Patagonian Glaciers Research Articles

Patagonian and southern South Atlantic view of Holocene climate

We present a comprehensive 10Be chronology for Holocene moraines in the Lago Argentino basin, on the east side of the South Patagonian Icefield. We focus on three different areas, where prior studies show ample glacier moraine records exist because they were formed by outlet glaciers sensitive to climate change. The 10Be dated records are from the Lago Pearson, Herminita Península-Brazo Upsala, and Lago Frías areas, which span a distance of almost 100 km adjacent to the modern Icefield. New 10Be ages show that expanded glaciers and moraine building events occurred at least at 6120 ± 390 (n = 13), 4450 ± 220 (n = 7), 1450 or 1410 ± 110 (n = 18), 360 ± 30 (n = 5), and 240 ± 20 (n = 8) years ago. Furthermore, other less well-dated glacier expansions of the Upsala Glacier occurred between ~1400 and ∼1000 and ∼2300 and ∼2000 years ago. The most extensive glaciers occurred over the interval from ∼6100 to ∼4500 years ago, and their margins over the last ∼600 years were well within and lower than those in the middle Holocene. The 10Be ages agree with 14C-limiting data for the glacier histories in this area.We then link southern South American, adjacent South Atlantic, and other Southern Hemisphere records to elucidate broader regional patterns of climate and their possible causes. In the early Holocene, a far southward position of the westerly winds fostered warmth, small Patagonian glaciers, and reduced sea ice coverage over the South Atlantic. Although we infer a pronounced southward displacement of the westerlies during the early Holocene, these conditions did not occur throughout the southern mid-high latitudes, an important exception being over the southwest Pacific sector. Subsequently, a northward locus and/or expansion of the winds over the Patagonia-South Atlantic sector promoted the largest glaciers between ∼6100 and ∼4500 years ago and greatest sea ice coverage. Over the last few millennia, the South Patagonian Icefield has experienced successive century-scale advances superimposed on a long-term net decrease in size. Our findings indicate that glaciers and sea ice in the Patagonian-South Atlantic sector of the Southern Hemisphere did not achieve their largest Holocene extents over the last millennium. We conclude that a pattern of more extensive Holocene ice prior to the last millennium is characteristic of the Southern Hemisphere middle latitudes, which differs from the glacier history traditionally thought for the Northern Hemisphere.

Modeling modern glacier response to climate changes along the Andes Cordillera: A multiscale review

AbstractHere we review the literature preferentially concerned with modern glacier‐climate modeling along the Andes. We find a diverse range of modeling approaches, from empirical/statistical models to relatively complex energy balance procedures. We analyzed these models at three different spatial scales. First, we review global approaches that have included the Andes. Second, we depict and analyze modeling exercises aimed at studying Andean glaciers as a whole. Our revision shows only two studies dealing with glacier modeling at this continental scale. We contend that this regional approach is increasingly necessary because it allows for connecting the “average‐out” tendency of global studies to local observations or models, in order to comprehend scales of variability and heterogeneity. Third, we revise small‐scale modeling, finding that the overwhelming number of studies have targeted glaciers in Patagonia. We also find that most studies use temperature‐index models and that energy balance models are still not widely utilized. However, there is no clear spatial pattern of model complexity. We conclude with a discussion of both the limitations of certain approaches, as for example the use of short calibration periods for long‐term modeling, and also the opportunities for improved understanding afforded by new methods and techniques, such as climatic downscaling. We also propose ways to future developments, in which observations and models can be combined to improve current understanding of volumetric glacier changes and their climate causes.

Cold-Adapted Yeasts from Patagonia Argentina

The Patagonian Andes possess a great variety of glaciers, large temperate ice masses, and glacially formed water bodies. Most of these environments are included in protected areas characterized by low anthropogenic impact and minimal atmospheric pollution. Studies on occurrence of psychrotolerant (cold-adapted) and psychrophilic yeasts in these natural environments have allowed the characterization of native cold-adapted yeast communities, the description of six novel species, as well as description of the capability of these yeasts to produce extracellular enzymes, and other metabolites (carotenoids and mycosporines). Cold-adapted yeasts from Patagonian glaciers were able to hydrolyze natural polymers (casein, lipids, starch, pectin and carboxymethylcellulose) at low temperatures and some were able to produce photo-protective compounds. These results suggest a significant ecological role of these organisms as organic matter decomposers and nutrient cyclers, also reveal that some of these yeasts could be used for further metabolic, ecological and biotechnological studies. The objective of this review is to summarize all the findings related to cold adapted yeasts from glacial environments of the South Hemisphere (outside Antarctica), also to highlight the importance of continental ice masses from the microbiological perspective.
 Keywords: yeasts, psychrophilic, glaciers, extracellular enzymes.

Moraine-dammed lake failures in Patagonia and assessment of outburst susceptibility in the Baker Basin

Abstract. Glacier retreat since the Little Ice Age has resulted in the development or expansion of hundreds of glacial lakes in Patagonia. Some of these lakes have produced large (≥ 106 m3) Glacial Lake Outburst Floods (GLOFs) damaging inhabited areas. GLOF hazard studies in Patagonia have been mainly based on the analysis of short-term series (≤ 50 years) of flood data and until now no attempt has been made to identify the relative susceptibility of lakes to failure. Power schemes and associated infrastructure are planned for Patagonian basins that have historically been affected by GLOFs, and we now require a thorough understanding of the characteristics of dangerous lakes in order to assist with hazard assessment and planning. In this paper, the conditioning factors of 16 outbursts from moraine-dammed lakes in Patagonia were analysed. These data were used to develop a classification scheme designed to assess outburst susceptibility, based on image classification techniques, flow routine algorithms and the Analytical Hierarchy Process. This scheme was applied to the Baker Basin, Chile, where at least seven moraine-dammed lakes have failed in historic time. We identified 386 moraine-dammed lakes in the Baker Basin of which 28 were classified with high or very high outburst susceptibility. Commonly, lakes with high outburst susceptibility are in contact with glaciers and have moderate (> 8°) to steep (> 15°) dam outlet slopes, akin to failed lakes in Patagonia. The proposed classification scheme is suitable for first-order GLOF hazard assessments in this region. However, rapidly changing glaciers in Patagonia make detailed analysis and monitoring of hazardous lakes and glaciated areas upstream from inhabited areas or critical infrastructure necessary, in order to better prepare for hazards emerging from an evolving cryosphere.

What animals can live in cryoconite holes? A faunal review

AbstractDespite the large number of studies on glaciers, knowledge regarding biota in cryoconite holes is limited. Cryophilic animals are often neglected in ecological studies on glacial habitats, but are important for the functioning of these environments. Owing to climate change and the melting of polar ice, cryophilic fauna could be threatened in the near future. We provide the first comprehensive survey of invertebrates inhabiting the cryoconite holes of Alpine, Antarctic, Arctic, Himalayan and Patagonian glaciers. At present, the list of taxa is rather short and includes five phyla (Rotifera, Annelida, Tardigrada, Nematoda and Arthropoda). Owing to generally poor knowledge of the fauna of cryoconite holes, there could be more than the 25 currently known species. In addition, we present the geographical distributions of the taxa and discuss the diversity of invertebrates living in cryoconite holes and make predictions regarding the faunal diversity of these habitats.

Low level of genetic divergence between Harpagifer fish species (Perciformes: Notothenioidei) suggests a Quaternary colonization of Patagonia from the Antarctic Peninsula

The evolution of the marine benthic fauna of Antarctica has been shaped by geological and climatic atmospheric factors such as the geographic isolation of the continent and the subsequent installation of the Antarctic Circumpolar Current (ACC). Despite this isolation process, strong biogeographic links still exist between marine fauna from the Antarctic Peninsula and southern South America. Recent studies in different taxa have shown, for example, that shallow benthic organisms with long larval stages maintained contact after the physical separation of the continents and divergence may be associated with the intensification of the ACC in the late Miocene—early Pliocene. In this context, here we performed phylogenetic reconstructions and estimated the level of molecular divergence between congeneric species of Harpagifer, a marine notothenioid from the Antarctic Peninsula (Harpagifer antarcticus) and Patagonia (H. bispinis) using the mitochondrial control region. Phylogenies were reconstructed using Maximum Parsimony and Bayesian Inference, while the divergence time of H. antarcticus and H. bispinis was estimated following a relaxed Bayesian approach and assuming a strict molecular clock hypothesis. According to our estimation, the divergence between H. bispinis and H. antarcticus is more recent than expected if it was associated with the intensification of the ACC during the mid to late Miocene. We propose that climatic and oceanographic changes during the coldest periods of the Quaternary (i.e., Great Patagonian Glaciation, 1–0.9 Ma) and the northward migration of the Antarctic Polar Front may have assisted the colonization of southern South America by Harpagifer, from the Antarctic Peninsula via the Scotia Arc Islands.

Documentary and tree-ring evidence for a long-term interval without ice impoundments from Glaciar Perito Moreno, Patagonia, Argentina

Glaciar Perito Moreno (hereafter GPM; 50°30′S and 72°50′W) is a major outlet glacier from the South Patagonia Icefield. In contrast to most Patagonian glaciers, glaciological studies indicate that GPM has been advancing or remained stable during the 20th century. The advances periodically block Canal de los Témpanos creating an ice dam that impounds Brazo Sur–Rico arms of Lago Argentino, raising their elevations, until the water is released in a major outburst flood. Documentary evidence indicates that GPM reached the coast of Península de Magallanes for the first time in 1917. However, the first major damming and rupture event occurred in 1936, when the flooding of the shorelines of Brazo Sur–Rico killed thousands of Nothofagus trees, some still standing dead today. Naturalists who visited the area before 1936 described dense forests extending downslope to the shoreline, confirming the evidence of photographs from 1899 to 1928 displaying no standing dead trees by the shores. Estimates of the water level in Brazo Sur–Rico during each glacier damming vary but indicate values of 10–12 m for the 1936–1948 events and maxima of 23.5 m for the 1954–1956 ice dams. There is evidence for 21 ice dams between 1936 and 2013 with an average interval of c. four years from 1936 to 1988 and c. two years between 2004 and 2012. However, ring counts from standing Nothofagus dead trees along the flooded shorelines indicate that the oldest trees killed by drowning were at least 250 years old providing evidence of no major damming and rupture events from c. 1650 to 1936. These data indicate that damming and outburst events by GPM, world-renowned processes, did not occur for a long-term period before 1936. Unlike most glaciers in Patagonia, GPM was less extensive in the 1700s and 1800s than it is today.

Wind-driven modulation of warm water supply to a proglacial fjord, Jorge Montt Glacier, Patagonia

Projections of sea level rise due to ice loss from the land to the ocean have been hampered by a lack of understanding of the role the ocean is playing in glacier retreat, including the processes that contribute to the supply of warm water to the ice-ocean interface. Here shipboard, moored, and weather station data collected off Jorge Montt, a rapidly retreating glacier in Patagonia, are analyzed to understand the influence of wind forcing. During summer, synoptic-scale down-fjord wind events enhance an estuarine-like two-layer flow, increasing the inflow of oceanic deep water. During up-fjord wind events, the inflow of deep water is significantly reduced, and a three-layer exchange flow develops. Overall, along-fjord wind forcing is shown to modulate the inflow of warm water to the fjord by a factor of 2.5 The results sug- gest that local, channelized winds can be an important process modulating warm water supply and melting of tidewater glaciers.

Larval growth, condition and fluctuating asymmetry in the otoliths of a mesopelagic fish in an area influenced by a large Patagonian glacier

The interaction of melting glaciers and oceanic stormy weather produce a large variability in the water column structure of the coastal sea from the south Pacific coast of Patagonia. This area is largely utilized as spawning and nursery ground for the mesopelagic fish Maurolicus parvipinnis (Sternoptichyidae) during the austral spring. Using microstructure analysis of sagittal otoliths and fluctuating asymmetry of M. parvipinnis larvae from 4.0 to 11.4 mm standard length (SL), we studied the spatial distribution, the variation of larval condition and recent growth during October–November 2009 between 50°06′ and 52°45′S. Hydrographic conditions varied between 1.4 and 9.5°C, 14.6–33.5 units of salinity, 11.5–26.5 units of sigma-t and the stability ranged from 3.6 to 594 cycles h−1. Larval abundance ranged between 3.1 and 293.7 ind. 10 m−2, with the highest abundance associated with channels connecting fjords and the adjacent ocean. Larvae grew at a rate of 0.174 mm day−1, and those individuals collected in areas with intermediate water column stability (216–270 cycles h−1) showed greater body condition, measured as recent otolith growth index (ROGI). However, these larvae had a similar departure from ideal symmetry (FA1 residual model) as larvae collected in more stratified or well-mixed areas. Overall, larvae showed size-dependent asymmetry, sagittal otoliths of smaller larvae (< 7 mm SL) being more asymmetrical than those of large larvae (P < 0.05). This suggests that M. parvipinnis larvae may be experiencing the impacts of water column variability differently, as well as other ecological interactions at different larval stages. Thus, water column structure at hatching would be important for the survival of this fish inhabiting the Patagonian fjords of southern Chile.

Rapid retreat, acceleration and thinning of Glaciar Upsala, Southern Patagonia Icefield, initiated in 2008

AbstractThe Patagonia Icefields are characterized by a large number of outlet glaciers calving into lakes and the ocean. In contrast to the recent intensive research activities on tidewater glaciers in other regions, very few observations have been made on calving glaciers in Patagonia. We analysed satellite images of Glaciar Upsala, the third largest freshwater calving glacier in the Southern Patagonia Icefield, to investigate changes in its front position, ice velocity and surface elevation from 2000 to 2011. Our analyses revealed a clear transition from a relatively stable phase to a rapidly retreating and fast-flowing condition in 2008. The glacier front receded by 2.9 km, and the ice velocity increased by 20–50%, over the 2008–11 period. We also found that the ice surface lowered at a rate of up to 39 m a−1 from 2006 to 2010. This magnitude and the rate of changes in the glacier front position, ice velocity and surface elevation are greater than previously reported for Glaciar Upsala, and comparable to recent observations of large tidewater glaciers in Greenland. Our data illustrate details of a rapidly retreating calving glacier in Patagonia that have been scarcely reported despite their importance to the mass budget of the Patagonia Icefields.

Phylogenetic analysis and phylogeography of the tetraploid rodentTympanoctomys barrerae(Octodontidae): insights on its origin and the impact of Quaternary climate changes on population dynamics

The allotetraploid Tympanoctomys barrerae has a broad, patchy distribution around salt flats in western Argentina. To gain insights into its phylogenetic relationships, phylogeographical patterns, and origin, seven populations of T. barrerae and its allied taxa were studied through a 1075-bp fragment of cytochrome b and cytochrome oxidase I. Matrilineal phylogenetic relationships were explored with maximum likelihood and Bayesian approaches. The intraspecific genealogy was inferred by median-joining networks. The populational structure was assessed by molecular variance, and the demographic history through coalescence. The tree topology depicted sister-group relationship between Octomys mimax to the pair T. barrerae–Pipanacoctomys aureus, suggesting P. aureus belongs to the maternal lineage that gave rise to T. barrerae. High degrees of intrapopulational variation and the several instances of interpopulational polyphyly suggest range shifts and secondary contact. Consistent with the phylogenetic results, the network analysis revealed two haplotypic lineages depicting genetic admixtures unrelated to the current geographical distribution, and a deep split with the southernmost lineage of Chubut. The origin of T barrerae was estimated at approximately 2.52 Mya, whereas the divergence estimate for Chubut coincides with the end of largest Patagonian glaciation, at 1.47 Mya. Apparently, this population remained isolated during a northward Pleistocenic range shift. The historical demographic patterns of the lineages of T. barrerae fit with a contraction–expansion model coincident with Quaternary cycling events. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108, 453–469.

Younger Dryas and early Holocene age glacier advances in Patagonia

Reliable dating of Southern Hemisphere glacier fluctuations since the Last Glacial Maximum (LGM) is crucial to resolving debates about millennial-scale climate change. Here we present 10Be dates for lateral, valley-mouth and cross-valley moraines formed between the contemporary South American North Patagonian Icefield (NPI) and its LGM position in four separate valleys around 47°S. This is an area near the core of the precipitation-bearing southern westerly winds, where it is known that rapid shifts in climate occurred during Lateglacial times. The dates indicate that outlet glaciers advanced, or at least stabilised, to form large moraines east of an expanded NPI at 11.0 ± 0.5/11.2 ± 0.6, 11.5 ± 0.6, 11.7 ± 0.6 and 12.8 ± 0.7 ka (Putnam southern-hemisphere production rates and Dunai scaling scheme, assumed boulder erosion rate of 2 mm/ka). Four of these ages are statistically indistinguishable and probably represent a single, regional ice advance. The dates indicate that glaciers in Patagonia were larger during these times than at any point since the LGM and provide evidence in Patagonia for glacier advances around the time of the European Younger Dryas (12.9–11.7 ka) and into the very early Holocene. Although palaeoclimatic records from this area are often contradictory, these glacier advances were probably associated with a period of cooling or regionally increased precipitation related to the changes in the position of the southern westerly winds.

Plateau Icefield Dynamics in the Monadhliath Mountains, Central Highlands, Scotland

Reliable dating of Southern Hemisphere glacier fluctuations since the Last Glacial Maximum (LGM) is crucial to resolving debates about millennial-scale climate change. Here we present 10Be dates for lateral, valley-mouth and cross-valley moraines formed between the contemporary South American North Patagonian Icefield (NPI) and its LGM position in four separate valleys around 47°S. This is an area near the core of the precipitation-bearing southern westerly winds, where it is known that rapid shifts in climate occurred during Lateglacial times. The dates indicate that outlet glaciers advanced, or at least stabilised, to form large moraines east of an expanded NPI at 11.0 ± 0.5/11.2 ± 0.6, 11.5 ± 0.6, 11.7 ± 0.6 and 12.8 ± 0.7 ka (Putnam southern-hemisphere production rates and Dunai scaling scheme, assumed boulder erosion rate of 2 mm/ka). Four of these ages are statistically indistinguishable and probably represent a single, regional ice advance. The dates indicate that glaciers in Patagonia were larger during these times than at any point since the LGM and provide evidence in Patagonia for glacier advances around the time of the European Younger Dryas (12.9–11.7 ka) and into the very early Holocene. Although palaeoclimatic records from this area are often contradictory, these glacier advances were probably associated with a period of cooling or regionally increased precipitation related to the changes in the position of the southern westerly winds.

How lizards survived blizzards: phylogeography of theLiolaemus lineomaculatusgroup (Liolaemidae) reveals multiple breaks and refugia in southernPatagonia and their concordance with other codistributed taxa

Patagonia was shaped by a complex geological history, including the Miocene uplift of the Andes, followed by volcanism, marine introgressions, and extreme climatic oscillations during Pliocene-Pleistocene glaciation-deglaciation cycles. The distributional patterns and phylogenetic relationships of southern patagonian animals and plants were affected in different ways, and those imprints are reflected in the seven phylogeographic breaks and eight refugia that have been previously proposed. In this study, we estimated time-calibrated phylogenetic/phylogeographic patterns in lizards of the Liolaemus lineomaculatus group and relate them to historical Miocene-to-Pleistocene events of Patagonia and the previously proposed phylogeographic patterns. Individuals from 51 localities were sequenced for the mitochondrial marker (cyt-b) and a subsample of individuals from each mitochondrial lineage was sequenced for one nuclear (LDA12D) and one slow evolving mitochondrial gene (12S). Our analyses revealed strong phylogeographic structure among lineages and, in most cases, no signal of demographic changes through time. The lineomaculatus group is composed of three strongly supported clades (lineomaculatus, hatcheri and kolengh + silvanae), and divergence estimates suggested their origins associated with the oldest known Patagonian glaciation (7-5 Ma); subsequent diversification within the lineomaculatus clade coincided with the large Pliocene glaciations (~3.5 Ma). The lineomaculatus clade includes nine strongly genetically and geographically structured lineages, five of which are interpreted as candidate species. Our findings suggest that some Liolaemus lineages have persisted in situ, each of them in a different refugium, through several glaciation-deglaciation cycles without demographic fluctuations. We also summarize and update qualitative evidence of some shared phylogeographic breaks and refugia among plants, rodents and lizards.

Glacial, fluvial and volcanic landscape evolution in the Laguna Potrok Aike maar area, Southern Patagonia, Argentina

We describe the Pleistocene evolution of the landscape in the Laguna Potrok Aike area in southern Patagonia, Argentina, based on a geomorphological survey. Basaltic eruptions generated tablelands and scoria cones between the Late Miocene and Middle Pleistocene, and phreatomagmatic eruptions produced maars during Middle and Late Pleistocene time. The first glaciations during the Early Pleistocene generated a gently undulating to flat landscape that was affected by cryogenic processes; they are documented but not dated. Outwash surfaces indicate that the Greatest Patagonian Glaciation was multi-phased. The eruption that produced Potrok Aike maar truncated terrace levels dating to a Middle Pleistocene glaciation. The abundance of maars dating to this time may be linked to large amounts of water associated with meltwater streams and permafrost. The landscape in the Potrok Aike area has changed little since the Middle Pleistocene and only minor modifications of landforms have occurred due to cryogenesis, moderate fluvial incision, mass wasting and eolian activity.

Conflicting evolutionary patterns due to mitochondrial introgression and multilocus phylogeography of the Patagonian freshwater crab Aegla neuquensis.

BackgroundMultiple loci and population genetic methods were employed to study the phylogeographic history of the Patagonian freshwater crab Aegla neuquensis (Aeglidae: Decopoda). This taxon occurs in two large river systems in the Patagonian Steppe, from the foothills of the Andes Mountains east to the Atlantic Ocean.Methodology/Principal FindingsA nuclear phylogeny and multilocus nested clade phylogeographic analysis detected a fragmentation event between the Negro and Chico-Chubut river systems. This event occurred approximately 137 thousand years ago. An isolation-with-migration analysis and maximum-likelihood estimates of gene flow showed asymmetrical exchange of genetic material between these two river systems exclusively in their headwaters. We used information theory to determine the best-fit demographic history between these two river systems under an isolation-with-migration model. The best-fit model suggests that the Negro and the ancestral populations have the same effective population sizes; whereas the Chico-Chubut population is smaller and shows that gene flow from the Chico-Chubut into the Negro is four times higher than in the reverse direction. Much of the Chico-Chubut system appears to have only been recently colonized while the Negro populations appear to have been in place for most of the evolutionary history of this taxon.Conclusions/SignificanceDue to mitochondrial introgression, three nuclear loci provided different phylogeographic resolution than the three mitochondrial genes for an ancient fragmentation event observed in the nuclear phylogeny. However, the mitochondrial locus provided greater resolution on more recent evolutionary events. Our study, therefore, demonstrates the need to include both nuclear and mitochondrial loci for a more complete understanding of evolutionary histories and associated phylogeographic events. Our results suggest that gene flow between these systems, before and after fragmentation was through periodic paleolakes that formed in the headwaters region. Fragmentation between the Negro and Chico-Chubut systems was driven by the disappearance of these paleolakes during the Patagonian Glaciation.

Glaciers in Patagonia: Controversy and prospects

Lately, glaciers have been subjects of unceasing controversy. Current debate about planned hydroelectric facilities—a US$7‐ to $10‐billion megaproject—in a pristine glacierized area of Patagonia, Chile [Romero Toledo et al., 2009; Vince, 2010], has raised anew the matter of how glaciologists and global change experts can contribute their knowledge to civic debates on important issues. There has been greater respect for science in this controversy than in some previous debates over projects that pertain to glaciers, although valid economic motivations again could trump science and drive a solution to the energy supply problem before the associated safety and environmental problems are understood. The connection between glaciers and climate change—both anthropogenic and natural—is fundamental to glaciology and to glaciers' practical importance for water and hydropower resources, agriculture, tourism, mining, natural hazards, ecosystem conservation, and sea level [Buytaert et al., 2010; Glasser et al., 2011]. The conflict between conservation and development can be sharper in glacierized regions than almost anywhere else. Glaciers occur in spectacular natural landscapes, but they also supply prodigious exploitable meltwater.

Divergence between passerine populations from the Malvinas - Falkland Islands and their continental counterparts: a comparative phylogeographical study

Bursts of speciation have followed colonization of remote oceanic islands by diverse taxa, a process evidenced by island endemics around the world. The present study explores whether the Malvinas – Falkland Islands (MFI), a relatively understudied archipelago off the South Atlantic coast of Patagonia, harbour endemic genetic lineages of passerine birds. Nine passerine species nest regularly in the MFI (Cinclodes antarcticus, Muscisaxicola maclovianus, Troglodytes cobbi, Cistothorus platensis, Turdus falcklandii, Anthus correndera, Melanodera melanodera, Sturnella loyca, and Carduelis barbata). Mitochondrial DNA (cytochrome c oxidase I sequences) are used to quantify and compare divergence between insular and continental populations, finding genetic patterns to vary across these nine species. Most MFI passerines do not show significant genetic differentiation from continental populations, whereas C. platensis, M. melanodera, and T. falcklandii are modestly diverged. Finally, T. cobbi differes markedly from its closest continental relative Troglodytes aedon, a result that is confirmed using nuclear and vocal data. The study also identifies broadly divergent lineages within continental populations of C. platensis and T. aedon. Taken together, these results suggest that the land bird populations of the MFI were established at different times. Troglodytes cobbi is the oldest MFI land bird, splitting from continental T. aedon during the Great Patagonian Glaciation of the Pleistocene. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.

Current state of knowledge regarding South America wetlands and their future under global climate change

The exact size of the wetland area of South America is not known but may comprise as much as 20% of the sub-continent, with river floodplains and intermittent interfluvial wetlands as the most prominent types. A few wetland areas have been well studied, whereas little is known about others, including some that are very large. Despite the fact that most South American countries have signed the Ramsar convention, efforts to elaborate basic data have been insufficient, thereby hindering the formulation of a wetland-friendly policy allowing the sustainable management of these areas. Until now, the low population density in many wetland areas has provided a high level of protection; however, the pressure on wetland integrity is increasing, mainly as a result of land reclamation for agriculture and animal ranching, infrastructure building, pollution, mining activities, and the construction of hydroelectric power plants. The Intergovernmental Panel on Climate Change has predicted increasing temperatures, accelerated melting of the glaciers in Patagonia and the Andes, a rise in sea level of 20–60 cm, and an increase in extreme multiannual and short-term climate events (El Niño and La Niña, heavy rains and droughts, heat waves). Precipitation may decrease slightly near the Caribbean coast as well as over large parts of Brazil, Chile, and Patagonia, but increase in Colombia, Ecuador, and Peru, around the equator, and in southeastern South America. Of even greater impact may be a change in rainfall distribution, with precipitation increasing during the rainy season and decreasing during the dry season. There is no doubt that the predicted changes in global climate will strongly affect South American wetlands, mainly those with a low hydrologic buffer capacity. However, for the coming decades, wetland destruction by wetland-unfriendly development planning will by far outweigh the negative impacts of global climate change. South American governments must bear in mind that there are many benefits that wetlands bring about for the landscape and biodiversity as well as for humans. While water availability will be the key problem for the continent’s cities and agroindustries, intact wetlands can play a major role in storing water, buffering river and stream discharges, and recharging subterranean aquifers.

Accelerating shrinkage of Patagonian glaciers from the Little Ice Age (~AD 1870) to 2011

AbstractWe used Little Ice Age (LIA) trimlines and moraines to assess changes in South American glaciers over the last ~140 years. We determined the extent and length of 640 glaciers during the LIA (~AD1870) and 626 glaciers (the remainder having entirely disappeared) in 1986, 2001 and 2011. The calculated reduction in glacierized area between the LIA and 2011 is 4131 km2 (15.4%), with 660 km2 (14.2%) being lost from the Northern Patagonia Icefield (NPI), 1643km2 (11.4%) from the Southern Patagonia Icefield (SPI) and 306 km2 (14.4%) from Cordillera Darwin. Latitude, size and terminal environment (calving or land-terminating) exert the greatest control on rates of shrinkage. Small, northerly, land-terminating glaciers shrank fastest. Annual rates of area loss increased dramatically after 2001 for mountain glaciers north of 52° S and the large icefields, with the NPI and SPI now shrinking at 9.4km2a-1 (0.23% a-1) and 20.5 km2a-1 (0.15% a-1) respectively. The shrinkage of glaciers between 52° S and 54° S accelerated after 1986, and rates of shrinkage from 1986 to 2011 remained steady. Icefield outlet glaciers, isolated glaciers and ice caps south of 54° S shrank faster from 1986 to 2001 than they did from 2001 to 2011.