Instituto Antartico Chileno INACH

Punta Arenas, Chile

Instituto Antartico Chileno INACH

Punta Arenas, Chile
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Torres D.,Pedro de Valdivia University | Acevedo J.,University of Magallanes | Torres D.E.,University of the Americas in Chile | Aguayo-Lobo A.,Instituto Antartico Chileno INACH
Polar Biology | Year: 2012

A vagrant adult male Subantarctic fur seal Arctocephalus tropicalis was observed among Antarctic fur seals A. gazella at Cape Shirreff, Livingston Island, Antarctica, which is located to ~4,190 and ~5,939 km from the nearest breeding colonies of Subantarctic fur seals. Although the colony of origin of this animal and the reason for its movement outside its distribution range are unknown, this sighting shows the high dispersal capacity of this species and provides an insight into possible changes in its distribution. Although this vagrant was not observed with females Antarctic fur seal, news sightings in the future could result in viable hybrid, and introgressive hybridization could represent a threat for Cape Shirreff population recovery, if still the population way to go to recover to presailing levels. © 2011 Springer-Verlag.

Matus R.,Natura Patagonia | Droguett D.,Wildlife Conservation Society | Vila A.,Wildlife Conservation Society | Aguayo-Lobo A.,Instituto Antartico Chileno INACH | Torres D.,Pedro de Valdivia University
Polar Biology | Year: 2011

The Antarctic fur seal, Arctocephalus gazella, in the eastern South Pacific Ocean, first reported on Hoste Island, Cape Horn in 1973, and then on the Juan Fernandez Archipelago in 1982 and 1983, was recorded again in October and December 2009 on the southern coast of Chile. Three different individuals were seen simultaneously on a single day at Punta Dungenes, Magellan Strait, and a fourth individual was sighted at the northeastern coast of Almirantazgo Sound, Tierra del Fuego. These records represent the first sightings of live Arctocephalus gazella in southern Chile. Although it is difficult to establish both their origin and rationale for dispersion outside of their distribution range, the substantial breeding population recovery in South Georgia and food shortages during the breeding and post-breeding season are suggested as possible explanations. © 2011 Springer-Verlag.

Molina-Montenegro M.A.,Católica del Norte University | Carrasco-Urra F.,University of Concepción | Rodrigo C.,Instituto Antartico Chileno INACH | Convey P.,Natural Environment Research Council | And 5 more authors.
Conservation Biology | Year: 2012

Few non-native species have colonized Antarctica, although increased human activity and accelerated climate change may increase their number, distributional range, and effects on native species on the continent. We searched 13 sites on the maritime Antarctic islands and 12 sites on the Antarctic Peninsula for annual bluegrass (Poa annua), a non-native flowering plant. We also evaluated the possible effects of competition between P. annua and 2 vascular plants native to Antarctica, Antarctic pearlwort (Colobanthus quitensis) and Antarctic hairgrass (Deschampsia antarctica). We grew the native species in experimental plots with and without annual bluegrass under conditions that mimicked the Antarctic environment. After 5 months, we measured photosynthetic performance on the basis of chlorophyll fluorescence and determined total biomass of both native species. We found individual specimens of annual bluegrass at 3 different sites on the Antarctic Peninsula during the 2007-2008 and 2009-2010 austral summers. The presence of bluegrass was associated with a statistically significant reduction in biomass of pearlwort and hairgrass, whereas the decrease in biomass of bluegrass was not statistically significant. Similarly, the presence of bluegrass significantly reduced the photosynthetic performance of the 2 native species. Sites where bluegrass occurred were close to major maritime routes of scientific expeditions and of tourist cruises to Antarctica. We believe that if current levels of human activity and regional warming persist, more non-native plant species are likely to colonize the Antarctic and may affect native species. © 2012 Society for Conservation Biology.

Molina-Montenegro M.A.,Católica del Norte University | Torres-Diaz C.,University of Bío Bío | Gallardo-Cerda J.,Instituto Antartico Chileno INACH | Leppe M.,Instituto Antartico Chileno INACH | And 2 more authors.
Ecology | Year: 2013

Oceanic island ecosystems are particularly sensitive to El Niñ o effects due to their dependence on energy and nutrient inputs from marine systems. Seabirds play a key role in transporting resources of marine origin to insular ecosystems. We report tree-growth patterns showing how the effects of El Niñ o rainy events on tree species in a southern Pacific island depend on the presence of local seabird colonies. We performed manipulative experiments in order to assess the mechanisms underlying these patterns. Tree ring data showed that, in normal years, the growth of all tree species (Aextoxicon punctatum, Cryptocarya alba, and Pinus radiata) was significantly lower in seabird sites compared to adjacent patches without seabirds (control sites). In contrast, in El Niñ o years, trees formerly hosting seabird colonies grew more than those in control sites. Experiments showed that (1) pine plants on soil from seabird sites grew more than those on soil from control sites, (2) pine individuals with seabird feces on their leaves grew less than those sprayed with an aqueous solution, and (3) soil moisture had little effect on plant growth. The stress produced by massive cormorant nesting on trees, which impairs tree growth and physiological performance, is relieved during El Niñ o events because of seabird migration due to decreased prey availability and pouring rains that flood nests. Soils enriched by the seabird guano, together with the increased water availability associated with El Niñ o, foster the growth of trees from seabird sites. We suggest that El Niñ o may be a key determinant of tree performance in forest communities from island and coastal ecosystems of the Pacific Ocean. © 2013 by the Ecological Society of America.

Cardenas C.A.,University of Magallanes | Cardenas C.A.,Instituto Antartico Chileno INACH | Montiel A.,University of Magallanes
Polar Biology | Year: 2015

Previous studies from other latitudes have demonstrated that depth and spatial heterogeneity, produced by surface inclination, can have strong effects on diversity and distribution of sessile assemblages on rocky reefs. Rocky reef communities in the subantarctic Magellan region have been rarely studied, and the factors influencing diversity, distribution and abundance of benthic communities remain poorly understood. Sessile benthic assemblages inhabiting rocky reefs habitats were studied by SCUBA diving at Punta Santa Ana, Magellan Strait from 0 to 30 m water depth. We describe the sessile assemblages assessing the effect of depth, inclination and other environmental factors on species richness and community structure. A total of 37 taxa of invertebrates and 31 taxa of macroalgae were identified based on 280 high-resolution photoquadrats. Species richness and percent coverage varied with depth and inclination. Macroalgae dominated in abundance in the shallows, while bryozoans and ascidians (mound and tree-like forms) increased their coverage with depth. Lithothamnion sp. dominated on vertical and inclined surfaces while sheet-like organism such as bryozoans increased their coverage on overhanging surfaces. Multivariate analyses showed that sessile assemblages at Punta Santa Ana are strongly influenced by the interaction between inclination and depth, which alter the effect of other physical factors such as light and sedimentation. In this regard, our results suggest that sedimentation may play a role structuring benthic assemblages in Punta Santa Ana, especially in deeper zones, where it may replace the structuring effect produced by light in the shallows. © 2015, Springer-Verlag Berlin Heidelberg.

Mansilla H.G.,Instituto Antartico Chileno INACH | Stinnesbeck W.,University of Heidelberg | Varela N.,Instituto Antartico Chileno INACH | Leppe M.,Instituto Antartico Chileno INACH
Antarctic Science | Year: 2014

The first fossil avian feather from Antarctica is reported here, from the early to middle Eocene Fossil Hill Formation at Fildes Peninsula, King George Island, Antarctica. Characteristics such as its form, asymmetry of vanes, closed-pennaceous vanes with barbules and a deep ventral groove indicate that the feather was used for flight. The site from which the feather was collected is known to yield a variety of well-preserved trace fossils, palaeobotanical and palaeoenvironmental remains, suggesting a shorebird ecotype for the owner of this feather, certainly belonging to a Neornithes. The continental position, preservation as an external mould and type of feather makes this specimen a novel and an exceedingly rare record. © Antarctic Science Ltd 2013.

Mansilla H.G.,Instituto Antartico Chileno INACH | De Valais S.,National University of Rio Negro | Stinnesbeck W.,University of Heidelberg | Varela N.A.,Instituto Antartico Chileno INACH | Leppe M.A.,Instituto Antartico Chileno INACH
Antarctic Science | Year: 2012

Trace fossils are long known to exist in the Fossil Hill Formation (lower to middle Eocene) at Fildes Peninsula, King George Island, Antarctica. During fieldwork in 2009, abundant new avian tracks were recovered, which are analysed here. Three avian ichnotaxa are distinguished. The most common impressions are tridactyls and tetradactyls with slender digit imprints II-IV and a posterior hallux. They are included in the ichnogenus Gruipeda. In addition tridactyl and tetradactyl footprints with short and thick digit impressions are conferred to Uhangrichnus. The third ichnotaxon is a tridactyl impression with broad and short digits assigned to Avipeda. The latter taxon is here documented for the first time from Antarctica. These avian tracks are preserved in volcaniclastic sediments consisting in reddish-brown layers of mudstone intercalated with coarse sandstone. The sequence represents lacustrine environments which seasonally dried and were episodically refilled. © Copyright 2012 Antarctic Science Ltd.

Bell J.J.,Victoria University of Wellington | Mcgrath E.,Victoria University of Wellington | Biggerstaff A.,Victoria University of Wellington | Bates T.,Victoria University of Wellington | And 3 more authors.
Conservation Biology | Year: 2015

Sponges are important for maintaining ecosystem function and integrity of marine and freshwater benthic communities worldwide. Despite this, there has been no assessment of their current global conservation status. We assessed their status, accounting for the distribution of research effort; patterns of temporal variation in sponge populations and assemblages; the number of sponges on threatened species lists; and the impact of environmental pressures. Sponge research effort has been variable; marine sponges in the northeastern Atlantic and Mediterranean and freshwater sponges in Europe and North America have received the most attention. Although sponge abundance has increased in some locations since 1990, these were typically on coral reefs, in response to declines in other benthic organisms, and restricted to a few species. Few data were available on temporal trends in freshwater sponge abundance. Despite over 8500 described sponge species, only 20 are on threatened species lists, and all are marine species from the northeastern Atlantic and Mediterranean. Of the 202 studies identified, the effects of temperature, suspended sediment, substratum loss, and microbial pathogens have been studied the most intensively for marine sponges, although responses appear to be variable. There were 20 studies examining environmental impacts on freshwater sponges, and most of these were on temperature and heavy metal contamination. We found that most sponges do not appear to be threatened globally. However, little information is available for most species and more data are needed on the impacts of anthropogenic-related pressures. This is a critical information gap in understanding sponge conservation status. © 2015 Society for Conservation Biology.

Acevedo J.,Centro Regional Of Estudios Del Cuaternario Fuego Patagonia Y Antartica Fundacion Cequa | Mora C.,Centro Regional Of Estudios Del Cuaternario Fuego Patagonia Y Antartica Fundacion Cequa | Aguayo-Lobo A.,Instituto Antartico Chileno INACH
Marine Mammal Science | Year: 2014

We investigated sex-related site fidelity by humpback whales to the Fueguian Archipelago, a new feeding area in the eastern South Pacific, by examining the resighting histories of 45 males and 39 females recorded from 2003 to 2012. Results indicated an overall annual return to the feeding area of 74.8%, and annual sex ratio is roughly equal in the population. The probability of an individual being resighted across years and in subsequent years was not significantly different for both males and females, however, the proportion of resighting within a year was significantly higher for individual males compared to females. Potential sources of sex-related bias were analyzed, but none were found to be significant. Greater intraannual resighting frequency for males may reflect sex-based differences in spatial occupation and short-range movements due to potential differences in energy budgets. © 2013 Society for Marine Mammalogy.

Cardenas C.A.,Victoria University of Wellington | Cardenas C.A.,Instituto Antartico Chileno INACH | Davy S.K.,Victoria University of Wellington | Bell J.J.,Victoria University of Wellington
Journal of the Marine Biological Association of the United Kingdom | Year: 2015

Experimental removals of the dominant canopy-forming kelp Ecklonia radiata were conducted at two sites on rocky walls in New Zealand and monitored for approximately 1.5 years. We hypothesized that the removal of the E. radiata canopy would affect the structure of subcanopy assemblages, such that there would be a reduction in sponge species richness and abundance. Furthermore, we investigated the biological and physical (predictor) variables that best explained variability in sponge assemblages after canopy removal. Canopy removal led to a community dominated by turf algae, which corresponded with a decrease in sponge abundance and richness. Our results suggest that the Ecklonia canopy may positively influence the presence of sponge species such as Crella incrustans; we propose that the canopy may allow its coexistence with turf algae underneath the canopy by altering the light regime and other environmental factors, which may be detrimental for some species. Our results highlight how any loss of canopy-forming species might have negative effects on sponge assemblages, which could affect the energy flow and the overall biodiversity found in these habitats. Copyright © Marine Biological Association of the United Kingdom 2015

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