CEAZA
Effects of temperature and ocean acidification on shell characteristics of Argopecten purpuratus: implications for scallop aquaculture in an upwelling-influenced area.
Lagos, N., Benítez, S., Duarte, C., Lardies, M., Broitman, B., & Tapia, C. et al.
Coastal upwelling regions already constitute hot spots of ocean acidification as naturally acidified waters are brought to the surface. This effect could be exacerbated by ocean acidification and warming, both caused by rising concentrations of atmospheric CO2. Along the Chilean coast, upwelling supports highly productive fisheries and aquaculture activities. However, during recent years, there has been a documented decline in the national production of the native scallop Argopecten purpuratus. We assessed the combined effects of temperature and pCO2-driven ocean acidification on the growth rates and shell characteristics of this species farmed under the natural influence of upwelling waters occurring in northern Chile (30°S, Tongoy Bay). The experimental scenario representing current conditions (14°C, pH ~8.0) were typical of natural values recorded in Tongoy Bay, whilst conditions representing the low pH scenario were typical of an adjacent upwelling area (pH ~7.6). Shell thickness, weight, and biomass were reduced under low pH (pH ~7.7) and increased temperature (18°C) conditions. At ambient temperature (14°C) and low pH, scallops showed increased shell dissolution and low growth rates. However, elevated temperatures ameliorated the impacts of low pH, as evidenced by growth rates in both pH treatments at the higher temperature treatment that were not significantly different from the control treatment. The impact of low pH at current temperature on scallop growth suggests that the upwelling could increase the time required for scallops to reach marketable size. Mortality of farmed scallops is discussed in relation to our observations of multiple environmental stressors in this upwelling-influenced area.
Año: 2016
Palabras claves: Calcification, Shell growth, Scallop farming, Upwelling, Chile.
Referencia APA: Lagos, N., Benítez, S., Duarte, C., Lardies, M., Broitman, B., & Tapia, C. et al. (2016). Effects of temperature and ocean acidification on shell characteristics of Argopecten purpuratus: implications for scallop aquaculture in an upwelling-influenced area. Aquaculture Environment Interactions, 8, 357-370.
3-D surface properties of glacier penitentes over an ablation season, measured using a Microsoft Xbox Kinect.
Nicholson L. I., Pętlicki M., Partan B., and MacDonell S.
In this study, the first small-scale digital surface models (DSMs) of natural penitentes on a glacier surface were produced using a Microsoft Xbox Kinect sensor on Tapado Glacier, Chile (30°08′ S, 69°55′ W). The surfaces produced by the complete processing chain were within the error of standard terrestrial laser scanning techniques, but insufficient overlap between scanned sections that were mosaicked to cover the sampled areas can result in three-dimensional (3-D) positional errors of up to 0.3 m. Between November 2013 and January 2014 penitentes become fewer, wider and deeper, and the distribution of surface slope angles becomes more skewed to steep faces. Although these morphological changes cannot be captured by manual point measurements, mean surface lowering of the scanned areas was comparable to that derived from manual measurements of penitente surface height at a minimum density of 5 m−1 over a 5 m transverse profile. Roughness was computed on the 3-D surfaces by applying two previously published geometrical formulae: one for a 3-D surface and one for single profiles sampled from the surface. Morphometric analysis shows that skimming flow is persistent over penitentes, providing conditions conducive for the development of a distinct microclimate within the penitente troughs. For each method a range of ways of defining the representative roughness element height was used, and the calculations were done both with and without application of a zero displacement height offset to account for the likelihood of skimming air flow over the closely spaced penitentes. The computed roughness values are on the order of 0.01–0.10 m during the early part of the ablation season, increasing to 0.10–0.50 m after the end of December, in line with the roughest values previously published for glacier ice. Both the 3-D surface and profile methods of computing roughness are strongly dependent on wind direction. However, the two methods contradict each other in that the maximum roughness computed for the 3-D surface coincides with airflow across the penitente lineation, while maximum roughness computed for sampled profiles coincides with airflow along the penitente lineation. These findings highlight the importance of determining directional roughness and wind direction for strongly aligned surface features and also suggest more work is required to determine appropriate geometrical roughness formulae for linearized features.
Año: 2016
Palabras claves:
Referencia APA: Nicholson L. I., Pętlicki M., Partan B., and MacDonell S. (2016). 3-D surface properties of glacier penitentes over an ablation season, measured using a Microsoft Xbox Kinect. The Cryosphere, 10(5), 1897.
Dairy slurry application to grasslands and groundwater quality in a volcanic soil.
Huertas, J., Cuevas, J. G., Paulino, L., Salazar, F., Arumí, J. L., & Dörner, J.
Research in volcanic-ash soils has shown that they largely capture the dairy slurry following application to land; however, their hydrological properties would favor nutrient leaching. Our objective was to evaluate the contribution of biogeochemical and hydrological controls on the pollution of groundwater by cattle slurry applied to a permanent grassland growing on a volcanic soil. We sampled groundwater chemistry since 10 months before the fertilization (three samplings), and 16 months after, with samplings 1-2 months after the fertigation. Following fertilization, ammonium, exchangeable potassium, and magnesium soil concentrations increased in the fertilized plots compared to the control plots. In contrast, no effect of slurry on groundwater quality was detected, with the exception of dissolved organic nitrogen, a main component of dairy slurry that increased in the groundwater below the fertilized plots. Despite the fact that biogeochemical controls predominate, hydrological aspects would be important when rainfall is high, evapotranspiration is low, groundwater table level is high, and water movement in the saturated zone increases. We concluded that the application of slurry to pastures under rates comparable to a high fertilization in the short term, does not generally impact the groundwater quality in volcanic ash-derived soils.
Año: 2016
Palabras claves: Andisol; groundwater pollution; hydraulic properties; saturated zone; dissolved organic nitrogen.
Referencia APA: Huertas, J., Cuevas, J. G., Paulino, L., Salazar, F., Arumí, J. L., & Dörner, J. (2016). Dairy slurry application to grasslands and groundwater quality in a volcanic soil. Journal of soil science and plant nutrition, 16(3), 745-762.
Late Holocene environmental changes as recorded in the sediments of high Andean Laguna Chepical, Central Chile (32° S; 3050ma. sl).
Martel-Cea, A., Maldonado, A., Grosjean, M., Alvial, I., de Jong, R., Fritz, S. C., & von Gunten, L.
We present a reconstruction of environmental changes from sediments of high-altitude Laguna Chepical in the subtropical Andes of Central Chile (32°16′S; 70°30′W, 3050 m a.s.l.) for the past 3100 years. Based on subfossil pollen, microscopic charcoal and diatoms, we inferred changes in moisture (related to precipitation) and ice-cover/ice-free season (related to summer temperature) at decadal to millennial scales. Sustained wetter and colder summer temperatures than today prevailed between 1100 BC and ca. AD 1. Afterward, decreasing pollen accumulation rates and increased fire activity suggest drier conditions and possibly enhanced seasonality and/or inter-annual climate variability. Frequent changes between cold and warm summers were observed, particularly for the last 1000 years. About AD 1250 (during the Medieval Climate Anomaly), wet years and early break up of ice-cover occurred in central Chile, which is today typical for El Niño-like mean conditions. Conversely, and with the exception of a few wet pulses, a generally dry period with extended ice-cover (cool summers) was observed between AD 1400 and AD 1850 (Little Ice Age). This can be interpreted as a trend toward more La Niña-like mean conditions. Recent climate change and human disturbances during the last 100 years have prompted changes in diatom and plant communities that are unprecedented in the late Holocene. First, planktonic diatoms increased as a result of hydraulic interventions in the lake during the late 19th century, and secondly, the Andean vegetation shifted upward as result of recent warming, and the frequency of arboreal taxa was significantly reduced. At the same time peaks of fire activity were observed.
Año: 2016
Palabras claves: Late Holocene; ENSO; Pollen; Diatom; Andes; Climate change.
Referencia APA: Martel-Cea, A., Maldonado, A., Grosjean, M., Alvial, I., de Jong, R., Fritz, S. C., & von Gunten, L. (2016). Late Holocene environmental changes as recorded in the sediments of high Andean Laguna Chepical, Central Chile (32° S; 3050ma. sl). Palaeogeography, Palaeoclimatology, Palaeoecology, 461, 44-54.
Castaways can’t be choosers — Homogenization of rafting assemblages on floating seaweeds.
Gutow, L., Beermann, J., Buschbaum, C., M. Rivadeneira, M., & Thiel, M.
After detachment from benthic habitats, the epibiont assemblages on floating seaweeds undergo substantial changes, but little is known regarding whether succession varies among different seaweed species. Given that floating algae may represent a limiting habitat in many regions, rafting organisms may be unselective and colonize any available seaweed patch at the sea surface. This process may homogenize rafting assemblages on different seaweed species, which our study examined by comparing the assemblages on benthic and floating individuals of the fucoid seaweeds Fucus vesiculosus and Sargassum muticum in the northern Wadden Sea (North Sea). Species richness was about twice as high on S. muticum as on F. vesiculosus, both on benthic and floating individuals. In both seaweed species benthic samples were more diverse than floating samples. However, the species composition differed significantly only between benthic thalli, but not between floating thalli of the two seaweed species. Separate analyses of sessile and mobile epibionts showed that the homogenization of rafting assemblages was mainly caused by mobile species. Among these, grazing isopods from the genus Idotea reached extraordinarily high densities on the floating samples from the northern Wadden Sea, suggesting that the availability of seaweed rafts was indeed limiting. Enhanced break-up of algal rafts associated with intense feeding by abundant herbivores might force rafters to recolonize benthic habitats. These colonization processes may enhance successful dispersal of rafting organisms and thereby contribute to population connectivity between sink populations in the Wadden Sea and source populations from up-current regions.
Año: 2015
Palabras claves: Epibiota; Wadden Sea; Population Connectivity; Habitat Destruction; Migration; Dispersal.
Referencia APA: Gutow, L., Beermann, J., Buschbaum, C., M. Rivadeneira, M., & Thiel, M. (2015). Castaways can't be choosers — Homogenization of rafting assemblages on floating seaweeds. Journal Of Sea Research, 95, 161-171.
Facilitative Effect of a Generalist Herbivore on the Recovery of a Perennial Alga: Consequences forPersistence at the Edge of Their Geographic Range.
Aguilera MA, Valdivia N, Broitman BR.
Understanding the impacts of consumers on the abundance, growth rate, recovery and persistence of their resources across their distributional range can shed light on the role of trophic interactions in determining species range shifts. Here, we examined if consumptive effects of the intertidal grazer Scurria viridula positively influences the abundance and recovery from disturbances of the alga Mazzaella laminarioides at the edge of its geographic distributions in northern-central Chilean rocky shores. Through field experiments conducted at a site in the region where M. laminarioides overlaps with the polar range edge of S. viridula, we estimated the effects of grazing on different life stages of M. laminarioides. We also used long-term abundance surveys conducted across ~700 km of the shore to evaluate co-occurrence patterns of the study species across their range overlap. We found that S. viridula had positive net effects on M. laminarioides by increasing its cover and re-growth from perennial basal crusts. Probability of occurrence of M. laminarioides increased significantly with increasing density of S. viridula across the range overlap. The negative effect of S. viridula on the percentage cover of opportunistic green algae—shown to compete for space with corticated algae—suggests that competitive release may be part of the mechanism driving the positive effect of the limpet on the abundance and recovery from disturbance of M. laminarioides. We suggest that grazer populations contribute to enhance the abundance of M. laminarioides, facilitating its recolonization and persistence at its distributional range edge. Our study highlights that indirect facilitation can determine the recovery and persistence of a resource at the limit of its distribution, and may well contribute to the ecological mechanisms governing species distributions and range shifts.
Año: 2015
Palabras claves: Algae, Fronds, Grazing, Herbivory, Plant-herbivore interactions, Species interactions, Geographic distribution,Trophic interactions.
Referencia APA: Valdivia N, Broitman BR. (2015). Facilitative Effect of a Generalist Herbivore on the Recovery of a Perennial Alga: Consequences for Persistence at the Edge of Their Geographic Range. PLoS ONE 10(12): e0146069.
A recolonization record of the invasive Poa annua in Paradise Bay, Antarctic Peninsula: modeling of the potential spreading risk.
Molina-Montenegro, M., Pertierra, L., Razeto-Barry, P., Díaz, J., Finot, V., & Torres-Díaz, C.
Antarctica is one of the most extreme environments for vascular plants occurrence worldwide, and only two native vascular plants have colonized this continent: Deschampsia antarctica and Colobanthus quitensis. Nevertheless, in recent years, several alien plant species has been found in Antarctica with negative effects on the native flora. In this study, we show a recolonization record of the most widespread plant invader in Antarctica (Poa annua) and the risk of a potential spreading in a highly visited site on the Antarctic Peninsula. Overall, two new P. annua individuals were recorded, where four specimens were previously reported and removed in 2010, suggesting that either a propagule load is continuous, or that a seed bank prevailed in the site. On the other hand, the spreading modeling suggests that the probability to colonize and spreading of P. annua increases notoriously with the possibility of dispersion of propagules, with consequent risk of displacement for the native flora. Biological invasions are a major threat to the integrity of native biodiversity in all biomes, and they have the potential to change irreversibly Antarctica’s fragile ecosystems.
Año: 2015
Palabras claves: Antarctica, Biodiversity, Invasions, Poa annua.
Referencia APA: Molina-Montenegro, M., Pertierra, L., Razeto-Barry, P., Díaz, J., Finot, V., & Torres-Díaz, C. (2015). A recolonization record of the invasive Poa annua in Paradise Bay, Antarctic Peninsula: modeling of the potential spreading risk. Polar Biol, 38(7), 1091-1096.
Dust fluxes and iron fertilization in Holocene and Last Glacial Maximum climates.
Lambert, F., Tagliabue, A., Shaffer, G., Lamy, F., Winckler, G., & Farias, L. et al.
Mineral dust aerosols play a major role in present and past climates. To date, we rely on climate models for estimates of dust fluxes to calculate the impact of airborne micronutrients on biogeochemical cycles. Here we provide a new global dust flux data set for Holocene and Last Glacial Maximum (LGM) conditions based on observational data. A comparison with dust flux simulations highlights regional differences between observations and models. By forcing a biogeochemical model with our new data set and using this model's results to guide a millennial-scale Earth System Model simulation, we calculate the impact of enhanced glacial oceanic iron deposition on the LGM-Holocene carbon cycle. On centennial timescales, the higher LGM dust deposition results in a weak reduction of <10 ppm in atmospheric CO2 due to enhanced efficiency of the biological pump. This is followed by a further ~10 ppm reduction over millennial timescales due to greater carbon burial and carbonate compensation.
Año: 2015
Palabras claves: Paleoclimate; dust; iron fertilization; atmospheric CO2; carbon cycle; LGM.
Referencia APA: Lambert, F., Tagliabue, A., Shaffer, G., Lamy, F., Winckler, G., & Farias, L. et al. (2015). Dust fluxes and iron fertilization in Holocene and Last Glacial Maximum climates. Geophys. Res. Lett., 42(14), 6014-6023.
Biogeographic structure of the northeastern Pacific rocky intertidal: the role of upwelling and dispersal to drive patterns.
Fenberg, P., Menge, B., Raimondi, P., & Rivadeneira, M.
Identifying the environmental conditions that drive biogeographic structure remains a major challenge of biogeography, evolutionary ecology and increasingly, conservation biology. Here, we use multivariate classification trees to assess the biogeographic structure of northeast Pacific (∼ 26–58°N) rocky intertidal species (406 species of algae and invertebrates) from 102 field sites. Random forest analyses are used to assess the importance of 29 environmental variables, encompassing a broad range of potential drivers, to predict biogeographic structure. Analyses are repeated for species with different larval dispersal capabilities and by broad taxonomic categories (invertebrates and algae). Results show that overall biogeographic structure is in general agreement with classic classification schemes, but patterns are variable among species with different larval dispersal capabilities. Random forest models show a very high fit (pseudo r2 > 0.94) and indicate that biogeographic structure can be predicted by a relatively modest subset of variables. Upwelling related variables are the best overall predictors of biogeographic structure (nutrient concentrations, sea-surface temperature, upwelling/downwelling seasonal switch index), but the relative importance of predictors is geographically variable and top predictors are dependent on the type of larval dispersal. Upwelling related variables are more important to predict biogeographic structure for invertebrates with lower-medium dispersal capabilities and algae, whereas species with high larval dispersal (planktotrophic) are better predicted by a different subset of variables (i.e. salinity, precipitation seasonality). Our results lend support to the influence of coastal upwelling in structuring biogeographic patterns and highlight the potential for climate change-induced alterations of upwelling regimes to profoundly affect biodiversity at biogeographic scales.
Año: 2015
Palabras claves:
Referencia APA: Fenberg, P., Menge, B., Raimondi, P., & Rivadeneira, M. (2015). Biogeographic structure of the northeastern Pacific rocky intertidal: the role of upwelling and dispersal to drive patterns. Ecography, 38(1), 83-95.
Poa annua L. in the maritime Antarctic: an overview.
Chwedorzewska, K., Giełwanowska, I., Olech, M., Molina-Montenegro, M., Wódkiewicz, M., & Galera, H.
Poa annua is the only flowering plant species that has established a breeding population in the maritime Antarctic, through repeated anthropogenic introduction. The first appearance of this species in the Antarctic was observed in 1953. Annual bluegrass inhabits mainly anthropogenic sites, but recently has entered tundra communities. The functioning of P. annua in the Antarctic could not have been possible without adaptations that enable the plants to persist in the specific climatic conditions typical for this zone. Poa annua is highly adaptable to environmental stress and unstable habitats: huge phenotypic and genotypic variability, small size, plastic life cycle (life-history types ranging from annual to perennial forms). The spreading of P. annua in the Antarctic Peninsula region is a classic example of the expansion process following anthropogenic introduction of an invasive species, and illustrates the dangers to Antarctic terrestrial ecosystems that are associated with increasing human traffic.
Año: 2015
Palabras claves:
Referencia APA: Chwedorzewska, K., Giełwanowska, I., Olech, M., Molina-Montenegro, M., Wódkiewicz, M., & Galera, H. (2015). Poa annua L. in the maritime Antarctic: an overview. Polar Record, 51(06), 637-643.
Biological invasions in terrestrial Antarctica: what is the current status and can we respond?.
Hughes, K., Pertierra, L., Molina-Montenegro, M., & Convey, P.
Until recently the Antarctic continent and Peninsula have been little impacted by non-native species, compared to other regions of the Earth. However, reports of species introductions are increasing as awareness of biological invasions as a major conservation threat, within the context of increased human activities and climate change scenarios, has grown within the Antarctic community. Given the recent increase in documented reports, here we provide an up-to-date inventory of known terrestrial non-native species introductions, including those subsequently removed since the 1990s, within the Antarctic Treaty area. This builds on earlier syntheses of records published in the mid-2000s, which focused largely on the sub-Antarctic islands, given the dearth of literature available at that time from the continental and maritime Antarctic regions. Reports of non-native species established in the natural environment (i.e. non-synanthropic) are mainly located within the Antarctic Peninsula region and Scotia Arc, with Deception Island, South Shetland Islands, the most impacted area. Non-native plants have generally been removed from sites of introduction, but no established invertebrates have yet been subject to any eradication attempt, despite a recent increase in reports. Legislation within the Protocol on Environmental Protection to the Antarctic Treaty has not kept pace with environmental best practice, potentially presenting difficulties for the practical aspects of non-native species control and eradication. The success of any eradication attempt may be affected by management practices and the biology of the target species under polar conditions. Practical management action is only likely to succeed with greater co-operation and improved communication and engagement by nations and industries operating in the region.
Año: 2015
Palabras claves: Antarctic Treaty area, Environmental Protocol, Alien species, Biosecurity, Invasion, Eradication.
Referencia APA: Hughes, K., Pertierra, L., Molina-Montenegro, M., & Convey, P. (2015). Biological invasions in terrestrial Antarctica: what is the current status and can we respond?. Biodiversity And Conservation, 24(5), 1031-1055.
Assimilation of GRACE Terrestrial Water Storage Observations into a Land Surface Model for the Assessment of Regional Flood Potential.
Reager, J., Thomas, A., Sproles, E., Rodell, M., Beaudoing, H., Li, B., & Famiglietti, J.
We evaluate performance of the Catchment Land Surface Model (CLSM) under flood conditions after the assimilation of observations of the terrestrial water storage anomaly (TWSA) from NASA’s Gravity Recovery and Climate Experiment (GRACE). Assimilation offers three key benefits for the viability of GRACE observations to operational applications: (1) near-real time analysis; (2) a downscaling of GRACE’s coarse spatial resolution; and (3) state disaggregation of the vertically-integrated TWSA. We select the 2011 flood event in the Missouri river basin as a case study, and find that assimilation generally made the model wetter in the months preceding flood. We compare model outputs with observations from 14 USGS groundwater wells to assess improvements after assimilation. Finally, we examine disaggregated water storage information to improve the mechanistic understanding of event generation. Validation establishes that assimilation improved the model skill substantially, increasing regional groundwater anomaly correlation from 0.58 to 0.86. For the 2011 flood event in the Missouri river basin, results show that groundwater and snow water equivalent were contributors to pre-event flood potential, providing spatially-distributed early warning information.
Año: 2015
Palabras claves: GRACE; gravity; flood; assimilation.
Referencia APA: Reager, J., Thomas, A., Sproles, E., Rodell, M., Beaudoing, H., Li, B., & Famiglietti, J. (2015). Assimilation of GRACE Terrestrial Water Storage Observations into a Land Surface Model for the Assessment of Regional Flood Potential. Remote Sensing, 7(11), 14663-14679.