Southernmost Chile Research Articles

The ecological roles of the European rabbit in the Magellanic/Fuegian ecosystem of southernmost Chile

The European rabbit has invaded numerous ecosystems worldwide, but rarely steppes. Since its various introduction attempts into the ecosystems of the Magallanes/Fuegian region, the rabbit has become a key player, interacting with species at different trophic levels and generating impacts on ecosystems. To better understand the role of the rabbit in steppe and scrub ecosystems, we characterised the food web in the Magallanes/Fuegian region to understand the identity of their interacting species, the mechanisms and complexities of their interactions to demonstrate that rabbit management may become more complex than just controlling a single species. Based on a bibliographic review and wildlife specialists’ opinions, we built the Magellanic/Fuegian food web, evaluated their topological properties and performed a rabbit extinction simulation to assess the possible short-term ecological mechanisms operating in the community. We found that the network had 206 nodes (64% native, 13% exotic, and 22% mixed) and 535 links among nodes. The European rabbit was the most connected node of the food web, had the second largest dietary breadth, and ranked as the seventh prey item with more predators. A rabbit extinction simulation shows a possible release of herbivory pressure on plants, including that on several native plants (e.g., Gunnera tinctoria, Pratia repens, Gavilea lutea, Tetroncium magellanicus), and a possible release of competition for some herbivores that share resources with the rabbit (e.g., Ovis aries, Lama guanicoe, Bos taurus). Although rabbit predators have a broad and generalist diet, some such as the native Galicitis cuja, could face a 20% reduction in their trophic width and could intensify predation on alternative prey. These results show that the European rabbit is strongly embedded in the Magellanic/Fuegian ecosystem and linked to several native species. Therefore, rabbit management should consider ecosystem approaches accompanied by monitoring programs on native fauna and experimental pilot studies on native flora to conserve the Chilean Patagonia community.

Understanding ground-nesting habitat selection by waterbirds to prioritize invasive predator control on islands

The introduction of carnivores to islands affects the conservation status of native prey. For two decades, American mink (Neogale vison) has expanded its distribution in the sub-Antarctic archipelago of Austral Patagonia, while preying on nests of solitary ground-nesting birds. Here, upland geese (Chloephaga picta) and flightless steamer ducks (Tachyeres pteneres) are naïve to such predation risk because of the lack of native terrestrial predators. We used nest occupancy models to reveal preferred breeding habitats of those two ground-nesting waterbirds to prioritize areas for future mink control programs. We searched for nests along 80 transects on Navarino Island, southernmost Chile, and 11 transects on 10 nearby islets (3 ± 2.9 ha). Our results showed that islets were essential for breeding in comparison to the main island (5.3 nests/km versus 0.8 nests/km, respectively). The occupancy models revealed that islets were particularly important for flightless steamer ducks, endemic to western Patagonia. As breeding habitat, upland geese preferred medium-dense shrubland, and flightless steamer ducks preferred rocky coastlines. Nest detection was negatively affected by dense vegetation and, in the case of the upland geese, towards the end of the survey. Ten camera traps (n = 385 trap nights) revealed mink presence on all islets, highlighting their capacity to swim in cold water, up to 340 m distance from the main island. We conclude that islets represent breeding refuges for ground-nesting waterbirds and therefore advocate allocating resources for mink control during the warm season on islets. We also provide predictive maps of nesting habitat preference of upland geese and flightless steamer ducks for conservation managers to focus their often scarce human and financial resources on areas critical for breeding. Finally, we argue that detection probability should be an integral part of bird breeding studies, which can be methodologically achieved through targeting transects, not nests, as sample units.

Glacial geomorphology between the Gran Campo Nevado and Estrecho de Magallanes, Chile (52–53°S, 73°W)

ABSTRACT We present the first extensive high-resolution glacial geomorphic map west of the Andean Cordillera in southernmost Chile (52.8–53.1°S, 73.0–73.9°W). The map extends over 1565 km2 and is based on high-resolution satellite images and aerial photographs. At selected locations, the remotely mapped geomorphology was corroborated by field observations. The study area is dominated by glacial erosional landforms (77%) over depositional landforms (23%), with published submarine depositional landforms having been included (e.g. moraines). Glacial drift, kettle kame topography and lateral and frontal moraines form the primary depositional landforms and sediment associations. Glacial cirques, wide U-shaped valleys, whalebacks, roches moutonnées and scoured bedrock characterize most of the mapped area. The spatial distribution of whalebacks and roches moutonnées in the study area indicates a lack of lithological control on their formation and a warm-based, dynamic ice velocity and thickness regime during Patagonian Ice Sheet cover and retreat during the last glacial cycle.

Revision of the short-necked Cretaceous plesiosaurians from New Zealand

Polycotylidae Cope, 1869 is a clade of short-necked plesiosaurians that achieved a cosmopolitan distribution by the Late Cretaceous. Here, the material previously referred to Polycotylidae/Pliosauridae from the Upper Cretaceous of New Zealand is reviewed, concluding that only 2.4% and 7.7% respectively of the total plesiosaurians specimens recovered in these formations (late Campanian-early Maastrichtian Tahora Formation and Campanian-Maastrichtian Conway Formation) belong to Polycotylidae. This proportion is similar to that recorded in upper Campanian-Maastrichtian levels of the Allen, Los Alamitos and La Colonia formations, northern Patagonia (Argentina) and southernmost Chile, but contrasts with the coeval absence of polycotylids in Campanian-Santonian levels of Antarctica and central Chile. These new results improve our knowledge about the representation of Weddellian polycotylids and underline the relative scarcity of Campanian-Maastrichtian records in the Weddellia Province.

Petrology and quartz grain microtextures of marine shoreline sands from the Punta Arenas area, southernmost Chile and King George Island, Antarctica and implications for their depositional history

Petrology and quartz grain microtextures of marine shoreline sands from the Punta Arenas area, southernmost Chile and King George Island, Antarctica and implications for their depositional history

Hydrothermal Exploration of the Southern Chile Rise: Sediment‐Hosted Venting at the Chile Triple Junction

AbstractWe report results from a hydrothermal plume survey along the southernmost Chile Rise from the Guamblin Fracture Zone to the Chile Triple Junction (CTJ) encompassing two segments (93 km cumulative length) of intermediate spreading‐rate mid‐ocean ridge axis. Our approach used in situ water column sensing (CTD, optical clarity, redox disequilibrium) coupled with sampling for shipboard and shore based geochemical analyses (δ3He, CH4, total dissolvable iron (TDFe) and manganese, (TDMn)) to explore for evidence of seafloor hydrothermal venting. Across the entire survey, the only location at which evidence for submarine venting was detected was at the southernmost limit to the survey. There, the source of a dispersing hydrothermal plume was located at 46°16.5’S, 75°47.9’W, coincident with the CTJ itself. The plume exhibits anomalies in both δ3He and dissolved CH4 but no enrichments in TDFe or TDMn beyond what can be attributed to resuspension of sediments covering the seafloor where the ridge intersects the Chile margin. These results are indicative of sediment‐hosted venting at the CTJ.

Distribution of coccoliths in surface sediments across the Drake Passage and calcification of <i>Emiliania huxleyi</i> morphotypes

Abstract. The Southern Ocean is experiencing rapid and profound changes in its physical and biogeochemical properties that may influence the distribution and composition of pelagic plankton communities. Coccolithophores are the most prolific carbonate-producing phytoplankton group, playing an important role in Southern Ocean biogeochemical cycles. However, knowledge is scarce about the record of (sub-)fossil coccolith assemblages in the Southern Ocean, which constitute invaluable indicators for palaeoenvironmental reconstructions. This study investigates coccolith assemblages preserved in surface sediments of southernmost Chile and across the Drake Passage that were retrieved during R/V Polarstern expedition PS97. We focused on the coccolith response to steep environmental gradients across the frontal system of the Antarctic Circumpolar Current and to hydrodynamic and post-depositional processes occurring in this region. We used statistical analyses to explore which environmental parameters influenced the coccolith assemblages by means of cluster and redundancy analyses. We specifically assessed the morphological diversity of the dominant taxa, i.e. Emiliania huxleyi, emphasizing biogeographical variability of morphotypes, coccolith sizes and calcite carbonate mass estimations. High coccolith abundances and species diversity compared to studies in the same area and in other sectors of the Southern Ocean occur, with a high species richness especially south of the Polar Front. While the surface sediments offshore Chile and north of the Polar Front provide suitable material to reconstruct overlying surface ocean conditions, further factors such as temporary thriving coccolithophore communities in the surface waters or transport of settling coccoliths via surface and bottom currents and eddies influence the (sub-)fossil coccolith assemblages south of the Polar Front. Additionally, deeper samples in the southern part of the study area are particularly affected by selective carbonate dissolution. We identified five E. huxleyi morphotypes (A, A overcalcified, R, B/C and O) and estimated coccolith carbonate masses on the basis of scanning electron microscope images. E. huxleyi morphologies reflect diverging biogeographical distributions, trending towards smaller and lighter coccoliths to the south and emphasizing the importance of documenting those morphologies in relation to changing environmental conditions to assess their response to projected environmental change in the Southern Ocean.

Bizarre tail weaponry in a transitional ankylosaur from subantarctic Chile.

Armoured dinosaurs are well known for their evolution of specialized tail weapons-paired tail spikes in stegosaurs and heavy tail clubs in advanced ankylosaurs1. Armoured dinosaurs from southern Gondwana are rare and enigmatic, but probably include the earliest branches of Ankylosauria2-4. Here we describe a mostly complete, semi-articulated skeleton of a small (approximately 2 m) armoured dinosaur from the late Cretaceous period of Magallanes in southernmost Chile, a region that is biogeographically related to West Antarctica5. Stegouros elengassen gen. et sp. nov. evolved a large tail weapon unlike any dinosaur: a flat, frond-like structure formed by seven pairs of laterally projecting osteoderms encasing the distal half of the tail. Stegouros shows ankylosaurian cranial characters, but a largely ancestral postcranial skeleton, with some stegosaur-like characters. Phylogenetic analyses placed Stegouros in Ankylosauria; specifically, it is related to Kunbarrasaurus from Australia6 and Antarctopelta from Antarctica7, forming a clade of Gondwanan ankylosaurs that split earliest from all other ankylosaurs. The large osteoderms and specialized tail vertebrae in Antarctopelta suggest that it had a tail weapon similar to Stegouros. We propose a new clade, the Parankylosauria, to include the first ancestor of Stegouros-but not Ankylosaurus-and all descendants of that ancestor.

Celebrating Women in Paleobotany: A Tribute to Edith L. Taylor—Introduction and Dedication

Celebrating Women in Paleobotany: A Tribute to Edith L. Taylor—Introduction and Dedication

Potential mineral resources of the Chilean offshore: an overview

The seabed included in the Chilean Exclusive Economic Zone (EEZ) has proper conditions to originate and host different ore deposits, but its geological knowledge is scarce and scattered. The existent studies are very limited in terms of geochemical and mineralogical analyses. The most significant non-energetic mineral resources off Chile correspond to Fe-Mn nodules and crusts, phosphorite deposits, gold and titanium placer deposits and massive sulfide deposits. Fe-Mn nodule sites occur in abyssal plains and seamounts, and around volcanic islands, at depths from 2,890 to 4,332 m, and can contain important concentrations of Cu and Ni (up to 1.38% Cu+Ni) and Co (up to 0.53%). Co-rich Fe-Mn crust occurrences have been reported around the Rapanui and Salas y Gómez islands, with Cu+Ni contents up to 0.3%. Phosphorite sites occur in Holocene sedimentary beds of the continental shelf off Peru and northern Chile, with P2O5 average content of 22.6%. Gold placer deposits are found in beaches and channels of southern Chile and may extend offshore probably in submarine canyons. Titanium placer deposits have been evaluated in different beaches of Chile and could also be continued offshore. Platinum anomalies have been found in channels and bays of southernmost Chile. No samples of Volcanogenic Massive Sulfide (VMS) mineralization are known in the Chilean EEZ to date. However, samples of hydrothermal vents, with potential for polymetallic VMS type mineralization, have been recovered around the Rapanui Island, and several seamount and volcanic island chains indicate favorable conditions for formation and preservation of these ore-deposits. The available geological information on the seabed of the Chilean EEZ is insufficient to estimate the real potential of its non-energetic mineral resources.

Breutelia tundrae (Bartramiaceae), a new moss species from the Cape Horn Archipelago (Prov. Antártica Chilena, Chile)

Breutelia tundrae is newly described from southernmost Chile. It seems to be restricted to the Magellanic tundra, and thus its name. It is distinguished by the expanded, appressed leaf base, often with lax cells at the shoulders, widest well above the insertion, with only scant alar differentiation. The upper laminal cells are long-rectangular, very thick-walled, and porose. It seems closest to the northern Andean B. karsteniana, which is similar in aspect. However, B. tundrae differs from B. karsteniana in having leaves slightly more spreading when dry (or moist) and somewhat shorter. In addition, the laminal cells are shorter, broader, even thicker-walled and more porose. The projecting prorulae are slightly taller than those in B. karsteniana. The species are best differentiated by differences in their leaf bases. In B. karsteniana they are spreading from the insertion and widest immediately above the insertion in the area of the extensively differentiated alar cells; in B. tundrae the leaf base is appressed to the stem, almost always orange, and widest well above the insertion and there are only 1–3 differentiated alar cells. A key to the species of Breutelia in the Cape Horn Archipelago is provided.

Campanian-Maastrichtian and Eocene stratigraphic architecture, facies analysis, and paleoenvironmental evolution of the northern Magallanes Basin (Chilean Patagonia)

The stratigraphic architecture and environmental evolution of the Cerro Guido-Rio de las Chinas Valley Complex contains the upper Cretaceous to Eocene record of the Magallanes/Austral Basin, located in southernmost Chile. This retroarc foreland basin contains a significant record of early Cretaceous to Miocene biogeographic and environmental changes that occurred in high paleolatitudes after the break-up of Gondwana. Using 37 stratigraphic sections, we generated a 1390 m thick stratigraphic column, which was used to developed sedimentary facies and an analysis of sequence stratigraphy. Results show, in general, aggradation composed of six third-order depositional sequences each delimited by an erosive surface. A lowstand systems tract developed above each surface, represented by alluvial environments similar to braided fluvial systems, and coastal plain environments, with the development of meandering fluvial and lacustrine systems. Above the lowstand tract, the transgressive systems tract is composed of a shallow marine environment with foreshore, shoreface, and offshore systems. A highstand systems tract was observed in one sequence, and is represented by shallow marine facies. The extensive outcrop in the studied area contains a diverse and voluminous fossil record, containing fossilized invertebrates (bivalves, gastropods, bryozoans, and brachiopods), vertebrates (hadrosaurs, ornithischians, sauropods, theropods, birds, mammals, frogs, turtles, plesiosaurs, mosasaurs, and sharks), and plants (wood, leaves impressions, flowers, pollen, and spores). Thus, this study broadens the understanding of the South American-Antarctic connection during the late Cretaceous-Paleogene, through a diverse fossil record and study of the paleoenvironmental evolution of this high-latitude basin.

Glacial geomorphology of the Marinelli and Pigafetta glaciers, Cordillera Darwin Icefield, southernmost Chile

ABSTRACTThis paper presents a glacial geomorphological map relating to two rapidly receding glaciers in the Cordillera Darwin Icefield. The Marinelli marine-terminating glacier and Pigafetta freshwater-terminating glacier are selected to represent different glacial regimes producing different geomorphological records under similar climatic conditions. We combine mapping from satellite and aerial imagery with fieldwork, updating limited previous mapping. The map reveals two principal glacial landform assemblages: (1) a marine-terminating system, dominated by the formation of a large arcuate terminal morainic complex, glaciolacustrine landforms (shorelines) and extended ice-contact topography in the Fiordo Marinelli area; and (2) an assemblage of sequential frontal moraine ridges and outwash plains that formed when the former land-terminating Pigafetta glacier retreated from the Bahía Ainsworth area. Finally, the map is designed as a basis for future chronological campaigns and to enable a refined reconstruction of the glacial history of these two glaciers in a climatologically significant part of the world.

An update on morphology and distribution of Ruppia filifolia (Philippi) Skottsberg in the Magellan region, southern Chile

Vegetative and reproductive morphology of Ruppia filifolia (Philippi) Skottsberg is updated and completed by examining natural specimens, reviewing the literature, comparing to specimens from different locations and generating new iconography of the species from waters across the Magellan region, Subantarctic Chile. We expand current knowledge on morphology (rhizome-root, branching, foliage, inflorescence, fruit, habits) and geographical distribution of R. filifolia in Austral South America, with the addition of six new localities for the taxon in Chile. Our results are used to identify this macrophyte and to distinguish it from R. maritima after some authors reported their co-occurrence in the southern tip of South America, leading to taxonomic confusion. Also, the new information on R. filifolia distribution in the Magellan region broadens the research on a neglected seagrass. In the Southern Hemisphere, contrary to global trends of seagrass ecosystems decline, new niche distributions are opening up in southernmost Chile, reflecting environmental changes.

Retreat of the Cordillera Darwin icefield during Termination I

During the last glaciation, the Cordillera Darwin icefield expanded northward toward the Straits of Magellan, eastward across Isla Grande de Tierra del Fuego and through Canal Beagle, and south and west across the numerous islands of southernmost Chile. Deglaciation commenced at ~18 ka during Termination I. Alpine glaciers in the Fuegian Andes also likely retreated at that time. Radiocarbon ages from the interior regions of Cordillera Darwin suggest ice in at least some locations had retreated close to its present-day limit as early as ~16.5 ka. The most likely cause for such rapid ice retreat was rising atmospheric temperatures at the start of Termination I.

Dactylospora inopina (Lecanorales), a new biotrophic parasite on Radula (Hepaticae) from the Cape Horn Archipelago, Chile

The lecanoralean fungus Dactylospora inopina Dobbeler & W.R.Buck sp. nov. (Dactylosporaceae) is described on the liverwort Radula spp. (Radulaceae, Jungermanniales) based on collections from southernmost Chile. The species is characterized by small, warty apothecial ascomata, polysporous asci and subcylindrical, four-celled, brown ascospores. Polyspory has previously been known only in five lichenicolous species having two-celled spores. The combination of polyspory and phragmospory is a new character in the genus. The parasite grows by a mycelium within the host cell walls and does not cause visible damage. Dactylospora inopina is one of the relatively few hepaticolous discomycetes known so far. Apart from two Octosporella species with perithecia-like apothecia it is the first one on the large genus Radula, which is a good host for pyrenocarpous ascomycetes.

First record of a common endolithic lichenized fungus species Catenarina desolata Schting, Sgaard & Elvebakk. from James Ross Island (Antarctic Peninsula)

Catenarina desolata, a species which was recently described from southernmost Chile is reported from the Antarctica for the first time. Although it was described as lichenicolous, in James Ross Island, many specimens belonging to this species have non lichenicolous habit. The dubious reports of Caloplaca aff. anchonphoenicon from James Ross Island actually belongs to Catenarina desolata. Collections were evaluated using morphological, anatomical and molecular characteristics (nrITS). The morphological and ecological variations of this species are discussed in this paper.

Two new host-specific hepaticolous species ofCatinaria(Ramalinaceae)

AbstractTwo species ofCatinariawith an unusual hepaticolous (i.e. growing on liverworts) lifestyle are described as new to science.Catinaria brodoanais described from species ofCheilolejeuneasect.Leucolejeunea(Lejeuneaceae) growing in south-eastern North America. Catinaria radulaeis described fromRadula flavifolia(Radulaceae) growing in the Cape Horn Archipelago of southernmost Chile, South America. The species are compared with the type ofCatinaria(C. atropurpurea). In addition to occurring on hepatics,C. brodoanais characterized by its cellular exciple, warted ascospores and thallus composed of goniocysts, whileC. radulaeis characterized by its exciple of radiating hyphae, warted ascospores and absence of a lichenized thallus.

Larrainia, a new genus of Amblystegiaceae from the Cape Horn region of Chile

Larrainia prorulosa W.R.Buck is described as a new genus and species of Amblystegiaceae from southernmost Chile. The new genus is characterized by a very small stature, differentiated branch and stem leaves, and short prorulose laminal cells. The two known collections are both sterile. Based on DNA sequence data, Larrainia is placed in the Amblystegiaceae, most closely related to Vittia. However, it is most similar morphologically to Conardia. The new species would probably have previously been placed in Rhynchostegiella in the Brachytheciaceae (as has been Conardia). The diversity within Rhynchostegiella is discussed.

Potential impacts of uv exposure on lichen communities: a pilot study of nothofagus dombeyi trunks in southernmost chile

High‐latitude terrestrial ecosystems face the triple threats of climate warming, increased exposure to UV arising from polar ozone depletion, and deforestation. Lichen communities of southernmost Chile are recognized for their high diversity, which includes nitrogen‐fixing cyanolichens. Such lichens are common on forest trees, contribute nitrogen to forests, and are sensitive to exposure following deforestation (widespread in this region). In a pilot study of exposure effects on tree lichens, using nondestructive imaging methods, we compared lichen communities on trunks of isolated vs. forest tree trunks of southern Chilean beech (Nothofagus dombeyi, Nothofagaceae). We chose trees of similar diameter and trunk lean angle in conserved forest and nearby logged meadow on Navarino Island, XII Region Magallanes and Chilean Antarctica, Chile, within the annual southern ozone hole. Ninety‐five percent of cyanolichen records, including Nephroma antarcticum, and 66% of records for other foliose lichens were from the forest, whereas pendulous usneoid lichens dominated N. dombeyi bark at the meadow site. Limitation of cyanolichen growth on isolated trees could affect ecosystem function in this poorly studied habitat. Possible factors contributing to strong community differences were increased light intensity, UV radiation, and wind stress, plus limited ability of lichens to colonize isolated trees in the logged meadow. UV radiation was likely an important stressor for some lichen species but not others. We recommend more extensive monitoring to pinpoint causes of differing lichen communities, and we encourage better protection of bark‐dwelling lichens in southern hemisphere regions facing multiple threats.