Northern Chilean Patagonia Research Articles

Variability of herbaceous productivity along Nothofagus pumilio forest-open grassland boundaries in northern Chilean Patagonia

In order to develop a general model of aboveground net primary production (ANPP) of herbaceous communities in grazing systems that combine forested and open grasslands in temperate areas, biomass production and a set of biotic and abiotic variables were measured at four adjacent forest and grassland sites in Chile’s northern Patagonia for two consecutive growing seasons. At each site, one transect of 80 m long (40 m in open grassland and 40 m in forest) × 10 m wide was established. ANPP was significantly higher in open grasslands but no gradual change in biomass production was observed from inside the forest towards the open grassland. In open grasslands ANPP was spatially uniform but highly variable between years of contrasting weather conditions, whereas in forests it was more spatially heterogeneous and less variable over time. ANPP was highly correlated with cattle consumption. Structural equation models developed for the whole system confirm that ANPP was driven mainly by photosynthetically active radiation (PAR) and available nitrogen. However, we found important differences between forests and the adjacent open grasslands. In forests ANPP was enhanced by positive feedbacks between the amount of transmitted PAR through the canopy and soil nutrient input via cattle dung deposition. In open grasslands nitrogen availability appeared to be the main limiting factor but also influenced by weather conditions (dryer or wetter years). The coexistence of forests and grasslands patches, with different susceptibility of ANPP to meteorological and soil nutrient availability, highlights the importance of implementing an integrated silvopastoral system with lenga (Nothofagus pumilio [Poepp. & Endl.] Krasser) in northern Patagonia.

On the hydrography of Puyuhuapi Channel, Chilean Patagonia

This work describes the hydrographic conditions found in Puyuhuapi Channel (northern Chilean Patagonia) during recent years on a seasonal scale. Puyuhuapi Channel was once a glacial valley, but the retreating ice allowed the inflow of marine waters. Five surveys were conducted between 2008 and 2012; historical data from 1995 to 2007 were included. A meteorological/oceanographic buoy was also installed in the northern section of Puyuhuapi Channel and was operational beginning on April 12th, 2011. Puyuhuapi Channel’s surface characteristics highlight a fresher northern part and a more haline southern part except during winter when the pattern can reverse due to the intrusion of oceanic water via Jacaf Channel. The channel exhibits a highly variable meridional and seasonal vertical stratification, especially in its northern part where during spring and summer the water column is highly stratified but partially mixed during winter. Puyuhuapi Channel is the only fjord/channel with severe hypoxic conditions in all of Chilean Patagonia.

A null model to study community structure of microcrustacean assemblages in north Patagonian urban wetlands (39-41°S, Chile)

The inland water bodies of northern Chilean Patagonia (38-41°S) have many lakes, wetlands and ponds with different littoral and zooplanktonic crustacean assemblages. This study presents field observations of species associations sampled from shallow wetlands located in the urban zones of Valdivia (39°S) and Puerto Montt (41°S). A species presence-absence matrix was created for calculating the Jaccard Index of community similarity and for testing null models of species associations, with the aim of determining whether species associations are random or not. The results of the Jaccard Index calculations indicated the existence of non-defined groups. The results of the null model analysis denoted the presence of regulating factors for Valdivia wetlands, whereas for Puerto Montt wetlands no such factors could be demonstrated. The outcomes of both the Jaccard Index and the significant null model analysis agree with previous ecological descriptions of changes in trophic status as a consequence of changes in the surrounding basin as a determinant of species associations. The ecology of these communities is also discussed.

Native and non-native herbaceous species dependence on tree cover in grazing systems from northern Chilean Patagonia

Grazing systems that combine grasslands and woodlands represent changes in tree cover that influences herbaceous vegetation and may threaten the native forest flora. We studied these influences in Chilean Patagonia where recent colonization resulted in the fragmentation of the lenga (Nothofagus pumilio) forests leading to a mosaic-type landscape. The herbaceous vegetation, transmitted photosynthetically active radiation (PAR) and other forest structure characteristics were sampled in 15 (20m×20m) plots differing in tree cover for two years, while considering the relative position (below or beyond) of tree crowns. Herbaceous species were classified as forest, non-forest, and forest indifferent species according to their preference, rejection or indifference to the forest environment. Species richness decreased with increasing PAR but this was dependent on the response of non-natives. Species composition varied gradually from open grasslands to dense forests, according to transmitted PAR values. Native species were associated to either forests or open areas, but the number of native species did not vary along the tree cover gradient (beyond tree crowns) or even decreased (below tree crowns). Non-native species dominated in the open grasslands and beyond tree crowns and its richness increased with transmitted PAR. The occurrence of grasslands and dense forests within this grazing system is shown to promote higher species richness. Management will consider that dense forest patches are necessary for maintaining a high diversity of native species, since isolated trees or low wooded areas do not guarantee the persistence of all native species associated to the original forests.

A new record of the non indigenous freshwater jellyfish Craspedacusta sowerbii Lankester, 1880 (Cnidaria) in Northern Patagonia (40° S, Chile)

A new record of the freshwater jellyfish Craspedacusta sowerbii in northern Chilean Patagonia is reported. The specimens were collected from Laguna Illahuapi, an oligotrophic shallow lake (15 m maximum depth) in early austral autumn, May 2013. This water body is located in the upper zone of the Rio Bueno basin, Province of Ranco, Region de los Rios, Chile. The region is characterized by a great diversity of freshwater environments with minimal human pressure. This report confirms the presence of C. sowerbii in Chilean Patagonia and represents the southernmost range of distribution of this exotic medusa in South America. This study also contributes additional information on the limnological characterization of this water body.

Vertical and horizontal distribution ofDesmophyllum dianthusin Comau Fjord, Chile: a cold-water coral thriving at low pH

Cold-water corals provide an important habitat for a rich fauna along the continental margins and slopes. Although these azooxanthellate corals are considered particularly sensitive to ocean acidification, their responses to natural variations in pH and aragonite saturation are largely unknown due to the difficulty of studying their ecology in deep waters. Previous SCUBA investigations have shown an exceptionally shallow population of the cold-water coral Desmophyllum dianthus in near-surface waters of Comau Fjord, a stratified 480 m deep basin in northern Chilean Patagonia with suboxic deep waters. Here, we use a remotely operated vehicle to quantitatively investigate the distribution of D. dianthus and its physico-chemical drivers in so far uncharted naturally acidified waters. Remarkably, D. dianthus was ubiquitous throughout the fjord, but particularly abundant between 20 and 280 m depth in a pH range of 8.4 to 7.4. The persistence of individuals in aragonite-undersaturated waters suggests that present-day D. dianthus in Comau Fjord may show pre-acclimation or pre-adaptation to conditions of ocean acidification predicted to reach over 70% of the known deep-sea coral locations by the end of the century.

Provision of ecosystem services by the Aysén watershed, Chilean Patagonia, to rural households

How much do ecosystems contribute to the wellbeing of rural populations in developing nations? In this article we provide an answer to this question through an eco-social study of two provisioning ecosystem services (wood from native forest and clean water) of the Aysén watershed in northern Chilean Patagonia. Social data was gathered by means of a semi-structured survey to rural households while ecological data was obtained from the available literature and Chilean Government databases. Results show that provisioning ecosystem services contribute, on average, 148USD per month (range: 155–345USD) to the livelihood of rural households. We discuss the potential effect of rural wood exploitation on native forest coverage and the role of uncertainties in the available information.

Changes in sub-fossil chironomid assemblages in two Northern Patagonian lake systems associated with the occurrence of historical fires

Patagonia is commonly seen as an exceptionally pristine area because of its wildlife and practically unpolluted waters. However, during the twentieth century the burning of natural forests was one of the most important human activities in Northern Chilean Patagonia. Some estimations indicate that three million hectares were burned during the first three decades of the century. Hence the objective of this study was to evaluate the impacts of the historical fires in Lake Burgos (45o42′S) and Lake Thompson (45o38′S) in Chilean Patagonia. The impact was measured by evaluating chironomid assemblage since they are sensitive enough to be used as an indicator of aquatic ecosystem health. Fires have a direct and drastic effect on a lake watershed but also indirectly affect a lake ecosystem, changing sedimentation patterns or increasing nutrient inputs. In the studied lakes the periods with higher prevalence of fires were identified by charcoal analysis, while organic matter and magnetic susceptibility allowed the confirmation of pre-fire and post-fire periods. The chironomid composition was evaluated through a PCA and an analysis of similarity (ANOSIM) to test the significance among periods while a Detrended Correspondence Analysis was applied to the chironomid assemblage downcore to assess compositional structure and taxa turnover. In Lake Burgos the ANOSIM test indicated significant differences between the pre-fire and fire periods (p < 0.05), while in Lake Thompson differences were not significant. However, in Lake Thompson the PCA clearly separated the pre-fire from the fire period but not the fire from the post-fire periods. In both lakes chironomid composition changed in relation to the period of higher prevalence of fires, which in turn implies catchment changes, pollution, and other anthropogenic impacts. Particularly a marked change in mesotrophic/eutrophic taxa was detected, reflecting an increase in nutrient input due to deforestation. Our findings point out that the lacustrine ecosystems are still affected by the impact of fires and the subsequent increase in nutrient supply that occurred almost 50 years ago. No sign of reverting to pre-disturbance conditions was observed, which makes these lakes highly sensitive to current human-induced impacts.

A historical feeding ground for humpback whales in the eastern South Pacific revisited: the case of northern Patagonia, Chile

ABSTRACT Since 2000, an increasing number of humpback whale sightings have been recorded in northern Chilean Patagonia (mostly between 41.5°S and 44°S) from dedicated aerial and marine surveys and also opportunistic and land‐based platforms during austral summer and autumn months. Based on local knowledge from the early years of coastal whaling suggesting the historic presence of humpback whales in the area, and more recent observations confirming feeding groups, mother–calf pairs, and philopatry, it is proposed that a proportion of the eastern South Pacific humpback whales consistently use the Chiloe‐Corcovado region to feed and nurse their young. This mid‐latitude area could be regarded as the northernmost feeding ground for humpback whales in South America, extending the previous known range some 1300 km north. These findings provide further evidence for alternative life‐strategies other than traditional migration and highlight the importance of northern Patagonian fjords to resolve questions that are central for large baleen whale conservation and management such as the extent and characteristics of spatio‐temporal habitat use and overlap with human activities. The need for future research on the migratory movements and population structure of this poorly understood population of humpback whales is emphasized, while an account is given of the threats they currently face. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Late Holocene air temperature variability reconstructed from the sediments of Laguna Escondida, Patagonia, Chile (45°30′S)

Climate and environmental reconstructions from natural archives are important for the interpretation of current climatic change. Few quantitative high-resolution reconstructions exist for South America which is the only land mass extending from the tropics to the southern high latitudes at 56°S. We analyzed sediment cores from two adjacent lakes in Northern Chilean Patagonia, Lago Castor (45°36′S, 71°47′W) and Laguna Escondida (45°31′S, 71°49′W). Radiometric dating (210Pb, 137Cs, 14C-AMS) suggests that the cores reach back to c. 900BC (Laguna Escondida) and c. 1900BC (Lago Castor). Both lakes show similarities and reproducibility in sedimentation rate changes and tephra layer deposition. We found eight macroscopic tephras (0.2–5.5cm thick) dated at 1950BC, 1700BC, at 300BC, 50BC, 90AD, 160AD, 400AD and at 900AD. These can be used as regional time-synchronous stratigraphic markers. The two thickest tephras represent known well-dated explosive eruptions of Hudson volcano around 1950 and 300BC. Biogenic silica flux revealed in both lakes a climate signal and correlation with annual temperature reanalysis data (calibration 1900–2006AD; Lago Castor r=0.37; Laguna Escondida r=0.42, seven years filtered data). We used a linear inverse regression plus scaling model for calibration and leave-one-out cross-validation (RMSEv=0.56°C) to reconstruct sub decadal-scale temperature variability for Laguna Escondida back to AD 400. The lower part of the core from Laguna Escondida prior to AD 400 and the core of Lago Castor are strongly influenced by primary and secondary tephras and, therefore, not used for the temperature reconstruction. The temperature reconstruction from Laguna Escondida shows cold conditions in the 5th century (relative to the 20th century mean), warmer temperatures from AD 600 to AD 1150 and colder temperatures from AD 1200 to AD 1450. From AD 1450 to AD 1700 our reconstruction shows a period with stronger variability and on average higher values than the 20th century mean. Until AD 1900 the temperature values decrease but stay slightly above the 20th century mean. Most of the centennial-scale features are reproduced in the few other natural climate archives in the region. The early onset of cool conditions from c. AD 1200 onward seems to be confirmed for this region.

Covariability of precipitation and sea surface temperature changes in Northern Chilean Patagonia during the last 2000 years

Covariability of precipitation and sea surface temperature changes in Northern Chilean Patagonia during the last 2000 years

Regulatory factors in crustacean zooplankton assemblages in mountain lakes of northern Chilean Patagonia (38 41°S): a comparison with Bulgarian counterparts (42°N)

Chilean Patagonia has protected mountainous areas with evergreen native forests; in which the lakes and rivers, of volcanic or glacial origin, are oligotrophic. In Bulgaria, there are mountainous zones with native forests and associated lakes of volcanic origin. The aim of the present study is to carry out a preliminary comparison of zooplanktonic crustaceans in lake ecosystems associated with native forests of Chilean Patagonia and of Bulgarian mountains. The study revealed that the lakes studied in Chilean Patagonia are associated mainly with Nothofagus forests; they are oligotrophic, with a low number of zooplanktonic crustacean species. Similar results were observed for Bulgarian mountain lakes associated with Fagus forests. A null model analysis of species co-occurrence was applied to the two groups of lakes, and the result revealed the absence of regulatory factors in species associations. These studies agree with similar descriptions of lakes in Andean Patagonia and New Zealand. They highlight the important role of native Nothofagus forests in Argentina and Chile, and of Fagus forests with associated soil properties in Bulgaria, in the oligotrophy of the lakes studied.

Modeling suspended solids in a Northern Chilean Patagonia glacier-fed fjord: GLOF scenarios under climate change conditions

Suspended solids play an ecologically important role in glacier-fed fjords, given its dominant effect on their primary production arising from the generation of turbid water plumes by retreating glaciers, which increase light attenuation. Glacial-lake outburst floods, GLOFs, are sudden releases of lake-water impounded by a glacier which may affect either locally or regionally depending on the amount of water and suspended solids released. Chilean Patagonia has been characterized by some of the fastest glacial retreats worldwide and by an increase in GLOFs events. In this article we describe the development of a hydrodynamic model to study the distribution of suspended solids in the Baker channel, a glacier-fed fjord located in Northern Chilean Patagonia. We further describe the simulation of three climate change induced GLOF scenarios and discuss their potential effects on fjord's primary production. The model was implemented as a two-level, one-way, nested hierarchy using the MOHID water modeling system. The large extent, oceanic, level corresponded to a one-layer barotropic model, while the smaller extent, fjord, level corresponded to a 3D baroclinic model with 31 Cartesian layers. Velocities, salinity and suspended solids concentrations were calibrated using field measurements. Results show that the most likely scenario is a decrease in light penetration within the inner fjord's area. Only the most catastrophic scenario, equivalent to a large recorded paleo-discharge, would affect outer areas of the Northern Chilean fjords.

Using the N/C ratio to correct bulk radiocarbon ages from lake sediments: Insights from Chilean Patagonia

The offset between AMS radiocarbon ages obtained on bulk lake sediments and the true age of deposition was evaluated at four sites in Northern Chilean Patagonia. Our results show that the bulk radiocarbon ages are systematically older by 300 to 1100 years. In this region free of carbonate and carbonaceous rocks, we argue that this difference results from variable inputs of terrestrial organic carbon from the Holocene soils that cover the lake watersheds. For the four studied lakes, the age offset is clearly related to the fraction of terrestrial carbon preserved in the lake sediments, which was estimated using the N/C ratio of the bulk organic matter. We propose that N/C measurements can be used to significantly improve chronologies based on radiocarbon dating of bulk lake sediments.

Geochemistry of surface sediments from the fjords of Northern Chilean Patagonia (44–47°S): Spatial variability and implications for paleoclimate reconstructions

The Patagonian fjords have a clear potential to provide high-resolution sedimentary and geochemical records of past climate and environmental change in the Southern Andes. To improve our ability to interpret these proxy records, we investigated the processes that control fjord sediment inorganic geochemistry through a geochemical, mineralogical and sedimentological analysis of surface sediment samples from the fjords of Northern Chilean Patagonia. A simple Terrestrial Index based on measurements of salinity and Fraction of Terrestrial Carbon was used to estimate the terrestrial input/river discharge at each site. Our results demonstrate that, under the cold climate conditions of Patagonia, chemical weathering is weak and the inorganic geochemical composition of the fjord sediments is primarily controlled by hydrodynamic mineralogical sorting, i.e., the intensity of river discharge. Our results suggest that the distribution of Fe, Ti and Zr in surface sediments is controlled by their association with heavy and/or coarse minerals, whereas Al is independent of hydrodynamic processes. The elemental ratios Fe/Al, Ti/Al and Zr/Al are therefore well suited for estimating changes in the energy of terrestrial sediment supply into the fjords through time. Zr/Al is particularly sensitive in proximal environments, while Fe/Al is most useful in the outer fjords and on the continental margin. In the most proximal environments, however, Fe/Al is inversely related to hydrodynamic conditions. Caution should therefore be exercised when interpreting Fe/Al ratios in terms of past river discharge. The application of these proxies to long sediment cores from Quitralco fjord and Golfo Elefantes validates our interpretations. Our results also emphasize the need to measure Al-based elemental ratios at high precision, which can be achieved using simultaneous acquisition ICP-AES technology. This study therefore constitutes a strong basis for the interpretation of sedimentary records from the Chilean Fjords.

Land–ocean distribution of allochthonous organic matter in surface sediments of the Chiloé and Aysén interior seas (Chilean Northern Patagonia)

We investigated the relative distribution of allochthonous (i.e., terrigenous) organic matter in the complex, continuous, river–fjord–sound–channel–gulf system of Chile’s North Patagonia (41.5–46.5°S) in order to establish whether this organic matter can reach the open ocean or whether it is largely retained near its fluvial sources. Grain size distribution, total organic carbon and total nitrogen contents, and carbon stable isotope contents (δ 13C) were quantified in 53 surface sediment samples collected during the CIMAR Fiordos cruises 1, 4, 8, and 10, as were salinity and silicic acid concentrations in the surface waters. A principal component analysis segregated the Chiloé and Aysén interior seas into two zones: (i) the continental fjords, with sediment enriched in allochthonous organic matter, having higher C:N molar ratios (10–14) and lower δ 13C composition (−23‰ to −27‰); and (ii) the channels and gulfs, with a prevalent autochthonous marine source, having lower C:N values (6–10) and higher δ 13C composition (−20‰ to −23‰). Estuarine waters with low salinity (2–30) and high silicic acid (10–90 μM) were associated with high C:N ratios and low δ 13C in surface sediments, meaning that terrestrial organic matter was transported up to the mouth of the continental fjords. A two-source mixing model confirmed that allochthonous (terrestrial) organic matter contents (50–90%) associated with local river discharges were present within the continental fjords. On the contrary, autochthonous (marine) organic matter was prevalent (50–90%) at the sites in the marine influenced channels, sounds, and gulfs.

Importance of mixotrophic nanoplankton in Aysén Fjord (Southern Chile) during austral winter

Mixotrophy, the combination of autotrophic and heterotrophic nutrition in the same organism, is widespread in planktonic algae. Several reports from temperate and high-latitude fjords in Scandinavia suggest the occurrence of a niche in late summer and autumn during post-bloom conditions in which mixotrophic algae can become important grazers in pelagic ecosystems, accessing the nutrients bound in their prey to overcome nutrient limitation. Here, we experimentally determined the trophic modes and bacterivory rates for the nanoplankton community (2–20 μm) in Aysén Fjord located in the Chilean Northern Patagonia during two contrasting seasons: winter and spring. While mixotrophic nanoplankton was virtually absent from the system in spring, in winter at occasions it even constituted the dominant trophic group of the nanoplankton with abundances of >900 cells mL −1. This indicates a second niche for mixotrophs in winter, when mixotrophy allows overcoming light limitation.

An unexpected hotspot of moth biodiversity in Chilean northern Patagonia (Lepidoptera, Geometridae)

An unexpected hotspot of moth biodiversity in Chilean northern Patagonia (Lepidoptera, Geometridae)

Late Holocene sea-surface temperature and precipitation variability in northern Patagonia, Chile (Jacaf Fjord, 44°S)

A high-resolution multi-proxy study including the elemental and isotopic composition of bulk organic matter, land plant-derived biomarkers, and alkenone-based sea-surface temperature (SST) from a marine sedimentary record obtained from the Jacaf Fjord in northern Chilean Patagonia (∼44°20′S) provided a detailed reconstruction of continental runoff, precipitation, and summer SST spanning the last 1750 yr. We observed two different regimes of climate variability in our record: a relatively dry/warm period before 900 cal yr BP (lower runoff and average SST 1°C warmer than present day) and a wet/cold period after 750 cal yr BP (higher runoff and average SST 1°C colder than present day). Relatively colder SSTs were found during 750–600 and 450–250 cal yr BP, where the latter period roughly corresponds to the interval defined for the Little Ice Age (LIA). Similar climatic swings have been observed previously in continental and marine archives of the last two millennia from central and southern Chile, suggesting a strong latitudinal sensitivity to changes in the Southern Westerly Winds, the main source of precipitation in southern Chile, and validating the regional nature of the LIA. Our results reveal the importance of the Chilean fjord system for recording climate changes of regional and global significance.

Evidence of Interactive Segregation between Introduced Trout and Native Fishes in Northern Patagonian Rivers, Chile

AbstractIntroduced rainbow troutOncorhynchus mykissand brown troutSalmo trutta farioare the most abundant fishes in the northern Chilean Patagonia, and their effect on native fishes is not well known. We tested for interactive segregation between trout and native fishes by using a before‐after, control‐impact design in which we deliberately reduced the density of trout and observed the response of the native fishes in their mesohabitat use (pool, run, riffle). Three native fish species,Brachygalaxias bullocki, Galaxias maculatus(inanga), andTrichomycterus areolatus, apparently had niche overlap with introduced trout and changed their mesohabitat use after trout reduction. The expansion of the three species into a wider range of mesohabitats after trout reduction suggests that these fishes occupy a broader spatial area when trout are reduced or possibly absent. However, some native fish species, such asGeotria australis, did not respond to the trout reductions. To protect Chilean native fishes, policymakers need to consider providing legal protection for native fishes because native fishes currently have no protection in their catchments.