Biogeographical and bioclimatic outline of Antarctica

Abstract

This study proposes a bioclimatic characterization and a new biogeographic division for the Antarctic territories up to the province level following the criteria and models of Rivas-Martínez et al. The Antarctic Kingdom comprises the continent of Antarctica, the surrounding ice-covered Antarctic islands, and the associated cold oceanic islands and archipelagos. It has two biogeographic regions: the Antarctic Region and the Subantarctic Insular Region. The Antarctic Region includes the entire pergelid Antarctic continent and the surrounding islands and archipelagos, and is characterized by upper suprapolar hyperoceanic and oceanic or Polar pergelid bioclimates on the coasts. The region has been divided into three pr6ovinces: Maritime Antarctica, West Antarctica and East Antarctica. The Subantarctic Insular Region comprises the circumantarctic islands and archipelagos that are widespread at the southern tip of the planet’s most important oceans, mostly in the subtemperate latitudinal zone inside or not far from the Antarctic Convergence. Bioclimatically, all insular subantarctic territories (excluding the South-American Tierra de Fuego, Terra Magellanica and large islands) are characterized by thermo-suprapolar and semipolar antarctic hyperoceanic bioclimates on the coasts. Four provinces – Falklandian-South Georgian, Kerguelenian, Macquarian and Aucklandian-Campbellian – have been recognized in this region. All these units are characterized by floristic bioindicators.     

Evidence for geographic isolation and signs of endemism within a protistan morphospecies

The possible existence of endemism among microorganisms resulting from and preserved by geographic isolation is one of the most controversial topics in microbial ecology. We isolated 31 strains of "Spumella-like" flagellates from remote sampling sites from all continents, including Antarctica. These and another 23 isolates from a former study were characterized morphologically and by small-subunit rRNA gene sequence analysis and tested for the maximum temperature tolerance. Only a minority of the Spumella morpho- and phylotypes from the geographically isolated Antarctic continent follow the worldwide trend of a linear correlation between ambient (air) temperature during strain isolation and heat tolerance of the isolates. A high percentage of the Antarctic isolates, but none of the isolates from locations on all other continents, were obligate psychrophilic, although some of the latter were isolated at low ambient temperatures. The drastic deviation of Antarctic representatives of Spumella from the global trend of temperature adaptation of this morphospecies provides strong evidence for geographic transport restriction of a microorganism; i.e., Antarctic protistan communities are less influenced by transport of protists to and from the Antarctic continent than by local adaptation, a subtle form of endemism.     

China's antarctic policy and the Antarctic Treaty system

Abstract

China began to express its interest in Antarctica in the early 1980s. China acceded to the Antarctic Treaty in 1983 and obtained consultative party status within the Antarctic Treaty System (ATS) two years later. Since 1984, China has been sending national scientific expeditions annually to this white continent and the surrounding seas. This article analyzes China's interests in and policy toward Antarctica as a whole by first discussing China's activities in Antarctica, its approaches to the Antarctic Treaty, and its role in the ATS and then exploring the future trend of China's Antarctic policy from political, economic, scientific, and environmental perspectives. The article concludes that, with China's involvement in Antarctic affairs, the vitality of the ATS has been further strengthened and Antarctica can better serve the interest of all mankind.     

Antarctic terrestrial life--challenging the history of the frozen continent?

Antarctica is a continent locked in ice, with almost 99.7% of current terrain covered by permanent ice and snow, and clear evidence that, as recently as the Last Glacial Maximum (LGM), ice sheets were both thicker and much more extensive than they are now. Ice sheet modelling of both the LGM and estimated previous ice maxima across the continent give broad support to the concept that most if not all currently ice-free ground would have been overridden during previous glaciations. This has given rise to a widely held perception that all Mesozoic (pre-glacial) terrestrial life of Antarctica was wiped out by successive and deepening glacial events. The implicit conclusion of such destruction is that most, possibly all, contemporary terrestrial life has colonised the continent during subsequent periods of glacial retreat. However, several recently emerged and complementary strands of biological and geological research cannot be reconciled comfortably with the current reconstruction of Antarctic glacial history, and therefore provide a fundamental challenge to the existing paradigms. Here, we summarise and synthesise evidence across these lines of research. The emerging fundamental insights corroborate substantial elements of the contemporary Antarctic terrestrial biota being continuously isolated in situ on a multi-million year, even pre-Gondwana break-up timescale. This new and complex terrestrial Antarctic biogeography parallels recent work suggesting greater regionalisation and evolutionary isolation than previously suspected in the circum-Antarctic marine fauna. These findings both require the adoption of a new biological paradigm within Antarctica and challenge current understanding of Antarctic glacial history. This has major implications for our understanding of the key role of Antarctica in the Earth System.     

Evidence for Geographic Isolation and Signs of Endemism within a Protistan Morphospecies

The possible existence of endemism among microorganisms resulting from and preserved by geographic isolation is one of the most controversial topics in microbial ecology. We isolated 31 strains of “Spumella-like” flagellates from remote sampling sites from all continents, including Antarctica. These and another 23 isolates from a former study were characterized morphologically and by small-subunit rRNA gene sequence analysis and tested for the maximum temperature tolerance. Only a minority of the Spumella morpho- and phylotypes from the geographically isolated Antarctic continent follow the worldwide trend of a linear correlation between ambient (air) temperature during strain isolation and heat tolerance of the isolates. A high percentage of the Antarctic isolates, but none of the isolates from locations on all other continents, were obligate psychrophilic, although some of the latter were isolated at low ambient temperatures. The drastic deviation of Antarctic representatives of Spumella from the global trend of temperature adaptation of this morphospecies provides strong evidence for geographic transport restriction of a microorganism; i.e., Antarctic protistan communities are less influenced by transport of protists to and from the Antarctic continent than by local adaptation, a subtle form of endemism.     

Low cyanobacterial diversity in biotopes of the Transantarctic Mountains and Shackleton Range (80-82°S), Antarctica

The evolutionary history and geographical isolation of the Antarctic continent have produced a unique environment rich in endemic organisms. In many regions of Antarctica, cyanobacteria are the dominant phototrophs in both aquatic and terrestrial ecosystems. We have used microscopic and molecular approaches to examine the cyanobacterial diversity of biotopes at two inland continental Antarctic sites (80-82°S). These are among the most southerly locations where freshwater-related ecosystems are present. The results showed a low cyanobacterial diversity, with only 3-7 operational taxonomic units (OTUs) per sample obtained by a combination of strain isolations, clone libraries and denaturing gradient gel electrophoresis based on 16S rRNA genes. One OTU was potentially endemic to Antarctica and is present in several regions of the continent. Four OTUs were shared by the samples from Forlidas Pond and the surrounding terrestrial mats. Only one OTU, but no internal transcribed spacer (ITS) sequences, was common to Forlidas Pond and Lundstr?m Lake. The ITS sequences were shown to further discriminate different genotypes within the OTUs. ITS sequences from Antarctic locations appear to be more closely related to each other than to non-Antarctic sequences. Future research in inland continental Antarctica will shed more light on the geographical distribution and evolutionary isolation of cyanobacteria in these extreme habitats.     

Planktonic microbial assemblages and the potential effects of metazooplankton predation on the food web of lakes from the maritime Antarctica and sub-Antarctic islands

Antarctica is the continent with the harshest climate on the Earth. Antarctic lakes, however, usually presents liquid water, at least during part of the year or below the ice cover, especially those from the sub-Antarctic islands and the maritime Antarctic region where climatic conditions are less extreme. Planktonic communities in these lakes are mostly dominated by microorganisms, including bacteria and phototrophic and heterotrophic protists, and by metazooplankton, usually represented by rotifers and calanoid copepods, the latter mainly from the genus Boeckella. Here I report and discuss on studies performed during the last decade that show that there is a potential for top–down control of the structure of the planktonic microbial food web in sub-Antarctic and maritime Antarctic lakes. In some of the studied lakes, the effect of copepod grazing on protozoa, either ciliates or flagellates, depending on size of both the predator and the prey, could promote cascade effects that would be transmitted to the bacterioplankton assemblage.     

Cleaning up after human activity in Antarctica: legal obligations and remediation realities

National Antarctic Programmes do not have a strict legal obligation to remediate the Antarctic environment following human activity. The Protocol on Environmental Protection to the Antarctic Treaty (the “Madrid Protocol”) obliges parties to conduct environmental impact assessments to prevent adverse impacts on the polar environment and to “clean up” pollution from waste disposal sites. The obligations stemming from the Madrid Protocol are not clearly defined, and give potential scope for parties to neglect past sites of human activity on the continent. This scope is narrowed by the work of the Committee for Environmental Protection in implementing clear practical clean‐up guidelines for National Antarctic Programmes based on scientific‐based recommendations from the Antarctic Treaty Parties. Despite better modern practice, Parties are still faced with damage from past activities. Some of these sites are deemed to be “beyond help.” This article proposes that rather than abandoning waste disposal sites because of widely acknowledged difficulties, that National Antarctic Programmes prioritize research into restorative methodologies and techniques, while increasing cooperation with other parties to overcome the enormous logistical and economic costs of cleaning up pollution in Antarctica.     

The exclusive economic zone and antarctica: The dilemmas of non‐sovereign jurisdiction

Abstract

Antarctica is the only continent from which no exclusive economic zones extend. This article examines the EEZ as a legal concept, particularly its relevance for enhancing maritime jurisdiction offshore Antarctica. The study analyzes the political setting in the Antarctic which would affect creation of EEZs in the region, especially the division of the continent into sector claims by certain states and the implications presented by various island groups in the area. An appraisal is made of the legal situation and the jurisdictional opportunities afforded by the Antarctic Treaty System. The author concludes that a recognized political authority, with demonstrated legal competence and capabilities, is administering jurisdictional considerations in the Antarctic area. In its operation, this Antarctic Treaty regime fulfills management and conservation functions analogous to those of EEZs in waters offshore the continent.     

Gene flow on the ice: genetic differentiation among Adélie penguin colonies around Antarctica

Each summer Adélie penguins breed in large disjunct colonies on ice-free areas around the Antarctic continent. Comprising > 10 million birds, this species represents a dominant feature of the Antarctic ecosystem. The patchy distribution within a large geographical range, natal philopatry and a probable history of refugia, suggest that this species is likely to exhibit significant genetic differentiation within and among colonies. We present data from seven microsatellite DNA loci for 442 individuals from 13 locations around the Antarctic continent. With the exception of one locus, there was no significant genic or genotypic heterogeneity across populations. Pairwise FST values were low with no value > 0.02. When all colonies were compared in a single analysis, the overall FST value was 0.0007. Moreover, assignment tests were relatively ineffective at correctly placing individuals into their respective collection sites. These data reveal a lack of genetic differentiation between Adélie penguin colonies around the Antarctic continent, despite substantial levels of genetic variation. We consider this homogeneity in terms of the dispersal of individuals among colonies and the size of breeding groups and discuss our results in terms of the glacial history of Antarctica.     

Biogeographic traits and checklist of Antarctic demosponges

Summary The biogeography of Antarctic demosponges has been studied by dividing Antarctic and circumantarctic areas into geographic entities, and then assigning to these entities all recorded species according to literature reports. Correspondence analysis ordination based on the presence or absence of species shows the existence of a distinct Antarctic Faunistic Complex (AFC), including continental Antarctica, most of the Antarctic and circumantarctic islands and the Magellan area. Such a result has enabled us to drawup a checklist of 352 Antarctic demosponge species. Investigation of within-AFC patterns indicates that the continent is a highly homogeneous area, establishing closer relationships with the Scotia Arc and to a lesser extent with the Magellan region. The AFC has low specific affinities with the other circumantarctic regions (South Africa, temperate Australia and New Zealand), whereas at the generic level relationships appear more pronounced. This biogeographic pattern may lead us to suppose a common Gondwanian origin for Antarctic and circumantarctic sponge faunas, followed by differentiation due to Gondwana fragmentation. Antarctica moved towards polar latitudes and became progressively isolated, only maintaining active interchanges with South America. Climatic changes possibly induced intense processes of speciation in the Antarctic demosponge fauna, thus contributing to its differentiation.     

Invasive non‐native species likely to threaten biodiversity and ecosystems in the Antarctic Peninsula region

The Antarctic is considered to be a pristine environment relative to other regions of the Earth, but it is increasingly vulnerable to invasions by marine, freshwater and terrestrial non‐native species. The Antarctic Peninsula region (APR), which encompasses the Antarctic Peninsula, South Shetland Islands and South Orkney Islands, is by far the most invaded part of the Antarctica continent. The risk of introduction of invasive non‐native species to the APR is likely to increase with predicted increases in the intensity, diversity and distribution of human activities. Parties that are signatories to the Antarctic Treaty have called for regional assessments of non‐native species risk. In response, taxonomic and Antarctic experts undertook a horizon scanning exercise using expert opinion and consensus approaches to identify the species that are likely to present the highest risk to biodiversity and ecosystems within the APR over the next 10 years. One hundred and three species, currently absent in the APR, were identified as relevant for review, with 13 species identified as presenting a high risk of invading the APR. Marine invertebrates dominated the list of highest risk species, with flowering plants and terrestrial invertebrates also represented; however, vertebrate species were thought unlikely to establish in the APR within the 10 year timeframe. We recommend (a) the further development and application of biosecurity measures by all stakeholders active in the APR, including surveillance for species such as those identified during this horizon scanning exercise, and (b) use of this methodology across the other regions of Antarctica. Without the application of appropriate biosecurity measures, rates of introductions and invasions within the APR are likely to increase, resulting in negative consequences for the biodiversity of the whole continent, as introduced species establish and spread further due to climate change and increasing human activity.     

Die Wälder der Antarktis

Forests of Antarctica Antarctica is a continent of extremes, demanding a lot from the organisms living there. Antarctic macroalgae, as an important component of the coastal ecosystem of the Southern Ocean, have adapted their metabolism to permanent cold and to long periods of darkness. Due to the long cold‐water history and the isolation of the continent, a high number of endemic species developed in Antarctica. Antarctic macroalgae are important primary producers and serve as food for many organisms. Their more detailed investigation began relatively late and is far from complete. Climate change is visible in Antarctica as well, threatening the fragile ecosystem. Increased UV radiation e. g. can lead to changes in the depth zonation and increased temperature to changes in the geographical distribution of the individual macroalgal species.     

Dissemination and survival of non-indigenous bacterial genomes in pristine Antarctic environments

Continental Antarctic is perceived as a largely pristine environment, although certain localized regions (e.g., parts of the Ross Dependency Dry Valleys) are relatively heavy impacted by human activities. The procedures imposed on Antarctic field parties for the handling and disposal of both solid and liquid wastes are designed to minimise eutrofication and contamination (particularly by human enteric bacteria). However, little consideration has been given to the significance, if any, of less obvious forms of microbial contamination resulting from periodic human activities in Antarctica. The predominant commensal microorganism on human skin, Staphylococcus epidermidis, could be detected by PCR, in Dry Valley mineral soils collected from heavily impacted areas, but could not be detected in Dry Valley mineral soils collected from low impact and pristine areas. Cell viability of this non-enteric human commensal is rapidly lost in Dry Valley mineral soil. However, S. epidermidis can persist for long periods in Dry Valley mineral soil as non-viable cells and/or naked DNA.     

Prokaryotic Diversity in the Antarctic: The Tip of the Iceberg

In contrast to the rather limited diversity of plants and animals to be found in the Antarctic, the microbial diversity of this continent has been shown to be "surprisingly" diverse. Apparently barren soil and rock landscapes, as well as the numerous and diverse lakes found at the edges of the continent, harbor a range of prokaryotes which indicate that the extremely low temperatures which prevail seasonally are no obstacle to microbial colonization. Both direct cultivation methods and modern molecular genetic methods have contributed to our understanding of the range of organisms to be found. Cultivation based studies are often hampered by constraints inherent in the methods selected for the isolation of organisms. Molecular-based approaches do not suffer from the same cultivation-based biases, but other problems need to be taken into consideration. It has rarely been possible to combine both techniques in a single study, nor has it usually been possible to take the results and conclusions drawn from the study of one environment and apply this knowledge to a further series of experiments on the same environment. The Antarctic may be considered to be a geographically well isolated area to study. Comparison with other environments that may also be "isolated" from their surroundings (i.e., hot springs or highly saline lakes) allows parallels to be drawn. The conclusions drawn provide important insights into the way the Antarctic may have been colonized and the microbiota diversified. Much work still needs to be done beyond the simple task of making an inventory. The functioning of complex communities, such as mat systems, requires an understanding of the ecology of the systems, not only at the level of the whole system, but also the role of localized environments within that system. Perhaps these ecosystems have, in the absence of plant and animal communities, a role to play in the monitoring of polar climate change. The information available at present clearly indicates that the Antarctic is deserving of further study at the microbial level.     

Airborne Bacterial Populations Above Desert Soils of the McMurdo Dry Valleys,Antarctica

Bacteria are assumed to disperse widely via aerosolized transport due to their small size and resilience. The question of microbial endemicity in isolated populations is directly related to the level of airborne exogenous inputs, yet this has proven hard to identify. The ice-free terrestrial ecosystem of Antarctica, a geographically and climatically isolated continent, was used to interrogate microbial bio-aerosols in relation to the surrounding ecology and climate. High-throughput sequencing of bacterial ribosomal RNA (rRNA) genes was combined with analyses of climate patterns during an austral summer. In general terms, the aerosols were dominated by Firmicutes, whereas surrounding soils supported Actinobacteria-dominated communities. The most abundant taxa were also common to aerosols from other continents, suggesting that a distinct bio-aerosol community is widely dispersed. No evidence for significant marine input to bio-aerosols was found at this maritime valley site, instead local influence was largely from nearby volcanic sources. Back trajectory analysis revealed transport of incoming regional air masses across the Antarctic Plateau, and this is envisaged as a strong selective force. It is postulated that local soil microbial dispersal occurs largely via stochastic mobilization of mineral soil particulates.     

Evidence for a lacustrine faunal refuge in the Larsemann Hills, East Antarctica, during the Last Glacial Maximum

Aim  There is no previous direct evidence for the occurrence of lacustrine refuges for invertebrate fauna in Antarctica spanning the Last Glacial Maximum (LGM). In the absence of verified LGM lacustrine refuges many species are believed to result from Holocene dispersal from sub-Antarctic islands and continents further north. If freshwater lake environments were present throughout the LGM, extant freshwater species may have been associated with Antarctica prior to this glacial period. This study looked at faunal microfossils in a sediment core from an Antarctic freshwater lake. This lake is unusual in that, unlike most Antarctic lakes, the sediment record extends to c . 130,000 yr bp , i.e. prior to the LGM.
Location  Lake Reid, Larsemann Hills, East Antarctica (76°23' E; 69°23' S).
Methods  Palaeofaunal communities in Lake Reid were identified through examination of faunal microfossils in a sediment core that extended to c . 130,000 yr bp .
Results  Ephippia and mandibles from the cladoceran Daphniopsis studeri and loricae of the rotifer Notholca sp. were found at all depths in the sediment, indicating that these two species have been present in the lake for up to 130,000 years. Copepod mandibles were also present in the older section of the core, yet were absent from the most recent sediments, indicating extinction of this species from Lake Reid during the LGM.
Main conclusion  The presence of D. studeri and Notholca sp. microfossils throughout the entire Lake Reid core is the first direct evidence of a glacial lacustrine refugium for invertebrate animals in Antarctica, and indicates the presence of a relict fauna on the Antarctic continent.     

Fuegian plants in Antarctica: natural or anthropogenically assisted immigrants?

Two species of flowering plant of Fuegian montane provenance have been discovered on Deception Island in the maritime Antarctic, 950 km south of South America. Four individuals of Nassauvia magellanica and one of Gamochaeta nivalis (both Asteraceae) are growing robustly and in close proximity of each other on dry ash and scoria soil near a ruined whaling station which, in recent years, has been frequently visited by large numbers of ship-borne tourists. The Protocol on Environmental Protection to the Antarctic Treaty and the Management Plan for the island, designated an Antarctic Specially Managed Area, provide strict regulations for the conduct of visitors to this site and precautions against the accidental introduction of non-indigenous species. While their establishment on this remote volcanic island may have been anthropogenically mediated, natural immigration cannot be ruled out as both species produce seed adapted for wind-dispersal in their native Tierra del Fuego. The ecological consequences if one or both of these aliens spreads beyond their present restricted location are considered. While determined efforts are being made to implement rigorous biosecurity measures in Antarctica, current Antarctic Treaty policy on dealing with colonizing invasive alien species is indecisive and requires urgent action and clear recommendations.     

Protection of the antarctic ecosystem: A study in international environmental law

Abstract

The Antarctic region constitutes a fragile eco‐system closely related to the unique features of the physical environment of that continent. The Antarctic Ocean is central to the region's living systems, with krill as the ecological basis of life in the ocean and on land. So far, man's impact upon the Antarctic environment has been negligible, but there is concern that overharvesting of krill and possible marine pollution resulting from any future offshore oil exploration may undermine the krill basis of the Antarctic ecosystem. The legal status of Antarctica is largely determined by the 1959 Antarctic Treaty, and especially by the inner circle of the currently fourteen “consultative”; status signatories. These states have given high priority to ecological considerations by enacting a series of environmental and conservationist regulations, as well as two conventions, one protecting the Antarctic seals and the other marine living resources in general. Environmental regulations will form an important part of the legal regime for the exploration and exploitation of the Antarctic mineral resources, primarily oil and gas. The Antarctic Treaty framework does not legally bind nonsignatory states, but under general international law all states are bound to refrain from inflicting damage upon the planet's environment. Also, some marine pollution conventions apply to the Antarctic waters, and the 1982 U.N. Convention on the Law of the Sea comprehensively covers the protection and preservation of the marine environment of all oceans and seas. The preservation of the Antarctic environment will remain a high priority irrespective of what legal regime will govern Antarctica after 1991 when the Antarctic Treaty may, and most probably will, be subject to review.     

Conservation biogeography of the Antarctic

Aim

To present a synthesis of past biogeographic analyses and a new approach based on spatially explicit biodiversity information for the Antarctic region to identify biologically distinct areas in need of representation in a protected area network.

Location

Antarctica and the sub‐Antarctic.

Methods

We reviewed and summarized published biogeographic studies of the Antarctic. We then developed a biogeographic classification for terrestrial conservation planning in Antarctica by combining the most comprehensive source of Antarctic biodiversity data available with three spatial frameworks: (1) a 200‐km grid, (2) a set of areas based on physical parameters known as the environmental domains of Antarctica and (3) expert‐defined bioregions. We used these frameworks, or combinations thereof, together with multivariate techniques to identify biologically distinct areas.

Results

Early studies of continental Antarctica typically described broad bioregions, with the Antarctic Peninsula usually identified as biologically distinct from continental Antarctica; later studies suggested a more complex biogeography. Increasing complexity also characterizes the sub‐Antarctic and marine realms, with differences among studies often attributable to the focal taxa. Using the most comprehensive terrestrial data available and by combining the groups formed by the environmental domains and expert‐defined bioregions, we were able to identify 15 biologically distinct, ice‐free, Antarctic Conservation Biogeographic Regions (ACBRs), encompassing the continent and close lying islands.

Main conclusions

Ice‐free terrestrial Antarctica comprises several distinct bioregions that are not fully represented in the current Antarctic Specially Protected Area network. Biosecurity measures between these ACBRs should also be developed to prevent biotic homogenization in the region.