Torishima Island Research Articles

High‐Frequency Tsunamis Excited Near Torishima Island, Japan, Observed by Distributed Acoustic Sensing

AbstractRecent distributed acoustic sensing (DAS) experiments in ocean areas throughout the world have accumulated records for various wavefields. However, there are few tsunami records because tsunami observation depends on the DAS experimental period and its location. From continuous DAS records, we found tsunami signals at a frequency band of 5–30 mHz, which correspond to high‐frequency components of tsunamis and their propagation velocities differ from low‐frequency tsunamis. We estimated time series of the tsunami excitations at the source using the DAS records, which are consistent with those using records of ocean‐bottom absolute pressure gauges. Our study suggests that DAS records can be used for detecting tsunami propagations in the regions where other geophysical instruments are not available, and contribute to elucidating their excitation mechanisms.

Neotype designation of the Short-tailed Albatross Phoebastria albatrus (Pallas, 1769) (Aves: Procellariiformes: Diomedeidae).

The Short-tailed Albatross Phoebastria albatrus (Pallas, 1769) is a threatened seabird widely distributed in the northern Pacific Ocean with its largest breeding sites on the Senkaku Islands and Torishima Island, Japan, which are separated by over 1700 km. A recent taxonomic revision based on morphological, behavioral, and DNA sequence evidence has revealed that this species consists of two cryptic species: a smaller species which breeds mainly in the Senkaku Islands, and a larger species which breeds mainly on Torishima Island. However, it has remained unclear to which of these species the scientific name Phoebastria albatrus applies, because the type specimens are lost. Here a neotype is designated to resolve this taxonomic issue. From now on, the scientific name Phoebastria albatrus should be applied only to the smaller species breeding on the Senkaku Islands. The name of the larger species is more problematic, as the types of each synonym of P. albatrus must be traced, found, and examined.

Rapid response of the giant protist xenophyophores (Foraminifera, Rhizaria) to organic matter supply at abyssal depths revealed by an in situ dual stable isotope labeling experiment

The trophic ecology of xenophyophores (Foraminifera, Rhizaria) was examined during a 2-day in situ feeding experiment on the seafloor (water depths of 5370 m) off the east coast of Torishima Island, Japan. Both 13C-labeled glucose (as an example of labile dissolved organic matter) and 15N-labeled diatoms (as an example of labile particulate organic matter sinking from the ocean surface) were supplied to the specimens captured in in-situ incubation cores using the manned submersible Shinkai 6500. We found that xenophyophores took up both dissolved and particulate organic matter during the 2 days of incubation in situ. The higher concentrations of 15N-labeled diatoms in the xenophyophores than in the surrounding sediments suggest efficient collection and use of food resources by xenophyophores, and may support their rapid growth. It is likely that the agglutinated test of xenophyophores, which forms a contorted plate-like structure with upper open fan-like and funnel-like elements, also contributes to their ability to collect phytodetritus derived from the ocean surface.

Time-lapse camera photographs reveal arrival and breeding timing of short-tailed albatrosses Phoebastria albatrus

Monitoring the ecology of seabirds breeding on remote islands is often challenging. However, time-lapse cameras have enabled the surveillance of inaccessible sites. We examined arrival/departure movements and breeding timing of the endangered short-tailed albatrossPhoebastria albatruswith time-lapse cameras on Torishima, a remote and uninhabited island in the northwestern Pacific, from November 2016 to June 2017. The photographic images revealed that the first arrival of the albatrosses on the island was on 7 October 2016, and the number of birds reached a peak of 506 on 5 November. The white pairs arrived and began incubating approximately 1 wk earlier than the white/brownish pairs. From the end of January, the number of birds repeatedly increased and decreased within a short period of time. The birds’ movement out of the breeding colony often occurred synchronously with a rapid decline in the mean daily air pressure. Adult birds began to leave the colony in April. The number of chicks reached up to 200 at the beginning of May, but they all left the colony before 1 June. The processing of the photographic images taken during the incubation and early guard periods revealed that hatching failed in approximately 10% of the pairs. The validity of information collected by time-lapse cameras was confirmed by comparing it with the results of previous field studies. This study will contribute to the collection of essential information for monitoring and conserving seabirds breeding on remote islands where successive or frequent fieldwork is difficult.

特異な津波を引き起こす鳥島近海の火山性地震の物理メカニズム：海底カルデラ火山における Trapdoor型断層破壊

特異な津波を引き起こす鳥島近海の火山性地震の物理メカニズム：海底カルデラ火山における Trapdoor型断層破壊

コバルトリッチクラストからの金属回収技術の現状と課題

The cobalt rich manganese crusts are distributed on the flat top or the slope of seamounts in the economic zone and the open sea around Minami Torishima Island. Cobalt rich manganese crust and manganese nodule are iron manganese oxide mainly composed of oxide of Mn and Fe. However, their distribution condition and composition are different. Manganese nodule contains some 2.0% of copper and nickel together. On the other hand, the cobalt rich manganese crust includes less copper and nickel than manganese nodule does, but contains a higher level of cobalt and platinum. Metal Mining Agency of Japan (MMAJ), which is current Japan Oil, Gas and Metals National Corporation (JOGMEC), has selected“ Smelting and Chlorine Leaching” as the most suitable technique from the viewpoint of nickel, cobalt and copper's recovery from the manganese nodule. (Kojima, in 1996) For the treatment of cobalt rich crust, JOGMEC has established an improved metal recovery technology, which is called the“ Improved Smelting and Chlorine Leaching”, after the investigation from 2003 through 2008. . In the“ Improved Smelting and Chlorine Leaching”, JOGMEC has introduced“ slag cleaning” process for cobalt and another process for platinum in order to enhance the recovery level. Also JOGMEC found technique to recover metal using bioleaching effectively.

Checklist of marine fishes of the Zunan Islands, located between the Izu and Ogasawara (Bonin) islands, Japan, with zoogeographical comments

The Zunan Islands are located 360–650 km south of Tokyo, and consist of four uninhabited volcanoes: the Bayonnaise Rocks, the Smith Rocks, Torishima Island and the Sofugan Rock. Although all of the elements of the Zunan Islands are tiny islets and rocks, they form a series of stepping stones for shallow water fishes between the Izu Islands in the north and the Ogasawara (Bonin) Islands in the south. We report here the first comprehensive survey of marine fishes in the Zunan Islands. A total of 139 species of fishes (88 genera of 46 families in 11 orders) were recorded on the basis of specimens and/or underwater photographs. Although our survey showed that the fish fauna of the Zunan Islands was more similar to that of the Ogasawara than that of the Izu islands, most of the species from the Zunan Islands occurred in all three island groups.

Translocation and hand-rearing techniques for establishing a colony of threatened albatross

SummaryMany breeding colonies of Procellariiformes have been threatened with extinction. Chick translocation has been shown to be an effective method for establishing new “safer” colonies of burrow-nesting species, but techniques for surface-nesting species have not been fully developed. The entire breeding population of the threatened Short-tailed AlbatrossPhoebastoria albatrusis restricted to two sites, Torishima Island and the Senkaku Islands, and neither site is secure due to volcanic activity or political instability. The Short-tailed Albatross Recovery Team has recommended facilitating the recovery of this species by establishing at least one additional colony through the translocation and hand-rearing of chicks at a safe historical breeding site. To evaluate the feasibility of this approach, we hand-reared 10 post-guard phase chicks of two related species in 2006–2007: Laysan AlbatrossP. immutabilistranslocated from Midway Atoll to Kaua’i Island, Hawai’i and Black-footed AlbatrossP. nigripestranslocated from a nearby islet in the Ogasawara (Bonin) Islands to Mukojima Island, Japan. In these pilot studies, 40% of Laysan Albatross chicks and 90% of Black-footed Albatross chicks fledged successfully. Following this groundwork, 40 post-guard phase Short-tailed Albatross chicks were translocated from Torishima Island to Mukojima Island in February 2008–2010 and hand-reared to fledging. Their fledging success has been 100% in all three years. Fledging body sizes were similar or greater in hand-reared chicks at the release site than parent-reared chicks on Torishima Island. There were significant differences in levels of some blood chemistry parameters between pre-fledging hand-reared and parent-reared chicks. The techniques developed in our studies have broad-reaching implications for the future conservation of threatened populations of other surface-nesting seabirds.

Unexpectedly high genetic diversity of mtDNA control region through severe bottleneck in vulnerable albatross Phoebastria albatrus

In the late part of the nineteenth century and the early part of the last century, the short-tailed albatross Phoebastria albatrus was in danger of extinction owing to feather hunting. In the middle of the last century, the total number of this species was inferred to be approximately 50-60 with breeding occurring only on Torishima Island of the Izu Islands. Recently, the number of individuals has increased to more than 2,000 and that of their breeding islands to three, namely, Torishima Island, and Minami- and Kita-kojima Islands of the Senkaku Islands. Here, we show that the 44 short-tailed albatrosses we examined represent 29 haplotypes in the control region of mitochondrial DNA, and have a considerably higher genetic diversity than most avian species, but not very high in albatross species; the h and π were 0.96 and 0.013, respectively. However, the parsimony network clearly showed that many intermediate haplotypes were lost. It was concluded that the majority of the haplotypes in the founder population have been maintained. Judging from these findings and the exponential increase in the number of individuals, the present population of the short-tailed albatross seems not to be affected by inbreeding depression through a severe bottleneck. The conservation and expansion of their breeding grounds, and effective protection from bycatch mortality in foraging areas are important for the future survival of this species.

The anatomy of a (potential) disaster: Volcanoes, behavior, and population viability of the short-tailed albatross ( Phoebastria albatrus)

Catastrophic events, either from natural (e.g., hurricane) or human-induced (e.g., forest clear-cut) processes, are a well-known threat to wild populations. However, our lack of knowledge about population-level effects of catastrophic events has inhibited the careful examination of how catastrophes affect population growth and persistence. For the critically endangered short-tailed albatross ( Phoebastria albatrus), episodic volcanic eruptions are considered a serious catastrophic threat since approximately 80% of the global population of ∼2500 birds (in 2006) currently breeds on an active volcano, Torishima Island. We evaluated how short-tailed albatross population persistence is affected by the catastrophic threat of a volcanic eruption relative to chronic threats. We also provide an example for overcoming the seemingly overwhelming problems created by modelling the population dynamics of a species with limited demographic data by incorporating uncertainty in our analysis. As such, we constructed a stochastic age-based matrix model that incorporated both catastrophic mortality due to volcanic eruptions and chronic mortality from several potential sources (e.g., contaminant exposure, fisheries bycatch) to determine the relative effects of these two types of threats on short-tailed albatross population growth and persistence. Modest increases (1%) in chronic (annual) mortality had a 2.5-fold greater effect on predicted short-tailed albatross stochastic population growth rate (lambda) than did the occurrence of periodic volcanic eruptions that follow historic eruption frequencies (annual probability of eruption 2.2%). Our work demonstrates that periodic catastrophic volcanic eruptions, despite their dramatic nature, are less likely to affect the population viability and recovery of short-tailed albatross than low-level chronic mortality.

Emergency Aero-transport from Minami Torishima Island

Emergency Aero-transport from Minami Torishima Island

Population impacts of endangered short-tailed albatross bycatch in the Alaskan trawl fishery

We conduct a decision analysis that explores the effects of trawl-related fishery mortality on achieving the population recovery goals for the US federally-endangered short-tailed albatross (Phoebastria albatrus), proposed by the US Fish and Wildlife Service. A population model is constructed and its parameters estimated using data on counts of the numbers of albatross chicks and eggs at Torishima Island, Japan, where 83% of the world’s population of this species is found. Bayesian inference is used to assign probabilities to alternative plausible rates of fishing mortality and as the basis for population projections with different levels of trawl mortality to determine their effects on achieving the population recovery goals. The analyses of the impact of trawl mortality on the Torishima short-tailed albatross population suggests that exceeding the current expected incidental take in the Alaskan groundfish trawl fishery, two in any 5-year period, by as much as a factor of 10 would have little impact on when the proposed recovery goals for the species are achieved. A quantitative approach that addresses uncertainty, such as that outlined in this study, could aid the process to evaluate allowable limits in light of species recovery goals by addressing both take limits and recovery goals within the same framework.

Alkalimonas collagenimarina sp. nov., a psychrotolerant, obligate alkaliphile isolated from deep-sea sediment

A psychrotolerant, obligately alkaliphilic, collagenolytic enzyme-producing bacterium, strain AC40(T), was isolated from a deep-sea sediment off Torishima Island, Japan, at a depth of 4026 m. Phylogenetic analysis of 16S rRNA gene sequences indicated that this bacterium was closely related to members of the genus Alkalimonas, with highest sequence similarity (97.9 %) to Alkalimonas delamerensis 1E1(T). DNA-DNA hybridization experiments of strain AC40(T) with A. delamerensis 1E1(T) revealed a level of relatedness of less than 30 %. Cells of strain AC40(T) were strictly aerobic, rod-shaped, Gram-negative and motile by means of a single polar flagellum. The organism grew over a range of temperatures from 5 to 37 degrees C and at initial pH values between 7.0 and 10.5. Optimal growth was observed at 33 degrees C and at pH 8.5-10.0. Cellular fatty acids of strain AC40(T) were predominantly saturated and mono-unsaturated straight-chain components (C(16 : 0) and C(18 : 1)). The major isoprenoid quinone was Q-8. The G+C content of the DNA was 49.3 mol%. Phylogenetic characteristics, physiological properties and DNA-DNA hybridization data indicate that strain AC40(T) represents a novel species of the genus Alkalimonas, for which the name Alkalimonas collagenimarina sp. nov. is proposed. The type strain is AC40(T) (=JCM 14267(T)=NCIMB 14266(T)).

Dioxins and Related Compounds in Albatrosses from the Torishima Island, Japan: Accumulation Features by Growth Stage and Toxicological Implications

Concentrations of dioxins and related compounds (DRCs), such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs), were determined in eggs, nestlings, and adults of black-footed albatross (BfA; Diomedea nigripes) and short-tailed albatross (StA; Diomedea albatrus) collected from the Torishima Island in Japan during 2002, which is one of their breeding grounds. Observed DRC concentrations, especially PCDFs and non-ortho Co-PCBs, in eggs of BfA and StA were relatively higher than those in other oceanic, coastal, and inland wild birds reported recently and were comparable to those in a pooled BfA egg from Midway Atoll in 1993, implying continuous input of these contaminants into open ocean and possible albatross-specific exposure. Concentrations of PCDDs except 12378-P5CDD and high-chlorinated PCDFs in 3-month-old BfA nestling were lowerthan those in 1-month-old nestling, indicating their developmental dilution. On the other hand, higher levels of T4-H6CDFs and Co-PCBs, especially low-chlorinated congeners such as 2378-T4CDF and T4CB77, were found in 3-month-old BfA nestling, suggesting specific exposure to these contaminants, possibly due to their higher transportability than high-chlorinated congeners. Estimated biomagnification factors of almost all the congeners in adults were apparently greater than those in nestlings, except 2378-T4CDF, T4CB77, and H7-O8-CDD/Fs. This could be due to preferential metabolism of 2378-T4CDF and T4CB77 and lower uptake efficiency of high-chlorinated congeners through the gastrointestinal tract in adults. Toxic equivalents in BfA and StA eggs estimated using WHO-avian toxic equivalency factors exceeded some toxicity thresholds for avian embryos, indicating possible adverse effects of DRCs to albatross embryos.

Non-destructive monitoring of trace element levels in short-tailed albatrosses ( Phoebastria albatrus) and black-footed albatrosses ( Phoebastria nigripes) from Torishima Island, Japan using eggs and blood

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl and Pb) were determined in abandoned eggs of short-tailed albatrosses and abandoned eggs and blood of black-footed albatrosses from Torishima Island, Japan in 2002. Mercury concentration was highest among the toxic elements in egg content of both the two species. In some egg contents of black-footed albatrosses, Hg concentrations were higher than the threshold level that may cause decreased hatchability and aberrant nesting behavior in some avian species. Concentrations of Cd in egg content and Ba in egg content and shell increased with an increase in egg breadth/length ratio, whereas Hg in egg content showed an opposite trend in black-footed albatrosses. Since egg breadth/length ratio is known to increase with the age of mother bird, this result may imply that concentrations of these elements in eggs vary with age of mother bird. In blood of black-footed albatross chicks, concentration of Hg was highest among the toxic elements and the Hg concentration showed an increase in the later growth stages. In contrast, concentration of Sr in blood decreased with growth stage. Since the behaviour of Sr is similar to that of Ca in animals, it is conceivable that Sr was used along with Ca for the formation of bone.

Trace element accumulation in short-tailed albatrosses (Diomedea albatrus) and black-footed albatrosses (Diomedea nigripes) from Torishima Island, Japan

Concentrations of 19 trace elements (V, Cr, Mn, Co, Cu, Zn, Ga, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl, and Pb) were determined in liver, kidney, muscle, feather and stomach content of short-tailed albatross and feather of black-footed albatross from Torishima Island, Japan. For most of the elements, concentrations in liver and kidney were higher than those in musde and feather, whereas concentrations of Ga, Sr and Ba were highest in feather of short-tailed albatross. Metal concentrations in tissues of short-tailed albatross were within the range of those reported for albatrosses from other locations. Conceptions of Cr, Mn, Hg and Pb were relatively low in the tissues of short-tailed albatross. indicating less contamination by these metals in this species of Torishima Island. No significant differences were observed in metal concentrations in feather between short-tailed albatross and black-footed albatross. To our knowledge, this is the first report on the trace element accumulation in tissues of short-tailed albatross.

Mitochondrial Sequence Variation in Carios capensis (Neumann), a Parasite of Seabirds, Collected on Torishima Island in Japan

Partial mitochondrial 16S ribosomal ribonucleic acid gene sequences in the ticks Carios capensis collected from black-footed albatross. Diomedea nigripes, colonies on Torishima Island, Japan (30 degrees 28'N, 140 degrees 18'E), were examined. The sequence was compared with those of C. capensis from Hawaii, South Carolina, and Texas. The sequences were all identical in ticks from Torishima and 2 from Hawaii. There were 2-3 transitions between the other Hawaiian and Texas ticks and Torishima specimens. Two transitions were also observed when compared with the ticks from South Carolina. The results suggest the possibility of gene flow between tick populations at each of the 2 geographic sites, which probably was accomplished by tick-infested migratory seabirds at their breeding sites. Sequence comparison analysis indicated that the C. capensis ticks are on the branch with C. marginatus and C. mexicanus ticks and not with Ornithodoros. This supports the revision suggested by Klompen and Oliver (1993).

Torishima Whale Bone Deep-sea Animal Community Assemblage

A deep-sea animal community crowded around whale bones was found near the summit of the Torishima Seamount during the submersible Shinkai 6500 cruise of Japan Marine Science and Technology Center (JAMSTEC). The Torishima Seamount, east of Torishima Island, about 550 km south off Tokyo, is tectonically situated in forearc of the Izu-Ogasawara (Bonin) arc-trench system. The focus of Shinkai 6500 dives was on forearc seamounts of the system, where serpentinite was recovered at the time of Leg 125 of the Ocean Drilling Program. The deep-sea animal community, therefrom, offers some significant insight on origin of deep-sea ones. Deep sea animal communities have hitherto known along the oceanic ridge system and from the landward slopes of the subduction zones. The former is a hydrothermal vent community in divergent plate boundary. whereas the latter is cold seep community in convergent plate boundary. Another quite rare type of chemosynthetic animal community, life of which supported by nutrition of lipid seepage from sunken whale bones, was found in the Santa Catalina Basin, west of the United States. The deep-sea animal community from the Torishima Seamount is biologically similar to the last one in depending on nutrition of whale bones. The whale bones was discovered as white cubic materials on the way to the summit of the Torishima Seamount during the dive #148 of Shinkai 6500. The white cubic stuffs were linealy distributed and were together with various kind of deep-sea animals such as shrimps, sea urchins, star fish, vivalves, worms, and gastropods. Such different type of queer animal community were recorded by video movie and photographs, and specimen of the whale bones was collected.

Deep sea trial of 1.55 µm optical fibre submarine cable system

The first 6000 m deep sea trial of a 1.55 µm optical fibre submarine cable system was successfully conducted in the Pacific Ocean, near Torishima Island, in January 1988. By using 1.55 µm loss-minimised single-mode fibre cables and submerged fully monolithic Si-IC regenerators with DFB lasers, excellent transmission performances at 140, 280 and 565 Mbit/s were obtained through 150 km repeater spacings, respectively.