Observations in Hemichloris antarctica Tschermak-Woess & Friedmann (Chlorophyceae) and the occurrence of a second Hemichloris species, Hemichloris polyspora n. sp

The chlorococcalean genus Hemichloris is characterized by the possession of two chloroplasts per vegetative cell. The occurrence of a second species of the genus is reported (H. polyspora sp. nov.). Just as H. antarctica it grows cryptoendolithically in sandstone in Southern Victoria Land, Antarctica. In H. antarctica propagation by two autospores prevails over four, whilst in the new species H. polyspora in general four or eight (rarely 16 or 32) autospores are produced and Borodinella-stages do occur typically. Sexuality and zoosporulation do not exist in both species. Internal structures of chloroplasts can be observed by light microscopy more regularly in H. polyspora than in H. antarctica and under various conditions. Investigations of both Hemichloris species by transmission electron microscopy show them to go back to more or less extended assemblages of plastoglobuli. In both species the plastoglobuli are arranged around tubular inflations of thylakoids and apparently attached to the thylakoids. Keeping the cultures for three (even up to seven) months without light makes them survive and causes coming forth of the chloroplast structure throughout.     

An experimental assessment of the temperature responses of two sympatric seagrasses,Amphibolis antarctica and Amphibolis griffithii,in relation to their biogeography

Walker, D. I. and Cambridge, M. L. 1994. An experimental assessment of the temperature responses of two sympatric seagrasses, Amphibolis antarctica and Amphibolis griffithii, in relation to their biogeography.Seedlings of the viviparous seagrasses, Amphibolis antarctica (Labill.) Sonder & Aschers. and Amphibolis griffithii (Black) den Hartog, were grown in seawater cultures at temperatures of 10–30 °C. This temperature range exceeded the range of temperatures occurring in habitats where Amphibolis grows.All seedlings of both species survived at 15 °C, and all A. antarctica at 10 and 20 °C. There was some mortality at 25 °C, but more in A. griffithii than in A. antarctica. All seedlings showed marked senescence at 30 °C within 2 weeks, and all seedlings of both species were dead at this temperature in 6 weeks. Leaf production rates were different at different temperatures for each species, but were high across the 15–25 °C temperature range for both species. Given the time of release of seedlings from parent plants (winter), these results are consistent with the observed distribution of adult plants, and so the more restricted range of A. griffithii can be explained partially by its' response to temperature in culture. These results do not explain the absence of both Amphibolis species from the east coast of Australia, which may be a consequence of habitat availability.     

Medusae from Mcmurdo Sound,Ross Sea including the descriptions of two new species,Leuckartiara brownei and Benthocodon hyalinus

Seven species of medusae were collected using scuba equipment in neritic waters of McMurdo Sound, Ross Sea, Antarctica. Two species dominated, the narcomedusa Solmundella bitentaculata and the scyphomedusa Diplulmaris antarctica. Two new taxa were found. Leuckartiara brownei n. sp., a pandeid anthomedusa, has gonads with two major longitudinal folds in the interradii and several smaller perradially directed folds. Besides four large perradial tentacles, it has up to 28 short rudimentary tentacles. This is the first report of this genus from the Southern Ocean. Benthocodon hyalinus n. gen., n. sp., a rhopalonematoid trachymedusa, has 8 linear to sinuous gonads on the radial canals. The tubular manubrium is attached to a gastric peduncle. The tentacles are numerous (about 800) and grow successively. This is the second reported trachymedusa from the Ross Sea. Solmundella bitentaculata ate the thecosome pteropod Limacina helicina. Diplulmaris antarctica medusae fed on the gymnosome pteropod Clione antarctica and on L. helicina. The hyperiid amphipod Hyperiella dilatata, mostly females, was seen attached to the exumbrellas of both D. antarctica and S. bitentaculata. Up to 54 amphipods were seen on each D. antarctica medusa. The amphipods did no visible damage to the medusae.     

Size distribution of the amphipod Paramoera walkeri (Stebbing) along a depth gradient in Antarctica

Body weight distributions of the amphipod Paramoera walkeri colonizing litter-bags at different depths (2, 5, and 10 m) in Terra Nova Bay were compared. This species dominated the vagile benthic community and was found nearly alone at the shallow sites. At the deepest site it co-occurred with two smaller benthic species (the gastropod Laevilitorina antarctica and the isopod Munna antarctica) but still accounted for most of the animal biomass (80.2%). The frequency size-class distributions of the three dominant species were sharply distinct in a condition of stable coexistence. The total biomass was inversely related to the abundance of animals and diminished with increasing depth. Both species and size-class diversities were higher in deep water which offered a more diversified and favourable habitat than shallow water. At the shallow sites only the large size classes of P. walkeri were present. Differences in the mean individual ash content between samples support the hypothesis that different size individuals of P. walkeri segregated along the depth gradient on the basis of their metabolic requirements and the related ability to exploit sub-optimal environments.     

Mollugo viscosa sp. nov. (Molluginaceae), a segregate of M. brasiliensis from Minas Gerais in eastern Brazil

The new species Mollugo viscosa Thulin & Harley is described from Minas Gerais in eastern Brazil. It was previously part of the recently published M. brasiliensis Thulin & Harley, a species that was found to be non‐monophyletic in molecular phylogenetic analyses. Mollugo brasiliensis is here divided into a northern species (M. brasiliensis s.str.) in Bahia and a southern species (M. viscosa sp. nov.) in Minas Gerais. The new species differs from M. brasiliensis in its denser and more viscous indumentum, and in its distinctly smaller seeds with smaller tubercles and a smaller hilar peg, and from its sister species M. ulei by being a perennial herb with bisexual flowers.     

Characterization of rhizospheric bacteria isolated from Deschampsia antarctica Desv.

Deschampsia antarctica Desv. is the only gramineae capable of colonizing the Antarctic due to the region’s extreme climate and soil environment. In the present research, bacteria colonizing the rhizospheric soil of D. antarctica were isolated and characterized. The soil studies showed that D. antarctica possesses a wide spectrum of psychrotolerant bacteria with extensive and varied antibiotic resistance, as well as heavy metal tolerance. The bacterial strains isolated from the rhizosphere of D. antarctica also produced a diverse pattern of enzymes. Based on the strain identification with partial characterization of the 16S rRNA gene, the majority of the isolates correspond to different Pseudomonas species, and species of the genus Flavobacterium sp. and Arthrobacter sp. The isolated strains collected from this research constitute a unique collection for future, more detailed taxonomic analysis and physiological characterization, contributing to the search for potential biotechnological uses. These findings and others have great potential for developing new biotechnological products from Antarctic microorganisms.     

Epiphytic ferns and bryophytes of Tasmanian tree‐ferns: A comparison of diversity and composition between two host species

Abstract Ferns, bryophytes and lichens are the most diverse groups of plants in wet forests in south‐eastern Australia. However, management of this diversity is limited by a lack of ecological knowledge of these groups and the difficulty in identifying species for non‐experts. These problems may be alleviated by the identification and characterization of suitable proxies for this diversity. Epiphytic substrates are potential proxies. To evaluate the significance of some epiphytic substrates, fern and bryophyte assemblages on a common tree‐fern species, Dicksonia antarctica (soft tree‐fern), were compared with those on a rare species, Cyathea cunninghamii (slender tree‐fern), in eastern Tasmania, Australia. A total of 97 fern and bryophyte species were recorded on D. antarctica from 120 trunks at 10 sites, and 64 species on C. cunninghamii from 39 trunks at four of these sites. The trunks of C. cunninghamii generally supported fewer species than D. antarctica, but two mosses (particularly Hymenodon pilifer) and one liverwort showed significant associations with this host. Several other bryophytes and epiphytic ferns showed an affinity for the trunks of D. antarctica. Species assemblages differed significantly between both sites and hosts, and the differences between hosts varied significantly among sites. The exceptionally high epiphytic diversity associated with D. antarctica suggests that it plays an important ecological role in Tasmanian forests. Evidently C. cunninghamii also supports a diverse suite of epiphytes, including at least one specialist species.     

Conservation value of timber quality versus associated non-timber quality stands for understory diversity in Nothofagus forests

Conservation strategies of forested landscapes must consider biodiversity of the included site types, i.e. timber-quality forests and associated non-timber-quality stands. The objectives were to characterize forest overstory structure in timber-quality versus associated non-timber-quality stands; and to compare their understory communities. Six forest types were sampled in Nothofagus forests of Tierra del Fuego (Argentina): two timber-quality N. pumilio forests, and four associated non-timber-quality stands (edge, N. antarctica, wetlands and streamside forests). Overstory structure and understory vegetation (species richness, frequencies, cover and biomass) were characterized during spring and summer seasons. Analysis of variance and multivariates were carried out. Overstory structure differed across the site types, with higher tree size, canopy closure and tree volume in timber-quality stands. Fifty-one understory plant species were observed, but understory variables varied with site types, especially wetlands (highest native and exotic richness, cover and biomass, and 25% of exclusive species). Site types were grouped in three: N. antarctica stands, streamside stands and the other N. pumilio forests according to multivariate analysis. Forty three percent of plants were distributed in all site types, and all timber-quality forest understory species were present in some associated non-timber-quality stands. Timber-quality N. pumilio forests have a marginal value for understory conservation compared to associated non-timber-quality stands, because these last include all the plants observed in timber-quality forests and also possess many exclusive species. Therefore, protection of associated non-timber-quality stands during forest management planning could increase understory conservation at landscape level, and these could be better reserves of understory diversity than retentions of timber-quality stands.     

Phylogenetic relationships of Deschampsia antarctica (Poaceae): Insights from nuclear ribosomal ITS

Deschampsia antarctica E. Desv. is the only monocot in the Antarctic floristic zone. We evaluated the phylogenetic relationships of Deschampsia antarctica to other grasses using parsimony as the optimality criterion. Five different sets of gap, transversion and transitions costs were explored to analyze the effect of parameter choice on the phylogenetic results. Both internal transcribed spacers (ITS1 and ITS2) and the 5.8S subunit of nuclear ribosomal DNA were included in the analysis. A total of 43 species were analyzed including seven species of Deschampsia. Deschampsia antarctica forms a well supported group with five species of Deschampsia. Deschampsia does not appear monophyletic as D. flexuosa (L.) Trin. is not included in this clade. The clade to which D. antarctica belongs is sister to some Aveneae in all analyses. This study is the first contribution that evaluates the phylogenetic position of D. antarctica in relation to other species of Deschampsia.     

SYSTEMATIC NOTES ON BIRDS OF THE CAPE PROVINCE: PART III.—PARISOMA SUBCAERULEUM (Vieillot): PART IV.—ANTHUS RICHARDI (Vieillot): PART V.—GALERIDA MAGNIROSTRIS Stephens

Fraser, M. W. 1984. Foods of Subantarctic Skuas on Inaccessible Island. Ostrich 55: 192–195.

Analysis of over 140 prey remains and 500 pellets of Subantarctic Skuas Catharacta antarctica collected from a site on Inaccessible Island. Tristan da Cunha, between October 1982 and January 1983 showed that 13 species of bird and one invertebrate were taken. Storm Petrels (Oceanitidae) made up 52% of the items recorded, Broadbilled Prions Pachyptila vittata 21%, and Common Diving Petrel Pelecanoides urinatrix 15%. Landbirds were rarely taken.     

Materials for the fungus flora of Japan (56)Mariannaea camptospora andM. elegans var.punicea from Japan

One additional species and a variety ofMariannaea, M. camptospora andM. elegans var.punicea, were recorded for the first time in Japan.Mariannaea camptospora formed two types of conidiophores. One type was characterized by simple verticillate phialides sometimes with punctuate walls at the base, producing long oblique conidial chains, and symmetrical spindle-shaped conidia. The other type was characterized by more crowded and shorter phialides with small conidial droplets and hemispherical to concave smaller conidia.Mariannaea elegans var.punicea was characterized by distinct red purple pigmentation in agar media. (55): Udagawa, S. and Uchiyama, S., Mycoscience41: 263–267, 2000.     

Pseudonotohymena antarctica n. g., n. sp. (Ciliophora,Hypotricha), a New Species from Antarctic Soil

A new soil ciliate, Pseudonotohymena antarctica n. g., n. sp., from King George Island, Antarctica, is described based on live observation, protargol impregnation, and its 18S rRNA gene. The new genus Pseudonotohymena is morphologically similar to the genus Notohymena Blatterer and Foissner 1988 in the following characteristics: 18 fronto‐ventral‐transverse cirri, a flexible body, undulating membranes, dorsomarginal kineties, and the number of cirri in the marginal rows. However, Pseudonotohymena differs from Notohymena particularly in the dorsal ciliature, that is, in possessing a nonfragmented dorsal kinety (vs. fragmented). In addition, the molecular phylogenetic relationship of the new species differs from that of Notohymena species. On the basis of the morphological features, the genetic data, and morphogenesis, we establish P. antarctica n. g., n. sp. In addition, the cyst morphology of this species is described.     

Antarctic macrolichen modifies microclimate and facilitates vascular plants in the maritime Antarctica – a reply to Casanova‐Katny et al. (2014)

In a current article in the Journal of Vegetation Science, Casanova‐Katny et al. addressed a comment about an article by Molina‐Montenegro et al., which demonstrated the climate modification induced by the macrolichen Usnea antarctica and its role as facilitator. They provided useful corrections concerning species identification and pointed out several issues that, in their view, weakened our study. They indicated that the role of U. antarctica as a facilitative species in the maritime Antarctica is merely philosophical and has no ecological relevance. In this commentary, we argue why these critiques are unsubstantial, and provide evidence that the macrolichen can modify the microclimate, ameliorating the harsh conditions prevailing in Antarctica, establishing positive interactions and eventually facilitating vascular species. Thus, the macrolichen U. antarctica would act as a ‘nurse species’, playing a key role in structuring the maritime Antarctic plant community.     

Contrasting thermal acclimation of leaf dark respiration and photosynthesis of Antarctic vascular plant species exposed to nocturnal warming

Leaf respiration and photosynthesis will respond differently to an increase in temperature during night, which can be more relevant in sensitive ecosystems such as Antarctica. We postulate that the plant species able to colonize the Antarctic Peninsula – Colobanthus quitensis (Kunth) Bartl. and Deschampsia antarctica Desv. – are able to acclimate their foliar respiration and to maintain photosynthesis under nocturnal warming to sustain a positive foliar carbon balance. We conducted a laboratory experiment to evaluate the effect of time of day (day and night) and nocturnal warming on dark respiration. Short (E₀ and Q₁₀) and long‐term acclimation of respiration, leaf carbohydrates, photosynthesis (A_sat) and foliar carbon balance (R/A) were evaluated. The results suggest that the two species have differential thermal acclimation respiration, where D. antarctica showed more thermosensitivity to short‐term changes in temperature than C. quitensis. Experimental nocturnal warming affected respiration at daytime differentially between the two species, with a significant increase of R₁₀ and A_sat in D. antarctica, while no changes on respiration were observed in C. quitensis. Long thermal treatments of the plants indicated that nocturnal but not diurnal respiration could acclimate in both species, and to a greater extent in C. quitensis. Non‐structural carbohydrates were related with respiration in C. quitensis but not in D. antarctica, suggesting that respiration in the former species is likely controlled by total soluble sugars and starch during day and night, respectively. Finally, foliar carbon balance was differentially improved under warming conditions in Antarctic plants by different mechanisms, with C. quitensis deploying respiratory acclimation, while D. antarctica increased its A_sat.     

Feeding preferences of the sandhopper Orchestoidea tuberculata: the importance of algal traits

Factors such as nutritional quality and the secondary metabolite content of food resources have been shown to influence the feeding behavior of herbivores in many marine habitats. For intertidal macroalgae consumers on sandy beaches, the influence of these factors on feeding behavior and the consequences on their performance is poorly understood. In this study, we evaluated the relationships of nutritional quality, chemical defenses (phlorotannins), and the structure of three macroalgal species that form the bulk of imported wrack subsidies to beaches in southern Chile, with the feeding behavior, absorption efficiency, and growth rate of the talitrid amphipod Orchestoidea tuberculata, one of the most abundant organisms in this environment. The amphipods preferred Durvillaea antarctica over Lessonia nigrescens and Macrocystis pyrifera when simultaneously offered fresh pieces of each alga. Similar results were observed when artificial food made of dry powdered algae of each species was provided, suggesting that the structure of these three algae did not influence preference. The performance of amphipods when reared on a diet of a single algal species matched feeding preferences; higher growth rates were observed in treatments with the preferred alga, D. antarctica. These results imply that D. antarctica is a superior food item for O. tuberculata when compared to L. nigrescens or M. pyrifera, and also that the alga’s intrinsic quality (i.e., not structure) may influence dietary preference in these consumers. The higher content of proteins and carbohydrates found in D. antarctica may explain why this macroalga represents better quality food for O. tuberculata. Phlorotannin content did not have obvious negative effects on diet choice or growth, as D. antarctica, the alga with greater content of these secondary metabolites, was preferred and associated with higher growth rates of O. tuberculata. However, it is necessary to emphasize that the low phlorotannins concentrations registered in the three macroalgae species examined in this study, may not have been sufficient to deter O. tuberculata. When the amphipods were fed with each alga individually, they consumed significantly higher quantities of D. antarctica, which suggests that O. tuberculata did not eat more to compensate for the lower nutritional quality of the other algal species in order to maintain growth. Nor was compensation for lower food quality achieved by increasing absorption efficiency. Our results imply that the composition of the macroalgae arriving on the beach can significantly affect the performance and subsequent life history traits of O. tuberculata and by extension other amphipod species.     

Lecanoric acid,a secondary lichen substance with antioxidant properties from <Emphasis Type="Italic">Umbilicaria antarctica</Emphasis> in maritime Antarctica (King George Island)

Eight lichen species, Cetraria aculeata, Cladonia furcata, Pseudephebe pubescens, Sphaerophorus globosus, Stereocaulon alpinum, Umbilicaria antarctica, Usnea antarctica and Usnea aurantiacoatra, were collected from King George Island, maritime Antarctica, for the evaluation of antioxidant activities. Anti-linoleic acid peroxidation activity, free radical scavenging activity, reducing power and superoxide anion scavenging activity were assessed of methanol and acetone extract of the lichens in vitro. Extract of Umbilicaria antarctica, Cladonia furcata, Sphaerophorus globosus and Usnea antarctica were found to have strong in vitro antioxidant properties. In general, acetone extract exhibited stronger activities than methanol extract. The activity-guided bioautographic TLC and HPLC analysis demonstrated that lecanoric acid was the main antioxidant compound in the acetone extract of Umbilicaria antarctica, the most potent antioxidant lichen species among the test species. The results suggested that several Antarctic lichens and their substances can be used as novel bioresources of natural antioxidants.     

Predatory behavior of giant Antarctic sea spiders (Colossendeis) in nearshore environments

Pycnogonids in the genus Colossendeis are found in the deep sea and Southern Ocean. Although the genus contains the largest and most conspicuous species of sea spiders, little is known about their ecology or behavior. We documented two species feeding on a variety of benthic and pelagic invertebrates during three diving field seasons at McMurdo Station, Antarctica. Individuals of one species, Colossendeis megalonyx, fed on a variety of pelagic organisms, particularly the pteropod Clione antarctica. We used video to document rapid capture of individuals of C. antarctica by captive specimens of C. megalonyx in the laboratory, and we suggest that, at least in the nearshore environment, pelagic invertebrates are an important food source for this and potentially other pycnogonid species.     

Size scaling of photophysiology and growth in four freshly isolated diatom species from Ryder Bay,western Antarctic peninsula

Diatoms are one of the dominant groups in phytoplankton communities of the western Antarctic Peninsula (WAP). Although generally well‐studied, little is known about size dependent photophysiological responses in diatom bloom formation and succession. To increase this understanding, four Antarctic diatom species covering two orders of magnitude in cell size were isolated in northern Marguerite Bay (WAP). Fragilariopsis sp., Pseudo‐nitzschia cf. subcurvata, Thalassiosira cf. antarctica, and Proboscia cf. alata were acclimated to three different irradiances after which photophysiology, electron transport, carbon fixation, and growth were assessed. The small species Fragilariopsis sp., Pseudo‐nitzschia cf. subcurvata, and large species Proboscia cf. alata showed similar photoacclimation to higher irradiances with a decrease in cellular chlorophyll a and an increase in chlorophyll a specific absorption and xanthophyll cycle pigments and activity. In contrast, pigment concentrations and absorption remained unaffected by higher irradiances in the large species Thalassiosira cf. antarctica. Overall, the small species showed significantly higher growth rates compared to the large species, which was related to relatively high light harvesting capacity and electron transport rates in the smaller species. However, photophysiological responses related to photoinhibition and photoprotection and carbon fixation showed no relationship with cell size. This study supports the dominance of small diatoms at low irradiances during winter and early spring, but does not provide photophysiological evidence for the dominance of large diatoms during the phytoplankton bloom in the WAP. This suggests that other factors such as grazing and nutrient availability are likely to play a major role in diatom bloom formation.     

Karyological studies in <Emphasis Type="Italic">Deschampsia antarctica</Emphasis> Desv. (Poaceae)

Deschampsia antarctica Desv. (Poaceae), known as Antarctic hairgrass, is the only grass species and one of the two vascular plant species native to Antarctica and it is a valuable source for gene discovery associated with freezing-tolerance. In this work the karyotype of D. antarctica collected near Jubany Antarctic Base was reported for the first time. This species presents a chromosome number of 2n = 2x = 26, with karyotypic formula 10m + 6sm + 8st + 2t. The nucleolar organizer region is located in the short arm in one of the submetacentric pairs forming a terminal satellite. Aneusomaty, a phenomenon already reported in the genus, was detected during this study. The cytogenetic information, together with the recent phylogenetic data will be useful for breeding strategies in agronomically valuable crops.     

Age structure and dynamics of Patagonian beech forests in Torres del Paine National Park,Chile

This study documents the stem size and age-structure in forests dominated by different species of Nothofagus in Torres del Paine National Park (51° S), in the Chilean Patagonian region. We also explored the relationship between the various types of Nothofagus forest and postglacial succession. Pioneer stands on moraine fields 1–2 km of the glacier front are dominated by Nothofagus betuloides and Nothofagus antarctica. Moraines appear to be first colonized by the evergreen N. betuloides, followed within 5–7 years by deciduous N. antarctica. Nothofagus antarctica may replace the former species and develop monospecific stands on glacial valleys. Most trees in the N. antarctica stand studied were older than 40 years and floods may cause a significant mortality of young trees. Recruitment from seed seems to be infrequent. Old-growth stands dominated by deciduous Nothofagus pumilio occupy more stable substrates, and probably represent the last stage of postglacial succession. This long-lived tree species had recorded ages over 200 years. The canopy of N. pumilio forests appears to be a mosaic of even-aged, old-growth patches. We propose that regeneration episodes follow the blowdown of a large portion of the canopy, with long intervals with little or no regeneration. Windstorms may be an important force influencing the regeneration of N. pumilio. Exogenous disturbances, such as floods and windstorms, are an integral part of the forest cycle in the Patagonian region.