Showing papers in "Polar Biology in 2019"

Bottom trawl surveys in the northern Bering Sea indicate recent shifts in the distribution of marine species

Abstract: The climate regime in the eastern Bering Sea has recently been dominated by a pattern of multi-year stanzas, in which several successive years of minimal sea-ice formation and warm summer temperatures (e.g., 2002–2005, 2014–2017) alternate with several years of relatively extensive sea-ice formation and cold summer temperatures (e.g., 2006–2013). This emerging climate pattern may be forcing long-term changes in the spatial distributions of the Bering Sea’s marine fauna. The National Marine Fisheries Service’s Alaska Fisheries Science Center recently conducted two bottom trawl surveys covering the entire Bering Sea shelf from the Alaska Peninsula to the Bering Strait. The first, in the summer of 2010, was conducted during a cold year when the majority of the continental shelf was covered by a pool of cold (< 2 °C) water. The second, in the summer of 2017, was during a warmer year with water temperatures above the long-term survey mean. These two surveys recorded significantly different spatial distributions for populations of several commercially important fish species, including walleye pollock (Gadus chalcogrammus), Pacific cod (Gadus macrocephalus), and several flatfish species, as well as jellyfishes. Population shifts included latitudinal displacement as well as variable recruitment success. The large-scale distributional shifts reported here for high-biomass species raise questions about long-term ecosystem impacts, and highlight the need for continued monitoring. They also raise questions about our management strategies for these and other species in Alaska’s large marine ecosystems.

Polystyrene nanoparticles affect the innate immune system of the Antarctic sea urchin Sterechinus neumayeri

Abstract: Plastic debris has been recognised as a potential stressor for Antarctic marine organisms. In this study, the effects of surface charged polystyrene nanoparticles (PS NPs) on the immune cells (coelomocytes) of the Antarctic sea urchin Sterechinus neumayeri were assessed through in vitro short-term cultures. The behaviour of anionic carboxylated (PS-COOH) and cationic amino-modified (PS-NH2) NPs in filtered natural sea water (NSW) from King George Island (South Shetland Islands) was characterised by dynamic light scattering. Cellular morphology, NP uptake, phagocytic capacity and gene expression were evaluated after 6 and 24 h of exposure to 1 and 5 µg mL−1 PS NPs. Secondary characterisation showed an initial good dispersion of PS NPs in NSW, followed by nano-scale aggregation after 24 h. Both PS NPs affected cellular phagocytosis and generated an inflammatory response against oxidative stress and apoptosis at the molecular level. Fluorescently labelled PS-COOH aggregates were internalised by phagocytes and associated to the modulation of genes related to external challenges, antioxidant responses and cell protection against stress and apoptosis. Exposure to PS-NH2 caused a strong decrease in phagocytic capacity and the formation of cellular debris at 5 µg mL−1 after 24 h, but low gene modulation, suggesting a threshold in coelomocytes defence ability against PS-NH2. This study represents the first attempt to assess the impact of nanoplastics on Antarctic marine organisms. Our findings demonstrate that PS NPs with different surface charges constitute a challenge for S. neumayeri immune cells.

Study of fauna population changes on Penguin Island and Turret Point Oasis (King George Island, Antarctica) using an unmanned aerial vehicle

Abstract: An unmanned aerial vehicle (UAV) as an alternative to manned aircrafts is an excellent, less invasive, safe tool, especially in sensitive polar regions. Here we used a fixed-wing UAV to collect data on seabird and pinniped populations in hardly accessible Antarctic areas. The implementation of an auto-piloted UAV equipped with a digital camera (Canon EOS 700D, 35 mm f/2.0 lens) allowed us to collect high-quality material applicable to a quantitative analysis of the fauna populations. A successful photogrammetric mission, at an altitude of 550 m above sea level, was accomplished during one Beyond Visual Line of Sight flight above hard-to-access Penguin Island and Turret Point Oasis (King George Island). Obtained selected RGB images were processed to generate a panoramic image stitch with resolution of 0.07 m ground sampling distance. A total of 4290 (SD = 33.08) breeding individuals of two penguin species, Adelie (Pygoscelis adeliae) and chinstrap (Pygoscelis antarcticus), 426 (SD = 7.78) individuals of the southern elephant seal (Mirounga leonina) and 6 individuals of the Weddell seal (Leptonychotes weddellii) were identified in both study areas. Additionally, 222 (SD = 2.0) individuals of the southern giant petrel (Macronectes giganteus) and 76 (SD = 1.0) of the Antarctic shag (Phalacrocorax atriceps bransfieldensis) in the Turret Point area were recognized. The presented observations on the natural history of the investigated fauna together with the available literature may be useful in future research on population trends. A comparison with available historical data for both investigated areas suggests a decrease of 68.29% in both penguin species in the 1980–2016 period. The presented results confirmed that UAVs are useful for remote census work for Antarctic seabirds.

Antarctic phytoplankton community composition and size structure : Importance of ice type and temperature as regulatory factors

Abstract: Climate change at the Western Antarctic Peninsula (WAP) is predicted to cause major changes in phytoplankton community composition, however, detailed seasonal field data remain limited and it is largely unknown how (changes in) environmental factors influence cell size and ecosystem function. Physicochemical drivers of phytoplankton community abundance, taxonomic composition and size class were studied over two productive austral seasons in the coastal waters of the climatically sensitive WAP. Ice type (fast, grease, pack or brash ice) was important in structuring the pre-bloom phytoplankton community as well as cell size of the summer phytoplankton bloom. Maximum biomass accumulation was regulated by light and nutrient availability, which in turn were regulated by wind-driven mixing events. The proportion of larger-sized (> 20 µm) diatoms increased under prolonged summer stratification in combination with frequent and moderate-strength wind-induced mixing. Canonical correspondence analysis showed that relatively high temperature was correlated with nano-sized cryptophytes, whereas prymnesiophytes (Phaeocystis antarctica) increased in association with high irradiance and low salinities. During autumn of Season 1, a large bloom of 4.5-µm-sized diatoms occurred under conditions of seawater temperature > 0 °C and relatively high light and phosphate concentrations. This bloom was followed by a succession of larger nano-sized diatoms (11.4 µm) related to reductions in phosphate and light availability. Our results demonstrate that flow cytometry in combination with chemotaxonomy and size fractionation provides a powerful approach to monitor phytoplankton community dynamics in the rapidly warming Antarctic coastal waters.

Physical and biological drivers of zooplankton communities in the Chukchi Sea

Abstract: The physical environments of high-latitude systems are rapidly changing. For example, the Chukchi Sea has experienced increased water temperatures, advection from the Bering Sea, declines in sea-ice concentration, earlier spring ice retreat, and delayed fall ice formation. This physical restructuring is expected to impact ecosystem structure and function. In this study, a series of bio-oceanographic research surveys were conducted in the summers of 2010, 2011, and 2012 to characterize the physical environment and to examine the influence of physical forcing on zooplankton community distribution and abundance. Results revealed yearly advection from the Bering Sea influenced zooplankton community structure, but this influence became less apparent in the northeastern Chukchi due to changes in current speeds and patterns. Decreased advection and later ice retreat in colder years resulted in zooplankton communities that exhibited more diversity, had higher abundances of the lipid-rich copepod Calanus glacialis, and were less closely related to water masses advected from the south. These findings suggest more localized processes are influencing zooplankton community structure in the Chukchi Sea. Increased inflow of water into the Chukchi is predicted with increased warming in the Arctic and changes in food-web structure and function are likely to result.

Decoupling light harvesting, electron transport and carbon fixation during prolonged darkness supports rapid recovery upon re-illumination in the Arctic diatom Chaetoceros neogracilis

Abstract: During winter in the Arctic marine ecosystem, diatoms have to survive long periods of darkness caused by low sun elevations and the presence of sea ice covered by snow. To better understand how diatoms survive in the dark, we subjected cultures of the Arctic diatom Chaetoceros neogracilis to a prolonged period of darkness (1 month) and to light resupply. Chaetoceros neogracilis was not able to grow in the dark but cell biovolume remained constant after 1 month in darkness. Rapid resumption of photosynthesis and growth recovery was also found when the cells were transferred back to light at four different light levels ranging from 5 to 154 µmol photon m−2 s−1. This demonstrates the remarkable ability of this species to re-initiate growth over a wide range of irradiances even after a prolonged period in the dark with no apparent lag period or impact on survival. Such recovery was possible because C. neogracilis cells preserved their Chl a content and their light absorption capabilities. Carbon fixation capacity was down-regulated (ninefold dark decrease in $$P_{\text{m}}^{\text{C}}$$ ) much more than was the photochemistry in PSII (2.3-fold dark decrease in ETRm). Rubisco content, which remained unchanged after one month in the dark, was not responsible for the decrease in $$P_{\text{m}}^{\text{C}}$$ . The decrease in PSII activity was partially related to the induction of sustained non-photochemical quenching (NPQ) as we observed an increase in diatoxanthin content after one month in the dark.

Underwater photogrammetry in Antarctica: long-term observations in benthic ecosystems and legacy data rescue

Abstract: The need for sound baseline information about community structure and composition against which changes can be detected and quantified is a well-recognised priority in Antarctica. Here, the collection of such data is challenging, especially at sea, where long-term monitoring is usually logistically feasible only in the proximity of permanent research stations. In recent years, underwater photogrammetry has emerged as a non-destructive and low-cost method for high-resolution topographic reconstruction. We decided to apply this technique to videos, recorded during standard SCUBA surveys of Antarctic benthos in Tethys Bay (Ross Sea, Antarctica) in 2006 and 2015 and originally not meant for photogrammetry. Our aim was to assess the validity and utility of the photogrammetric method to describe benthic communities from the perspective of long-term monitoring. For this purpose, two of the transects surveyed in 2015 were revisited in 2017. Videos were processed with photogrammetric procedures to obtain 3D models of the seafloor and inhabiting organisms. Overall, a total of six 20 m-long transects, corresponding to a total area of ~ 200 m2 of seafloor were analysed. Accuracy of the resulting models, expressed in terms of Length Measurement Error (LME), was 1.9 mm on average. The 2017 transects showed marked differences in some species, such as a 25–49% increase in the number of sea urchins Sterechinus neumayeri (Meissner, 1900) and the complete disappearance of some sponges Mycale (Oxymycale) acerata Kirkpatrick, 1907. Our analyses confirm the efficacy of photogrammetry for monitoring programmes, including their value for the re-analysis of legacy video footage.

The importance of macroalgae and associated amphipods in the selective benthic feeding of sister rockcod species Notothenia rossii and N. coriiceps (Nototheniidae) in West Antarctica

Abstract: Studies on feeding selectivity in Antarctic fish with comparison between diet organisms and those available in the wild are scarce. We explored this issue in Notothenia rossii (NOR) and N. coriiceps (NOC) at Potter Cove in summer 2016 to test: (1) their preference among different benthic groups, primarily species of algae and amphipods and (2) differences between these nototheniids given their distinct morphology but their known similar general ecology in the fjords. The methodology included a comparative analysis of benthic organisms identified in the stomachs and those collected on macroalgal beds (Ivlev Index). Benthic amphipods, mainly Gondogeneia antarctica and Cheirimedon femoratus, followed by macroalgae, mainly Palmaria decipiens and Desmarestia spp., were the most important and frequent dietary items (IRI%) for both nototheniids. However, NOC was more herbivorous and fed more intensively on a wider diversity of benthic organisms such as certain algal-associated groups like gastropods and bivalves, whereas NOR fed on a greater proportion of epibenthic amphipods and other epibenthic prey. Although in the last three decades the physiognomy of the inner cove has been changed due to the retreat of the Fourcade Glacier, at our sampling site in the outer cove the abundance and vertical distribution of macroalgae did not show substantial changes compared with those reported in the literature in 1994–1996. Temporal differences in the feeding selectivity of NOC on amphipod species, between contemporary and historical samples, may be explained by variations in the assemblage of the algal-associated epifauna. We suggest factors that may have produced these changes.

DNA barcoding of the marine macroalgae from Nome, Alaska (Northern Bering Sea) reveals many trans-Arctic species

Abstract: Marine macroalgal species are expected to shift northward with temperature regimes in the wake of climate change. Monitoring ecosystem shifts in the Arctic will depend on accurate and consistent species level datasets from key locations. The Northern Bering Sea is an area with limited sampling, and will be critical to monitoring the potential movement of Pacific species into the Arctic. We therefore sampled the marine flora of Nome, Alaska, and surrounding area, August 12–22 (2017). Specimens were pressed and/or preserved in silica for DNA barcoding procedures. Several genetic markers were sequenced including the 5′ end of the cytochrome c oxidase subunit I gene (COI-5P; n = 551), elongation factor Tu (tufA; n = 41), full length reads of the internal transcribed spacer of the ribosomal cistron (ITS; n = 56), and full or partial reads of the ribulose-1, 5-biphosphate carboxylase large subunit (rbcL or rbcL-3P, respectively; n = 24). These collections represented eight species of green algae, 21 species of brown algae, and 24 species of red algae. Most of the species sampled (66%, n = 35) represented trans-Arctic species, 17% (n = 9) represented species with distributions restricted to the Pacific, 8% (n = 4) represented species restricted to the Arctic, and the remaining 9% (n = 5) represented previously unsampled genetic groups. Our survey revealed that the marine flora of Nome, Alaska, is largely contiguous with the North-west Atlantic. Repeated sampling from Nome and other key locations in the Northern Bering Sea (e.g., St. Lawrence Island) will be critical to further establishing baseline data for monitoring ecosystem shifts in an era of climate change.

Spatio-temporal distribution of polar cod ( Boreogadus saida ) and saffron cod ( Eleginus gracilis ) early life stages in the Pacific Arctic

Abstract: Polar cod (Boreogadus saida) and saffron cod (Eleginus gracilis) are key fishes in the Arctic marine ecosystem, serving as important trophic links between plankton and apex predators, yet our understanding of their life histories in Alaska’s Arctic is extremely limited. To improve our knowledge about their early life stages (ELS), we described the spatial and temporal distributions of preflexion larvae to late juveniles (to 65 mm in length) in the Chukchi and western Beaufort seas based on surveys conducted between 2004 and 2013, and examined how their abundances varied in response to environmental factors. Species-specific differences in habitat use were found, with polar cod having a more offshore and northern distribution than saffron cod, which were found closer inshore and farther south. Polar cod preflexion and flexion larvae were encountered throughout the sampling season across much of the shelf, which suggests that spawning occurs over several months and at multiple locations, with Barrow Canyon potentially serving as an important spawning and/or retention area. Polar cod ELS were abundant at intermediate temperatures (5.0–6.0 °C), while saffron cod were most abundant at the highest temperatures, which suggests that saffron cod may benefit from a warming Arctic, while polar cod may be adversely affected. This research provides new insights into how environmental variability influences the distribution and abundance of gadids in the Pacific Arctic and advances our understanding of the habitats occupied by these key forage species during their first few months of life.

First evidence of mouse attacks on adult albatrosses and petrels breeding on sub-Antarctic Marion and Gough Islands

Abstract: Invasive house mice Mus musculus are significant predators of seabird chicks on islands where they are the only introduced mammal, but there are very few records of attacks on adult birds. We report the first evidence of mouse attacks on adult albatrosses and petrels breeding on Marion and Gough Islands, where there has been a recent increase in attacks on seabird chicks. In September 2017, wounds consistent with a mouse attack were recorded on an incubating adult male Northern Giant Petrel Macronectes halli on Marion Island. The nest was deserted, and breeding success within 500 m was 18% (n = 11) compared to 68% at nests > 500 m away (n = 123), suggesting that other incubating adults in the immediate vicinity also might have been affected. In March 2018, an incubating Tristan Albatross Diomedea dabbenena was found on Gough Island with a typical mouse wound on its rump. The egg hatched and the same bird was later seen brooding and feeding the chick. In October 2018, an incubating Atlantic Yellow-nosed Albatross Thalassarche chlororhynchos was found on Gough Island with a wound on its back suggestive of a mouse attack and 23 freshly dead carcasses of this species were found, next to empty nests, in nearby colonies. These observations add to mounting evidence of the impacts of mice on seabirds, and further support calls to eradicate mice from Marion and Gough Islands.

Diversity of mycelial fungi in natural and human-affected Antarctic soils

Abstract: Environmental disturbance is an unpreventable consequence of human impact after exploration and research station management in Antarctica. Environmental pollution may directly influence Antarctic mycobiota. However, information about the effect of anthropogenic factors on microscopic fungi at extremely low temperatures is insufficient. This work compared the abundance and the species diversity of mycelial fungi from soils of six Russian research Antarctic stations—Bellingshausen, Progress-2, Druzhnaya-4, Molodezhnaya, Novolazarevskaya and Oasis−affected by various anthropogenic impacts (operation of tracked and wheeled vehicles, storage and use of petroleum products and petroleum leakage sites) with that from their background analogues. New data were obtained on the taxonomic diversity of mycelial fungi from Antarctic soils with different anthropogenic loads. Cultural, morphological and physiological studies of 142 isolated strains of mycelial fungi were supplemented by molecular–biological research into sterile mycelium strains and those with vague morphological characters. This contributed not only to the verification but also to a significant increase in the number of taxa of mycelial fungi isolated from low-temperature ecotopes. Leotiomycetes and Dothideomycetes were found to be the most dominant classes in the studied samples. It was shown that several ecological groups of micromycetes could be isolated among the mycobiota of the investigated habitats, the abundance and species composition of which changed differently under the influence of anthropogenic factors. The current results highlight that microbiota changes in human-affected soils can serve as an indicator of the state of low-temperature ecotopes in general.

Spatial distribution and habitat preferences of demersal fish assemblages in the southeastern Weddell Sea (Southern Ocean)

Abstract: Our knowledge on distribution, habitats and behavior of Southern Ocean fishes living at water depths beyond scuba-diving limits is still sparse, as it is difficult to obtain quantitative data on these aspects of their biology. Here, we report the results of an analysis of seabed images to investigate species composition, behavior, spatial distribution and preferred habitats of demersal fish assemblages in the southern Weddell Sea. Our study was based on a total of 2736 high-resolution images, covering a total seabed area of 11,317 m2, which were taken at 13 stations at water depths between 200 and 750 m. Fish were found in 380 images. A total of 379 notothenioid specimens were recorded, representing four families (Nototheniidae, Artedidraconidae, Bathydraconidae, Channichthyidae), 17 genera and 25 species. Nototheniidae was the most speciose family, including benthic species (Trematomus spp.) and the pelagic species Pleuragramma antarctica, which was occasionally recorded in dense shoals. Bathydraconids ranked second with six species, followed by artedidraconids and channichthyids, both with five species. Most abundant species were Trematomus scotti and T. lepidorhinus among nototheniids, and Dolloidraco longedorsalis and Pagetopsis maculatus among artedidraconids and channichthyids, respectively. Both T. lepidorhinus and P. maculatus preferred seabed habitats characterized by biogenous debris and rich epibenthic fauna, whereas T. scotti and D. longedorsalis were frequently seen resting on fine sediments and scattered gravel. Several fish species were recorded to make use of the three-dimensional structure formed by epibenthic foundation species, like sponges, for perching or hiding inside. Nesting behavior was observed, frequently in association with dropstones, in species from various families, including Channichthyidae (Chaenodraco wilsoni and Pagetopsis macropterus) and Bathydraconidae (Cygnodraco mawsoni).

Sea-ice properties and nutrient concentration as drivers of the taxonomic and trophic structure of high-Arctic protist and metazoan communities

Abstract: In the Arctic Ocean, sea-ice decline will significantly change the structure of biological communities. At the same time, changing nutrient dynamics can have similarly strong and potentially interacting effects. To investigate the response of the taxonomic and trophic structure of planktonic and ice-associated communities to varying sea-ice properties and nutrient concentrations, we analysed four different communities sampled in the Eurasian Basin in summer 2012: (1) protists and (2) metazoans from the under-ice habitat, and (3) protists and (4) metazoans from the epipelagic habitat. The taxonomic composition of protist communities was characterised with 18S meta-barcoding. The taxonomic composition of metazoan communities was determined based on morphology. The analysis of environmental parameters identified (i) a ‘shelf-influenced’ regime with melting sea ice, high-silicate concentrations and low NOx (nitrate + nitrite) concentrations; (ii) a ‘Polar’ regime with low silicate concentrations and low NOx concentrations; and (iii) an ‘Atlantic’ regime with low silicate concentrations and high NOx concentrations. Multivariate analyses of combined bio-environmental datasets showed that taxonomic community structure primarily responded to the variability of sea-ice properties and hydrography across all four communities. Trophic community structure, however, responded significantly to NOx concentrations. In three of the four communities, the most heterotrophic trophic group significantly dominated in the NOx-poor shelf-influenced and Polar regimes compared to the NOx-rich Atlantic regime. The more heterotrophic, NOx-poor regimes were associated with lower productivity and carbon export than the NOx-rich Atlantic regime. For modelling future Arctic ecosystems, it is important to consider that taxonomic diversity can respond to different drivers than trophic diversity.

Temperature effects on photosynthetic performance of Antarctic lichen Dermatocarpon polyphyllizum : a chlorophyll fluorescence study

Abstract: Chlorophyll fluorescence is an important indicator of a photosynthetic energy conversion in chloroplast photosystem II and responds sensitively to stress factors affecting photosynthesizing organisms. Three different methods were employed to identify the most sensitive fluorescence parameters responding to thallus temperature decrease within Antarctic lichen Dermatocarpon polyphyllizum: (1) Fast chlorophyll fluorescence transient (OJIP with parameters characterizing photosystem II functioning) (2) Slow Kautsky kinetics supplemented by saturation pulses (to evaluate quantum yield of photosynthetic processes in photosystem II, as well as maximum quantum PSII efficiency and non-photochemical and photochemical quenching), and (3) Linear cooling from + 22 to − 40 °C (to determine change in ΦPSII and the critical temperature for PSII). A K-step (usually documented at highly stressed organisms) was found in OJIPs measured at + 22 °C at 0.22–0.40 ms and attributed to the negative effect of high temperature on PSII functioning, PSII donor side limitation in particular. At subzero temperature (− 0.5, − 5 °C), an L-step was detected at 0.05 ms and related to a low temperature-induced decrease in connectivity between light-harvesting complexes and PSII. An increase of DI0/RC (the flux of dissipated excitation energy) was reported for the first time in lichens. The OJIP-derived parameters, DI0/RC and Phi_D0 (quantum yield of energy dissipation) in particular, indicated that they might be used for the detection of early events in low temperature-affected lichens. Linear cooling data determined the critical temperature (− 12 °C) for primary photosynthetic processes (ΦPSII) in Dermatocarpon.

An analysis of maximum body size and designation of size categories for notothenioid fishes

Abstract: There has been no comprehensive study of body size in notothenioid fishes. Therefore I evaluated maximum total length (TL) as an axis of the evolutionary radiation. Lengths are provided for 141 species that collectively range in maximum adult size from 5.7 cm (Harpagifer nybelini) to 225 cm (Dissostichus eleginoides), a 39-fold difference. For the 138 species analyzed, the mean length is 33.5 cm and the median is 26.6 cm. Based on 10 cm-bins, notothenioids are apportioned into small ( 200 cm) size categories. The 20–29 cm bin contains the most species (32%). Most species (71%) are of medium size, 21% of species are medium-large, and 7% and ≈ 1% are small and large, respectively. The median lengths vary among the five cryonotothenioid families as well as among eight clades (genera and families). Among families, median and mean lengths are smallest in the Harpagiferidae and largest in Channichthyidae. Among clades, Harpagifer has the smallest median length (8.3 cm) followed by Artedidraco (12.5 cm). Several middle-sized clades do not differ in median size: Patagonotothen, Trematomus, Pogonophryne, and Bathydraconidae. Two clades of medium-large size species, Notothenia and Channichthyidae, are of similar size. A significant but weak positive relationship exists between maximum length and maximum depth. With the exception of miniature species ( ≤ 1 cm), the 126 species of cryonotothenioids (the Antarctic clade) encompass the range in size categories in actinopterygians in general, and the disparity in maximum lengths among individual species indicates that body size is an axis of the radiation. I discuss the size of notothenioids relative to other teleosts, the ecological implications of large species in the food web, and the similarity of the cryonotothenioid axes of diversification to those of Lake Baikal sculpins.

Hiding in the background : community-level patterns in invertebrate herbivory across the tundra biome

Abstract: Invertebrate herbivores depend on external temperature for growth and metabolism. Continued warming in tundra ecosystems is proposed to result in increased invertebrate herbivory. However, empirica ...

Life cycle and phenology of an Antarctic invader: the flightless chironomid midge, Eretmoptera murphyi.

Abstract: Knowledge of the life cycles of non-native species in Antarctica is key to understanding their ability to establish and spread to new regions. Through laboratory studies and field observations on Signy Island (South Orkney Islands, maritime Antarctic), we detail the life stages and phenology of Eretmoptera murphyi (Schaeffer 1914), a brachypterous chironomid midge introduced to Signy in the 1960s from sub-Antarctic South Georgia where it is endemic. We confirm that the species is parthenogenetic and suggest that this enables E. murphyi to have an adult emergence period that extends across the entire maritime Antarctic summer season, unlike its sexually reproducing sister species Belgica antarctica which is itself endemic to the Antarctic Peninsula and South Shetland Islands. We report details of previously undescribed life stages, including verification of four larval instars, pupal development, egg gestation and development, reproductive viability and discuss potential environmental cues for transitioning between these developmental stages. Whilst reproductive success is limited to an extent by high mortality at eclosion, failure to oviposit and low egg-hatching rate, the population is still able to potentially double in size with every life cycle.

Mass mortality event of White Sea sponges as the result of high temperature in summer 2018

Abstract: Although Arctic communities are very sensitive to global warming, direct evidence of the effects of high temperature on bottom communities is quite rare. We observed a mass mortality event (MME) of sponges by SCUBA diving in July and August 2018 along the coasts of Kandalaksha Bay, White Sea, and sub-Arctic. This event severely affected sponges from hard-substratum communities in particular, the demosponges Isodyctia palmata and Halichondria sitiens. Constant and exceptionally high temperatures throughout the water column (average temperature differences of 6.5 °C in July and 5.6 °C in August 2018, relative to the average temperatures in previous years at a depth of 20 m) may have led to an environmental context favorable to the MME. As was observed for the thermal anomaly, mortality was limited at the depth below a thermocline. However, it is not possible to ascertain whether temperature had a direct effect on organisms or whether it acted in synergy with a latent and/or waterborne agent. However, viewed in the context of global warming, there is an urgent need to rapidly set up monitoring programs of physical–chemical parameters and vulnerable populations in benthic communities through the Arctic Basin.

Characterization of the lipid profile of Antarctic brown seaweeds and their endophytic fungi by gas chromatography–mass spectrometry (GC–MS)

Abstract: The marine environment supports vast habitats with prodigious biodiversity comprising the largest source of unique bioactive compounds biosynthesized by macro and microorganisms, including seaweeds and their associated fungi. In this context, the interest in studying and characterizing marine natural products has increased in the last years. Among these metabolites, lipids and their derivatives play an important role in the metabolism of marine organisms and are sources of substances with therapeutic properties and biotechnological purposes. In this research, it was investigated the lipid amount present in the algae species Ascoseira mirabilis, Adenocystis utricularis, Desmarestia anceps, Phaeurus antarcticus and in their associated endophytic fungi Aspergillus flavus, Penicillium echinulatum, Microascus croci and Penicillium purpurogenum, respectively. This study was achieved by gas chromatography–mass spectrometry, using a standard methodology to analyze all of the components present in the eight organisms. Fatty acids (FAs) and sterols are among the lipids of the highest concentration in the studied algae and fungi. In general, phytol and fucosterol were the most abundant metabolites in all seaweed, while in endophytic fungi, the FAs (palmitic, linoleic, oleic and stearic acid) and ergosterol appeared in major concentrations. This work contributes to new chemical information on the underexploited biodiversity of macroalgae and endophytic fungi belonging to the Antarctic Peninsula and, furthermore, to increase the possibilities for the discovery of bioactive substances and apply it on biotechnological approaches.

Cross-shelf structure and distribution of mesozooplankton communities in the East-Siberian Sea and the adjacent Arctic Ocean

Abstract: The East-Siberian Sea (ESS) plays a significant role in circulation of surface water and biological production in the Arctic, yet due to its remote location and historically difficult sampling conditions remains the most understudied of all Arctic shelf seas, with even baseline information on biological communities absent in literature. We aim to fill this gap by describing the distribution and community structure of mesozooplankton in the ESS and the adjacent Arctic Ocean based on recent (September 2009, 2015) as well as historical (August–September 1946, 1948) observations. We found that the overall biomass and abundance during our studies were significantly lower than in the adjacent Chukchi Sea, but higher than historical estimates from the ESS, around 25–35 mg DW m−3. The diversity was low and characteristic for other Arctic shelf seas, with increasing number of species in deeper waters. Biomass was highest at the shelf break, where it approached 70 mg DW m−3, and was mainly composed of the large copepod Calanus glacialis. On the shelf, abundance and biomass were low (10–20 mg DW m−3) and was dominated by small copepods and chaetognaths. Several distinct assemblages of zooplankton were identified and related to the physical properties of the water masses present. A striking result was the presence of both Atlantic and Pacific expatriates in offshore waters close to the shelf break, but generally not on the shelf itself. Tracking these advected organisms could be a useful tool in determining the pathways, extent, and transit time of Atlantic and Pacific water entering the Arctic.

Tourism and stress hormone measures in Gentoo Penguins on the Antarctic Peninsula

Abstract: The impacts of tourism on wildlife have long been a concern in areas where ecotourism is a major industry. The issue is especially pressing in Antarctica, which has a rapidly growing tourism industry largely concentrated around penguin colonies on the Antarctic Peninsula. Guidelines developed by both the Committee for Environmental Protection and the International Association of Antarctica Tour Operators include measures to minimize wildlife impacts. In this study, we examined the relationship between physiologic stress in Gentoo Penguins (Pygoscelis papua) and tourism. Corticosterone is an adrenal glucocorticoid that has been shown in previous studies to increase in response to stressors such as low food availability, environmental conditions, as well as human visitation and proximity. Fecal glucocorticoids (FGM; primarily corticosterone and metabolites) were measured in Gentoo Penguin guano collected at 19 breeding colonies (n = 108, 3–10 samples per site) on the Antarctic Peninsula and the South Shetland Islands, representing a wide range of tourism visitation. We found a large degree of variation in FGM concentrations, and no relationship between FGM concentrations and number of tourists landed at that site. These results suggest that current tourism management guidelines on the Antarctic Peninsula are effective at preventing increased stress in Gentoo Penguins as measured by hormonal markers, and demonstrate the use of guano as a non-invasive, low-impact methodology for monitoring Gentoo Penguin stress.

Mitogenomic data to study the taxonomy of Antarctic springtail species (Hexapoda: Collembola) and their adaptation to extreme environments

Abstract: Mitochondrial DNA (mtDNA) encodes for proteins mainly involved in the oxidative phosphorylation process, and due to its molecular features, it is one of the most used molecular markers for phylogenetic and taxonomic purposes. Since mitochondria are the primary source of energy for aerobic organisms, it has been suggested that modifications of the mitochondrial genome’s features could be linked with major adaptive processes to particular environmental conditions. In this respect, Antarctic Collembola (springtails) may be considered an interesting model to study whether positive selective pressure has occurred, inducing significant changes in the mtDNA characteristics that have eventually led to cold adaptation. In this study, we describe the molecular features of the mitochondrial genome of Cryptopygus terranovus, a springtail species endemic to Victoria Land. Molecular data are also employed to support the new taxonomic placement of C. terranovus, and to establish if the conspecific lineages of Friesea antarctica, that lives in separated biogeographical regions of the Antarctic Continent, are indeed distinct species. Finally, all the mitochondrial genomes of springtails, so far sequenced, were applied for calculating the ratio (ω) of nonsynonymous versus synonymous nucleotide substitutions. This approach allowed us to investigate if Antarctic collembolans could have experienced Darwinian selective pressures compared to the non-Antarctic springtail species. Indeed, our data does indicate positive selection (ω > 1), suggesting that survival at extreme environmental conditions could be also related to mtDNA modifications.

Phytoplankton composition and bloom formation in unexplored nearshore waters of the western Antarctic Peninsula

Abstract: Fil: Mascioni, Martina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Division Ficologia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata; Argentina

High Arctic Mytilus spp.: occurrence, distribution and history of dispersal

Abstract: Many marine species are known to change their distribution in response to changing climatic conditions. One such example is the blue mussel Mytilus spp., spreading northward coincident with an increase in ocean temperatures. On Svalbard, the first living specimens of Mytilus spp. were discovered in 2004. Here we present an analysis of the current distribution of Mytilus spp. on Svalbard, with a focus on the west coast of Spitsbergen where strong Atlantification has been documented over the last few decades. We conducted diver-based surveys to develop a distributional map and to compare the current distribution with that of the Holocene. Furthermore, we investigate the recent history of recruitment of mussels on Svalbard to help identify invasion pathways. Our results show that blue mussels have been present on the archipelago at least since 2000 and are widespread along the west coast today. We also present evidence of local reproduction in one of the sites explored.

Biochemical composition and energy content of size-fractionated zooplankton east of the Kerguelen Islands

Abstract: Food quality is recognized as a key parameter of food web functioning in which zooplankton plays a crucial role not only in linking lower to upper trophic levels but also in transforming the quality of the organic matter available to predators. The influence of size and taxonomic group composition of zooplankton in these processes was assessed in eastern Kerguelen waters (Southern Ocean) at the onset of the spring bloom in 2011. Biochemical (lipids, proteins and carbohydrates) and elemental (carbon and nitrogen) composition were measured in five size—fractions of bulk zooplankton ranging from 80 µm to > 2000 µm and in large copepods, euphausiids, annelids and salps, and energy content was derived from biochemical contents. Proteins were the dominant component of zooplankton dry weight (21.5% dw), followed by lipids (8.9% dw), soluble carbohydrates (2.2% dw) and insoluble carbohydrates (1.0% dw). A concentration increase with zooplankton size for all biochemical components was observed, particularly stronger for proteins and lipids. Copepods and salps provided, respectively, the highest and the lowest amount of lipids and energy. A four-fold increase in energy content was observed from the smallest to the largest fraction inducing a significant increase (> 10 kJ g−1 dw) in the quality of zooplankton matter. This may explain why large zooplankton represent a major food resource for numerous fish, seabirds and marine mammals in the Southern Ocean. Such unique results are required to better quantify energy dynamics in polar food webs.

Seasonal and diel differences in dive and haul-out behavior of adult and subadult ringed seals (Pusa hispida) in the Bering and Chukchi seas

Abstract: Changing environmental conditions in the Pacific Arctic are expected to affect ice-adapted marine food webs. As such, understanding ringed seal (Pusa hispida) dive and haul-out behavior is vital to understanding if and how these environmental changes affect seal foraging behavior. Working with Alaska Native subsistence hunters, we tagged 14 adult and 20 subadult ringed seals with satellite-linked data recorders in Kotzebue Sound, Alaska, during late-September and October 2007–2009. Information about dive and haul-out behavior in the Bering and Chukchi seas was collected for 12–297 days. We analyzed indices of dive depth, duration, and rate, and haul-out probability using a model selection framework for adults during fall (late-September–November) and winter (December–March) and for subadults during fall, winter, and also spring (April–June). We found differences by season and time of day, but not by sex. Where subadults and adults occurred together, they dove to similar depths; although subadults were commonly located in deeper waters where they generally dove deeper than adults. Both age classes dove longer during winter and subadults tended to make a few more (~3.5) dives per hour than adults. Both age classes hauled out less and dove deeper, longer, and more frequently during midday than at other times of day. We suspect that seals dive deeper during midday because their prey migrates deeper. Dive and haul-out behaviors of ringed seals are influenced by a combination of factors, including prey distribution and abundance, sea ice, and seal diving physiology.

New records of invasive mammals from the sub-Antarctic Cape Horn Archipelago

Abstract: The southernmost archipelago of the Americas is dominated by invasive mammals that outnumber their native counterparts. Despite the relatively low ability of most invasive mammals to cross cold sea water channels, invaders are apparently colonizing new islands. Our objective was to provide an assessment of the expansion of invasive mammals within these sub-Antarctic ecosystems, determine whether human-mediated movement of invasive species is a plausible dispersal mechanism, and identify areas likely to be colonized in the near future. We report a decade of fieldwork (2006–2017) in 44 sites on 13 islands within the Cape Horn Biosphere Reserve including opportunistic and systematic camera trapping, carnivore diet, questionnaires, small mammal trapping, and walks/transects. We found new records of invasive mammals on seven islands, particularly for American mink (Neovison vison) and American beaver (Castor canadensis). Interviews with fishermen showed that mink, dogs (Canis familiaris), and small rodents are likely passengers in vessels. Finally, species distribution models revealed that the putative invasive-free Cape Horn National Park (55°S) is suitable for several invasive species, suggesting a high risk of invasion if species are introduced. We conclude that it is urgent to implement barriers to dispersal to prevent further invasion. In the case of dogs and cats (Felis catus), the first step should be control actions that target pet owners. Finally, we highlight the need of systematic, long-term biodiversity monitoring and citizen science in the Cape Horn Archipelago and common conservation guidelines for the terrestrial sub-Antarctic ecosystems.

Habitat preferences of Adélie Pygoscelis adeliae and Chinstrap Penguins Pygoscelis antarctica during pre-moult in the Weddell Sea (Southern Ocean)

Abstract: In order to understand and mitigate for the potential impacts of anthropogenic disturbance on marine predators, it is fundamental to gain insight into the drivers behind the temporal variation in their current distribution. With this in mind, we used platform terminal transmitter devices to track Adelie Pygoscelis adeliae and Chinstrap Penguins Pygoscelis antarctica breeding on the South Orkney Islands during the pre-moult phase of their annual cycles. We show that Adelie Penguins have an affinity to forage near and moult on sea-ice, and that Chinstraps remain over the shallower shelf waters during pre-moult, and return to the colony to moult. However, habitat models developed to predict the preferred foraging habitats of penguins during pre-moult had low predictive power. This indicates that predictive models may be insufficient to understand the distribution and foraging behaviour of penguins during certain stages of the life-cycle, and that collecting empirical data from individual colonies or archipelagos is vital if we are to understand the potential implications of future climate warming, or indeed the overlap with potentially competing fisheries.

The importance of long-term surveys on species introductions in Maritime Antarctica: first detection of Ceratophysella succinea (Collembola: Hypogastruridae)

Abstract: Biological invasions are one of the major threats to Antarctic native biodiversity and to ecosystems integrity. Regional environmental change and increasing human activity in Maritime Antarctica facilitates the introduction, establishment and colonisation of an increasing number of non-indigenous species. Systematic monitoring is an essential tool for the early detection of the arrival of non-indigenous arthropods. In this study, we compiled the results of a long-term monitoring effort from 2011 to 2017 to survey non-native collembolan species on Deception Island, a highly visited terrestrial site in South Shetland Islands (Maritime Antarctica). Results include the first record of Ceratophysella succinea (Gisin) (Hypogastruridae) in Antarctica. Moreover, the global dataset indicates that the total number and the list of cumulatively occurrence localities for non-native species observed on the island has increased over this monitoring period. This suggests that repeated monitoring is advisable to characterise the full extent of microarthropod introductions into a high biosecurity risk area and improve the effectiveness of surveillance efforts.