Antarctic Thresholds - Ecosystem Resilience and Adaptation (AnT-ERA)
for more information see News
21 August 2016
23 - 26 August 2016
XXXIV SCAR OSC, Malaysia
26 - 31 March 2017
10 - 14 July 2017
XIIth SCAR Biology Symposium
15 - 27 June 2018
SCAR & IASC Conference, Davos
last update: 14 June 2016. New contributions are always welcome!
antFOCE is a new experiment which manipulated pH in situ to examine the effects of predicted ocean acidification on Antarctic benthic communities under ice. /more...
The Antarctic Environments Portal provides science-based information on the Vulnerability of Southern Ocean biota for stakeholders. /more...
Glacier derived particles can affect the trophic physiology of Antarctic krill and cause local mass mortalities. /more...
A special issue of Polar Biology has been published, based on findings of a Polarstern expedition to the tip of the Antarctic Peninsula. /more...
...of marine mammals and birds to reveal ecological hotspots in the Southern Ocean. /more...
Exploring the ecology of the western flank of the Filchner Trough in the southern Weddell Sea: Polarstern expedition PS96. /more...
Related to the Paris aggreement of the COP21 (UN climate conference) we carry out an OPINION SURVEY on the future of Antarctic biological research (survey finished 15 May 2016). Please participate in the survey (only 5 minutes needed). Results will be discussed during our mini-workshop at the Open Science Conference with the background of ideas developed during the Barcelona workshop.
After the Paris aggreement of the COP21 (UN climate conference) one mission for scientists seems to be accomplished, to evidence the impact of climate change on our bioshpere. We would like to discuss with you consequences for biological research in the Antarctic.
21 Aug, 16:00-19:30, IPS building, Anggerik room: 70 seats, University of Malaya. /more...
Events with major contributions from AnT-ERA are:
MS2: Environmental drivers
S24: Physiological adaptation
S26: Effects of sea-ice changes
S27: Impacts of environmental changes
For full session descriptions click here.
CONTRIBUTIONS ARE WELCOME
until 29 February!
The project PELAGIC and the James Clark Ross expedition to South Orkney Islands, Jan. - Feb. 2016. /more...
Seal-borne cameras and ROV footage document dense aggregations of invertebrates underneath the Riiser-Larsen Ice Shelf (Weddell Sea). /more...
Studying the effect of warming oceans and glacier melting on Antarctic plankton at Carlini Station, Potter Cove, King George/25 de Mayo Island. /more...
Climate-relevant research, under the umbrella of SCAR, was well represented at the UN climate conference in Paris. /more...
New results and ideas compiled in an opinion paper by L.S. Peck decipher mechanisms that slow physiological processes of polar organisms to an unexpected extend. /more...
Multidiscilplinary time-series reveal sensitivity of a polar marine ecosystems to environmental changes: A successfull example from the Arctic. /more...
AnT-ERA congratulates Graham for having awarded the honour of being the first Emeritus Life Fellow of the Sir Alister Hards Foundation for Ocean Science. /more...
23 articles have been published by Hydrobiologia. They represent 30 years of research of the Italian Antarctic National Research Program with international partners. /more...
Monika Kędra is the new AnT-ERA - IASC liaison officer. We look forward for an intensified Arctic - Antarctic cooperation in studies of biological processes and related research issues. /more...
New maps predict the habitat of shallow Antarctic invertebrate communities, based on estimated sea-ice dynamics, light regimes, and bathymetry. /more...
38 scientists from 14 countries met in September 2015 in Barcelona, Spain, to discuss improvements in interdisciplinary Antarctic and Southern Ocean research. /more...
The new Chilean "IDEAL" Reserach Centre will play a major role in studying ecosystem-levels impact on Antarctic and Subantarctic ecosystem. Headquaters will open in 2016. /more...
The Rauschert-Arntz field guide on Southern Ocean invertebrates is now available. It comprises 80 colour plates on individual taxa. /more...
Paul Dayton's visionary studies from the early 1960s, in combination with recent observations, provide invaluable insights into marine ecosystem functioning. /more...
Prof. Dr. Bruno David became the new president of the National Museum of Natural History in Paris, France. /more...
Knowledge on the physiology of productive Antarctic macroalgae is fundamental to predict the adaptability of coastal system to global change. /more...
Introducing Antarctic hairgrass DaCBF7 gene to rice plants resulted in increased tolerance of the rice plant to low-temperature stress. /more...
Potter Cove (King George Island, South Shetland Islands) a bay-scale showcase for Antarctic coastal change. /more...
The SCAR initiatives AnT-ERA, AntClim21, ACCE and other institutions compared areal coverage of climate stressors, quantified multiply affected areas and complied imapcts on SO fauna and flora. /more...
Studies on environmental correlations with the dive behaviour of Southern elephant seals suggest regional differences in likely impacts associated with climate change. /more...
The spatially-explicit and individual-based simulation model SIMBAA was developed to analyse the response of benthic diversity to iceberg scouring. It is now available at the data repository PANGAEA. /more...
The understanding and valuing of Antarctic terrestrial ecosystems is the key for the protection of highly fragile vegetation in cold desert environments. /more...
How will the cold-adapted Antarctic fishes respond to a warming Southern Ocean? Sequencing the genome of the Antarctic Bullhead notothen provides clues to the future adaptability of Antarctic fishes. /more...
The collapse of the Larsen A and B Ice Shelves more than a decade ago, enabled primary production over hundreds of km² triggering the arrival of fresh organic matter and biogenic silica to the sea floor. /more...
Seafloor communities in fjords along the Antarctic Peninsula are unexpectedly rich in biomass and species, and maybe very sensitive to rapid regional warming. /more...
The Antarctic Climate and the Environment (ACCE) report is the most comprehensive compilation of knowledge on climate and the Antarctic including its ecosystems. /more...
The "1st SCAR Antarctic and Southern Ocean Science Horizon Scan" identified 80 high priority science questions from all disciplines for the next two decades and beyond. /more...
The CAML / SCARMarBIN Biogeographic Atlas of the Southern Ocean shows maps of the distribution of more than 9000 species, complemented by environmental information and show cases. Available at: www.amazon.co.uk/gp/product/0948277289. /more...
Satellite tracking data show how Grey-headed albatrosses try to adapt their behaviour, when searching for food, when come across warm conditions: are they successful and able to survive in the future? /more...
An interdisciplinary team of ecologists discovers a unique and rare fauna under the collapsed iceshelves and follow unexpected ecosystem dynamics. /more...
By: Jonathan Stark, Australian Antarctic Division
antFOCE is a new experiment which manipulated pH in situ to examine the effects of predicted ocean acidification on Antarctic benthic communities under ice.
Polar waters are susceptible to the effects of ocean acidification due to their naturally low carbonate concentration, higher CO2 solubility and low buffering capacity. Polar pH is changing at twice the rate of tropical waters. Thus the poles serve as both a bellwether of climate change and example of the ecosystem-level consequences that we can expect elsewhere. The predicted consequences of ocean acidification for marine plants and animals, food security and human health are profound. Based on current emissions trajectories, pH in the Southern Ocean will drop to 7.8 by 2100, lower than at any point in the last 20 million years. There is a critical need for information on impacts at the community-ecosystem level and in benthic ecosystems. The Australian Antarctic Division (AAD) performed the first in situ Antarctic seafloor CO2 enrichment experiment (antFOCE) to determine the likely impacts of ocean acidification on Southern Ocean benthic communities. Free Ocean CO2 Enrichment (FOCE) systems were developed by the Monterey Bay Aquarium Research Institute (MBARI) to allow controlled pH treatments in field experiments in natural communities, without isolating the study area from natural inputs. They have been run in locations around the world and this was the first polar FOCE. Our project aims to determine the likely benthic community compositional changes, functional changes and vulnerability of natural polar benthic communities to high CO2/low pH conditions. What level of resilience do natural polar benthic communities have to ocean acidification? Are there tipping points or effects on food webs?
A team of 15 people deployed and ran the antFOCE experiment at Casey in late 2014/early 2015. Land-based infrastructure (power generator, pumps, sensor system, seawater CO2 enrichment; Fig. 1, for part of the equipment also see cover photograph) was installed in a small bay above the intertidal zone adjacent to the underwater site. Divers deployed the underwater infrastructure (Fig. 2): electronics, thruster tubes, mixing ducts (40m long per chamber) and 4 experimental chambers: 2 acidified and 2 control. The polycarbonate chambers were 2m long x 0.5 wide x 0.5 high. The experiment ran for 9 weeks, to late February 2015. The system functioned well, maintaining a 0.4 pH offset in the treatment chambers. A variety of samples were taken at the end from each chamber and in 2 open plots (without chambers), including: bacterial/microbial, meiofaunal, microphytobenthos, and macrofaunal communities, as well as sediment for biogeochemistry. Samples are still being analysed, but preliminary results indicate changes in a range of communities due to acidification including biofilms (pro- and eukaryotes), macrofauna and in benthic diatoms, as indicated by differences in pigments in the sediment. These indicate there may potentially be changes in all other components of the ecosystem. The project is a collaboration between researchers from the AAD, MBARI, Plymouth Marine Laboratory and CSIRO and was funded by the ARC Antarctic Gateway Partnership, an ARC LIEF grant and the AAD.
By Julian Gutt, 14 June 2016
The Antarctic Environments Portal provides science-based information on the vulnerability of Southern Ocean biota for stakeholders.
The aim of the Antarctic Environments Portal (AEP) is to link Antarctic science and policy. It provides science-based information to the Antarctic Treaty System's Committee for Environmental Protection (CEP) and recommendations to the Antarctic Treaty Consultative Parties on environmental protection. Members of the AnT-ERA steering committee and additional experts in Southern Ocean ecology published a web-article on the Vulnerability of Southern Ocean biota to climate change. The scientific information is provided in a popular science style to attract the attention of non-scientists. This article as all such AEP-publications clustered into Information Summaries and Emerging Issues is based on published, peer-reviewed science and has been through an editorial review process.
By Irene R. Schloss, Gastón Alurralde and Verónica Fuentes, 14 June 2016
Glacier derived particles can affect the trophic physiology of Antarctic krill and cause local mass mortalities.
Glaciers around coastal Antarctica are melting at a rapid pace; meltwater entering coastal marine systems carries not only large amounts of freshwater, but also inorganic particles. This phenomenon has intensified in the last decades affecting especially in coastal areas in summer, when the concentration of particles sharply increases. These particles have been shown to affect zooplankton in many glacially influenced areas throughout the world. Recently a negative effect of particles has been also detected in the Antarctic krill, something unexpected for a species considered mainly oceanic, and of great relevance in the Antarctic ecosystem.
A study conducted in Potter Cove, in the vicinities of the Argentinian Station Carlini, showed that these particles together with a suite of environmental conditions, were related to large krill mortality and beach stranding events observed since 2002, in which more than 103 ind m-2 were counted (cover photo and Fig.1). In a recent published study (Fuentes et al. 2016, http://www.nature.com/articles/srep27234), authors show how glacier derived particles were the main content in the gut of stranded krill and affected the trophic physiology of krill (Fig. 2).
One may wonder if this is a common process in the Southern Ocean, or if it is something to be expected under current climate change scenario. The poor record of krill strandings in other Antarctic areas and the relatively low number of stranded animals would indicate that these are rare events. The number of strandings observed probably reflects only a small fraction of all the sediment-related krill mortality events, as most coastal areas in Antarctica are not monitored. However, the probability of detecting a stranding event depends on specific physical conditions that push the dead organisms onto the beaches. Most of these dead krill will eventually sink to the seafloor, thereby remaining undocumented. In addition, the delay between a stranding and its observation is also crucial for the quantification of dead animals. Not only will tides and waves wash the dead organisms out back to the sea, but also animals such as birds will profit from this easily available food source. The importance of these massive death events is of main relevance for the ecosystem. Krill may represent an important pathway for carbon export and be a major source of fresh organic matter for benthic system. On the other hand, these events might also have impacts on the population dynamic, considering that high densities of krill are a common feature close to coastal areas during summer. Krill is a key component in the Antarctic food web. On-going climate-induced glacier melting can impact the krill populations in coastal areas and consequently the coastal ecosystems in Antarctica which relies on krill.
Reference: Fuentes V, Alurralde G, Meyer B, Aguirre G, Canepa A, Wölfl AC, Hass HC, Williams GN, Schloss IR 2016. Glacial melting: an overlooked threat to Antarctic krill. Sci. Rep. 6, 27234; doi: 10.1038/srep27234.
by Julian Gutt, 27 April 2016
A special issue of Polar Biology 39 (5) has recently been published, based on findings of a Polarstern expedition to the tip of the Antarctic Peninsula.
The waters around the tip of the Antarctic Peninsula are characterized by steep natural environmental gradients, various benthic habitats, regionally high biological productivity and high species richness. This region of the Southern Ocean attracts attention from ecologists and stakeholders, because the development of atmospheric and oceanic climate change is faster than the global average over the past decades and the marine ecosystem is strongly affected by multiple stressors. Moreover, commercial fishing has disturbed the sea floor until it became prohibited in 1990, and whaling, sealing and exploitation of penguin and krill stocks modified the pelagic system in the 20th century. In austral summer 2013, this region was the study area of the cruise PS81 (ANT-XXIX/3) of the German research icebreaker Polarstern.
Within a multidisciplinary whole-ecosystem approach analyses of a number of working groups focussed on the overarching research question: How does the variability of various environmental factors impact biological patterns and processes? The study was developed to provide scientific information for addressing one of the key issues identified in the 1st SCAR Antarctic and Southern Ocean Horizon Scan as being of high priority for the next 20 years and beyond: How will threshold transitions vary over different spatial and temporal scales, and how will they impact ecosystemfunctioning under future environmental conditions? The project was also a major research contribution to AnT-ERA and its key questions: (1) How do species traits impact community stability, and key ecosystem processes? (2) What are the likely consequences of a changing environment for key ecosystem functions and services?
During the cruise also Antarctic krill was investigated in the framework of a regular survey programme of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). An article by Herr et al. on whale-krill interaction had been selected by the Springer publisher as a case study for a press release. Most of the scientific output of this project was discussed during a post-expedition workshop in September 2014 at the University of Burgundy in Dijon, France and CNRS.
The results have recently been published in the special issue of Polar Biology Vol. 39, Issue 5 by a total of 47 authors in 13 articles including an editorial under the title: High environmental variability and steep biological gradients in the waters off the northern Antarctic Peninsula: Polarstern expedition PS81 (ANT-XXIX/3). The volume was edited by Julian Gutt, Bruno David, and Enrique Isla. It comprises an overview of the environmental settings, whale stock assessment related to their environment including the Antarctic krill, benthic patterns and their drivers at various spatial and ecological scales, ecologically relevant sediment properties, and sponge, echinoderm, ascidian as well as amphipod biology. Results on the meiofauna are published elsewhere by F. Hauquier et al. and on an unusually shallow flat topped hill in the western Weddell Sea by B. Dorschel et al. The faunistic and environmental primary data collected during the PS81 cruise were uploaded to data repositories ANTABIF and PANGAEA.
Reprints available on request from Julian Gutt or any other author.
by Marc Hindell, Yan Ropert-Coudert, Anton P. Van de Putte, and Horst Bornemann, 27 April 2016
...of marine mammals and birds to reveal ecological hotspots in the Southern Ocean
A recent meeting at the Hanse-Wissenschaftskolleg in Delmenhorst, Germany, brought together a team of scientists specialising in tracking of Antarctic marine mammals and birds. The Southern Ocean is a remote, hostile environment where conducing marine biology is challenging, so we know relatively little about this important region, which is critical as a habitat for breeding and foraging of many marine endotherms. But this team use animals to help them find Areas of Ecological Significance – or biological hotspots in the Southern Ocean.
Scientists from around the world have been tracking seals, penguins, whales and albatrosses for more than two decades to learn how they spend their time at sea. In the Retrospective Analysis of Antarctic Tracking Data (RAATD), this team has brought together tracking data from 38 biologists from 11 different countries to accumulate the largest animal tracking database in the world, containing information from 15 species, containing over 3,400 individual animals and almost 2.5 million at-sea locations.
RAATD is an initiative of the Expert Group on Birds and Marine Mammals (EGBAMM) within the Scientific Committee on Antarctic Research (SCAR). Analysing a dataset of this size brings its own challenges and the team is developing new and innovative statistical approaches to integrate these complex data. The meeting in Delmenhorst enabled the RAATD team to complete the daunting task of compiling and checking this enormous dataset, and to develop and run the statistical models that will lead to the identification of the hotspots. When complete RAATD will provide a greater understanding of fundamental ecosystem processes in the Southern Ocean, help predict the future of top predator distribution and help with spatial management planning.
by Enrique Isla, 27 April 2016
Exploring the ecology of the western flank of the Filchner Trough in the southern Weddell Sea: Polarstern expedition PS96
During the austral summer of 2015/2016 R/V Polarstern visited the southwestern Weddell Sea, under the frame of AnT-ERA and the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). Two projects formed the core of the research activities: Dynamics of the Antarctic Marine Shelf Ecosystems (DYNAMO) and Filchner-Ronne Outflow System Now (FROSN). The aim of this multidisciplinary expedition was to study, among other aspects of the system, the benthic ecosystem dwelling on the continental shelf at the West of the Filchner Trough.
The Filchner-Ronne outflow system plays an important role in the global climate regulation since here a super cooled water mass flowing from beneath the Filchner-Ronne ice shelf sinks beyond the continental shelf break boosting the global thermo-haline circulation. This global feature transports mass and energy across the world oceans from the poles to the equator and viceversa, with great impact on the Earth’s climate as heat flows to the poles and cool water to the Equator. Regarding biology, this region is of special interest because sea ice covers it for most of the year and in some years it persists throughout the summer into the next winter, in contrast to the eastern flank where usually a rather big polynya develops every year. Presumably, this meteorological difference among flanks may strongly determine the characteristics of the biological system including the abundance and composition of the benthic communities. Persistent sea ice also makes the western flank system different to the typical high latitude Antarctic conditions, where a phytoplankton bloom develops every summer in open water, delivering a rich pulse of fresh organic matter to the seabed.
Sea ice characteristics this summer were rather harsh; however, we could visit several stations on the western side where sediment, benthos and seabed image samples were recovered. Preliminary results showed that mainly silt and clay constitute the sea floor sediment in the western flank coexisting with rocks of more than 50 cm diameter; a typical feature of glacial erosion. In several spots, mainly at the western most extreme, rather sandy deposits were found hampering the collection of samples with the coring gears. Comparatively, the macrofauna observed on the sea floor was rather poor and less diverse than that found on the eastern side, particularly close to the ice shelf edge. Solitary, small sponges and mostly echinoderms (e.g., holothurians and ophiuroids) were found at the West, whereas numerous and larger sponges, gorgonians, echinoderms and ascidians were more common at the East.
Earlier attempts to visit the area failed (expedition PS 82) due to heavy sea ice conditions; thus, this expedition could be considered a big success that finally allowed completing a data set on the benthic environment at the southern Weddell Sea.
by José C. Xavier, 26 February 2016
Antarctic research expedition to South Orkney Islands – Jan.- Feb. 2016
Pelagic invertebrates play a key role in the Antarctic marine ecosystem and might be affected by climate change. Squid are among the few Antarctic fisheries with potential to be exploited whereas the Antarctic krill and fish already are. However, our understanding of the role of pelagic organisms in the Antarctic marine ecosystem is surprisingly poor and needs to be urgently addressed, as emphasized in the 1st Antarctic and Southern Ocean Science Horizon Scan initiative. Our project PELAGIC, of the University of Coimbra and British Antarctic Survey (BAS), is a novel multi-disciplinary and international project aiming to better understand the role of the pelagic squid, fish and Antarctic krill within the Antarctic marine food web around the South Orkneys Islands (Atlantic sector of the Southern Ocean). Organized by BAS, the research cruise of the RRS James Clarke Ross brought together about 20 scientists from the United Kingdom, Norway, USA, Canada, Germany, Lithuania and Portugal, to characterize the invertebrate pelagic fauna around the South Orkneys.
We used a variety of equipments (e.g. CTD, to collect data on the Conductivity, Temperature and Depth of the Ocean, GLIDER to assess distribution of marine organisms, Ecosounders to assess abundance of marine pelagic organisms) and scientific nets (RMT25, Rectangular Mid-water Trawl of 25m2 to catch fish and squid), RMT8, Rectangular Mid-water Trawl of 8 m2 to catch Antarctic krill, MAMOTH, Multi-net instrument to catch zooplankton) to catch Antarctic krill, fish and squid to obtain information about their distribution, abundance, habitat, diet, trophic level and toxicology (trace metals). Our group was particularly interested in collecting samples from marine organisms across the various trophic levels (from algae to top predators) to assess the levels of trace metals. As this research took place, a Norwegian fishing vessel in the area was also collecting data on Antarctic krill abundance and distribution. Moreover, top predators (Antarctic fur seals, gentoo and chinstrap penguins) were GPS tracked from the South Orkneys, to assess the feeding and foraging strategies of these different predators in relation to prey abundance.
The analyses of the data from these different sources will be analysed in the coming months/years. These data will be incorporated into food web models of the Southern Ocean that are being developed under SCAR AnT-ERA, ICED and SCAR-EGBAMM, relevant to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and the Commision for Environmental Protection of the Antarctic Treaty (CEP). Educational and science communication activities took place in collaboration with BAS and our educational project EDUCAÇÃO PROPOLAR (Portugal). Skype calls to schools (Portugal and Mozambique) and 2 blogs were produced for this cruise, which were received well (e.g. one of the blogs had > 2000 views in 3 weeks).
by Dominik Nachtsheim and Horst Bornemann, 26 February 2016
Sea-borne cameras and ROV footage document dense aggregations of invertebrates underneath the Riiser-Larsen Ice Shelf (Weddell Sea).
A joint seal and ROV (Remotely Operated Vehicle) research project was carried out at the Drescher Inlet (Riiser-Larsen Ice Shelf) in the eastern Weddell Sea during austral summer 2015/2016. The campaign was conducted via a temporary field camp located on the shelf ice. The fieldwork consisted primarily of the instrumentation of Weddell seals (Leptonychotes weddellii) with infrared still picture camera loggers (Little Leonardo) and the deployment of an ROV (Ocean Modules) through the fast ice of the inlet. The stimulus for this project emerged on the basis of results from an earlier expedition and ongoing collaboration of scientists of the Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (Germany) and the National Institute of Polar Research (Japan). Data obtained from seal-mounted cameras and 3D-multi-channel loggers in 2003/2004 documented that Weddell seals dived along the steep cliffs of the shelf ice and made foraging excursions under the ice shelf in the Drescher Inlet. The seal-borne images led to the discovery of an unknown community of marine invertebrates, being attached head-down to the underside of the floating ice shelf at depths of around 130-150 m. The term “hanging gardens” was coined to describe this particular under-shelf-ice fauna. The images taken at the times did not allow to assess the exact species composition as well as the horizontal extent of this community and thus called for a reassessment and further investigations.
During the recent campaign an ROV was deployed to provide high-resolution video recordings of the under-shelf-ice community. The footage showed dense aggregations of isopods (possibly Antarcturus spp.) at the cliff and underside of the floating ice shelf, and samples were taken for taxonomic and genetic analyses. The seal-borne images revealed the same aggregations of organisms under the ice shelf and thus confirmed our earlier findings. We believe that these “hanging gardens” represent an attractive food horizon where Weddell seals may benefit from the availability and abundance of prey.
This very first quantitative assessment of the under-shelf-ice fauna raises several questions: What is the geographic extent and species composition of the under-shelf-ice community in general? How stable or variable are these communities? Which role do these communities play in the high Antarctic food web and bentho-pelagic coupling processes? How does the increased melting rate and collapse of ice shelves induced by climate change affect or alter these communities? Approaches to answer these questions would open a so far unexplored field of Antarctic research.
Selected references: Naito Y, Bornemann H, Takahashi A, McIntyre T, Plötz J (2010) Fine-scale feeding behavior of Weddell seals revealed by a mandible accelerometer. Polar Science 4:309-316. Plötz J, Bornemann H, Knust R, Schröder A, Bester M (2001) Foraging behaviour of Weddell seals, and its ecological implications. Polar Biology 24: 901-909. Watanabe Y, Bornemann H, Liebsch N, Plötz J, Sato K, Naito Y, Miyazaki N (2006) Seal-mounted cameras detect invertebrate fauna on the underside of an Antarctic ice shelf. Marine Ecology Progress Series 309: 297-300.
by Irene R. Schloss, 26 February 2016
Studying the effct of warming oceans and glacier melting on Antarctic plankton.
The majestic glaciers in northern Antarctica are melting at a rate that is visible to the human eye. This is due to warming air temperatures that in certain regions of Antarctica –such as the Western Antarctic Peninsula- are augmenting more than anywhere else on the planet. While glacier melting adds to sea level rise, it also affects plankton, the mostly microscopic organisms leaving in the sea, which especially in coastal areas are seasonally and increasingly exposed to a fresher and warmer environment.
A study was conducted from December 2015 to February 2016 at the Argentinean Carlini Station, in the vicinities of Potter Cove, King George (25 de Mayo) Island, South Shetlands, Antarctica. A research team from Argentina and Canada (Fig. 1), collaborating with researchers from Spain, Germany, Belgium, The Netherlands and Sweden studied the combined effects of two stressors, glacier melting and increased temperature on plankton, from bacteria to zooplankton.
An automatically controlled setup of 12 microcosms (Fig. 2), each containing 100 L of seawater, was used to simulate the combined effects of low salinity, as found close to melting glaciers and temperature warming, as expected for 2015, on coastal plankton. The evolution of the community was followed during about 10 days at different successional stages of the summer phytoplankton assemblage. To understand how plankton will respond to these stressors, we quantified damage and responses from the cellular-physiological to the community level. In addition, plankton dynamics was simultaneously studied in the natural environment (Fig. 3) together with the physical and chemical characteristics of the water column in Potter Cove.
Plankton are at the base of the Antarctic food web. By gaining new insights on how they will respond to these global warming-related processes, we should be able to predict how changes in plankton dynamics might affect the whole Antarctic ecosystem.
The project benefited from the financial support of the Agencia Nacional de Promoción Científica y Tecnológica from Argentina. Support for this project also came from the Natural Sciences and Engineering Research Council of Canada (Varela). Other co-PIs: Gustavo Ferreyra (Can.), Gastón Almandoz (Arg.) and Verónica Fuentes (Spa.).
For further information please contact Irene R. Schloss, Instituto Antártico Argentino and CONICET (Argentina) and Intitut des sciences de la mer de Rimouski (Quebec, Canada).
by Julian Gutt, 7 December 2015
Climate-relevant research, under the umbrella of SCAR, was well presented at the UN climate conference in Paris. Presentations on glaciological and biological topics contributed to an important knowledge transfer between scientists, stakeholders and, importantly, decision makers.
France chaired and hosted the 21st Conference of the Parties (COP21) of the United Nations Framework Convention on Climate Change (UNFCCC), from 30 November to 11 December 2015 (www.cop21.gouv.fr/en/). The UNFCCC was adopted in 1992 as a result of the UN Rio de Janeiro Earth Summit. It is a convention of principle, acknowledging the existence of anthropogenic (human-induced) climate change and giving industrialized countries the major part of the responsibility for combating it. It has the objective to “stabilize greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system”, with universal membership (196 parties), and a framework to report national greenhouse gas emission inventories, negociate specific protocols including greenhouse gas emission targets for individual countries. The COP21 was crucial because for the first time in over 20 years of UN negotiations, it was attempted to achieve a legally binding agreement on climate, with the aim of keeping global warming below 2°C. Besides the preparatory contributions of 186 countries, opening statements by 150 Heads of State and the official negotiations, the COP21 provided a huge "EXPO-style" market place for information and knowledge transfer related to climate change. The conference attracted close to 50,000 participants including 25,000 official delegates from governments, non- and inter-governmental organizations, UN agencies, media and civil societies. Topics for discussion included long-term consequences associated with different levels of future warming, in a context where the IPCC will have to select 2 or 3 topics for special reports ahead of the 6th assessment report. The Paris agreement asked for a special report on the impacts and trajectories associated with a1.5°C target.
At the "Antarctica Day", 1 December, SCAR organised, in cooperation with the International Cryosphere and Climate Initiative (ICCI) led by Svante Bodin, a side event on "View from Two Poles: Climate Lessons from the Arctic and Antarctic", chaired by Valérie Masson-Delmotte. Four talks by Ricarda Winkelmann, Jonathan Bamber, Jeremy Wilkinson and Frank Pattyn centred on Arctic sea-ice changes and on the instability of the Antarctic and Greenland ice sheets and resulting sea-level rise, which is the central theme of the SCAR/IASC/CliC-ISMASS expert group (Ice Sheet mass balance and sea level). A fifth presentation by Julian Gutt focused on shifts of benthic and pelagic systems, including top predators as a response to complex environmental changes. These results are part of the most recent update of the SCAR Antarctic Climate Change and the Environment (ACCE) Report to the Antarctic Treaty Consultative Meetings. The results were mainly based on an cross-disciplinary study with AnT-ERA and AntClim21 being the main SCAR contributors. All speakers also held a press conference, which provided a good opportunity for a number of additional interviews on Climate Change issues in the Southern Ocean and Antarctica. To view the recorded UNFCCC webcast of the press briefing click here. Julian Gutt was also invited to an additional event organized by the International Union for Conservation of Nature (IUCN) to talk about life in the Southern Ocean. One major message was to better implement results from climate impact projections into conservation strategies.
By chance in both sessions almost the same question was asked from the audience: What, besides evaluating the state of science is the role and engagement of scientists to reduce the emission of greenhouse gases? A condensed version of the answer is: We join this conference. Since we are scientists we do have only very limited opportunities to make corresponding decisions. However, we are here to inform decision makers and the public about our results and knowledge on the effects of climate change that are relevant for our life on Earth. Applying the best technologies for our research campaigns we can also contribute directly to reduce environmental damage.
By these contributions to the UNFCCC COP21, SCAR, including its biology program AnT-ERA and the expert group ISMASS, contributed to accomplish its mission "…expanding its advisory sphere of influence on global issues to other audiences..." (from the SCAR Strategic Plan 2011-2016).
by Lloyd S. Peck, 7 December 2015
New results and ideas compiled in an opinion paper in Trends in Ecology and Evolution decipher mechanisms that slow many physiological processes of polar organisms to an unexpected extend.
Temperature affects biological functions by altering reaction rates. Physiological rates increase with temperature and usually double to treble for every 10°C rise; with increases of between 1 and 4 times encompassing normal biological functions. In polar marine environments, however, where species permanently live at temperatures around 0°C many processes are slowed beyond the expected relationships relating them to warmer water species (the Arrhenius relationships). Growth, embryonic development, the duration of the increase in metabolic rate when animals are fed (the Specific Dynamic Action of feeding, SDA), and time to acclimate to altered temperature, are all five to twelve times slower in species living near 0°C than at 10°C. This cold marine physiological transition to slower states than expected is absent, however, in plots of oxygen consumption and the size of the rise in metabolism after feeding. In these relationships capacity is related to aerobic scope (the maximum ability to raise metabolic rates) which does not seem to be affected in the same way as development, growth and SDA duration. The figure (after Peck 2015) shows plots of relationships between development rate, growth rate, respiration rate and the duration of the rise in metabolism after feeding (SDA) and temperature. The plots are the standard physiological way of comparing a biological rate with temperature, called an Arrhenius plot, where the logarithm of the rate is plotted against the inverse of absolute temperature. In each case tropical and temperate species (black dots, each point represents a single species) fit the expected straight line relationship for effects of temperature on biological processes. Extensions of the line for temperate and tropical species (dotted line) show that for development, growth and SDA duration, Antarctic species (open circles) are markedly slower than expected for the effect of temperature (red circles), but for respiration rate Antarctic species are not significantly different from the extrapolated line (green circles).
All of the processes that are markedly slowed require significant increases in protein synthesis and/or modification. Proteins are made as a string of amino-acids, but for any protein to function properly it needs to fold into a 3 dimensional shape. It seems likely that problems with protein synthesis or folding are important in the slowing of rates of a wide range of physiological processes beyond the expected effects of temperature on biological systems.
Another piece of evidence that Antarctic marine species have problems making proteins is that they have higher levels of heat-shock proteins (HSP) in their tissues, and HSPs help with badly made proteins. An example of this is the giant amphipod crustacean Paraceradocus gibber in the cover photograph. Interestingly many of the species with high standing levels of HSPs lack the ability to raise concentrations when heated up, which all marine invertebrates at lower latitudes do, and this may be an evolutionary outcome of living at very stable temperatures for millions of years.
Original article: Peck LS online available. A cold limit to adaptation in the sea. Trends in Ecology and Evolution 31, http://dx.doi.org/10.1016/j.tree.2015.09.014
by Thomas Soltwedel, 07 December 2015
Multidisciplinary time-series research reveals sensitivity of polar marine ecosystems to environmental changes: A unique and successful example from the Arctic suited for polar comparison.
The warming of seawater is likely to produce radical changes in the marine Arctic. This is indicated by data from time-series observations at the LTER (Long-Term Ecological Research) observatory HAUSGARTEN in Fram Strait (http://www.awi.de/en/science/special-groups/deep-sea-research/observatories/lter-hausgarten.html#c35864), operated by scientists from the Alfred Wegener Institute (AWI). Their most important finding: even an episodic warm water and sea-ice anomaly (Fig. 1) in the Arctic Ocean would be sufficient to fundamentally impact marine communities from surface waters down to the deep seafloor. As the authors recently reported in the journal Ecological Indicators, that’s precisely what happened between 2005 and 2008.
Responses in the ecosystem were partly extreme and tackled local symbiotic communities, from the phyto- and zooplankton to the deep-sea benthos. Prior to the unexpected influx of warm water, diatoms made up roughly 70 per cent of the phytoplankton in the Fram Strait. During the warm phase, the flagellate algae Phaeocystis pouchetii took their place (Fig. 2). A change with consequences: Unlike diatoms, P. pouchetii tends to form floating colonies with hundreds of cells embedded in a polysaccharide gel matrix, sinking rapidly to the ocean floor where they become a food source for seafloor organisms.
The sudden rise in available food led to major changes in deep-sea life, including changes in bacterial community structure and a noticeable increase in the density of benthic organisms (Fig. 3 and 4). Since the flow of warm water has subsided, the water temperature in the Fram Strait has stabilised – though it is still slightly above the average value from before 2005. Yet some changes in the ecosystem have partly become lasting realities.
Although it cannot be concluded with absolute confidence that the warming of waters in the Fram Strait between 2005 and 2008 is part of a broad human-induced shift towards a warmer Arctic Ocean, the observed alterations due to this warm water pulse may be seen as a 'blueprint' for how the marine ecosystem might develop in an overall warming Arctic Ocean. It can serve as an example for similar studies in other ecosystems especially the Southern Ocean, which would provide an excellent opportunity for comparisons of ecosystem functioning.
Original publication: Soltwedel T, Bauerfeind E, Bergmann M, Bracher A, Budaeva N, Busch K, Cherkasheva A, Fahl K, Lalande C, Metfies K, Nöthig E-M, Meyer K, Quéric N-V, Schewe I, Wlodarska-Kowalczuk M, Klages M 2015. Natural variability or anthropogenically-induced variation? Insights from 15 years of multidisciplinary observations at the arctic marine LTER site HAUSGARTEN. Ecological Indicators, doi:10.1016/j.ecolind.2015.10.001.
by Julian Gutt, 29 October 2015
Dr. Graham Hosie, chair of the SCAR Standing Scientific Group of Life Sciences was recently awarded the honour of being the first, and so far only, Emeritus Life Fellow of the Sir Alister Hardy Foundation for Ocean Science.
The official reasons for this prestigious award is Graham Hosie's long-standing service to the Foundation and to Continuous Plankton Recorder work. Graham has been associated and collaborating with the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) for about 25 years, and became a trustee (governor) of the Foundations Council in 2006, and then a member of the Scientific Advisory Board in 2013. The ceremony took place on 30 September 2015 in Plymouth (UK) at the headquaters of the foundation.
SAHFOS is responsible for the longest running geographically extensive marine biological survey in the world. The plankton research helps to address pressing global issues such as pollution, climate change, biodiversity and overfishing; educate and alert the public, scientific community and increasingly industry and business on the pollution and status of our seas; inform and support commercial decisions and operations for food suppliers, fisheries, shipping and exploration; influence and shape fishing and environmental government policy at national, European and international levels and combat human health challenges. SAHFOS is greatly appreciated of all the shipping companies, the ships’ masters and the crews who assist with the Survey. Using the unique Continuous Plankton Recorder (CPR) survey, SAHFOS data archives are an irreplaceable resource and source of information for ocean science.
SAHFOS provided essential advice and support when Graham intitiated and developed the Southern Ocean CPR Survey (SO-CPR). SO-CPR has grown into the largest pelagic biological montoring programme in the Antarctic, and has helped other nations develop their own CPR surveys. SO-CPR has involved 16 vessels from 12 nations, and has produced a data set of more than 50,000 records for about 240 zooplankton and krill taxa. It’s one of the largest datasets held by SCAR‘s biodiversity.aq. The data were used in the production of the SCAR Biogeographic Atlas of the Southern Ocean.
by Stefano Schiaparelli, 29 October 2015
A total of 23 articles dedicated to the Ross Sea and surrounding areas have been published by the journal Hydrobiologia. The special issue has been assembled to celebrate the 30 years of research of the Italian National Antarctic Reserach Program in the Ross Sea and the cooperation with international partners.
The Italian research program, called PNRA (the acronym for the Italian version of National Antarctic Research Program: http://www.pnra.it) started its activity on the shores of Terra Nova Bay in the Ross Sea 30 years ago and the present volume is meant as a celebration of such continuous research activities. The volume appears exactly 15 years after the book ‘‘Ross Sea Ecology: Italiantartide Expeditions (1987–1995)’’ (Faranda et al. 2000), which celebrated the first 15 years of Italian research in Antarctica.
The special volume edited by Diego Fontaneto (Consiglio Nazionale delle Richerche, CNR) and Stefano Schiaparelli (Dipartimento di Scienze della Terra dell'Ambiente e della Vita, University of Genova and Museo Nazionale dell'Antartide) is structured in four groups of papers that (1) describe diversity in the sea and on land, demonstrating how Antarctica is, contrary to most common assumptions, biologically rich and diverse; (2) analyse the ecological correlates of such diversity, trying to infer theprocesses that lead to the origin of species and communities; (3) explore the extraordinary adaptations of species that thrive in the frozen world and (4) provide potential biotechnological applications from the advances in our knowledge on the Antarctic biota.
The special issue (Hydrobiologia Volume 761, Number 1) has been supported by the Museo Nazionale dell'Antartide and can be accessed on SpringerLink.
by Monika Kędra, 14 November 2015
I am a research scientist at the Institute of Oceanology Polish Academy of Sciences in Sopot, Poland (http://www.iopan.gda.pl/, mail to: firstname.lastname@example.org). My scientific interests include studies of structure and functioning of Arctic marine ecosystems with special focus on biodiversity, ecology and functioning of benthic populations, benthic food webs and carbon cycling. In my PhD research I investigated climate change effects on benthic macrofauna in Svalbard fjords, later I have widened my studies into open sea and the Pacific sector of the Arctic Ocean. I am a co-chair of the Arctic in Rapid Transition (http://www.iarc.uaf.edu/ART/), Arctic scientific IASC Network (http://www.iasc.info/home/networks/arctic-in-rapid-transition-art) developed and steered by early-career scientists. Since 2015, I am Polish Representative to the Marine Working Group of IASC (http://www.iasc.info/home/groups/working-groups/marineaosb). I look forward to support the communication between the Antarctic and Arctic biology community.
by Graeme Clark, 02 October 2015
New maps predict the habitat of shallow Antarctic invertebrate communities, based on estimated sea-ice dynamics, light regimes, and bathymetry.
The structure of shallow Antarctic marine benthic communities is strongly regulated by light, which in turn is governed by sea-ice dynamics. Areas of seabed where sea-ice breaks out early in summer receive enough light to support algal forests, while areas where sea-ice remains for most of the year are often inhabited by shallow invertebrate communities (Clark et al. 2013). Antarctic shallow invertebrate communities are unique in that they resemble deep sea fauna (e.g. Fig. 1), but occur in depths of just a few metres. They may also be considered globally rare, since the majority of Antarctic coast is ice cliff or covered by permanent ice that descends into deep water. There is concern, however, that if sea-ice were to break out earlier each spring season, the light reaching these invertebrate communities has the potential to dramatically increase, and would induce ecological tipping-points in which invertebrate communities transition to algal-dominated states (Clark et al. 2013).
One of the main problems in quantifying vulnerability is knowing where shallow benthic communities currently exist. The vast majority of the Antarctic coastline is unsurveyed, and most studies are concentrated around research stations. However, since we know the approximate light (or, more to the point, darkness) requirements of invertebrate communities, we can use continent-wide estimates of sea-ice dynamics and bathymetry to estimate light at the seabed, and subsequently predict where invertebrate communities are likely to live. An example of this method in the coast around Davis and Mawson Stations (East Antarctica) is shown in Fig. 2, and Fig. 3 shows predicted habitats scaled up to the whole of Antarctica. Past surveys of the seabed are generally in agreement with the predictions.
Eventually, we hope to use a similar model to predict how the distribution of shallow invertebrates might change in response to climate-driven change in sea-ice dynamics. There there is still much uncertainty to be overcome before getting there, such as finer scale models of very-nearshore sea-ice dynamics and bathymetry, but this model of potential suitable habitat is a necessary first step. Another dimension to vulnerability is the effect of localised human disturbances (e.g. from tourism and research stations), which tend to be concentrated around seasonally ice-free areas of coast – the same locations where shallow benthic habitat exist.
References: Clark GF, Raymond B, Riddle MJ, Stark JS, Johnston EL 2015. Vulnerability of Antarctic shallow invertebrate-dominated ecosystems. Austral Ecology 40: 482-491, doi:10.1111/aec12237. Clark GF, Stark JS, Johnston EL, Runcie JW, Goldsworthy PM, Raymond B, Riddle MJ 2013. Light-driven tipping points in polar ecosystems. Global Change Biology, 19: 3749–3761. doi: 10.1111/gcb.12337
by Julian Gutt with participants of the workshop, 9 October 2015, photographs: © ICM, Barcelona
38 scientists from 14 countries had been invited by the SCAR Scientific Research Programs AnT-ERA, AntEco and AntClim21. They met in September 2015 in Barcelona, Spain, to discuss improvements in interdisciplinary Antarctic and Southern Ocean research.
The aim of this workshop was to exchange novel ideas among scientists in order to gain an improved understanding of interactions between biological and environmental processes in the Antarctic and Southern Ocean. The background of this interdisciplinary brainstorming was the awareness that in the past 5-8 years scientific knowledge and research opportunities have increased enormously. These advances include biogeographic information as well as the mapping of environmental factors including the fast availability of data and expeditions, experiments and advanced modelling approaches for environmental projections and biological processes, respectively. These advances now allow us to address and specify questions that have recently been identified during the 1st SCAR Antarctic and Southern Ocean Science Horizon Scan to be relevant for the next 20 years, especially on the threats and vulnerability of Antarctic ecosystems. Whilst advances in mono-disciplinary studies are relatively fast the focus of the workshop was interdisciplinary approaches, which demand significant efforts especially in the coordination of ideas, plans and research activities.
The workshop was held at ICM in Barcelona, Spain, and was comprised of 38 participants from 14 countries from 14 countries who were invited by the SCAR scientific programs Antarctic Thresholds - Ecosystem Resilience and Adaptation (AnT-ERA), State of the Antarctic Ecosystem (AntEco) and Antarctic Climate Change in the 21th Century (AntClim21) including the Antarctic Climate Change and the Environment advisory group and met at the ICM in Barcelona, Spain. Additional scientific initiatives, such as BEPSII, PAIS, EGBAMM, ICED, and IPCC were also represented (for acronyms see below). Titles of the sessions (see box) were based on topics proposed by the participants in a questionnaire prior to the workshop. At the beginning of the workshop all participants summarised their scientific background and their interdisciplinary questions in flash presentations. Special attention was paid to questions, which could be answered through improved or newly developed interdisciplinary interactions. The largest part of the workshop was dedicated to discussions. A maximum of two parallel topical sessions partly covered a diverse and broad range of scientific issues, e.g. on spatial and temporal scales and climate change impact or in some cases had a more narrow focus, e.g. on sea-ice or terrestrial ecology. Different levels of biological organisation were covered. These ranged from biomolecular and physiological to full ecosystem approaches and included a variety of environmental factors. These included physical oceanography, marine and soil chemistry including nutrient cycles, plate tectonics, geology, sedimentology, atmospheric science and biogeochemistry. In order to achieve a structured output it was decided during the workshop to provide extra time to narrow the broad variety of discussed aspects and focus on the most important questions based on new developments and on first steps towards their implementation. The results were protocolled and briefly presented to the audience. The division of the workshop into parts with short flash presentations and a central time window with a larger amount of time for discussions helped shape this fruitful and successful brainstorming event.
This workshop is considered as an important step within a continued process. It builds upon predecessors including an ICED workshop in 2014 and the 1st SCAR Horizon Scan and will be continued until and during the SCAR Open Science Conference in 2016 in Kuala Lumpur, Malaysia. This summary and introduction to the single reports of the sessions is published on the AnT-ERA webpage in order to provide potential benefit to the broader community. The protocols of the sessions are not public but can be made available on request.
BEPSII: Biogeochemical Exchange Processes at Sea Ice Interfaces (SCOR), PAIS: Past Antarctic Ice Sheet dynamics (SCAR), EGBAMM: Expert Group on Birds And Marine Mammals (SCAR), ICED: Integrating Climate and Ecosystem Dynamics in the Southern Ocean (SCOR, IGBP; SCAR), IPCC: Intergovernmental Panel on Climate Change (UN).
by Humberto E. González, 02 October 2015
The Chilean "Research Centre: Dynamics of High Latitude Marine Ecosystems" (IDEAL) will play a major role in studying ecosystem-level impacts from climate change and human pressure on Antarctic and Subantarctic ecosystems and will open its headquarters in early 2016.
Last August 20th the IDEAL Research Center (acronym in Spanish for "Centro de Investigación: Dinámica de Ecosistemas marinos de Altas Latitudes”) got awarded after an extensive international review and tight competition among other significant proposals. This new Research Centre in Priority Areas for Chile is financed by CONICYT (Consejo Nacional de Ciencia y Tecnología – Chile) whereas Antarctic activities are supported by the Chilean Antarctic Institute (INACh). The Centre will bring together scientists from 6 Chilean Institutions – Universidad Austral de Chile (UACh, the sponsoring institution), Universidad de Concepción (UdeC), Centre for Quaternary Studies (CEQUA), the Patagonian Ecosystem Research Center (CIEP), the Center for Advanced Studies in Arid Zones CEAZA and the INACh – as well as significant collaboration from senior scientists from the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI-Germany), Scripps-USA, the Center for Coastal Physical Oceanography (CCPO-USA), and the Korean Polar Research Institute (KOPRI-Korea).
The IDEAL Development Plan identifies two strategic geographical areas: the Chilean Southern Patagonia (CSP) and the Antarctic Peninsula (AP). This region is facing unprecedented threats due to their vulnerability under a scenario of exacerbated global warming and anthropogenic impact. Important consequences include changes in regional and local climate regimes increasing melting and glacier runoff, generating unknown shifts in key species (including species of economical importance) and in turn, changes in ecosystems structure and functioning. As Dr. Humberto González, Director of IDEAL Centre, points out “the IDEAL Center, together with our international scientific partners, have a strong commitment with the Antarctic and Sub-Antarctic regions, where multiple stakeholders (from educational, productive, governmental, environmental sectors) are waiting for relevant scientific knowledge to cope with anthropogenic and natural threats”.
A major challenge of IDEAL will be integrating information from environment, organism, community and socio-ecological system levels into a comprehensive framework for assessing present and future impacts of climate and more direct human pressures, which will be achieved through an interdisciplinary modeling task group.
by Stacy Kim and Paul K. Dayton, 03 Spetember 2015
Growth of hexactinellid (glass) sponges is faster than previously reported, but recruitment is sporadic on decadal time scales, and mortality is high.
Giant volcano (glass) sponges (Anoxycalyx joubini) are an iconic Antarctic invertebrate species. In initial marine ecological research around McMurdo Station in the early 1960s, divers tagged individual sponges and tracked their growth – or lack thereof – over 22 years. The growth rates recorded were negligible, and it was concluded that these large individuals were centuries old (Dayton 1989). Additionally, no recruitment of this species has previously been documented.
Recent revisits to artificial substrates established beginning in 1960 show that recruitment of Anoxycalyx joubini is extremely sporadic; none recruited for 3 decades, but in the subsequent 20 years over 570 kg (wet weight) settled and grew. A. joubini mortality was 17% over 3 years (n = 35) and 100% over 35 years (n = 67).
A maximum growth rate of Anoxycalyx joubini can be calculated as 3.7 cm in diameter per year, with the caveat that growth rates are not consistent over the lifetime of the animals. Thus even the largest known 2 m sponges may be as young as 55 years, consistent with the mortality rates observed, but contradicting the previously accepted negligible growth rates and great ages of sponges. The single recruitment event over 50 years of observation indicates that this important, habitat-structure-forming taxa may be susceptible to small changes in environmental factors.
The life history of Anoxycalyx joubini is more dynamic than previously thought, with decadally-sporadic recruitment, rapid growth and equally rapid mortality. Thus, the long-standing perception of the Antarctic benthos as a stable community dominated by slow processes may be incorrect. This becomes especially significant as climate change and resource extraction become more intense in the Antarctic. As national funding shifts from science to logistics, the critical role played by international cooperative efforts such as AnT-ERA in supporting research over ecologically-relevant time scales becomes even more crucial.
References: Dayton PK (1989) Interdecadal variation in an Antarctic sponge and its predators from oceanographic climate shifts. Science 245: 1484–1486. Dayton PK, Kim S, Jarrell SC, Oliver JS, Hammerstrom K, Fisher JL, O’Connor K, Barber JS, Robilliard G, Barry J, Thurber AR, Conlan K (2013) Recruitment, growth and mortality of an Antarctic hexactinellid sponge, Anoxycalyx joubini. PLoS ONE 8(2): e56939. doi:10.1371/journal.pone.0056939
by Iván Gómez and Pirjo Huovinen, 18 June 2015
Antarctic macroalgae form highly productive submarine communities and, thus, knowledge on their physiology is fundamental in order to predict the adaptability of the non-glaciated coastal system to global change.
Antarctic seaweeds are abundant and represent the basis of the benthic communities and their biogeochemical processes down to 80 meters water depth. These organisms are highly adapted to live under extreme environmental conditions, such as strong seasonal changes of light and temperature. For example, photosynthetic light demands as low as 10-20 mol m-2 s-1 are common, especially in species growing at 30-40 m depth. This represents only 2-5 % of daylight required by terrestrial plants. Similarly, as Antarctic has been frozen for at least 14 million years, macroalgae show very low thermal demands for photosynthesis, growth and survival (between 0 ° and 10 °C). Thus, they differ in the degree of adaptation compared to the Arctic algae, whose low temperature history extends over 5 million years. However, some Antarctic macroalgae that live in the intertidal zone are exposed to even much more harsh conditions: during the ice-free summer, they have to tolerate thermal ranges from -10 to +15 °C over a tidal cycle. Thus, these organisms can provide important clues about the physiological mechanisms to withstand environmental shifts driven by climate change.
Currently the project “ANILLO ART1101” funded by Conicyt-Chile is studying the impact of increased UV radiation and temperature on the physiology of Antarctic macroalgae and implications for coastal processes including distribution, food webs and productivity.
An important finding is that Antarctic macroalgae, irrespective of their depth location, are highly tolerant to short-term (e.g. 4 h) increases in temperature. In the case of some endemic species, such as Himantothallus (Fig. 1) and Desmarestia, elevated temperature mitigates the UV induced decline in photosynthesis (Fig. 2). Interestingly, endemic brown algae (e.g. Desmarestia anceps and D. menziesii) growing at 20-30 m depth show remarkably high levels of phenolic substances (phlorotannins) (up to 20 % of dry weight). These substances have well known anti-herbivory and antifouling function, and furthermore absorb in the UV region of the solar spectrum. In these algae high levels of phlorotannins were correlated with lower UV photodamage and enhanced antioxidant protection after exposure to a combination of elevated temperature and UV radiation.
These results highlight two paradoxical features of Antarctic brown algae: shade adaptation does not preclude tolerance to high light stress.
References: Huovinen P, Gómez I. 2013. Photosynthetic characteristics and UV stress tolerance of Antarctic seaweeds along the depth gradient. Polar Biology 36:1319–1332 DOI 10.1007/s00300-013-1351-3; Rautenberger R, Huovinen P, Gómez I. 2015 Effects of increased seawater temperature on UV-tolerance of Antarctic marine macroalgae. Mar Biol 162:1087–1097 DOI 10.1007/s00227-015-2651-7
The titel photograph shows in situ photosynthesis measurements during the Antarctic summer. During this season macroalgae have not only to photosynthesize at high rates to store the energy for survival during the rest of the year, but also to avoid the harmful solar radiation (© proyecto ANILLO ART1101- Fildes Bay – King George Island, 10 m depth; Photographer: I. Garrido; Diver with Underwater Chlorophyll Fluorometer: M. J. Diaz).
by Jungeun Lee, 18 June 2015
Introducing Antarctic hairgrass DaCBF7 gene to rice plants resulted in increased tolerance of the rice plant to low-temperature stress.
The Antarctic, characterized by freezing temperatures, unusual photoperiods and high UV irradiation, is a harsh environment for land plants. Antarctic hairgrass (Deschampsia antarctica Desv.) is one of just two species of flowering plants that have evolved in this environment. As many extremophiles have evolved resistance to unfavorable environments, they are considered as an important genetic reservoir for use to improve crop yields in the face of unpredictable climate changes. That is one of the reasons we need to focus on this Antarctic plant.
Plant biologists have investigated the effects of environmental stresses on growth, development, and reproductive activity of higher plants. Due to plants being unable to move to avoid unfavorable conditions, they have developed cellular and molecular defense mechanisms, modulated by stress-responsive gene expressions. C-repeat binding factor (CBF) is a plant-specific protein and plays a central role in plant abiotic stress responses. CBF-dependent abiotic stress signaling pathways are well conserved among higher plants. CBF protein is a transcription factor acting as a primary element to regulate the expression of downstream genes, such as cold responsive genes, which can make plants stronger against low temperature stresses.
Recently, DaCBF7 gene was isolated from Deschampsia antarctica. The gene was induced by abiotic stresses, including cold, drought, and salinity. Surprisingly, when the gene was introduced into rice cultivar, the cold resistance of rice was observed to increase by 5 times without any growth defects, suggesting that it could be a valuable genetic target for crop improvement. The molecular assays have shown that DaCBF7 protein in transgenic plants binds to promoter regions of the cold responsive genes of rice and boosts up their expression more than wildtype plants. In conclusion, expression of DaCBF7 gene resulted in improved tolerance to low-temperature stress in transgenic rice plants by enhancing expression of several downstream cold responsive genes. These findings demonstrate a possible high potential of Antarctic plants to be used as genetic resources for improving crop tolerance to hazardous environmental stresses.
Reference: Byun MY, Lee J, Cui LH, Kang Y, Oh TK, Park H, Lee H, Kim WT 2015. Constitutive expression of DaCBF7, an Antarctic vascular plant Deschampsia antarctica CBF homolog, resulted in improved cold tolerance in transgenic rice plants. Plant Sciences 236: 61-74
by Doris Abele and Irene Schloss; Figs 1 & 2 by Francesca Pasotti et al. (2014), 18 June 2015
Potter Cove (King George Island / Isla 25 de Mayo, South Shetland Islands) a bay-scale showcase for Antarctic coastal change - Results from 20 years of international and interdisciplinary research.
There are not many locations in the Antarctic where biologists have really good knowledge of past ecosystem states, before the onset of climate warming and accelerated melting of tidewater glaciers in the 1970s. Biological studies in Potter Cove, the marine ecosystem in front of the Argentine Carlini Station (former Jubany) started as early as the ‘1980s and intensified from 1994 onwards, due to strong cooperation between the Instituto Antártico Argentino (Buenos Aires, Argentina) and the Alfred-Wegener-Institut (Bremerhaven, Germany). In 2015 we are looking back at least at 20 years of joint interdisciplinary investigation of past and present climate change related processes in an Antarctic cove. The high density of temporal and spatial data sets assembled for this 15 km2 fjord system in front of the rapidly retreating Fourcade Glacier enable us to relate cause and effects between visible change in glacial ice mass, stratification and turbidity in summer cove waters, and the effects on the coastal biota.
A trend of almost continuous warming in the late 1990s, has caused low primary production in many years, with warmer and turbid waters in spring and summer shading the cove s primary producer communities. After the year 2000, the warming trend has been interspersed with a few cold years of high near coast productivity. These annual variations in the system indicate that we are currently witnessing a transgression from a marine to a melt water influenced coastal system. As not all coastal species can cope with these variations, mismatches between planktonic food and consumers, or light climate and energetic needs in macroalgae, cause shifts in fjord primary and secondary productivity. Experiments are conducted to understand the effect of these mismatches, as well as other climate related processes, such as sea surface water temperature increase.
Turbid waters and sedimentation also impact benthic communities. While some key species cope extremely well with being buried under a thick layer of sludge, more sensitive filter feeders are decreasing in numbers in the affected areas. Characteristic communities are found at locations more or less exposed to sediment impact or scouring activity of coastal ice growlers and brash ice.
Presently, many individual projects under the umbrella of the European-South American network activity IMCONet (Marie Curie-IRSES, no 318718, http://www.imconet.eu/) allow us to further knowledge and to cooperate on a wider latitudinal gradient with researchers from other stations along the Western Antarctic Peninsula.
by Julian Gutt, 05 March 2015
Scientists from the SCAR initiatives AnT-ERA, AntClim21, ACCE and other institutions compared climatic stressors in terms of areal coverage and quantified multiple affected areas. In addition, all kinds of major impact of environmental change on the marine habitats: sea-ice, open water and sea-floor, were complied in an interdisciplinary scientific approach.
Climate change is still a top issue in Antarctic research with continuously growing interest. As a result, scientific knowledge on the historic background, recent developments and future projections are increasing in number and quality, which also reflects the growing demands of stakeholders. This refers especially to the impact of a changing Southern Ocean environment, on the marine biosphere comprising tens of thousands of species and feed back effects on the global climate, e.g. in terms of O2 production, CO2 uptake, remineralisation and production of food for world-wide occurring apex-predators, especially whales.
Despite hundreds of valuable single studies on such cause-and-effect relationships, deciphering difficult to observe ecological complexity is still in it's infancy. This refers, for example, to interactions between nutrient availability, CO2 content and phytoplankton growth, between sea-ice dynamics and primary production, or between the impact of the ozone hole and changing sea-ice cover, which protects the marine ecosystem from increased UV-B radiation. Such phenomena have first to be quantified before the response of the ecosystem to climate change can be assessed and ranked, an approach that it is already applied in the 5th assessment report of the IPCC.
Leading marine ecologists and physicists from 10 countries tried to address these issues to reach a significant step forward towards a quantitative assessment of ecologically relevant environmental changes and their impact to the Southern Ocean ecosystem. This meta-analysis represents an interdisciplinary cross-program co-production between SCAR's biology program Antarctic Thresholds - Ecosystem Resilience and Adaptation, the Antarctic Climate and the Environment action group (ACCE, www.scar.org/accegroup), and the climate research program Antarctic Climate Change in the 21th Century (AntClim21, www.scar.org/srp/antclim21), universities and other national research institutions. In a comparative approach the spatial distribution of major environmental changes were reviewed and their potential impact on the three habitats: sea-ice, open water and sea-floor, were ranked according to their spatial extent. The study is based on a spatially explicit analysis with a focus on multiple climate change stressors in the past and future.
In particular the results show that: (1) large proportions of the Southern Ocean are presently and will continue in the future to be affected by one or more climate change processes; areas projected to be affected in the future are larger than areas that are already under environmental stress, (2) areas affected by changes in sea-ice in the past and likely in the future are much larger than areas affected by ocean warming. In the future, decrease in the sea-ice is expected also to be more widespread than in the past. The smallest areas (<1% area) are affected by glacier retreat and warming of the deeper euphotic layer. Changes in iceberg impact resulting from further collapse of ice-shelves can potentially affect large shelf areas and ephemerally off-shore pelagic habitats. However, aragonite undersaturation (acidification) might become one of the biggest problems for the Antarctic marine ecosystem by affecting almost the entire Southern Ocean, but information on the response of ecological key-species and the ecosystem as a whole is still very scarce. The areas affected range from 33% of the Southern Ocean for a single stressor, 11% for two and finally <1 % for four and five overlapping factors. Areas expected to be affected by 2 and 3 overlapping factors are equally large, including potential iceberg changes, and together cover almost 86% of the SO ecosystem. A compilation of quantitative information on physical-biological interactions underlines a high complexity of the Southern Ocean ecosystem.
A SCAR cross-program workshop to be held in Barcelona in summer 2015 will support the continuation of the approach described herein and initiate new projects addressing climate-relevant and trans-disciplinary questions (http://www.scar.org/scar_media/documents/science/antera/CroPro_WS_BCN_AnTERA.pdf).
Reference: Gutt J, Bertler N, Bracegirdle TJ, Buschmann A, Comiso J, Hosie G, Isla E, Schloss IR, Smith CR, Tournadre J, Xavier JC (2015) The Southern Ocean ecosystem under multiple climate stresses - an integrated circumpolar assessment. Global Change Biology 21: 1434-1453; doi: 10.1111/geb.12794
by Trevor McIntyre, Horst Bornemann, Sina Löschke, 5 March 2015
Studies on environmental correlations with the dive behaviour of Southern elephant seals suggest regional differences in likely impacts associated with climate change.
The Southern elephant seals from Marion Island, located in the south western part of the Indian Ocean, are extreme divers in the truest sense of the word. The animals from this, one of the northern-most populations of southern elephant seals, spend more than 65 percent of their lives in water depths of more than 100 metres, on average diving deeper than their elephant seals from other breeding populations. The maximum dive depth of these seals is over 2000 metres. However, the water masses through which the elephant seals from Marion Island swim in search of food are becoming increasingly warmer due to climate change, and this will likely force the animals to dive deeper, or travel greater distances on their migrations to areas where food is available at shallower depths.
A collaboration between scientists from the Mammal Research Institute (MRI) at the University of Pretoria in South Africa, and the Alfred Wegener Institute (AWI) in Germany has resulted in the deployment of more than 80 satellite-linked recording devices on elephant seals at Marion Island. These transmitters, the size of a fist, are attached to the head of the seals using artificial resin immediately after moulting and measure the dive depth, water temperature and salinity every time the animals dive. When the animal resurfaces to breathe, the transmitters send their data to the respective research institutes via satellite. The project, spearheaded by Prof. Marthán Bester (MRI) and Drs. Horst Bornemann and Joachim Plötz (AWI) has resulted in the collection of data on the characteristics of more than 300,000 dives performed by elephant seals from Marion Island. Dr. Trevor McIntyre (MRI) has been analysing these datasets, and showed that the elephant seals dive deeper in warmer water, and ultimately have less time to actually search for food in the deeper water layers. This, the researchers assume, means that the elephant seals likely find less prey in warmer water masses, which would in turn correspond with results of ecophysiologic experiments in Antarctic fish species. More recent data from French colleagues illustrated similar relationships between the dive behaviour of elephant seals tracked from the Kerguelen Islands and water temperature, further indicating that seals were encountering prey less often in warmer waters. However, these animals did not show any differences in body condition, compared to those foraging in colder waters, suggesting that elephant seals may be able to switch to bigger and/or more nutritious prey occurring at deeper depths in warmer water masses.
The relationships between the behaviour of elephant seals and environmental parameters, such as seafloor depth, water temperature and sea-ice concentration, was also recently investigated for one of the southern-most populations of elephant seals. For this, the scientists from the AWI and MRI, in collaboration with researchers from the Argentine Antarctic Institute (IAA), deployed satellite-linked recorders on elephant seals hauled out at King George Island/Isla 25 de Mayo (Antarctic Peninsula). The analyses of data obtained from some of these animals was recently published in Polar Research. Interestingly, while seals from this location also tended to perform slightly deeper dives in relatively warmer waters, their dive behaviour was more strongly correlated with other parameters such as sea ice concentration and seafloor depth. Here, seals are apparently increasing their foraging efforts in shallower areas, and also areas characterised by higher sea ice concentrations. These results illustrate additional complexities to how elephant seals are likely to respond to changes in their marine environments.
Efforts to understand how elephant seal behaviour is linked to environmental conditions are ongoing, and include long-term monitoring of the at-sea behaviour of seals from Marion Island. The extent to which southern elephant seals are able to adapt to the warming of the ocean remains to be seen, and is currently thought to likely vary between populations. The more northerly populations, such as that on Marion Island, may have to extend their foraging areas to the colder water masses of the Antarctic or be forced to dive deeper in future. Since these seals are thought to already be performing dive behaviours that are close their physiological limits, more extreme diving may result in long-term decreases in both the condition, and survival of seals from this population. At the same time, seals already occurring in close vicinity to the Antarctic continent may even benefit from climate change, since more ice-free areas will become available for breeding. However, shifts in the prey communities for such populations may of course also require behavioural adaptations to successfully adapt.
Guinet C, Vacquié-Garcia J, Picard B, Bessigneul G, Lebras Y, Dragon A., … Bailleul F. 2014. Southern elephant seal foraging success in relation to temperature and light conditions : insight into prey distribution. Marine Ecology Progress Series, 499, 285–301
McIntyre T, Ansorge IJ, Bornemann H, Plötz J, Tosh CA, Bester MN 2011. Elephant seal dive behaviour is influenced by ocean temperature: implications for climate change impacts on an ocean predator. Marine Ecology Progress Series, 441, 257–272
McIntyre T, Bornemann H, de Bruyn PJN, Reisinger RR, Steinhage D, Marquez MEI, … Plötz J 2014. Environmental influences on the at-sea behaviour of a major consumer, Mirounga leonina, in a rapidly changing environment. Polar Research, 33, 23808. doi:http://dx.doi.org/10.3402/polar.v33.23808.
by Michael Potthoff & Karin Johst, 6 March 2015
The spatially-explicit and individual-based simulation model SIMBAA was developed to analyse the response of benthic diversity to iceberg scouring. It is now available at the data repository PANGAEA.
SIMBAA is a spatially explicit, individual-based simulation model, which is now available under CC-BY 3.0 licence in the database PANGAEA (http://doi.pangaea.de/10.1594/PANGAEA.842757). It was developed to analyse the response of populations of Antarctic benthic species and their diversity to iceberg scouring. This disturbance is causing a high local mortality providing potential space for new colonisation. Traits can be attributed to model species, e.g. in terms of reproduction, dispersal, and life span. Physical disturbances can be designed in space and time, e.g. in terms of size, shape, and frequency.
Environmental heterogeneity can be considered by cell-specific capacities to host a certain number of individuals. When grid cells become empty (after a disturbance event or due to natural mortality of an individual), a lottery decides, which individual from which species stored in a pool of candidates (for this cell) will recruit in that cell. After a defined period the individuals become mature and their offspring are dispersed and stored in the pool of candidates. The biological parameters and disturbance regimes decide on how long an individual lives.
Temporal development of single populations of species as well as Shannon diversity are depicted in the main window graphically and primary values are listed. Examples for simulations can be loaded and saved as sgf-files. The results are also shown in an additional window in a dimensionless area with 50 x 50 cells, which contain single individuals depicted as circles; their colour indicates the assignment to the self-designed model species and the size represents their age. Dominant species per cell and disturbed areas can also be depicted. Output of simulation runs can be saved as images, which can be assembled to video-clips by standard computer programs.
The understanding and valuing of Antarctic terrestrial ecosystems is the key for the protection of these highly fragile environments. Although thought to be almost sterile soils, for a long time, it is now common knowledge that most, if not all, terrestrial Antarctic ecosystems are home to a variety of organisms, from microbes to algae, lichens, invertebrates and mosses.
Biological soil crusts (BSC) are small-scale communities that are an assemblage of these organisms, and occur in almost all semi-arid and arid regions of the world. Nevertheless they have only rarely been described in Antarctic habitats and even less is known about their eco physiology and their capabilities to withstand the environmental extremes that the high latitudes of the Antarctic pose. Slow growth rates and short activity periods almost certainly limit BSC establishment in Antarctic cold deserts. To characterise the realised physiological niche it is necessary to understand the photosynthetic performance and possible limits to, or potentials of, BSC development.
BSC from the cold desert zone in continental Antarctic operate over a wide range of different climatic conditions, even at temperatures below zero. They are adapted to a general high light regime and show activity even at very low thallus water contents.
Carbon allocation patterns emphasize that there are effectively two functional types of lichens, those that are growth targeted and others, in harsh climates, which are survival targeted. Once carbon is photosynthetically fixed, the Antarctic lichens give high priority to store it as short chained sugars, which have several functions that emphasize survival (desiccation tolerance, freezing protection, antioxidants).
Reference: Colesie, C., Green, T.G.A., Haferkamp, I., Büdel, B. (2014) Lichen dominated soil crusts show changes in composition, CO2 gas exchange, and carbon allocation as stress-related traits across habitats of different severity. The ISME journal 8: 2104 – 2115; DOI:10.1038/ismej.2014.47
Sequencing the genome of the Antarctic Bullhead notothen provides clues to the future adaptability of Antarctic fishes.
Antarctic fishes, most of which belong to a single group of perch-like fishes called the Notothenioidei, have evolved characteristics that make them extremely well adapted to their Southern Ocean habitat, which cooled to the freezing point of seawater (-1.9°C) by approximately 8-10 million years ago. For example, they evolved a novel macromolecular antifreeze that is critically important for preventing the freezing of their body fluids in their chronically icy environment. Originally heavy, bottom-dwelling fishes without a swimbladder, many species evolved near neutral buoyancy (i.e., weightlessness) in water by reducing the mineralization of their bones and depositing more oils in their tissues, which enabled them to exploit the food-rich water column. Surprisingly, the family of icefishes (one of the eight families of notothenioids) even lost the capacity to make red blood cells and hemoglobin, a bizarre adaptational “option” available only in the cold, stable, and oxygen-saturated marine environment of the Southern Ocean.
Today, these cold-adapted “stenotherms” (organisms that can tolerate only a limited temperature range) are threatened by rapid warming of the Southern Ocean, the temperature of which is likely to increase by 2-5°C over the next two centuries. We are investigating the impact of this projected warming on the life history stages of notothenioid fishes to determine whether they have the capacity to survive under this climate change scenario. The key to predicting the thermal resilience or sensitivity of Antarctic fishes lies in understanding whether or not their evolutionary adaptation to cold temperatures has “painted them into a genetic corner” that is inconsistent with viability in a warmer environment. To capture a global perspective of these adaptations, we have sequenced the genome of the Antarctic Bullhead notothen, Notothenia coriiceps. When we examined the 46 most rapidly evolved protein-coding genes of this notothen, we found that they were enriched in mitochondrial and oxygen transport Gene Ontology terms (14 of the 17 categories). Therefore, our results indicate that a subset of genes involved in aerobic metabolism is most important with respect to the capability of Antarctic fishes to cope with future environmental warming.
Thus, we reach the critical issue. Is there enough evolutionary time available to the slowly reproducing Antarctic fishes for natural selection to reconfigure their mitochondrial systems to the demands of a warmer habitat? And what of the Antarctic icefishes, whose oxygen transport system is compromised relative to the other notothenioids? In my opinion, there is both bad news and good news. The bad news is that a warming Southern Ocean will probably lead to significant habitat loss for the Antarctic notothenioids, in particular the icefishes. The good news is that cold-water refugia around the Antarctic continent will likely remain available to Antarctic fishes for a considerable period in the future. Meanwhile, it is incumbent upon humankind to address anthropogenic contributions to global warming.
Reference: Shin SC, Ahn DH, Kim SJ, Pyo CW, Lee H, Kim M-K, Lee J, Lee JE, Detrich HW III, Postlethwait JH, Edwards D, Lee SG, Lee JH, Park H 2014. The Genome Sequence of the Antarctic Bullhead Notothen Reveals Evolutionary Adaptations to a Cold Environment. Genome Biology 15:468 (DOI: 10.1186/s13059-014-0468-1; http://genomebiology.com/2014/15/9/468).
The opinions expressed in this article are those of the author alone.
The collapse of the Larsen Ice A and B Shelves more than a decade ago, enabled primary production over hundreds of km2 of sea surface triggering the arrival of fresh organic matter and biogenic silica to the sea floor.
The disintegration of the Larsen Ice Shelves has been attributed to the ongoing anthropogenic and natural global warming, especially to the drastic increase in regional air temperatures. It opened the door for oceanographic expeditions and promising research to answer questions on the pace of pelagic-benthic coupling and general ecosystem functioning in the case of environmental regime shifts.
With the onset of primary production after hundreds of years of sun light isolation, a downward flux of phytoplankton and related detritus started supplying the seabed habitat with fresh organic matter. This change was evident in chlorophyll-a profiles obtained via sediment cores (Fig. 1a). Whereas in the Larsen B embayment the chlorophyll-a was only present in the upper 1.5 cm of the sediment; around the South Shetland Islands with open water conditions for thousands of years the pigment concentrations were relatively high, not only at the surface but down to at least 4.5 cm. This pattern was also observed in the biogenic silica concentration. The Larsen sediment cores showed relatively high biogenic silica concentration supplied by diatoms in the upper 2 cm, more than doubling that from sponge spicules at least at the Larsen central site (Fig. 1b & c). The extremely low abundance of sponges when the Larsen B area was still ice covered can not explain alone the spicule abundance in the sediment. These results together with current velocity measurements indicate that spicules in the sediments were transported by a strong current entering Larsen B from the south following the Weddell Gyre pattern.
Further support to explain these results is that in the area outside the Larsen embayments organic material is incorporated into deeper sediment layers. This is caused by bioturbation from a relatively rich fauna living inside the sediment, whilst the Larsen sediments almost lack such infauna and, consequently, the upper sediment column is less mixed. The Southern Ocean marine sediment is the major depository of biogenic silica in the ocean with approximately 50% of the global silica accumulation occurring there. The main constituents of the particulate biogenic silica are diatoms (Fig. 2a), radiolarians, silicoflagellates and sponge spicules (Fig. 2b). Sponge spicules dissolve at a much slower rate than diatom frustules meaning that the actual characteristics of Larsen sediments may favor the flux of silicic acid derived from biogenic silica dissolution across the sediment-water interphase from the sediment into the water column.
The study of the sediments (Fig. 1d) and the water column (Fig. 3) also provided insights into the dynamics of the area. The increase in coarser grain sizes in the upper part of the Larsen B central site sediments indicates higher accumulation of sands in the axis of the glacial trough where this sediment sample was recovered. Temperature-salinity-profiles confirm this conclusion, since they show a homogeneous water mass in the entire area but a thicker surface layer in the center of Larsen B; which suggests the presence of a gyre circulating clockwise in the Larsen B embayment also contributing to the supply of organic material to the sediment surface.
The changes indicated in the sedimentary records imply that besides the impact of the anthropogenic environmental change to the surface of the ocean there is a subsequent effect at the sea floor. From the biological point of view, the seabed in this region is becoming richer in organic matter and more attractive for benthic colonisers, but this process is just at its beginning and it will take many years until a new benthic system will be fully established.
Fjords are U-shaped marine inlets carved deep into the coastline by glacial ice. In subpolar climate regions, active glaciers descend from ice caps into fjords, forming floating tongues of ice called “tidewater glaciers” (Fig. 1). These floating glaciers pump icebergs, melting freshwater, and glacial sediments into fjords, and can dramatically alter the nature of fjord ecosystems. For example, glacial sediments can shade phytoplankton and limit primary production; they can also cause massive disturbance by rapidly burying seafloor animal communities in the inner and middle sections of fjords. Because the flows of glacial ice, meltwater and associated sediments into fjords may be altered by warming, the effects of tidewater glaciers on fjord ecosystem are expected to be very sensitive to climate change.
In both the high Arctic and along the West Antarctic Peninsula (WAP), fjords with tidewater glaciers are warming very rapidly. In the Arctic, numerous studies indicate that seafloor communities in fjords currently experience rapid buried under glacial sediments, yielding very low animal abundance and species diversity at the seafloor in inner and middle fjords. Climate warming in the Arctic is predicted to reduce the flux of glacial sediments and burial disturbance in Arctic fjords, yielding an increase in the abundance and biodiversity of animal communities at fjord floors. Until very recently, seafloor communities in fjords with tidewater glaciers along the subpolar West Antarctic Peninsula had remained essentially unstudied, but were expected to resemble their Arctic counterparts and harbor a low abundance and diversity of seafloor life.
During two recent expeditions, we tested ecosystem predictions from Arctic fjords on three subpolar, glacio-marine fjords along the WAP, Andvord, Flandres and Barilari Bays. With seafloor photographic surveys we evaluated the abundance, community structure, and species diversity of seafloor megafauna (animals larger than about 2 cm), as well as the abundance of demersal nekton and macroalgal detritus, in sediment-floored fjord basins at depths of 436–725 m. We then contrasted these fjord sites with three open shelf stations of similar depths. Based on Arctic fjord studies, we expected to find impoverished seafloor communities highly disturbed by glacial sedimentation, compare to our open shelf stations.
Contrary to Arctic predictions, WAP fjord basins exhibited 3 to 38-fold greater seafloor megafaunal abundance than the open shelf (Fig. 2), and local species diversity remained high from outer to inner fjord basins. Furthermore, WAP fjords contained distinct species composition, including approximately 50 species not found on the open shelf, indicating that the fjords contribute substantially to regional species richness. In particular, bristle worms, anemones, sea spiders, and amphipod crustaceans abounded in the fjord seafloor photographs, along with a number of sea cucumbers, deep ocean jellyfish and many other species (Fig. 3). The abundance of demersal nekton (e.g., krill) and macroalgal detritus was also substantially higher in WAP fjords compared to the open shelf. In two of the fjords, the waters were dense with krill and contained numerous feeding humpback whales (e.g., Nowacek et al 2011).
Seafloor ecosystems at the bottom of fjords are below the penetration of sunlight and thus rely on sinking detritus for food, so these WAP fjords must be getting enhanced food input, most likely from sinking phytoplankton blooms, seaweed sloughing from fjord walls, and falling krill carcasses. Researchers have even suggested that large aggregations of humpback whales may stimulate fjord primary productivity by releasing nutrients as they feed and defecate in the fjords during seasonal immigration, enhancing the phytoplankton blooms.
We speculate that the differences in seafloor community abundance and diversity between Arctic and Antarctic fjords can be explained by the fact that Antarctica is in an earlier stage of climate warming than the Arctic, allowing the Antarctic fjords to maintain high levels of productivity. While the Antarctic fjords sustain massive inputs of ice from tidewater glaciers (Fig. 1), there is still little glacial melting so few fine-grained glacial sediments are pumped into the fjords. This apparently allows the development of long-lasting phytoplankton blooms and little seafloor burial disturbance in inner-middle fjords, fostering abundant and diverse seafloor communities.
However, the Antarctic Peninsula is warming nearly as fast as anywhere in the world, and coastal ecosystems there are changing very quickly. The favorable conditions for high productivity and biodiversity in the WAP fjords are very likely to be altered as the climate continues to warm, accelerating glacial melting and dumping large amounts of fine-grained sediments into fjord headwaters. The resulting higher turbidity and seafloor sedimentation will likely shade the phytoplankton and bury diverse seafloor communities, smothering fjord primary production and biodiversity. Because productivity/biodiversity hotspots such as WAP fjords can play disproportionate roles in the feeding and reproduction of mobile species (such as krill, baleen whales, and juvenile fish), in maintaining biodiversity in heterogeneous ecological landscapes, and as destinations for Antarctic tourism, there is an urgent need for better understanding of the ecological functioning and climate sensitivity of these WAP subpolar fjord ecosystems.
Grange LJ, Smith CR 2013. Megafaunal communities in rapidly warming fjords along the west antarctic peninsula: Hotspots of abundance and beta diversity. PLoS ONE 8: e77917. doi:10.1371/journal.pone.0077917
Nowacek DP, Friedlaender AS, Halpin PN, et al 2011. Super-aggregations of krill and humpback whales in Wilhelmina Bay, Antarctic Peninsula. PLoS ONE 6: e19173. doi:10.1371/journal.pone.0019173.
by Julian Gutt, 1 August 2014
The floating extensions of the huge Antarctic ice shield, the ice shelves, cover one-third of the shallow-water margin of the continent. Consequently, the habitat under the ice shelf is typical for the Southern Ocean but not for any other region in the world's oceans and the associated marine life is largely unknown. Since the 1960s iceshelves disintegrate due to atmosphere and ocean warming, with the largest collapse events happening in 1996 and 2002 in the Larsen A and B areas in the northwestern Weddell Sea. It can be assumed that the iceshelf disintegration causes an exceptional regime shift in the environment and the ecosystem. (http://earthobservatory.nasa.gov/Features/LarsenIceShelf/)
Extensive ecological surveys, by an international team of scientists, were carried out in 2007 and 2011 after first records of unique selected findings. Two expeditions with the German research vessel Polarstern demanded excellent icebreaking capacity and good luck to operate in areas with a high probability of an occurrence of large local ice-fields and barriers. A third attempt failed in 2013, in a year with an extreme sea-ice cover.
An obvious element of the larger fauna on the seafloor (megabenthos) under the former ice shelves at approx. 200m depth were deep-sea organisms, which occur elsewhere between 1000 and 8000m depth (http://www.sciencedirect.com/science/journal/09670645/58/1-2). This phenomenon can be explained by a similarity in the nutrient-poor situation in both habitats. A peculiarity in this context is a well-known deep-sea sea-cucumber, Elpidia glacialis, which obviously responded to a recently increased food supply, documented by analyses of sediment and water column variables, with fast population growth. It seems unlikely that most of the deep-sea species survive in the new ecological regime, with a distinct summerly phytoplankton bloom. Also the explosive growth of Elpidial glacialis might be ephemeral. A high abundance of two species of sea-squirts (ascidians), considered as pioneer species, observed in 2007 in adjacent Larsen A and B sites represent the first stage of a long-term ecosystem shift. This aggregation, however, disappeared until 2011 in the Larsen A embayment, whilst other sea-squirts increased on a low abundance level (http://link.springer.com/journal/300/36/6/page/1). Similarly, filter feeding brittle stars (ophiuroids) decreased whilst their deposit feeding relatives increased. Non-identifiable "spider-webs" grew on the sediment in the same way as the abundant ascidians disappeared. They could be: mucus of the ascidian-feeding gastropod Marseniopsis, cellulose-like tunicin fibers being remnants of the dead ascidians or least likely bacteria remineralising the ascidian bodies. An extremely high proportion of small sponges indicated a successful recruitment in Larsen A. These sponges were observed to grow significantly between 2007 and 2011.
Bathymetric, oceanographic and glaciological measurements and analyses indicate that the Larsen A and B embayments are connected to each other and that ecosystem shifts in Larsen A depend on ecological developments in the southerly adjacent Larsen B rather than on in situ conditions, especially with respect to phytoplankton blooms triggered by the seasonal sea-ice dynamics and the long-term ice shelf disintegration. Whales and seals obviously discovered the areas as suitable new habitats, where they find new food sources in the form of krill aggregations and are maybe protected from predation pressure by orcas. Penguins have not yet been observed in the area. Dead bivalve shells indicated an ancient seep in the centre of Larsen B, whilst at its margin a patch of bacterial mats was photographed. The meiofauna samples from 2007 showed an intermediate stage of shift from the former to the new conditions and an affinity to deep-sea and seep-related biodiversity. Generally rare hydrocorals were found on a strong current, harsh bottom environment at the southern "entrance" of Larsen B and in the South of Larsen A. They are assumed to be potentially sensitive to ocean acidification.
In essence, the marine ecosystem showed faster dynamics to respond to environmental shifts than previously thought. This includes an increase in biodiversity and biomass as well as mortality and local extinction.
Besides traditional methods ROV-based (Remotely Operated Vehicle) imaging methods, played an important role to collect information to decipher ecosystem processes within a truly transdisciplinary approach.
The Antarctic Climate and the Environment (ACCE) report is the most comprehensive compilation of knowledge on climate and the Antarctic including its ecosystems.
Due to the increasing awareness and knowledge of global and Antarctic climate change a group of SCAR-scientists edited the ACCE report in 2009 which comprised contributions from approximately 100 experts. The biggest challenge was to connect evolutionary developments in the distant past with present and future ecological processes, which are directly linked through adaptation and plasticity. The complexity of such relationships is unique in biology; it is very dynamic and mainly based on physical conditions. Two of the four biologists being ACCE-editors, Guido di Prisco and Julian Gutt, became leading scientists of AnT-ERA.
The 2012 update comprises the 92 most important key points from all disciplines of natural science; of which more than 15 have a biological focus (http://www.scar.org/publications/occasionals/acce.html).
Another challenge of the ACCE-report was to cover all important aspects of the most actual knowledge and to make such information attractive for a broad readership and stakeholder community. As a result, anyone, who is interested in the Antarctic and its environment will find agglomerated information in the form of text, graphs and cartoons; as well as references of original scientific articles. Since knowledge in this field is growing four years after the first publication there was a strong need to update the report (1) to consider the newest information and (2) to reflect the response and criticism of a broad community of colleagues, e.g. in case of underrepresented topics. In addition, the SCAR ACCE Advisory Group presents yearly updates to the Antarctic Treaty Consultative Meetings.
The "1st SCAR Antarctic and Southern Ocean Science Horizon Scan" identified 80 high priority science questions from all disciplines for the next two decades and beyond.
Creativity is the most essential "driver" to facilitate a continuous advancement in science. To support this aspect within the community of Antarctic researchers SCAR performed a Horizon Scan process. The aim was to define key scientific questions that can be answered in the next 20 years and beyond. In an initial step, an international Steering Group selected experts from 789 nominations, which resulted in a group of 75 individuals, who participated later in the Retreat, meeting face to face. In a second step the community of Antarctic researchers, comprising all scientific disciplines, was asked to contribute to this process. This yielded 870 more or less novel scientific questions, which up till now have not yet sufficiently been answered. During the Retreat the 870 questions were revised, merged, modified and condensed, by democratically voting after intense discussion, until finally 80 of them were identified to represent high priority challenges. The questions were clustered into seven groups: (1) Antarctic Atmosphere and Global Connections; (2) Southern Ocean and Sea Ice in a Warming World; (3) Ice Sheet and Sea Level; (4) The Dynamic Earth beneath Antarctic Ice; (5) Life at the Precipice; (6) Near-Earth Space and Beyond; (7) Human Presence in Antarctica.
Discussions and science perspectives in environmental and biological disciplines are still dominated by concerns about the impact of climate change. Thus, it is not a surprise that most of the 26 biological questions deal with topics that are related to the main topics of AnT-ERA, which focus on climate-related biological processes. Further advances in the adaptation of organisms, including the novel "omics-level", is considered as a basis to assess the response of ecosystems; especially of those under the pressure: of multiple stressors, of contaminants including sound and of the invasion, dispersal and extension of non-indigenous species and of diseases. Interactions between ecosystems on land and in the sea, as well as within the Southern Ocean, are assumed to play important roles in future scientific approach with regard to the case of extreme environmental events. Aspects of the impact of climate change on fisheries, key ecosystem processes and aspects of conservation are also considered. In the topic "Human Presence in Antarctica" the question of the current and the potential of ecosystem services is raised. Major ecosystem services, in addition to aforementioned "ecosystem goods", are CO2 uptake, O2 production, remineralisation, food production for globally occurring apex predators, maintenance of global diversity and a contribution to a global healthy environment. The scientific questions are complemented by the description of a number of Technological Challenges and Extraordinary Logistics Requirements.
For further information and conclusions, as well as the complete list of questions see Comment in Nature 512: 23-25 (http://www.nature.com/news/polar-research-six-priorities-for-antarctic-science-1.15658); a scientific manuscript is submitted to the journal "Antarctic Science". Also the questions, which have not directly been considered but might consider challenging specific aspects, are public (http://www.scar.org/horizonscan/retreatquestions) and might serve for a more detailed analyses of ways into the future of science in the Antarctic and Southern Ocean.
The CAML / SCARMarBIN Biogeographic Atlas of the Southern Ocean.
After only a few decades of availability of scientific data, by computer-based information systems, The CAML / SCAR-MarBIN Biogeographic Atlas of the Southern Ocean will be published by SCAR 25 August 2014. On 512 pages comprehensive maps show the circum-Antarctic distribution of 9064 species, complemented by environmental information and analysed in exemplary show cases. For the official flyer click here.
Early sampling surveys took place in the 19th and 20th century. As results, first sets of circum-Antarctic species distributions in the Southern Ocean were published as part of the Antarctic Map Folio Series in the 1960s and 1970s by the American Geographical Society. Since then two developments marked a significant improvement in this field of science. Firstly, georeferenced biological information provided by electronic databases and online information services became publicly available only in approximately the past two decades. Secondly, from 2005-2010 the Census of Antarctic Marine Life increased the general acceptance and realisation of faunistic surveys and of species identification work.
As a result of these developments, species distribution maps were compiled based on information being available in the Antarctic Biodiversity Facility ANTABIF (biodiversity.aq). It hosts 1.07 million occurrences of 9064 species from 434000 sampling locations; additional records from other data repositories are included in the atlas. Organisms considered range from unicellular animals and plants, macroalgae, meiofauna and other benthic and pelagic invertebrates including krill, fish and most of the charismatic apex predators, like penguins, seals and whales. Overarching topics are evolution, plate tectonics, benthic communities and bioregionalisation, modelling of recent and future suitable habitats and conservation aspects; as well as comprehensive environmental settings.
The basic biological information compiled in the atlas is essentially important for any modern process-orientated biological studies, especially if they have an organismic background and are embedded in an Antarctic-specific ecological context. This is the reason why scientists from the AnT-ERA community will belong to the main user of the biogeographic atlas. Despite mapping biodiversity patterns not being a main topic of AnT-ERA scientists they contributed significantly to the atlas project as data provider, authors or co-editor.
Stakeholders will not only be scientists of all marine disciplines but also students and teachers as well as conservationists. A dynamic online version of the atlas is planned for the future at biodiversity.aq.
Satellite tracking data show how grey-headed albatrosses try to adapt their behavior, when searching for food, when come across warm conditions: are they successful and able to survive in the future?
In order to model what will be the effects of climate change in the Southern Ocean food webs, we need to know “what eats what”. Moreover, we also need information on how animals behave when confronted with warmer conditions.
The Grey-headed albatross Thalassarche chrysostoma, is a species that has been very well studied in the Southern Ocean in the last 40 years, useful to develop food web models and possibly explain what might happen in other Southern Ocean species, To provide information on the feeding ecology and behavior we studied its diet and behavior in “good” years (when Southern Ocean conditions were good for them to breed; i.e. food was abundant) and “bad” years (when conditions were bad for them to breed; i.e. food was not abundant).
Our study showed that in a “good” year, grey-headed albatrosses foraged north close to their breeding colony (taking 1-3 days) and feeding on their favorite prey, cephalopods (mainly squid) whereas in a “bad” year they behaved differently. In the “bad years”, they just initially went to the areas they used to go in previous “good” years but did not find they favorite prey. Therefore they went further away in the opposite direction (South, to the Antarctic Peninsula), taking trips up to 26 days (range: 5-26 days) and feeding on another prey, crustaceans (mainly Antarctic krill, Euphausia superba) but not in sufficient quantity. As these “bad” year trips were so long that when they returned to their colony to feed their chicks, their chicks were already dead.
These results show that grey-headed albatrosses do change their foraging areas in “good” and “bad” years, and their diets too. Unfortunately, in “bad” years their prey is not available, they try to adapt and forage further away, but unsuccessfully. This study highlights the risk of top predators if there is an increase of the frequency of “bad” years.
Reference: Xavier JC, Louzao M, Thorpe SE, Ward P, Hill C. Roberts D, Croxall JP, Phillips RA 2013. Seasonal Changes in the Diet and Feeding Behaviour of a Top Predator Indicates a Flexible Response to Deteriorating Oceanographic Conditions. Marine Biology 160: 1597-1606 (DOI 10.1007/s00227-013-2212-x).