Ship traffic connects Antarctica’s fragile coasts to worldwide ecosystems

Antarctica, an isolated and long considered pristine wilderness, is becoming increasingly exposed to the negative effects of ship-borne human activity, and especially the introduction of invasive species. Here, we provide a comprehensive quantitative analysis of ship movements into Antarctic waters and a spatially explicit assessment of introduction risk for nonnative marine species in all Antarctic waters. We show that vessels traverse Antarctica’s isolating natural barriers, connecting it directly via an extensive network of ship activity to all global regions, especially South Atlantic and European ports. Ship visits are more than seven times higher to the Antarctic Peninsula (especially east of Anvers Island) and the South Shetland Islands than elsewhere around Antarctica, together accounting for 88% of visits to Southern Ocean ecoregions. Contrary to expectations, we show that while the five recognized “Antarctic Gateway cities” are important last ports of call, especially for research and tourism vessels, an additional 53 ports had vessels directly departing to Antarctica from 2014 to 2018. We identify ports outside Antarctica where biosecurity interventions could be most effectively implemented and the most vulnerable Antarctic locations where monitoring programs for high-risk invaders should be established.

Phaeosphaeria deschampsii J. Putzke & A.B.Pereira (Ascomycota, Fungi) causing whitening in Deschampsia antarctica Desv. (Poaceae) in the South Shetland Islands

Phaeosphaeria deschampsii was described from dead leaves of Deschampsia antarctica (Antarctic Grass). We surveyed other islands of the South Shetland archipelago, Antarctica, and also found Arctic Grass whitening, the disease associated with this fungus, indicating that is disease is widespread.

Genome Sequence of Pseudomonas sp. Strain LAP_36, A Rhizosphere Bacterium Isolated from King George Island, Antarctica

Pseudomonas sp. strain LAP_36 was isolated from rhizosphere soil from Deschampsia antarctica on King George Island, South Shetland Islands, Antarctica. Here, we report on its draft genome sequence, which consists of 8,794,771 bp with 60.0% GC content and 8,011 protein-coding genes.

The chiasmata systems of Scottish Chysolina latecincta (Demaison, 1896) (Coleoptera, Chrysomelidae)

The meiotic systems of some Scottish individuals of the rare Chrysolina latecincta ssp. intermedia (Franz, 1938) have been analyzed from meiotic cells at diakinesis to study the types of chromosomal bivalents and the number and locations of their chiasmata. The mean number of unichiasmate was about two-thirds and that of bichiasmate bivalents about one-third. Most chiasmata were at distal positions and there were no pairwise statistically significant differences in the mean number of chiasmata and those of unichiasmate and bichiasmate bivalents between the three surveyed geographic sources of these Scottish individuals. However, pairwise significant differences were found in the mean number of proximal + interstitial chiasmata between Loch Etive (Argyllshire) and both Orkney and Shetland Islands individuals. The presumed higher values of genetic recombination due to the proximal + interstitial chiasmata with regard to the prevailing distal ones, might provide a slight selective advantage to the insular individuals against the more extreme climates of both islands compared with the Loch Etive site.

Periphyton diversity in two different Antarctic lakes assessed using metabarcoding

Antarctic lakes have generally simple periphyton communities when compared with those of lower latitudes. To date, assessment of microbial diversity in Antarctica has relied heavily on traditional direct observation and cultivation methods. In this study, sterilized cotton baits were left submerged for two years in two lakes on King George Island and Deception Island, South Shetland Islands (Maritime Antarctic), followed by assessment of diversity by metabarcoding using high-throughput sequencing. DNA sequences of 44 taxa belonging to four kingdoms and seven phyla were found. Thirty-six taxa were detected in Hennequin Lake on King George Island and 20 taxa were detected in Soto Lake on Deception Island. However, no significant difference in species composition was detected between the two assemblages (Shannon index). Our data suggest that metabarcoding provides a suitable method for the assessment of periphyton biodiversity in oligotrophic Antarctic lakes.

Geodetic Mass Balance of the South Shetland Islands Ice Caps, Antarctica, from Differencing TanDEM-X DEMs

Although the glaciers in the Antarctic periphery currently modestly contribute to sea level rise, their contribution is projected to increase substantially until the end of the 21st century. The South Shetland Islands (SSI), located to the north of the Antarctic Peninsula, are lacking a geodetic mass balance calculation for the entire archipelago. We estimated its geodetic mass balance over a 3–4-year period within 2013–2017. Our estimation is based on remotely sensed multispectral and interferometric SAR data covering 96% of the glacierized areas of the islands considered in our study and 73% of the total glacierized area of the SSI archipelago (Elephant, Clarence, and Smith Islands were excluded due to data limitations). Our results show a close to balance, slightly negative average specific mass balance for the whole area of −0.106 ± 0.007 m w.e. a−1, representing a mass change of −238 ± 12 Mt a−1. These results are consistent with a wider scale geodetic mass balance estimation and with glaciological mass balance measurements at SSI locations for the same study period. They are also consistent with the cooling trend observed in the region between 1998 and the mid-2010s.

Diversity and species composition of diatom communities of Ardley Island, South Shetland Islands

The Antarctic diatom flora has been at the centre of interest of many studies in past decades. The present paper brings new information on the species richness, biogeography and community composition of diatoms on the Ardley Island, South Shetland Islands. One fresh-water and ten soil samples had been collected from the Antarctic Special protected area (ASPA) in the spring of 2019. The following analysis revealed eighty-six diatom taxa in well-developed communities, dominated by Luticola muticopsis, L. truncata, Pinnularia australoschoenfelderi, P. austroshetlandica and P. borealis. According to the current biogeographical knowledge, the majority of species have restricted distribution among the Antarctic Realm; 46.5% of them are reported from various islands of the Maritime Antarctic Region. Based on the dominance of species as Luticola muticopsis and L. truncata and their ecological preferences, we concluded that the species composition of the diatom communities is driven by high nutrient input from breeding seabirds and the moisture availability during the austral summer.