Springer Science and Business Media LLC

The Antarctic region is known for its ecological conditions and the presence of some of the rarest microorganisms on earth. Antarctic krill rapidly degrades while at rest or during transport due to high-activity enzymes in its flesh or from microbes. In this study, we analyzed the microbial diversity of the Antarctic krill, Euphausia superba, and identified the dominant bacteria that cause spoilage during storage and transport using culture-independent high-throughput sequencing and microbial pure culture methods. Antarctic krill samples were incubated at temperatures of 0 °C, 4 °C, 16 °C, and 25 °C to determine the microbial diversity and abundance in decaying marine krill samples. Metagenome high-throughput sequencing indicated that, under incubation at 4 °C and 0 °C for 24 h, the microbial diversity of the Antarctic krill samples was high, with high species richness of microbes adapted to the low-temperature environment, as indicated by the overwhelming dominance of Enterococcus and Bacillus. On the other hand, Psychrobacter became the dominant bacteria at storage temperatures of 16 °C and 25 °C. Quantitative PCR results demonstrated that the microbial copy number increased as the temperature increased from 0 to 25 °C, and the quantity of bacteria was much greater than that of fungi under the same storage conditions. Microbial pure culture methods demonstrated that Psychrobacter was the dominant genus at each incubation temperature after 24 h of storage. Psychrobacter sp. and Psychrobacter-like strains isolated from the Antarctic krill samples exhibited protease activity. Our laboratory results indicated that Psychrobacter was the primary cause of spoilage of the Antarctic krill, E. superba. The results from ITS rDNA fungal sequencing showed that unclassified Saccharomycetes were the predominant microbes in all the Antarctic krill samples.

A eumelanistic chinstrap penguin Pygoscelis antarcticus was registered at Penguin Island, Maritime Antarctica during the 2014/2015 austral summer. Melanism mutations are quite rare for this species, and even though former informal records have been made, as far as we know, this is the first official report of eumelanism in chinstrap penguins.

The King Penguin (Aptenodytes patagonicus) is a pelagic seabird that breeds on Subantarctic islands and is considered a rare vagrant in South Africa. From 2001 to 2017, six King Penguins were rescued along the South African coast and admitted into rehabilitation centers. These and previous records of King Penguins were obtained near the country’s major ports, which suggests that some of these birds may have been ship-assisted. One of the King Penguins evaluated in this study died shortly after being admitted to the rehabilitation center due to extensive hemorrhage caused by a long-line fishing hook, and another had a beak wound consistent with fishing hook injury. Three King Penguins were infected with the tick-borne protozoan Babesia peircei and two died as a result of babesiosis. One King Penguin was diagnosed with an infection by Rickettsia-like organisms. Pox-like lesions, presumably mosquito-borne, developed on the eyelid skin of one penguin. Additionally, one of two King Penguins permanently captive in Cape Town during the same period also presented a lethal case of spirochetosis, which was possibly tick-borne. These novel records of vector-borne pathogens in King Penguins highlight the risk of seabird rehabilitation centers to serve as potential sources of pathogens to vagrant species, while also illustrating the opportunities that these centers provide for pathogen research and surveillance.

Extensive and rapid losses of sea ice in the Arctic have raised conservation concerns for the Pacific walrus (Odobenus rosmarus divergens), a large pinniped inhabiting arctic and subarctic continental shelf waters of the Chukchi and Bering seas. We developed a Bayesian network model to integrate potential effects of changing environmental conditions and anthropogenic stressors on the future status of the Pacific walrus population at four periods through the twenty-first century. The model framework allowed for inclusion of various sources and levels of knowledge, and representation of structural and parameter uncertainties. Walrus outcome probabilities through the century reflected a clear trend of worsening conditions for the subspecies. From the current observation period to the end of century, the greatest change in walrus outcome probabilities was a progressive decrease in the outcome state of robust and a concomitant increase in the outcome state of vulnerable. The probabilities of rare and extirpated states each progressively increased but remained <10% through the end of the century. The summed probabilities of vulnerable, rare, and extirpated (P(v,r,e)) increased from a current level of 10% in 2004 to 22% by 2050 and 40% by 2095. The degree of uncertainty in walrus outcomes increased monotonically over future periods. In the model, sea ice habitat (particularly for summer/fall) and harvest levels had the greatest influence on future population outcomes. Other potential stressors had much smaller influences on walrus outcomes, mostly because of uncertainty in their future states and our current poor understanding of their mechanistic influence on walrus abundance.

Biển Ross là một khu vực có năng suất rất cao của đại dương phía Nam, và sự phát triển phytoplankton ròng thay đổi theo mùa, dao động từ không tới gần mức tối đa bị giới hạn bởi nhiệt độ. Với việc sự biến đổi trong sự phát triển có thể xảy ra từ một số yếu tố (chẳng hạn như độ chiếu sáng và nồng độ sắt), sự biến đổi trong tỷ lệ tăng trưởng ròng đã được điều tra bằng cách sử dụng mô hình phương trình cấu trúc (SEM) và dữ liệu thu thập được trong chuyến khảo sát từ tháng 1 đến tháng 2 năm 2012 tại Biển Ross. Mô hình phương trình cấu trúc cho thấy rằng tỷ lệ tăng trưởng vào mùa hè bị ảnh hưởng đáng kể bởi nồng độ sắt và mức độ carbon hữu cơ hạt (POC), trong đó cái sau có khả năng cao đã góp phần vào sự thiếu hụt sắt theo mùa của phytoplankton. Ngược lại, tỷ lệ tăng trưởng không thay đổi mạnh với độ sâu lớp nước trộn (và do đó là độ chiếu sáng). SEM cho thấy rằng nếu nồng độ sắt được tăng thêm 1.0 độ lệch chuẩn (khoảng 0.12 nM), tỷ lệ tăng trưởng mùa hè sẽ tăng lên 0.5 độ lệch chuẩn (khoảng 0.07 ngày−1). Tương tự, nếu POC (một thước đo sinh khối phytoplankton trong khu vực này) được tăng thêm 1.0 độ lệch chuẩn (từ 23.0 đến 39.4 µmol L−1), tỷ lệ tăng trưởng sẽ giảm 0.31 độ lệch chuẩn (~0.04 ngày−1), điều mà chúng tôi suy đoán có thể là do sự giới hạn sắt gia tăng thông qua việc hấp thụ tổng thể sắt được tăng cường. Bài tập mô hình này xác nhận vai trò chính của sắt trong việc điều tiết tỷ lệ phytoplankton mùa hè trên thềm lục địa của Biển Ross.

The diatoms Nitzschia frigida and Thalassiosira antarctica grow exponentially even at temperatures between-4 and -6°C and a salinity between 73‰ and 100‰ Under these conditions the light saturation of growth is reached in continuous light at a scalar quantum irradiance of between 7 μmol·m−2·s−1 and 10 μmol · m−2 · s−1. The increase in salinity retards growth more than a decrease in temperature. For N. frigida the limit of growth is at -8°C (S = 145%.). At increasing quantum irradiance, the chlorophyll content per unit cell volume decreases, whereas there is a significant increase in the carbon content of the exponentially growing cells. In addition, there is hardly any change in the protein content. The results show that both species of diatom can survive in ice without forming resting spores and even grow at extremely low temperatures.

Halicarcinus planatus is the only member of the family Hymenosomatidae that occurs in the southern tip of South America. The aim of this study is to determine both the reproductive cycle and reproductive traits of the population of H. planatus nearest to southern limit of its geographical distribution. Results of this work allow us to determine two consecutive reproductive periods in this species. Maximum values of gonadosomatic index, oocyte diameter and ovarian development in March and August indicate that spawning takes place in May and September. The simultaneous ovarian maturity and the embryonic development show that female H. planatus can re-mature its ovary. The capability of H. planatus to develop their ovaries while females are ovigerous is a unique feature among the sub-Antarctic decapods and probably an adaptative advantage to extreme environments. Based on the different biological features and recent environmental changes along the Western Antarctic Peninsula, our hypothesis is that H. planatus possesses the potential to invade shallow waters and intertidal zones in this region.

Mitchell Peninsula is located towards the East of the Windmill Islands in eastern Antarctica. It is an ice-free polar desert, and knowledge of its soil microbial taxonomic composition is limited. In this study, we investigated the soil microbial taxonomic composition using multiplex 454 pyrosequencing targeting the bacterial 16S rRNA and the fungal ITS genes; and the bacterial and fungal abundances were estimated using quantitative PCR. In total, 40 bacterial and five fungal phyla were identified comprising 111 bacterial and 22 fungal classes, respectively. Mitchell Peninsula soil exhibited a unique bacterial taxonomic profile. In contrast to the usual dominance of Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes in polar and temperate soils, Mitchell Peninsula was rich in the poorly studied Chloroflexi (31.7 %), candidate divisions WPS-2 (8.1 %) and AD3 (5.1 %), while the commonly observed Bacteroidetes and Firmicutes were present in relative abundances below 1 %. The fungal community consisted of Ascomycota (77 %) and Basidiomycota (10 %), and was dominated by the lichenous fungal class Lecanoromycetes (46.4 %). Network analysis revealed the presence of several microbial clusters that each potentially occupied a different environmental niche, and fewer numbers of correlations were identified between bacteria within each cluster compared with the lichen community, where extensive community dynamics may be present. As Mitchell Peninsula exhibits a unique microbial taxonomic composition, not previously observed in any reported polar or temperate ecosystem, we believe it is a potential microbial biodiversity “hotspot”, which warrants further investigation to examine the role of the dominance of these uncharacterised candidate divisions in this extreme ecosystem.