Underwater soundscape in Seaview Bay, Antarctica, and triple ascending trill of the leopard seal (Hydrurga leptonyx) underwater vocalizations.

The underwater soundscape was recorded in Seaview Bay off Inexpressible Island, Ross Sea region Marine protected area, for 3 days in December 2021. Leopard seal Hydrurga leptonyx vocalizations were a prominent sound source that led to variations in ambient sound pressure levels in a frequency range of approximately 150-4500 Hz. Among the 14 call types previously identified, except ultrasound vocalizations, six types of broadcast calls were classified, and their acoustic characteristics were analyzed. We focused on the acoustic characteristics of four low-frequency calls, clustered in a relatively narrow bandwidth, which have been relatively less studied. We identified a new call type of a triple ascending trill consisting of three trill parts, expanding upon the findings of previous studies. The audio data extracted from leopard seal vocalization videos, recorded by a monitoring camera on sea ice, enhanced the reliability of identifications of the underwater triple ascending trill. We present the unique results of underwater passive acoustic monitoring conducted at Seaview Bay, designated as Antarctic Specially Protected Area No 178. Our results could contribute to the development of detection and localization algorithms for leopard seal vocalizations and can be used as fundamental data for studies related to the vocalization and behavior of this species.

Molecular Diet Analysis of Adélie Penguins (Pygoscelis adeliae) in the Ross Sea Using Fecal DNA.

The diet of Adélie penguins, Pygoscelis adeliae, is a useful indicator in understanding the ecological conditions of their habitats. The diets of Adélie penguins were studied using metabarcoding and quantitative PCR (qPCR) analyses of fecal DNA from seven habitats along the Ross Sea region. Using metabarcoding analysis with dual universal primers (18Sv9 and miniFish), the overall diet composition and detailed information about piscine prey were clearly elucidated. It was found that two krill species (Euphausia superba and Euphausia crystallorophias) and notothenioid fish were the most abundant in the diets of Adélie penguins. Among the notothenioid prey, Pleuragramma antarctica (56.50%) and Pagothenia borchgrevinki (18.21%) were the two most abundant species. qPCR analysis showed a significant geographic difference in the composition of main prey. Penguins inhabiting outbound parts of the Ross Sea (Capes Adare (CA) and Duke of York Island (DY)) mainly preyed on E. superba, without any significant changes in prey composition. By contrast, those inhabiting the inbound parts of the Ross Sea (Edmonson Point (EP) and Inexpressible Island (II)) preyed on E. crystallorophias and notothenioid fish rather than E. superba. Compared with the outbound habitats, prey compositions for penguins inhabiting the inbound regions were significantly different year to year, which was presumably due to the food availability based on the annual environmental and meteorological conditions of the coastal region along with the inbound parts of the Ross Sea.

Characterization of the complete mitochondrial genome of the Macaroni penguin Eudyptes chrysolophus from the Barton Peninsula, King George Island, Antarctica.

The Macaroni penguin Eudyptes chrysolophus is a small crested penguin. In this study, the complete mitochondrial genome of E. chrysolophus is revealed for the first time. The mitogenome sequence is circular and 17,059 bp in length. It contains 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and two ribosomal RNA (rRNA) genes similar to other Spheniscidae species. The total nucleotide composition is 30.53% (A), 32.86% (C), 13.96% (G), and 22.66% (T), and 46.81% for overall GC contents. The phylogenetic analysis shows a close relationship between E. chrysolophus and E. schlegeli. Our findings would be useful for further studies on phylogenetics and evolutionary history of the genus Eudyptes.

Genome of the Southern Giant Petrel Assembled Using Third-Generation DNA Sequencing and Linked Reads Reveals Evolutionary Traits of Southern Avian.

The southern giant petrel Macronectes giganteus, a large seabird of the southern oceans, is one of only two members of the genus Macronectes and is the largest species in the order Procellariiformes. Although these two families account for the vast majority of the avian fauna inhabiting the Antarctic and sub-Antarctic regions, studies on the status of some populations and the associated genetic data are currently extremely limited. In this study, we assembled the genome of M. giganteus by integrating Pacific Biosciences single-molecule real-time sequencing and the Chromium system developed by 10x Genomics. The final M. giganteus genome assembly was 1.248 Gb in size with a scaffold N50 length of 27.4 Mb and a longest scaffold length of 120.4 Mb. The M. giganteus genome contains 14,993 predicted protein-coding genes and has 11.06% repeat sequences. Estimated historical effective population size analysis indicated that the southern giant petrel underwent a severe reduction in effective population size during a period coinciding with the early Pleistocene. The availability of this newly sequenced genome will facilitate more effective genetic monitoring of threatened species. Furthermore, the genome will provide a valuable resource for gene functional studies and further comparative genomic studies on the life history and ecological traits of specific avian species.

Complete mitochondrial genome of the snow petrel, Pagodroma nivea.

The snow petrel, Pagodroma nivea is a small sea bird endemic to Antarctica and the Southern Ocean. Herein, we assembled a complete mitochondrial genome of the snow petrel as a first revealed genetic resource in Pagodroma family. The mitogenome is 17,279 bp in length and consists of 13 protein-coding genes (PCGs), 22 tRNA genes, and two rRNA genes. Base composition is 31.3% A, 25.3% T, 30.1% C, and 13.2% G with CG content of 43.4%. These results will provide a useful basis for further genetic and phylogenetic studies of this species.

Complete mitochondrial genome and phylogenetic analysis of the Weddell seal, Leptonychotes weddellii.

The Weddell seal, Leptonychotes weddellii, which belongs to the family Phocidae, is an abundant pinniped that inhabits the Antarctica. Here, we present the complete mitochondrial genome and phylogeny of L. weddellii. The total length of the mitogenome is 16,762 bp, consisting of 13 protein-coding genes (PCGs), 22 tRNA genes, and 2 rRNA genes. The base composition of the mitogenome is 34.26% (A), 25.51% (T), 27.09% (C), and 13.11% (G), and 40.22% for overall GC contents. The description of this mitogenome can provide information about variations at the intra-species level and aid phylogenetic studies in family Phocidae.

Home Range Estimates and Habitat Use of Siberian Flying Squirrels in South Korea.

Conservation measures or management guidelines must be based on species' ecological data. The home range of the target species was studied to understand its spatial ecology, in order to protect it. The Siberian flying squirrel is the only flying squirrel species present and is considered as a protected species in South Korea. In this study, we investigated the home range, habitat use, and daily movement of Siberian flying squirrels from February 2015 to June 2016 at Mt. Baekwoon, Gangwon Province, South Korea. We tracked 21 flying squirrels using radio transmitters and analyzed the home range of 12 individuals. Flying squirrels appeared to have an overall mean home range of 18.92 ± 14.80 ha with a core area of 3.54 ha ± 3.88 ha. Movement activity peaked between 18:00-19:00 with the longest distance traveled, coinciding with sunset. In addition, we observed the preference of Siberian flying squirrels to the old deciduous forest with dense crowns. The results of the present study indicate that it is important to manage their habitat; for instance, preserving an appropriate size of mature deciduous forest is essential for Siberian flying squirrels. While our study provides needed baseline information on the spatial activity of the species, further research on topics such as the national distribution, behavior, and population dynamics of Siberian flying squirrels is needed in South Korea.