Habitat use of loggerhead (Caretta caretta) and green (Chelonia mydas) turtles at the northern limit of their distribution range of the Northwest Pacific Ocean.

Verifying habitats, including the foraging and nesting areas for sea turtles, enables an understanding of their spatial ecology and successful planning of their conservation and management strategies. Recently, the observation frequency and bycatch of loggerhead (Caretta caretta) and green (Chelonia mydas) turtles have increased in the northern limit of their distribution range, in the northern part of the East China Sea and East (Japan) Sea. We conducted satellite tracking to investigate the habitat use of seven loggerhead and eight green turtles from June 2016 to August 2022 in this area, where little is known about their spatial ecology. We applied a 50 percent volume contour method to determine their main foraging areas and analyzed 6 environmental variables to characterize their habitats. Loggerhead turtles mainly stayed in and used the East China Sea as a foraging area during the tracking period, while two individuals among them also used the East Sea as a seasonal foraging area. Most green turtles also used the East China Sea as a foraging area, near South Korea and Japan, with one individual among them using the lower area of the East Sea as a seasonal foraging area. Notably, one green turtle traveled to Hainan Island in the South China Sea, a historical nesting area. Our results showed that the two sea turtle species included the East Sea as a seasonal foraging area, possibly owing to the abundance of food sources available, despite its relatively lower sea temperature. Considering that loggerhead and green sea turtles were observed using the northern part of the East China Sea and East Sea more frequently than previously known and that the sea temperature gradually increases due to climate change, conservation and management activities are required for sea turtles in these areas.

Movement Patterns of Juvenile Loggerhead Turtles (Caretta caretta L. 1758) and Green Turtles (Chelonia mydas L. 1758) Hatched in Captivity and Released in the Korean Waters.

With most sea turtle populations declining, activities to conserve their habitat and nesting grounds and restore their populations are being implemented worldwide. To preserve the Northwestern Pacific populations, the National Marine Biodiversity Institute of Korea has been releasing artificially propagated sea turtles, but whether these individuals join the wild population remains unknown. The present study aimed to determine the movement patterns of artificially propagated juvenile loggerhead (Caretta caretta) and green (Chelonia mydas) turtles fitted with satellite transmitters on their carapaces and released in the waters of Jeju or Yeosu, Republic of Korea, between August 2018 and April 2022. Loggerheads traveled northward to the East Sea, whereas green turtles moved west or southwest. Two 36-month-old and two 48-month-old loggerheads moved toward their potential nursery grounds and toward their feeding grounds, respectively. Three green turtles with a curved carapace length (CCL) of <40 cm moved toward their nursery or feeding grounds, while three individuals (CCL > 45 cm) moved toward their inshore foraging areas. The travel paths were closely related to the direction of local sea currents. Our results implied that releasing artificially propagated sea turtles, considering their age and CCL, can positively contribute to the conservation of Northwestern Pacific populations.

What type of plastic do sea turtles in Korean waters mainly ingest? Quantity, shape, color, size, polymer composition, and original usage.

Globally, sea turtles are at high risk of ingesting plastic. However, research on plastic ingestion by sea turtles in East Asia is scant, and no quantitative or qualitative investigation has been conducted in Korean waters. This study examined the plastic ingestion of sea turtles stranded, floating, or incidentally captured in Korean waters between 2012 and 2018. The quantity, shape, color, size, polymer type, and original usage of plastic debris (>1 mm) ingested by sea turtles were analyzed after being sorted from the gastrointestinal tracts of 34 turtles (21 loggerheads (Caretta caretta), 9 green turtles (Chelonia mydas), 2 leatherbacks (Dermochelys coriacea), and 2 olive ridleys (Lepidochelys olivacea)). The ingestion frequencies of greens, loggerheads, olive ridleys, and leatherbacks were 100%, 81%, 50%, and 50%, respectively. The mean amount of plastic ingested was 108 ± 253 mg/kg (38 ± 61 n/ind.). The ingested debris tended to be films and fibers (>80%), light in color (white and transparent; 65%), and light polymers (polyethylene, polypropylene, polypropylene [poly (ethylene:propylene)], expanded polystyrene; 93%). The original uses were identified for 187 pieces; single-use plastics (e.g., plastic bag and packaging) and fishing and aquaculture items (e.g., twine and net) were found to dominate. Green turtles (264 ± 433 mg/kg) ingested significantly higher amounts of plastic than loggerheads (72.8 ± 156 mg/kg). Green turtles ingested mostly fibers (51%), such as rope, twine, and net, while loggerheads ingested largely films (61%), such as plastic bags and packaging. Interspecies differences in quantities and shapes of ingested debris may be related to their distinct feeding habits and geographical range of movement. The present study demonstrates that sea turtles foraging in Korean waters are considerably affected by marine plastic debris, and indicates that proper waste management of single-use plastics and fishing gears is urgently needed to mitigate the damage that plastic debris causes to marine wildlife.

A comparison of gene organisations and phylogenetic relationships of all 22 squamate species listed in South Korea using complete mitochondrial DNA.

Studies using complete mitochondrial genome data have the potential to increase our understanding on gene organisations and evolutionary species relationships. In this study, we compared complete mitochondrial genomes between all 22 squamate species listed in South Korea. In addition, we constructed Maximum Parsimony (MP), Maximum Likelihood (ML) and Bayesian Inference (BI) phylogenetic trees using 13 mitochondrial protein-coding genes. The mitochondrial genes for all six species in the suborder Sauria followed the same organisation as the sequenced Testudines (turtle) outgroup. In contrast, 16 snake species in the suborder Serpentes contained some gene organisational variations. For example, all snake species contained a second control region (CR2), while three species in the family Viperidae had a translocated tRNA-Pro gene region. In addition, the snake species, Elapheschrenckii, carried a tRNA-Pro pseudogene. We were also able to identify a translocation of a tRNA-Asn gene within the five tRNA (WANCY gene region) gene clusters for two true sea snake species in the subfamily Hydrophiinae. Our BI phylogenetic tree was also well fitted against currently known Korean squamate phylogenetic trees, where each family and genus unit forms monophyletic clades and the suborder Sauria is paraphyletic to the suborder Serpentes. Our results may form the basis for future northeast Asian squamate phylogenetic studies.

The wavevector star channel and symmetry group.

The concepts of `wavevector star channel' and `wavevector star channel group' are newly defined, which allow the effective study of phase transitions considering directly the translational symmetry breaking in crystals. A method is suggested by which the wavevector star channels can be found using the image of the representation of the translational group. According to this method, the wavevector star channels are found for the 80 Lifschitz stars in the reciprocal lattice. The wavevector star channel group is defined as the set of symmetry elements of the parent phase which leave the star channel invariant, and the wavevector star channel groups with one, two, three and four arms are calculated. It is shown that the complicated symmetry changes in the pyroelectric crystal Pb1-xCaxTiO3 (PCT) can be described using the new five-component reducible order parameter transformed according to the representation of the wavevector star channel group, rather than the nine-component one based on the theory of the full irreducible representation of the space group.

Genetic analysis and population genetic structure of hard-shelled mussel, Mytilus coruscus Gould 1861 (Mytiloida: Mytilidae) from the coasts of South Korea based on mitochondrial cytochrome oxidase (COI) gene sequences.

BACKGROUND: Mytilus coruscus Gould, 1861 is a mussel species in the family Mytilidae, native to the Northwest Pacific Ocean, ranging from the East China Sea, the Yellow Sea, and as far as the Peter the Great Gulf in the East Sea. In Korea, this species has been heavily exploited for nutrient-rich food resources and experienced severe reduction in their population. OBJECTIVE: The aim of this study was to investigate the genetic diversity and population structure and to provide baseline data to facilitate the conservation and sustainable use of the vulnerable species M. coruscus in South Korea. METHODS: Mitochondrial DNA (mtDNA) cytochrome c oxidase I (COI) sequences of 91 adult individuals from four islands and one coastal localities in South Korea were sequenced. We then compared genetic diversity and haplotype data with previously published Chinese wild populations. RESULTS: Mytilus coruscus populations on Korean coasts were found to exhibit high genetic diversity despite concerns regarding recent population reduction. A total of 42 haplotypes were defined by 56 polymorphic sites. High-level genetic diversity was observed on four Island sites (Hd = 0.906-0.955, π = 0.0068-0.0090). The other seashore site represented relatively lower genetic diversity (Hd = 0.529, π = 0.0011) and was genetically differentiated from the others. In a previous study, wild populations on the East China Sea exhibited similarly high genetic diversity as that observed in our study. Additionally, Chinese M. coruscus populations exhibit a distinct regional haplotype distribution pattern while sharing six haplotypes with Korean populations. CONCLUSIONS: The results of this study provide insights that further the current understanding regarding the evolution of M. coruscus species and provides comprehensive genetic data to facilitate the development of an effective conservation strategy.

The complete mitochondrial genome of Montipora efflorescens (Scleractinia: Acroporidae).

The complete mitogenome of the Sclreractinia, Montipora efflorescens Bernard, 1897 was sequenced for the first time. It had 17,887 bp, with 13 protein-coding genes, and two rRNA and two tRNA genes. Composition of M. efflorescens mitogenome was identical to that of typical Scleractinians. In conclusion, the complete mitogenome may provide detailed information on coral phylogeny.

Descriptions of Two Digenean Trematodes Found from a Chinese Sea Snake, Laticauda semifasciata, in Republic of Korea.

We intended to describe 2 digenean trematodes found from a Chinese sea snake, Laticauda semifasciata, as the new fauna in the Republic of Korea. The snake was caught offshore of Aewol-eup, Jeju-do, in August 2017. Two species of fluke were found in the lung and intestinal tract of the snake in the process of necropsy. They were identified as Pulmovermis cyanovitellosus Coil and Kuntz, 1960 and Harmotrema laticaudae Yamaguti, 1933, respectively based on the morphological characters. Pulmovermis cyanovitellosus showed elongated body with well-developed and elongated male genital system and compact vitelline. And H. laticaudae was characterized by linguiform body with heavily armed cirrus with excretory system. This is the first time both species have been reported and described off the Korean coast. We provide morphological descriptions with some comments on their biology and geographical distribution. In addition, the taxonomic validity of the genus Hydrophitrema Sandars, 1960 was discussed, in terms of morphological descriptions and host ranges. This study provides novel insight into digenean fluke species existing off the coast of Korea.

The complete mitochondrial genome of blue-lined octopus Hapalochlaena fasciata (Hoyle, 1886) (Octopodiformes; Octopoda; Octopodidae).

The complete mitochondrial genome of the highly venomous blue-lined octopus, Hapalochlaena fasciata (Hoyle, 1886), was analyzed by the primer walking method. Its mitogenome was 15,479 bp in total length, comprising 13 protein-coding genes, 2 ribosomal RNA genes, and 23 transfer RNA genes. In the phylogenetic tree, the gene content and order were congruent with those of typical octopodiform species. The mitogenomic sequence presented could be very useful as the first record of the complete mitogenome for the genus Hapalochlaena.

The complete mitochondrial genome of a yellow-bellied sea snake (Hydrophis platurus) (Squamata, Elapidae).

In this study, we provide the first report of the complete mitochondrial genomic sequencing of a yellow-bellied sea snake (Hydrophis platurus) that has the broadest distribution range of all Squamata species. The mitogenome length was 18,101 bp and consisted of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 3 non-coding regions. The sequence presented could be very useful for further phylogenetic and evolutionary studies.

Spring and summer microhabitat use by Schlegel's Japanese gecko, Gekko japonicus (Reptilia: Squamata: Gekkonidae), in urban areas.

Differential microhabitat use may be beneficial to achieving fitness in seasonally variable environmental conditions. To explore whether the microhabitat use of the nocturnal Schlegel's Japanese gecko, Gekko japonicus, varies seasonally and depends on juvenile, male, and female reproductive groups, we investigated five categorical and five quantitative measure variables of microhabitat use in a wild population both in spring and summer. Most geckos were found on white, vertical planes of concrete and plastered brick walls. None of the categorical variables (type of location, substrate, substrate color, light source, and refuge) significantly differed according to season or group, while substrate temperature and irradiance at the location where geckos were observed and the distance from the nearest potential refuge were significantly greater in summer than in spring. The quantitative measure variables did not differ among the reproductive groups. These results suggest that G. japonicus seasonally adjusts its microhabitat use mainly in terms of quantitative measure variables rather than categorical variables.

Complete mitochondrial genome of the Ijima's Sea Snake (Emydocephalus ijimae) (Squamata, Elapidae).

In this study, we provide the first report of the complete mitochondrial genome of Emydocephalus ijimae. The mitogenome length is 18,259 bp and includes 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and three non-coding regions. The sequence presented could be very useful for further phylogenetic and evolutionary study.

Complete mitochondrial genome of Gymnocanthus intermedius and Gymnocanthus herzensteini (Scorpaeniformes: Cottidae).

Here, we report the complete mitochondrial genomes of the Sculpins species Gymnocanthus intermedius and Gymnocanthus herzensteini. The mitogenomes were determined to be 16,639 bp for G. intermedius and 16,691 bp for G. herzensteini. The mitogenomes comprised 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and a non-coding region. We then used the mitogenome data to construct a phylogenetic tree for these two species and an additional three species within the order Scorpaeniformes.

Development of 21 polymorphic microsatellite markers for the black-banded sea krait, Laticauda semifasciata (Elapidae: Laticaudinae), and cross-species amplification for two other congeneric species.

The genus Laticauda (Reptilia: Elapidae), commonly known as sea kraits, is venomous marine amphibious snakes distributed throughout the south and southeast Asian islands and mostly found in coastal waters. To facilitate genetic studies, we have developed microsatellite loci for L. semifasciata using the 454 GS-FLX pyrosequencing technique. A total of 65,680 sequences containing a minimum of five repeat motifs were identified from 451,659 reads. Among 80 loci containing more than nine repeat units, 34 primer sets (42.5%) produced strong PCR products, of which 21 were polymorphic among 36 samples of L. semifasciata. All loci exhibited high genetic variability, with an average of 7.38 alleles per locus, and the mean observed and expected heterozygosities were 0.73 and 0.76, respectively. The cross-species amplification of these loci in two laticaudine species, L. colubrina and L. laticaudata, revealed a high transferability (78.6%) and polymorphism (59.5%) of the loci. Our work demonstrated the utility of next-generation 454 sequencing as the rapid and cost-effective method for development of microsatellite markers. The high level of polymorphism in these microsatellite loci will be useful for the detection of population subdivision and the study of migration, gene flow, relatedness and philopatry of L. semifasciata and other laticaudine species.

Correction to: Development of 21 polymorphic microsatellite markers for the black-banded sea krait, Laticauda semifasciata (Elapidae: Laticaudinae), and cross-species amplification for two other congeneric species.

Unfortunately, one of the co-author's family name has been incorrectly published in the original online publication. The correct family name should be Tsai.

Phylogenetic relationships of three representative sea krait species (genus Laticauda; elapidae; serpentes) based on 13 mitochondrial genes.

To investigate the phylogenetic relationships of the genus Laticauda to related higher taxa, we compared the sequences of four mitochondrial genes (12S rRNA, 16S rRNA, ND4, Cytb) from three Laticauda species (L. colubrina, L. laticaudata, and L. semifasciata) with those of 55 Asian and Australo-Melanesian elapid species. We also characterized the complete mitogenomes of the three Laticauda species and compared the sequences of 13 mitochondrial genes from Laticauda species with five terrestrial elapid and one viperid species to estimate phylogenetic relationships and divergence times. Our results showed that the genus Laticauda is paraphyletic to terrestrial elapids and diverged from the Asian elapids approximately 16.23 Mya. The mitogenomes of the three Laticauda species commonly encoded 13 proteins, 22 tRNAs, 12S and 16S rRNAs and two control regions and ranged from 17,170 and 17,450 bp in size. The L. colubrina mitogenome was more similar to that of L. laticaudata than that of L. semifasciata. The divergence time among the three Laticauda clades was estimated at 8-10 Mya, and a close phylogenetic relationship between L. colubrina and L. laticaudata was found. Our results contribute to our understanding of the evolutionary history of sea kraits.

The complete mitochondrial genome of Alveopora japonica (Scleractinia: Acroporidae).

Here, for the first time, we sequenced the complete mitogenome of Alveopora japonica Eguchi, 1968 (Scleractinia: Acroporidae). Genome size was 17,886 bp with 13 protein-coding, two rRNA, and two tRNA genes. This gene composition was identical to the typical scleractinian pattern. Our results strongly support the recent transfer of this coral species to the family Acroporidae.

The wavevector substar group in reciprocal space and its representation.

A new concept of the wavevector substar group is established which, in the study of translational symmetry breaking of a crystal, only considers the particular arms of the wavevector star taking part in the phase transition; this is in contrast with the traditional Landau theory which considers all of the arms of the wavevector star. It is shown that this new concept can be used effectively to investigate the interesting physical properties of crystals associated with translational symmetry breaking. It is shown that studies on complicated phase transitions related to reducible representations, such as those in perovskite KMnF3 multiferroics and the high-temperature superconductor La2/3Mg1/2W1/2O3 (La4Mg3W3O18), are much simplified by the new concept. The theory of the wavevector substar group and its representation is a powerful mathematical tool for the study of various symmetry-breaking phenomena in solid-state crystals.

Northward dispersal of sea kraits (Laticauda semifasciata) beyond their typical range.

Marine reptiles are declining globally, and recent climate change may be a contributing factor. The study of sea snakes collected beyond their typical distribution range provides valuable insight on how climate change affects marine reptile populations. Recently, we collected 12 Laticauda semifasciata (11 females, 1 male) from the waters around southern South Korea-an area located outside its typical distribution range (Japan, China including Taiwan, Philippines and Indonesia). We investigated the genetic origin of Korean specimens by analyzing mitochondrial cytochrome b gene (Cytb) sequences. Six individuals shared haplotypes with a group found in Taiwan-southern Ryukyu Islands, while the remaining six individuals shared haplotypes with a group encompassing the entire Ryukyu Archipelago. These results suggest L. semifasciata moved into Korean waters from the Taiwan-Ryukyu region via the Taiwan Warm Current and/or the Kuroshio Current, with extended survival facilitated by ocean warming. We highlight several contributing factors that increase the chances that L. semifasciata establishes new northern populations beyond the original distribution range.

Complete mitochondrial genome of Lycodes tanakae (Perciformes: Zoarcidae).

The complete mitochondrial genome of Lycodes tanakae was sequenced for the first time from its muscle tissue using the next-generation sequencing method. Its mitochondrial genome was 16,594 base pairs in length, containing 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and one control region. Its overall A, C, G, and T contents were 25.6%, 30.6%, 18.7%, and 25.2%, respectively. Its, A + T content (50.8%) was slightly higher than its G + C content (49.2%). A phylogenetic tree was built using 10 belonging to the order Perciformes and two species belonging to the order Scorpaeniformes.