark spots on the pectoral-fin base; no postocular spots; and no strong dark spots on the caudal fin. The species share the most characters with E. afelei, E. bimaculata and E. punctulata, but differ from Eviota afelei and E. punctulata by having two versus three dark marks over the anal-fin base, and from Eviota bimaculata by lacking the two dark, prominent occipital spots present in that species. Both species differ from all other described species of Eviota in fresh coloration. Eviota flavipinnata has bright golden-yellow dorsal fins and an orange anal fin, and a fifth pelvic-fin ray that is 12% the length of the fourth ray. Eviota rubrimaculata has clear dorsal fins with red spots, large red spots on the body, and lacks the fifth pelvic-fin ray.

Active faults and subsurface structure in Yoron Island, Ryukyu Islands, Japan

Active faults and subsurface structure in Yoron Island, Ryukyu Islands, Japan

First Record of the Longlure Flatfish, Asterorhombus filifer (Pleuronectiformes: Bothidae), from Japan

Five specimens (10.4-86.5 mm standard length) of the Indo-West Pacific flatfish Asterorhombus filifer Hensley and Randall, 2003 were collected at depths of 12-21 m on sandy bottoms at Yoron Island and Amami-oshima Island, Ryukyu Islands, Japan. These specimens represent the first records of A. filifer from Japan and the northernmost records of this species.

Key species of hermatypic coral for reef formation in the northwest Pacific during Holocene sea-level change

Cores from Holocene reefs provided a growth history and species-level identification of corals and demonstrated the most important reef builders during the formation stage. This knowledge is important to determine a principle for reef formation and to provide preservation plans in the near future. A biological and sedimentological study of sediment cores recovered from the Palau Islands and Yoron Island, northwest Pacific, revealed four major facies: corymbose Acropora, arborescent Acropora, massive Porites, and detritus. Species-level observations show that arborescent Acropora (A. muricata and A. intermedia) contributed to reef growth under low- to moderate-energy conditions, whereas corymbose and tabular Acropora (A. digitifera, A. hyacinthus, and A. robusta/A. abrotanoides) and I. palifera were key species for reef formation under high-energy conditions during Holocene sea-level rise and the ensuing period of sea-level stability. Once sea level had stabilized, massive Porites became restricted to areas subjected to low-energy, turbid conditions. These key species are successful corals because the ecological strategy is rapid growth, determinate growth, a high degree of colony integration, strongly resistant to wave action, and rapid local dispersion via fragmentation. Moreover, the western boundary current (Kuroshio) flows along the reefs in the northwest Pacific and it is easy for key species to distribute throughout the region during the period of Holocene sea-level rise and stabilization. These features are a principle for reef formation during sea-level changes. These key species played a significant role in Holocene reef formation in the northwest Pacific; however, coral mortality, caused by climate change, has recently been widely reported. Moreover, the decrease in key species abundance in present-day reefs has been more severe than that in any other species. These geological findings have important implications regarding the appropriate use of coral transplantation and decisions regarding the optimal location and size of marine protected areas.

Notes on some plant-inhabiting fungi collected from the Nansei Islands (2)

In this paper, four fungi collected in Nansei Islands are reported. One is Strasseria garciniae, which must be transferred to the genus Phyllosticta. This fungus was collected in Okinawa Main Island and Iriomote Island. The other three fungi are newly added to the Japanese fungal flora. Phyllosticta ghaesembillae on Codiaeum variegatum and Cercospora asplenii on Asplenium antiquum were collected in Yoron Island. The last one, Coniella australiensis on Eucalyptus robusta was collected in Okinawa Main Island. Their morphology and symptoms on the host plant are described, with some mycological notes.

Notes on some plant-inhabiting fungi collected from the Nansei Islands (2)

In this paper, four fungi collected in Nansei Islands are reported. One is Strasseria garciniae, which must be transferred to the genus Phyllosticta. This fungus was collected in Okinawa Main Island and Iriomote Island. The other three fungi are newly added to the Japanese fungal flora. Phyllosticta ghaesembillae on Codiaeum variegatum and Cercospora asplenii on Asplenium antiquum were collected in Yoron Island. The last one, Coniella australiensis on Eucalyptus robusta was collected in Okinawa Main Island. Their morphology and symptoms on the host plant are described, with some mycological notes.

Calibrated radiocarbon ages of beach rock samples and late Holocene sea-level change of Amami Islands, southwest Japan

A total of 87 beach rock samples were collected from 37 sites of Amami Islands in order to determine formative ages of beach rocks on Amami Islands, and to clarify the sea-level change during the late Holocene period. Beach rocks began to form 5,720 yrs cal BP on Yoron Island at first, and formed continuously between 4,050 yrs cal BP and 380 yrs cal BP on the sandy coasts of Amami Islands. Relative sea-levels during the late Holocene period on Yoron Island and Okinoerabu Island were slightly higher than those of the present sea-level. Geomorphic evidences indicate that the islands have probably uplifted by earthquakes occurred along the subduction zone of Eurasian Plate. However the sea-level has remained similar to the present since at least the past 4,000 years at Amami-Oshima Island.

ランドサットTMデータを利用した与論島の地下水資源調査

ランドサットTMデータを利用した与論島の地下水資源調査

Three new species of fossil terrestrial Mollusca from fissure deposits within the Ryukyu Limestone in Okinawa and Yoron islands, Japan

Three new species and one new genus Masaophaedusa of fossil terrestrial Mollusca are described from fissure deposits within the Ryukyu Limestone in Okinawa and Yoron islands of the central Ryukyu Islands. They are Masaophaedusa takae, which occurred in Nishiku Fissure in Yoron Island and Katsuren Fissure in Okinawa Island, Chalepotaxis kenjii from Nishiku Fissure, and Coniglobus sashikiensis from Chinen Fissure in Okinawa Island. Masaophaedusa takae has characteristic, strong and long plicae, and its specialized clausilium has no relations with other genera of the Family Clausiliidae in Japan and adjacent areas. Chalepotaxis kenjii possesses a light brown, narrow band on the body whorl, and is closely related to Chalepotaxis spadix distributed in southern Taiwan. Coniglobus sashikiensis has a large shell and may be the ancestor of C. mercatorius, a living species of Okinawa Island.

沖縄島周辺島嶼のオリイオオコウモリPteropus dasymallus inopinatusの分布, 特に与論島における生息確認と若干の生態的知見について

沖縄島周辺島嶼のオリイオオコウモリPteropus dasymallus inopinatusの分布, 特に与論島における生息確認と若干の生態的知見について

サンゴ礁裾礁における空間構造把握のための自然地理的ユニットの設定―与論島東部サンゴ礁を例に―

The spatial structures of a 101-103 m scale on coral reefs were understood by reading aerial photographs and investigating the topography of the fringing reef at the eastern part of Yoron Island, Ryukyu Islands. This study set a new physiographic unit (PGU) at the coral reefs as well as studied zonation. PGU has the following characteristics. (1) In an aerial photo, a linear pattern comprising micro-landform arrangements is recognized on the reef flat; (2) Seawater flowing beyond the reef crest from the open sea and entering the moat before returning to the open sea through a breakout in the reef crest or a channel flowing parallel to the shoreline constitute a very common pattern in the research area; (3) The series of currents observed in the area constitute a water system resembling a drainage water system on land and 4 systems were arranged at the eastern part of Yoron Island ; (4) The movement of seawater is controlled by landforms such as reef crests, channels and lands (a cape), which might qualify as borders of PGUs ; (5) Movements controlled by such landforms are dominant, and tend to be longer in terms of time. In this study, a physiographic unit is defined as follows. (1) A unit that is distinguishable from other adjacent areas by its geomorphological borders ; (2) And, a unit that is distinguishable from other adjacent areas when referring to the movement systems of seawater and materials.The notion of spatial structures of coral reefs of a 101-103 meter scale was substantiated by this research using the overlapping zonation approach known here as PGU on reef flats. The spatial structure makes a frame of the coral reef ecosystem. Therefore, setting a PGU is thought to be effective for application to coral reef conservation.