Shetland Research Articles

Parasite assemblages of lanternfishes (Myctophidae) in deep subantarctic waters: Potential indicators for ecosystem monitoring

The Agujero Azul (Blue Hole) is an oceanic region located on the edge of the Southwestern Atlantic continental shelf that is especially impacted by intense fishing activity. It harbours a high biodiversity, including the mesopelagic lanternfishes of the numerically abundant family Myctophidae. Due to their high abundance and relevance in food webs, monitoring changes in the population and community structure of mesopelagic fishes is a valuable tool to trace changes in a warming world, especially in a highly exploited ecosystem where the effects of global change have been documented. Parasite communities of the lanternfishes Gymnoscopelus nicholsi and Electrona subaspera, caught at the Agujero Azul are analyzed. The aims of this work were to assess their value as indicators of host population structure and to establish a baseline for monitoring ecosystem variations under future scenarios of global change. The connectivity with the population of G. nicholsi from around South Georgia was also evaluated by comparing their parasite faunas. A parasitological study of 170 G. nicholsi and 31 of E. subaspera showed low parasite abundance and species richness, with significantly higher levels of parasitism in larger fishes. The paucity of parasitism in G. nicholsi from South Georgia compared to Agujero Azul suggests the existence of two discrete stocks. On the other hand, comparison with literature data supports a connection between fish from the Patagonian shelf and South Shetland Islands (Antarctica). Comparison across samples from Agujero Azul showed homogeneity in parasite assemblages, regardless of the distance separating them, ensuring that parasites are reliable representatives of such physical conditions. Thus, this representability suggests that parasites can be suitable indicators to estimate the amplitude of future changes due to global warming and other anthropogenic stressors in this region. This work provides a baseline for using the parasites of G. nicholsi as indicators to trace these ongoing and predicted changes.

Using ground-penetrating radar to investigate deposits from the Storegga slide tsunami and other sand sheets in the Shetland Islands, UK

We use ground-penetrating radar (GPR) to investigate the geometry, inland extent and continuity of sand layers interpreted as tsunami deposits in the Shetland Islands, UK. Four sites where sand layers within peat deposits have been recorded in previous studies are used to provide ground truth. In addition, we describe survey results from one site where deposits are not exposed to test the potential of GPR to identify candidate tsunami deposits in areas that are not well documented. Sand layers can be clearly imaged at all five locations because they are interbedded with peat and the contrast in lithology gives a good reflection on GPR profiles, even very thin sand layers, <1 cm thick, that are beneath the theoretical resolution of the GPR. 2D and 3D surveys show that tsunami deposits appear to drape a buried topography. Most sand layers form continuous reflections, although some gaps are attributed to later erosion, most likely by streams. Sand layers have been traced up to 150 m inland and 10 m above the present shoreline, which is consistent with data from boreholes. If a similar sized event occurred today, it would have a devastating impact on the Shetland Islands.

Molecular identification of whales remains from the Keller Peninsula, Admiralty Bay, King George Island, Antarctica.

At the beginning of the 20th century, intense whaling activity took place in the South Shetland Islands, which is represented today in the form of ruins and numerous whale bones scattered along several Antarctic beaches. Despite being exposed to a harsh environment throughout the last decades, the present manuscript tried to answer if these bone remains still have viable DNA to allow species' identification using molecular methods. Several individuals were collected from the shores of Keller Peninsula, Admiralty Bay, Antarctica, and submitted to DNA extraction, amplification and Sanger sequencing. The challenging identification of these bone fragments proved to be still feasible. Mitochondrial DNA was successfully extracted, amplified and sequenced. A database with 43 sequences including previously published and newly determined sequences were built and enabled the precise identification to species level for some of the collected samples, therefore shedding light on the whales species that inhabited the region and how their overexploitation seems to have affected modern day presence of these species within the study area.

Fiocruz in Antarctica - health and environmental surveillance facing the challenges of the 21st century.

FioAntar, FIOCRUZ's research project in Antarctica, is based on the One Health approach. FioAntar aims to generate relevant information that will help reduce the risk of future pandemics and improve the search for chemical compounds and new biological molecules. After four expeditions to Antarctica under the scope of PROANTAR, Fiocruz has identified Influenza H11N2 virus in environmental fecal samples, as well as Histoplasma capsulatum and Bacillus cereus in soil samples. In addition, in a prospective virome analysis from different lakes in the South Shetland Islands, six viral orders were described, supporting future research related to the biodiversity and viral ecology in this extreme ecosystem. Our findings of environmental pathogens of public health importance are a warning about the urgency of establishing a surveillance agenda on zoonoses in Antarctica due to the imminent risks that ongoing environmental and climate changes impose on human health across the planet. FioAntar strives to establish a comprehensive surveillance program across Antarctica, monitoring circulation of pathogens with the potential to transcend continent boundaries, thereby mitigating potential spread. For Fiocruz, Antarctica signifies a new frontier, teeming with opportunities to explore novel techniques, refine established methodologies, and cultivate invaluable knowledge.

Skeletal Mg content in common echinoderm species from Deception and Livingston Islands (South Shetland Islands, Antarctica) in the context of global change

Echinoderms with high levels of magnesium (Mg) in their skeletons may be especially sensitive to ocean acidification, as the solubility of calcite increases with its Mg content. However, other structural characteristics and environmental/biological factors may affect skeletal solubility. To better understand which factors can influence skeletal mineralogy, we analyzed the Mg content of Antarctic echinoderms from Deception Island, an active volcano with reduced pH and relatively warm water temperatures, and Livingston Island. We found significant interclass and inter- and intraspecific differences in the Mg content, with asteroids exhibiting the highest levels, followed by ophiuroids and echinoids. Specimens exposed to hydrothermal fluids showed lower Mg levels, which may indicate local environmental effects. These patterns suggest that environmental factors such as seawater Mg2+/Ca2+ ratio and temperature may influence the Mg content of some echinoderms and affect their susceptibility to future environmental changes.

Floristic Similarities between the Lichen Flora of Both Sides of the Drake Passage: A Biogeographical Approach.

This paper analyses the lichen flora of Navarino Island (Tierra del Fuego, Cape Horn Region, Chile), identifying species shared with the South Shetland Islands (Antarctic Peninsula). In this common flora, species are grouped by their biogeographic origin (Antarctic-subantarctic endemic, austral, bipolar, and cosmopolitan), their habitat on Navarino Island (coastal, forest, and alpine), their morphotype (crustaceous, foliaceous, fruticulose, and cladonioid), and the substrate from which they were collected (epiphytic, terricolous and humicolous, and saxicolous). A total of 124 species have been recognised as common on both sides of the Drake Passage, predominantly bipolar, crustaceous, and saxicolous species, and with an alpine distribution on Navarino Island. The most interesting fact is that more than 30% of the flora is shared between the southern tip of South America and the western Antarctic Peninsula, which is an indication of the existence of a meridian flow of propagules capable of crossing the Antarctic polar front.

Noninvasive Surveillance and Evolutionary Insight into Siadenovirus among Antarctic Penguins

Avian siadenoviruses infect diverse terrestrial and aquatic birds worldwide. Antarctica hosts several avian species that are susceptible to siadenovirus infection, such as penguins and South Polar skuas. However, the presence, diversity, and transmission of these viruses in Antarctic birds are poorly understood due to limited surveillance and sequence data. In this study, we performed a noninvasive surveillance of avian siadenoviruses using fecal samples collected from waterbirds at King George Island (part of South Shetland Islands, Antarctica) from late January to mid-February 2023. Polymerase chain reaction, sequencing, and phylogenetic analysis were used to investigate the occurrence, genetic diversity, and evolutionary relationships of these viruses in this unique environment. The results of these studies confirmed the presence of siadenoviruses in penguins living along the southeastern coast of King George Island. Distinct viral strains, specific to each penguin species studied, were found suggesting limited interspecies transmission and a complex viral ecosystem within Antarctic bird populations. Siadenovirus strains isolated from penguin’s species were genetically distinct from those infecting South Polar skuas. An in silico 3D modeling of hexon proteins from siadenoviruses gathered from gentoo penguins permitted to detect key amino acid substitutions in the FG2 domain that may affect capsid structure and function. The persistent prevalence of siadenoviruses in Antarctica underscores the need for ongoing surveillance to understand the evolutionary dynamics of viruses in this region. This study is the first to noninvasively detect siadenoviruses in Antarctic penguins, opening a new avenue for viral research. This approach not only sheds light on viral dynamics but also contributes to the conservation of Antarctica’s unique wildlife and biodiversity, especially in the face of increasing global warming.

Morphology and diet are decoupled in nearshore notothenoids from King George Island, West Antarctica.

Antarctic notothenioid fishes show wide adaptive morphological radiation, linked to habitat preferences and food composition. However, direct comparisons of phenotypic variability and feeding habits are still lacking, particularly in stages inhabiting nearshore areas. To assess these relationships, we collected juveniles and adults of the most common benthic species inhabiting shallow waters off the South Shetland Islands within a similar size range, the plunderfish Harpagifer antarcticus, the black rockcod Notothenia coriiceps, and the marbled rockcod Notothenia rossii. Individual size ranges varied from 44.0 to 98.9 mm standard length (LS) (H. antarcticus), from 95.8 to 109.3 mm LS (N. coriiceps), and from 63.0 to 113.0 mm LS (N. rossii). Notothenioid fish showed different morphospace variability, being larger for H. antarcticus than the other Notothenia species and associated with the position of the posterior end of the operculum, along with the location and relative size of the eye. The evolutionary allometry was low, but the static allometry was much higher, especially for H. antarcticus and N. rossii. The diet was mainly carnivorous, consisting of amphipods and euphausiids. Macroalgae were scarce or totally absent in the gut contents of all species. Only H. antarcticus showed an increase in the prey number and ingested prey volume with fish size. Finally, there was a significant covariation between shape changes and LS in all species (allometric effects), however, not with prey composition, probably due to the small size range or ontogenetic stage and the relative similarity (or lack of contrast) in the benthic environment that they utilized.

Properties and Mechanisms of Seawater Exchange in Marian Cove, King George Island, West Antarctic Peninsula

AbstractThe Antarctic Peninsula is one region that has recently experienced warming substantially more rapidly than the global mean over the past 50 years. Marian Cove is located in the South Shetland Islands connected to the Bransfield Strait via Maxwell Bay between King George Island and Nelson Island. In this study, we identified properties and mechanisms of seawater exchange in Marian Cove from multiple hydrographic surveys and a single bottom‐mounted mooring installed at the entrance to Marian Cove. Regardless of the season, the mean current velocity profiles at the entrance to Marian Cove were constant because of the influence of tidal forcing. Wind was the primary force that determined the variation in surface current; in response, a countercurrent occurred near the bottom area. We estimated salt transport to understand what effects Maxwell Bay′s saline water intrusion has on the Marian Cove environment. When the daily easterly wind was at its maximum of 18.5 m s−1, the salinity could increase to 7.20 × 10−4 g kg−1 in 1 day. In addition, the average freshwater residence time in Marian Cove for the quantitative evaluation of seawater exchange was approximately 9 days. However, the freshwater residence time was reduced to less than 2 days when there were extreme easterly winds.

Geochemistry of the Lake Sediments on Robert Island, South Shetland Islands, Antarctica: implications for weathering processes in Polar areas

Geochemistry of the Lake Sediments on Robert Island, South Shetland Islands, Antarctica: implications for weathering processes in Polar areas

The petrogenesis of analcime in the Coppermine Formation on Robert Island, South Shetland Islands, Antarctica

The petrogenesis of analcime in the Coppermine Formation on Robert Island, South Shetland Islands, Antarctica

Population ecology and juvenile density hotspots of thornback ray (Raja clavata) around the Shetland Islands, Scotland.

Elasmobranchs are facing global decline, and so there is a pressing need for research into their populations to inform effective conservation and management strategies. Little information exists on the population ecology of skate species around the British Isles, presenting an important knowledge gap that this study aimed to reduce. The population ecology of thornback ray (Raja clavata) around the Shetland Islands, Scotland, was investigated in two habitats: inshore (50-150 m deep) and shallow coastal (20-50 m deep), from 2011 to 2022, and 2017 to 2022, respectively. Using trawl survey data from the annual Shetland Inshore Fish Survey, the size composition of R. clavata catches was compared between shallow and inshore habitats across 157 trawl sets, and 885 individuals, over the years 2017-2022. Catch per unit effort (CPUE) of R. clavata was significantly higher in shallow than that in inshore areas (ANOVA, F = 72.52, df = 1, 5, p < 0.001). Size composition also significantly differed between the two habitats (analysis of similarities, R = 0.96, p = 0.002), with R. clavata being smaller in shallow areas and juveniles (<60 cm) occurring more frequently. Spatial distribution maps confirmed density hotspots of juveniles in shallow habitats, with repeated use of certain locations consistent over time. The results of this study provide the first evidence for R. clavata using shallow areas for potential nurseries in Shetland, which can inform the IUCN's Important Shark and Ray Area process. Furthermore, this study provides important new population ecology information for R. clavata around Shetland, which may have important conservation implications and be valuable for informing species and fisheries stock assessments in this region.

Net-phytoplankton communities and influencing factors in the Antarctic Peninsula region in the late austral summer 2019/2020

The waters near the Antarctic Peninsula are characterized with unique oceanographic conditions and rich krill resources. Based on samples collected around the South Shetland Islands (SSI) in austral summer of 2019/2020, the net- phytoplankton community structure and relevant major biotic and abiotic influencing factors were investigated. Eighty-one taxa were identified by light microscope, and diatoms were the most abundant group. The most abundant species were Chaetoceros atlanticus, C. criophilus, C. dichaeta, Fragilariopsis kerguelensis and Pseudo−nitzschia lineola. The abundance and Shannon-Weaver index of net-phytoplankton ranged from 100 to 2.64×107 cells/m3 and 0.0747 to 4.0176 respectively, with significantly low values detected in the Bransfield Strait (BS) and high values in the west of the SSI. The dissimilarity was mainly caused by the differences in abundance of diatoms (including Thalassiothrix antarctica and the species in genus Rhizosolenia, Chaetoceros, Fragilariophsis). These diatoms and Dictyocha speculum were found in higher abundance in the west of the SSI, while Corethron pennatum and cryptophytes were found in higher abundance in the BS. Combined with acoustic density of krill and environmental data (Sea Surface Temperature and Sea Ice Concentration). The multivariate analysis suggested that phytoplankton community was positively affected by the SST, and the acoustic- derived krill density would be associated with the spatial distribution of pennate diatoms. This study enhances the knowledge about the selective feeding for krill and provides ecological implications for the Antarctic marine ecosystem.

Determination of reference values for tear production and intraocular pressure in Pygoscelis penguins of the Antarctic Peninsula

BackgroundAccording to the literature review, this is the first study investigating tear production (TP) and intraocular pressure (IOP) in the Pygoscelis penguins living in their natural habitat. The study aimed to establish normal values for standard ocular tests in the genus Pygoscelis, namely, the Adélie (Pygoscelis adeliae), gentoo (Pygoscelis papua), and chinstrap (Pygoscelis antarctica) penguins, in four different islands of Antarctica. Sampling was made by specifically using the left eye of the penguins. The Schirmer's tear test type I (STT-I) and the Tonovet® (rebound tonometer) were used to measure the TP and the IOP, respectively.ResultsThe mean TP and IOP values of 129 Adélie, chinstrap, gentoo, and 120 adult Adélie, gentoo penguins were determined as 10.2 ± 4.0 mm/min and 38.9 ± 13.2 mmHg, respectively. No statistical difference was detected between the penguin species for the mean IOP values, while the difference was determined in all the locations. However, statistical differences in the mean TP values were determined between all locations.ConclusionThe results of this study provide a reference range of Schirmer's tear test (STT) and IOP values in Pygoscelis penguins and show that the IOP is significantly affected by locations. This result can be attributed to the harsh climatic conditions of the Antarctic Peninsula that change very quickly. The described data may help diagnose clinical pathological findings in Pygoscelis penguins.The STT and rebound tonometry appears to be safe and reproducible methods in Pygoscelis penguins, as the results were obtained quickly and were well tolerated by the birds.Based on our results, we propose that similar studies can be initiated in crowded colonies of three penguin species of this genus on the Antarctic Peninsula, the southern Shetland Islands, and other frequently visited islands in Antarctica.

A Deep Insight into the Diversity of Microfungal Communities in Arctic and Antarctic Lakes.

We assessed fungal diversity in water and sediment samples obtained from five Arctic lakes in Ny-Ålesund (Svalbard Islands, High Arctic) and five Antarctic lakes on Livingston and Deception Islands (South Shetland Islands), using DNA metabarcoding. A total of 1,639,074 fungal DNA reads were detected and assigned to 5980 ASVs amplicon sequence variants (ASVs), with only 102 (1.7%) that were shared between the two Polar regions. For Arctic lakes, unknown fungal taxa dominated the sequence assemblages, suggesting the dominance of possibly undescribed fungi. The phylum Chytridiomycota was the most represented in the majority of Arctic and Antarctic samples, followed by Rozellomycota, Ascomycota, Basidiomycota, and the less frequent Monoblepharomycota, Aphelidiomycota, Mortierellomycota, Mucoromycota, and Neocallimastigomycota. At the genus level, the most abundant genera included psychrotolerant and cosmopolitan cold-adapted fungi including Alternaria, Cladosporium, Cadophora, Ulvella (Ascomycota), Leucosporidium, Vishniacozyma (Basidiomycota), and Betamyces (Chytridiomycota). The assemblages displayed high diversity and richness. The assigned diversity was composed mainly of taxa recognized as saprophytic fungi, followed by pathogenic and symbiotic fungi.

A combined study of gamma spectrometry and inductively coupled plasma spectroscopy reveals persistent anthropogenic radioactive pollution on Deception Island, Antarctica

A comprehensive measurement of the concentrations of natural and anthropogenic radionuclides in soil, water, and air was carried out during the austral summer Antarctic campaign 2018–2019 in different locations around the Spanish Research Station “Gabriel de Castilla” (Deception Island, South Shetland Islands, Antarctica). Limited information is available on radionuclide contamination in the Antarctic region. This study was conducted to evaluate Deception Island’s capacity to remove and self-clean its environment. For this reason, samples from soil, water, and air were collected and analysed by gamma spectrometry, inductively coupled plasma mass spectrometry, and inductively coupled plasma optical emission spectroscopy. The obtained results revealed significant levels of 210Pb and anthropogenic 137Cs, in soil samples close to old human settlements and facilities. In terms of water samples, although more renovation was expected than Antarctic soil, human impact was confirmed again since significant levels of both anthropogenic radionuclides, 137Cs and 60Co, are still detectable in old hunting areas. Air quality studies are not totally conclusive because the obtained results are significantly higher than those previously reported, a fact that potentially points to resuspension processes.

Parasitological and molecular identification of cestode Bothriocephalus scorpii sensu stricto in the new host Chelidonichthys lucerna (L. 1758) (Triglidae, Scorpaenoidei) from the North Sea

A specimen of female tub gurnard (Chelidonichthys lucerna) caught as bycatch in commercial saithe, Pollachius virens, fisheries near the Shetland Islands was identified as a new definitive host for the cestode Bothriocephalus scorpii (Bothriocephalidea) sensu stricto. It was also the first Cestoda species recorded in tub gurnard. However, as shown in our study, the identification of complex species such as Bothriocephalus scorpii based only on external characteristics had to be supplemented with molecular marker analysis to determine the taxonomic status of the specimen. Therefore, to successfully identify the parasite specimen, DNA was extracted from it, and a partial sequence of lsrDNA was amplified and the PCR product was subjected to 2 × 300 bp PE sequencing with 10,000× coverage on MiSeq. A BLAST search using the 346 bp sequence showed 100% similarity to the lsrDNA sequence of B. scorpii deposited in GenBank under accession number AF286942. Relatedness between the sequence of B. scorpii found in our study and the 20 most similar records from GenBank was identified using a phylogenetic tree constructed under maximum likelihood. Our study proves that next-generation sequencing of partial lsrDNA supplemented the morphological identification of the parasite specimen and can be applied in future parasitological studies.

Occurrence and Trophic Transfer of Polychlorinated Naphthalenes (PCNs) in the Arctic and Antarctic Benthic Marine Food Webs.

Information about the occurrence and trophic transfer of polychlorinated naphthalenes (PCNs) in polar ecosystems is vital but scarce. In this study, PCNs were analyzed in benthic marine sediment and several biological species, collected around the Chinese polar scientific research stations in Svalbard in the Arctic and South Shetland Island in Antarctica. Total PCNs in biota ranged from 28 to 249 pg/g of lipid weight (lw) and from 11 to 284 pg/g lw in the Arctic and Antarctic regions, respectively. The concentrations and toxic equivalent (TEQ) of PCNs in polar marine matrices remained relatively low, and the compositions were dominated by lower chlorinated homologues (mono- to trichlorinated naphthalenes). Trophic magnification factors (TMFs) were calculated for congeners, homologues, and total PCNs in the polar benthic marine food webs. Opposite PCN transfer patterns were observed in the Arctic and Antarctic regions, i.e., trophic dilution and trophic magnification, respectively. This is the first comprehensive study of PCN trophic transfer behaviors in remote Arctic and Antarctic marine regions, providing support for further investigations of the biological trophodynamics and ecological risks of PCNs.

Analysis of Microbial Diversity in South Shetland Islands and Antarctic Peninsula Soils Based on Illumina High-Throughput Sequencing and Cultivation-Dependent Techniques.

To assess the diversity of bacterial taxa in Antarctic soils and obtain novel microbial resources, 15 samples from 3 sampling sites (DIS5, GWS7, FPS10) of South Shetland Islands and 2 sampling sites (APS18, CIS17) of Antarctic Peninsula were collected. High-throughput sequencing (HTS) of 16S rRNA genes within these samples was conducted on an Illumina Miseq platform. A total of 140,303 16S rRNA gene reads comprising 802 operational taxonomic units (OTUs) were obtained. After taxonomic classification, 25 phyla, 196 genera, and a high proportion of unidentified taxa were detected, among which seven phyla and 99 genera were firstly detected in Antarctica. The bacterial communities were dominated by Actinomycetota (40.40%), Pseudomonadota (17.14%), Bacteroidota (10.55%) and Chloroflexota (10.26%). Based on the HTS analyses, cultivation-dependent techniques were optimized to identify the cultivable members. A total of 30 different genera including 91 strains were obtained, the majority of which has previously been reported from Antarctica. However, for the genera Microterricola, Dyadobacter, Filibacter, Duganella, Ensifer, Antarcticirhabdus and Microvirga, this is the first report in Antarctica. In addition, seven strains represented novel taxa, two of which were psychropoilic and could be valuable resources for further research of cold-adaptability and their ecological significance in Antarctica.

Sedimentary evidence of the Late Holocene tsunami in the Shetland Islands (UK) at Loch Flugarth, northern Mainland

Tsunami deposits around the North Sea basin are needed to assess the long‐term hazard of tsunamis. Here, we present sedimentary evidence of the youngest tsunami on the Shetland Islands from Loch Flugarth, a coastal lake on northern Mainland. Three gravity cores show organic‐rich background sedimentation with many sub‐centimetre‐scale sand layers, reflecting recurring storm overwash and a sediment source limited to the active beach and uppermost subtidal zone. A basal 13‐cm‐thick sand layer, dated to 426–787 cal. a CE based on 14C, 137Cs and Bayesian age–depth modelling, was found in all cores. High‐resolution grain‐size analysis identified four normally graded or massive sublayers with inversely graded traction carpets at the base of two sublayers. A thin organic‐rich ‘mud’ drape and a ‘mud’ cap cover the two uppermost sublayers, which also contain small rip‐up clasts. Grain‐size distributions show a difference between the basal sand layer and the coarser and better sorted storm layers above. Multivariate statistical analysis of X‐ray fluorescence core scanning data also distinguishes both sand units: Zr, Fe and Ti dominate the thick basal sand, while the thin storm layers are high in K and Si. Enriched Zr and Ti in the basal sand layer, in combination with increased magnetic susceptibility, may be related to higher heavy mineral content reflecting an additional marine sediment source below the storm‐wave base that is activated by a tsunami. Based on reinterpretation of chronological data from two different published sites and the chronostratigraphy of the present study, the tsunami seems to date to c. 1400 cal. a BP. Although the source of the tsunami remains unclear, the lack of evidence for this event outside of the Shetland Islands suggests that it had a local source and was smaller than the older Storegga tsunami (8.15 cal. ka BP), which affected most of the North Sea basin.