SUMMER DISTRIBUTION OF PELAGIC BIRDS OFF THE COAST OF ARGENTINA

Eighteen species of sea–birds were observed from CSS 'Hudson' in the South Atlantic between the Rio de la Plata and Tierra del Fuego in late January and late February 1970. Major feeding areas were noted off Mar del Plata, the Valdes Peninsula and Tierra del Fuego, Argentina, the first two in rich modified or unmodified water of the subantarctic Falkland Current, associated with upwelling. The southernmost area had most birds, the northernmost fewest. A temperate–latitude assemblage including Yellow–nosed Albatross and Cory's Shearwater occurred off Mar del Plata in warmed water of subantarctic (Falkland Current) origin. South of 39°S these two species were replaced by Black–browed Albatross and Great Shearwater in cold offshore water of the Falkland Current. Off the Valdes Peninsula Black–browed Albatross, Great and Sooty Shearwaters, White–chinned Petrels and family groups of Magellanic Penguins occurred near the edge of highly–productive water of the Falkland Current. The largest feeding area, east of Tierra del Fuego, had Magellanic and Rockhopper Penguins, Great Shearwaters, King Cormorants, South American Terns and jaegers, but no oceanographic information is available. At 50°S prions and diving petrels appeared for the first time, marking a possible oceanographic discontinuity or proximity to colonies on the Falkland Islands. Several common species of the South Atlantic were not seen on the transect including Cape Pigeon, Southern Fulmar, Soft–plumaged Petrel, Schlegel's Petrel and Pediunker. Kelp Gull, South American Tern, Manx Shearwater and jaegers were rare or absent far from land. New southern limits for the western South Atlantic Ocean were established for Cory's and Manx Shearwaters, and the Great Shearwater was observed for the first time in Chilean waters.     

Human colonization of the central territory of Argentina: design matrix models and craniometric evidence

In this study we test several hypotheses about the peopling of the central territory of Argentina, archaeologically known as Sierras Centrales, by testing the association between four alternative models of the peopling of the area and cranial morphological variation through distance and matrix correlation analyses. Our results show that the ancient inhabitants of Sierras Centrales demonstrated close morphological similarities with the Patagonian and Tierra del Fuego populations. Moreover, the correlation and partial correlation analyses suggest that the peopling of the Sierras Centrales most likely took place as a migratory wave proceeding from the present area of Northeastern Argentina, and continued southward to Patagonia and Tierra del Fuego.     

Nest site selection of the Kelp gull (Larus dominicanus) in the Beagle Channel, Tierra del Fuego, Argentina

Nest site selection of Kelp gulls Larus dominicanus breeding in Conejo and Bridges islands, Tierra del Fuego, Argentina, was assessed between 14 and 30 December 2005 to describe variability in nest site features and determine variables affecting nest choice. Fourteen microhabitat variables were quantified at 40 nest sites and at 40 random points in each island during the late incubation stage. Nests at the two colonies were placed on different kinds of substrates across areas with varying degrees of cover provided either by rocks or vegetation. Despite the variability observed in nest site features, rock cover and rocky substrates were the main factors determining nest site selection. At Conejo Island, nest sites presented more rock cover, less percentage of vegetation cover and of vegetation debris substrate, and were placed further from the nearest vegetation in comparison to random points. Similarly, gulls at Bridges Island selected nest sites with more rock cover which were placed mainly on rocky and vegetation substrates. This contrasts with results previously obtained in Argentina, which indicated that vegetation is a key factor influencing Kelp gull nest site selection. Over 80% of the nests at both study colonies were placed on the northern slopes of the islands, relatively more protected from the strong prevailing southwest winds, and nests at both colonies tended to be more protected on their southern side either by rocks or vegetation. Results obtained at Tierra del Fuego confirm the plasticity of microhabitat use by Kelp gulls, and their ability to take advantage of nesting sites according to availability and local environmental factors.     

Mallomonas fuegiana (Synurophyceae), a new species of silica scaled chrysophytes from Tierra del Fuego, Argentina

Vigna, M. S. & Kristiansen, J. 1995. Mallomonas fuegiana (Synurophyceae), a new species of silica scaled chrysophytes from Tierra del Fuego, Argentina. — Nord. J. Bot. 15: 439–442. Copenhagen. ISSN 0107–055X.
During the research project "Cryptogamic Flora of Tierra del Fuego", a new species of Mallomonas has been found. It is described here as M. fuegiana , and is placed in the section Torquatae , close to Mallomonas schwemmlii and M. dickii .     

Trichomycetes living in the guts of aquatic insects of Misiones and Tierra del Fuego, Argentina

Fourteen species of Trichomycetes living in the guts of aquatic insects are reported from two provinces of Argentina, Misiones and Tierra del Fuego. Twelve of the species belong to the Harpellales and two are Amoebidiales. Five harpellid species are reported from Misiones in the extreme northeast of the country (Genistellospora homothallica, Harpella tica, Smittium culisetae, Smittium sp., Stachylina sp.) and seven are from Tierra del Fuego, the southern tip of South America (H. meridianalis, Glotzia sp., S. culicis, S. cellaspora, S. imitatum, Stachylina minima, Penella simulii). Insect hosts all were immature stages of Culicidae, Simuliidae, Chironomidae, Ceratopogonidae (Insecta: Diptera), and Ephemeroptera and Plecoptera. The lower diversity of Trichomycetes found at Misiones, which has a subtropical climate and rainforest vegetation, was due possibly to the warmer temperatures of the water (15-24 C), compared to the colder streams of Tierra del Fuego (9-15 C), with forests and steppes as typical vegetation.     

12. Bipolarity in the distribution of silica-scaled chrysophytes

An investigation of the chrysophyte flora of Tierra del Fuego (Argentina), 54–55 °S., has shown a high degree of similarity with the flora of climatically comparable regions on the northern hemisphere. All the Fuegian species (except two endemic to South America) also occur on the northern hemisphere—some are more or less cosmopolitan, others have pronounced bipolar distributions. Species in common with other Antarctic regions such as Tasmania are all cosmopolitan, and none of the interesting species originally described from Tasmania occur in Tierra del Fuego. Thus the Fuegian flora appears to be mainly climatically determined and a special Antarctic chrysophyte flora does not exist.     

Holocene glaciations in the Ema Glacier valley, Monte Sarmiento Massif, Tierra del Fuego

Investigations carried out in the Ema Glacier valley, Tierra del Fuego, on the eastern side of Monte Sarmiento Massif, enable the recognition of five Holocene glacial events. The oldest glacial advance deposited the so-called external moraines of Ema Glacier, with a probable occurrence between 6000 and 5000 14 C y BP without discarding the potential for these deposits to be from Lateglacial time. The remaining four readvances built up a complex inner moraine system named informally internal moraines of Ema Glacier. The oldest recognized till unit that constitutes this proximal moraine system was deposited shortly before 3135 14 C y BP, when glaciolacustrine sedimentation took place during glacier recession. Subsequent glacial advances accumulated till at about 1288 14 C y, shortly after 695 14 C y, and between 379 14 C y and 60 y BP. This chronology of Holocene glacier events coincides with and is well complemented by the one established by other authors for Fiordo Pía at Cordillera Darwin, 75 km to the east. The Ema-Pía chronology is used to calibrate tentatively a series of moraine belts previously identified in the mountain ranges adjacent to Ushuaia, 150 km SE of the surveyed region. A comparative chart shows that the chronological data obtained for the neoglacial readvances in Tierra del Fuego are in accordance with those for the southern Patagonian Andes further north. It follows that the Holocene behavior of the glaciers in the Andean region of Tierra del Fuego and southern Patagonia is essentially a response to the same regional climate change.     

The galaxiid fishes of South America

Four galaxiid species in two genera are recognized and redescribed from the South American region, viz., Galaxias maculatus (Jenyns), G. platei Steindachner, G. globiceps Eigenmann, and Brachygalaxias bullocki (Regan). All of these species occur in Chile, but G. maculatus and G. platei occur also east of the Andean divide in Argentina, in Tierra del Fuego, and the Falkland Islands. The two species east of the Andes are regarded as having crossed the mountains from west to east. The galaxiids, together with Aplochiton (family Aplochitonidae) and Geotria (family Petromyzonidae), are regarded as southern circumpolar elements in the South American freshwater fish fauna, distinct from the group of species of Amazonian derivation (trichomycterids, Nematogenys, Diplomystes, Cheirodon , etc.) and distinct also from oceanic derivatives, either recent (atherinids) or ancient (serranids).     

Population status of Andean Condors in central and southern Bolivia

Andean Condors (Vultur gryphus) are a Near Threatened species that was formerly distributed along the entire length of the Andes from western Venezuela to Tierra del Fuego. Populations have been severely reduced north of Peru, but several thousand Andean Condors still exist in the southern portion of their range in Argentina and Chile. Little is known, however, about the size of the Andean Condor population in the central part of their range in Peru and Bolivia. From June to September 2012, we used feeding stations to attract Andean Condors and estimate the size and structure of the population in the eastern Andes of central and southern Bolivia. We estimated a minimum population of 253 condors, an adult male‐to‐female ratio of 1:0.6, an immature male‐to‐female ratio of 1:0.9, and an adult‐to‐immature ratio of 1:1.1. At our five survey areas, estimated abundance ranged from 15 to 100 condors per area. Males outnumbered females in three areas and the opposite was true in two areas. Our estimated adult‐to‐immature ratio, overall and in each area, suggests that the populations could be reproducing at a high rate. As previously observed in other Andean Condor populations, skewed sex ratios could be associated with differences between sexes and age classes in habitat selection. Although our results suggest that Bolivian populations of Andean Condors are still reasonably large, population monitoring is urgently needed, including use of feeding stations throughout the entire Bolivian range of the species and intensive searches for roosting and nesting sites.     

Biological and behavioral determinants of fertility in Tierra del Fuego

The reproductive history of 182 women in postreproductive life or near menopause from the Chilean part of Tierra del Fuego was traced back by means of familial interviews. These postmenopausal women represent the population since almost the beginning of the settlement, and their reproductive years were spent on the island. Path analysis was applied to analyze fertility determinants of these women and to propose a complex model of interconnections among factors. The reproductive history of these women is characterized by a long fertile span, a short childbearing period, and low fertility. Age at menarche is relatively late, and the age of the women at first birth is mainly determined by their late age at marriage. The use of contraception is related to both spacing and stopping behaviors. The late age of women at marriage, the rhythm of conception, and practices of contraception are proposed as the main determinants of fertility in Tierra del Fuego.     

Winter migration of rockhopper penguins (Eudyptes c. chrysocome) breeding in the Southwest Atlantic: is utilisation of different foraging areas reflected in opposing population trends?

Rockhopper penguins (Eudyptes chrysocome) breeding on Staten Island, Argentina, were satellite tracked in 2002 and 2003 during the onset of their winter migration. After their moult, the dispersal of 24 birds was monitored for a mean period of 50.0±40.3 days. Birds travelled at a mean velocity of 3.1±1.1 km/h. The mean minimum distance travelled was 1,640±1,425 km; the maximum distance to the colony was generally less than 1,000 km, although one bird travelled more than 2,000 km from the colony. The penguins dispersed over an area totalling about 1.3 million km2, ranging from 50 to 62°S and from 49°W in the Atlantic to 92°W in the Pacific, and covering polar, sub-polar and temperate waters in oceanic regions as well as shelf waters. Despite the very wide dispersal, both temporally and spatially, two important wintering grounds for rockhopper penguins from Staten Island could be identified, both located over shelf regions: one extended from Staten Island to the north along the coast of Tierra del Fuego up to the Magellan Strait; the other was located over the Burdwood Bank, an isolated extension of the Patagonian Shelf to the south of the Falkland Islands. The Drake Passage also appeared to be an important area for wintering penguins, although dispersal was far more widely spread. Comparison with data obtained during winter from rockhopper penguins originating from the Falkland Islands showed that the area off the coast of Tierra del Fuego was used more or less exclusively by birds from Staten Island, whereas the Burdwood Bank was shared with penguins coming from southern colonies in the Falkland Islands. The implications of these findings are discussed with regard to (a) opposing population trends of rockhopper penguins in the Southwest Atlantic, and (b) the urgent need to establish adequate conservation measures for species and habitat protection.     

Mitochondrial DNA variation and population structure of Commerson’s dolphins (<Emphasis Type="Italic">Cephalorhynchus commersonii</Emphasis>) in their southernmost distribution

The Commerson’s dolphin, Cephalorhynchus commersonii, is found in shallow waters of the continental shelf off the eastern coast of South America between 40°S and 56°S. This species is taken incidentally in artisanal gillnet fisheries, especially along the shallow coastline of northern Tierra del Fuego and southern Patagonia. The biological importance of by-catch is likely to be underestimated if the boundaries of subpopulations are not properly defined. Here, we report on the sequence variation of the mitochondrial DNA control region of the Commerson’s dolphin from five areas defined in Tierra del Fuego, Argentina and Chile, to provide a preliminary assessment of population structure where conservation efforts are most needed. A 466 bp fragment of the mitochondrial DNA control region was sequenced from 196 samples of skin, teeth and bone, defining 20 haplotypes from 17 polymorphic sites. Nucleotide (π = 0.40%) and haplotype (h = 0.807) diversity were low compared to some other odontocete populations, but similar to that of other species of this genus. Genetic differentiation evaluated through analyses of molecular variance (AMOVA) showed significant overall differences among areas within Tierra del Fuego (Φ _ST  = 0.059, P < 0.01). An analysis of sex-specific population structure suggested that the dispersal rates of both females and males are low, indicative of females displaying greater site fidelity. The results from mtDNA control region sequences alone revealed significant differentiation among studied areas, which should be considered as independent management units. We recommend that the impact of localized gillnet mortalities should be managed on a local scale in these areas of Tierra del Fuego.     

Taxonomy, variation, and relationships in the Hordeum parodii group (Poaceae)

The Hordeum parodii group contains three species, viz. H. parodii Covas (6x), H. tetraploidum Covas (4x), and H. fuegianum Bothmer, Jacobsen, et Jørgensen, sp. nov. (4x). The former two species mainly occur in C and S Argentina, while H. fuegianum is native to Tierra del Fuego. All three species are probably of alloploid origin. Morphological, isoenzyme variation and cytogenetic data are presented.     

Craniometric analysis in groups from tierra del Fuego/Patagonia and the peopling of the south extreme of the Americas

Five large craniometric samples from extinct tribes (Selk’nam, Kawéskar and Yámana) from Tierra del Fuego and from Patagonia have been analyzed through multivariate techniques. The purpose was to test the hypothesis of one or two different migration waves in the peopling of the south extreme of South America. A cluster analysis has been made, using the squared Euclidean distance as a measure of proximity, and the UPGMA and neighbor joining algorithms as a tree building method. The robustness of the branches has been assessed with bootstrap analysis through 100 random iterations of the original data set. Results show that, despite their cultural differences, the three hunter-gatherer groups. from Tierra del Fuego tend to cluster together, indicating a similar morphological pattern. This suggests that geographic distance (in latitudinal sense) is the main factor that influenced the differentiation of the human groups from Tierra del Fuego and Patagonia, from a single ancestral population.     

PATTERNS AND PROCESSES IN THE DEVELOPMENT OF THE HIGH ANDEAN FLORA

Previous work has suggested that the floras of the separate regions of the high Andes are the products of disparate geographical, ecological, and geological factors. Among the important factors that differ among the regions are distances from source areas of propagules, climates, and differential effects of Pleistocene glaciations. To ascertain the relative importances of these factors in shaping the modern floras, and to test hypotheses about the causes of observed generic diversity patterns, models of abundances of species per genus were tested against data from three samples representing the major vegetation zones of the high Andes (páramo, puna, and austral alpine). While originally proposed for intraspecific phenomena, abundance models (broken stick, log normal, geometric series, and log series) appear to be applicable to supraspecific taxa and were used to assess alternative hypotheses. Potential sources of genera now present in the sample areas were compared, and coefficients of similarity were computed between these samples and between each of them and two North American high-elevation floras. Propagule types in the three Andean samples were also scored to see if methods of fruit dispersal differed. Results showed that all areas fit the geometric series model if abundance plots of ranked genera were compared, but these results were heavily influenced by the large number of genera represented by only one species. Both the puna and austral alpine samples fit the log series models, indicating that the habitats of these areas are relatively uniform and that arrival of propagules was random over time. The lack of a fit of the Colombian data to the log series or log normal models is due primarily to a large number of species-rich genera relative to other areas. These findings support the hypothesis that there has been a pronounced level of autochthonous speciation in the Colombian Andes relative to other areas. Coefficients of similarity at the generic level show that a given flora is most similar to that of the nearest sample area within the same continent. However, the floristic similarity between Tierra del Fuego and the high mountains of Colorado is as high as that between the Tierra del Fuego sample and the neighboring Argentina sample, indicating that similarities in climate can be as important as distance in determining the composition of some Andean floras.     

Testing the utility of Nothofagus pumilio for dating a snow avalanche in Tierra del Fuego, Argentina

In the subalpine forest zone, snow avalanches are potentially stand-devastating disturbances. Historical data regarding past avalanches in Argentina are scarce, but sufficiently old trees can show signs of past avalanche episodes that can be accurately dated using dendrochronological methods. Tree-ring analysis has not yet been used for dating avalanches in Tierra del Fuego, even though these disturbances are important to the dynamics of these southern forests. In this study, we evaluated the quality of Nothofagus pumilio for dating the avalanche that took place in the Martial Valley in 1976. Tree-ring data, complemented with vegetation analysis, was used to study the avalanche path. The dendrochronological study consisted of the analysis of wood samples taken from living trees located on the boundary between the undisturbed forest and the avalanche path. The vegetation analysis compared the forest structure within the avalanche path with the unaffected nearby forest. Wood scars and the abrupt increase in tree growth confirmed the occurrence of an avalanche event in 1976 in the Martial Valley of Tierra del Fuego, Argentina. The vegetation structure within the avalanche path was considerably different than that of the undisturbed forest. We found an important relationship between sapling abundance within the avalanche path and their distance from the undisturbed forest and their altitudinal position. The dendrochronological dating obtained in this research confirmed that the techniques and methodology used for N. pumilio in this study can be successfully applied for dating other avalanches that lack historical information.     

Epidemiological surveillance of cystic echinococcosis in rural population of Tierra del Fuego, Argentina, 1997-2006

Cystic echinococcosis (CE) is the most prevalent zoonosis in Tierra del Fuego. In 1997, ulrasonography (US) was selected as the method of choice for the development of population surveys for epidemiological surveillance and early diagnosis in rural population. The aim of this work was to present the results of the epidemiological surveillance of CE by means of US in rural population of Tierra del Fuego, Argentina between 1997 and 2006. The ultrasonographic diagnostic was realized once a year. The population was stratified in children (4 to 17 years) and adults. From each individual, name, age, sex, actual residence and origin were registered. The images compatible with cysts were graded according to location, number and characteristics. A total of 1400 rural inhabitants were examined for CE. From the total of studied individuals, 27 (1.9%) exhibited images compatible with cysts on the abdominal ultrasound scan. Thirteen of these persons were finally diagnosed as having CE. The overall prevalence of CE was 0.9%. This value is in accordance with the decrease in the prevalence observed in the definitive host and the intermediate hosts (sheep and cattle). The absence of cases in children during the studied period, evidence no transmission of the disease to humans in the recent past.     

Gastrointestinal helminths of Commerson's dolphins Cephalorhynchus commersonii from central Patagonia and Tierra del Fuego.

The stomachs and intestines of 9 Commerson's dolphins incidentally caught in trawl nets in central Patagonia and 23 stranded on beaches in Tierra del Fuego were surveyed for helminth parasites. A total of 267 individuals belonging to 4 species of parasites (1 nematode, 3 digeneans) were found in the dolphins from the first area: Anisakis sp. (larvae type 1 = A. simplex), Braunina cordiformis, Hadwenius sp. and Pholeter gastrophilus. In the Tierra del Fuego dolphins, 142 specimens belonging to 3 species (2 nematodes, 1 digenean, 1 cestode) were found: A. simplex, Hadwenius sp. and Strobilocephalus triangularis. Only 2 of the helminth species were shared in the 2 study areas, A. simplex and Hadwenius sp., and both were more common in central Patagonia. Among the species, A. simplex was most prevalent and abundant in both study areas. In Tierra del Fuego, adults of A. simplex appeared in only 1 host. Hadwenius sp., P. gastrophilus and S. triangularis are new host records for Commerson's dolphin. Species diversity and species richness were low in both study areas. Helminth communities were more diverse in central Patagonia (t = 1.97, df = 258, p < 0.05) and species richness was higher in central Patagonia (S = 4). No differences in diversity were observed between females and males of central Patagonia (t = 1.97, df = 139, p < 0.05) and between females of central Patagonia and Tierra del Fuego. The results may suggest some differences in habitat use, diet and sex between Commerson's dolphin populations in the 2 study areas.     

A new species of Oxelytrum Gistel (Coleoptera, Silphidae) from southern Argentina, with a key to the species of the genus

A new species of the forensically interesting genus Oxelytrum Gistel (Coleoptera, Silphidae), Oxelytrum selknan, is described from Santa Cruz and Tierra del Fuego provinces, Argentina. The new species resembles Oxelytrum biguttatum (Philippi) in outer aspect, but has different male genitalia, in particular a median lobe longer than the paramera. All the described species of Oxelytrum have the median lobe shorter than the paramera. The internal sac, as far as it could be reconstructed from dry-pinned specimens, also shows differences between the two species. A key to the species of Oxelytrum is given and illustrated.