CEAZA
Herbivore-Alga Interaction Strength Influences Spatial Heterogeneity in a Kelp-Dominated Intertidal Community.
Aguilera, M., Valdivia, N., & Broitman, B.
There is a general consensus that marine herbivores can affect algal species composition and abundance, but little empirical work exists on the role of herbivores as modifiers of the spatial structure of resource assemblages. Here, we test the consumption/bulldozing effects of the molluscan grazer Enoplochiton niger and its influence on the spatial structure of a low intertidal community dominated by the bull kelp Durvillaea antarctica and the kelp Lessonia spicata. Through field experiments conducted at a rocky intertidal shore in north-central Chile (~30°-32°S), the edge of the grazer and algae geographic distributions, we estimated the strength and variability of consumptive effects of the grazer on different functional group of algae. We also used data from abundance field surveys to evaluate spatial co-occurrence patterns of the study species. Exclusion-enclosure experiments showed that E. niger maintained primary space available by preventing algal colonization, even of large brown algae species. The grazing activity of E. niger also reduced spatial heterogeneity of the ephemeral algal species, increasing bare space availability and variability through time in similar ways to those observed for the collective effect with other grazers. Overall, our result suggests that E. niger can be considered an important modifier of the spatial structure of the large brown algae-dominated community. Effects of E. niger on resource variability seem to be directly related to its foraging patterns, large body size, and population densities, which are all relevant factors for management and conservation of the large brown algae community. Our study thus highlights the importance of considering functional roles and identity of generalist consumers on spatial structure of the entire landscape.
Año: 2015
Palabras claves: Algae, Niger, Seaweed, Herbivory, Grazing, Population density, Foraging, Fronds.
Referencia APA: Aguilera, M., Valdivia, N., & Broitman, B. (2015). Herbivore-Alga Interaction Strength Influences Spatial Heterogeneity in a Kelp-Dominated Intertidal Community. PLOS ONE, 10(9), e0137287.
Disentangling the effects of propagule supply and environmental filtering on the spatial structure of a rocky shore metacommunity.
Valdivia, N., Aguilera, M., Navarrete, S., & Broitman, B.
Environment-driven variation in the supply of individuals to local assemblages can determine patterns of community structure. Alternatively, local environmental conditions can determine the type of species that can be successfully established in a given community. Most communities are probably found somewhere between these 2 extremes, but few studies have attempted to disentangle their effects in a community-wide context. Using multivariate approaches in rocky shore communities, we showed that environmental variables (i.e. sea surface temperature and wind stress), the benthic abundance of 108 species of invertebrates and macroalgae, and recruitment rates of invertebrates all shared significant spatial and temporal patterns of variability across a 400 km shoreline marked by the presence of a prominent upwelling centre. Variance-partition analyses for the invertebrates with pelagic development showed that spatially structured environmental filtering alone explained only 7% of the variation in community structure. In contrast, the combination of environmental conditions and recruitment variation explained 45% of the variability in community structure and an additional 18% was jointly explained by recruitment and spatial relationships among sampling sites. Unexplained variation (41%) can be attributed to factors like local species interactions that are robust to environmental variability. Therefore, environment-driven variation in recruitment rates can have, in comparison to pure environmental filtering, stronger effects on the structure of this metacommunity. Our results can serve as a foundation for predictive models of the response of biodiversity to climate change and other human-induced disturbances, which are predicted to alter local environmental conditions and dispersal pathways.
Año: 2015
Palabras claves: Metacommunity, Recruitment, Environmental filtering, Dispersal, Biodiversity, Chile, Marine, Mesoscale.
Referencia APA: Valdivia, N., Aguilera, M., Navarrete, S., & Broitman, B. (2015). Disentangling the effects of propagule supply and environmental filtering on the spatial structure of a rocky shore metacommunity. Marine Ecology Progress Series, 538, 67-79.
Human harvesting impacts on managed areas: ecological effects of socially-compatible shellfish reserves.
Aswani, S., Flores, C., & Broitman, B.
We examined how human harvesting impacts on managed areas affect the abundance and size distribution of the edible mangrove shellfish Anadara granosa and Polymesoda spp. in the Roviana Lagoon, Solomon Islands. We tested two hypotheses: (1) in areas permanently and temporally closed to human exploitation, abundance and size distribution of these shellfish species is significantly greater than in sites open to exploitation and (2) moderate human disturbance of shell beds, particularly of Polymesoda spp., increases their abundance. Firstly, we studied perceptions of environmental states and processes coupled to foraging and management interventions to assess sociocultural influences on harvesting practices and ascertain the types of management regime that people would consider in a context where poaching and interloping are common practices. Secondly, we compared shellfish abundance and shell size from areas that were permanently protected, temporally reserved for communal harvest, and permanently open for exploitation. Thirdly, drawing from women’s local knowledge, we measured the abundance of Polymesoda spp. in relation to mud compactness in quadrats across the three management regimes. Results showed that both species were significantly more abundant in permanent and temporally closed sites than in open sites. In the mud compactness study, however, while shell abundance was greater in moderately compacted quadrats, there was no statistical relationship between mud compactness and shell abundance within or across the three management regimes. Results suggest that even under the strong impacts of poaching, temporally closed areas have more clams than open areas and are as effective as areas that are permanently closed nominally. The results also suggest that human harvesting regimes can influence the effectiveness of local management decisions and thus are important when designing community-based conservation programs in the Solomon Islands and other Pacific Islands.
Año: 2015
Palabras claves: Ecological disturbance, Foraging, MPAs, Shellfish, Ecological impacts, Social acceptability, Solomon Islands.
Referencia APA: Aswani, S., Flores, C., & Broitman, B. (2015). Human harvesting impacts on managed areas: ecological effects of socially-compatible shellfish reserves. Rev Fish Biol Fisheries, 25(1), 217-230.
Response of photosynthesis and respiration to temperature under water deficit in two evergreen Nothofagus species.
Sanhueza, C., Bascunan-Godoy, L., Turnbull, M., & Corcuera, L.
Respiration and photosynthesis were studied in two Nothofagus species with different drought tolerance in order to evaluate the effect of water deficit on foliar carbon balance and the possible role of the alternative pathway on respiratory adjustment. We propose that under severe water deficit the more drought-tolerant species N. dombeyi is able to decrease its respiration more than the less drought-tolerant species N. nitida, thus carbon gain could be maintained when photosynthesis is suppressed by drought. Dark respiration (Rd) and carbon assimilation under saturating light (Asat) were evaluated under seasonal field conditions and during drying and re-watering cycles under glasshouse. In addition, respiratory pathway changes were evaluated by oxygen isotope fractionation. In the field, N. dombeyi displayed greater light-saturated photosynthetic capacity than N. nitida, but Rd did not differ between species during summer. In the glasshouse, N. dombeyi displayed an unchanged rate of Rd and increased carbon loss under severe water deficit. Nothofagus nitida displayed a more flexible respiratory response to water deficit, with a lower thermal sensitivity of respiration (decrease in Q10) and a decrease in Rd. This contributed to maintaining leaf carbon balance during the water deficit period. Respiratory electron flow was mainly via the cytochrome pathway for both species and under all treatments, indicating no strong participation of alternative respiration. Our results suggest that under severe water stress, N. dombeyi could be more injured than N. nitida and that the lack of control in the carbon loss under prolonged periods of drought could be limiting for its survival.
Año: 2015
Palabras claves: Alternative oxidase; carbon balance; drought tolerance; isotopic discrimination; temperate forest.
Referencia APA: Sanhueza, C., Bascunan-Godoy, L., Turnbull, M., & Corcuera, L. (2015). Response of photosynthesis and respiration to temperature under water deficit in two evergreen Nothofagus species. Plant Species Biology, 30(3), 163-175.
A hydrogeochemistry and isotopic approach for the assessment of surface water–groundwater dynamics in an arid basin: the Limarí watershed, North-Central Chile.
Oyarzún, R., Jofré, E., Morales, P., Maturana, H., Oyarzún, J., & Kretschmer, N. et al.
This paper describes the results of a hydrochemistry and isotopic study of surface water and groundwater dynamics at the Limarí River basin, arid North-Central Chile. The study involved two sampling campaigns, performed in April (Fall, at the end of the irrigation season) and December 2010 (late Spring, at the peak of the irrigation season). The main results show the effect of La Paloma and Hurtado dams on the chemical and isotopic compositions of the Grande and Hurtado rivers (main tributaries of the Limarí River), the influence of return flows to the Limarí River from surface water irrigation in agricultural areas, the local effects of metallurgical operations in the El Ingenio Creek, the effect of water–rock interaction processes, and the nearby coastal belt influence on the Punitaqui Creek area and the lower part of the Limarí River. In addition, this study shows an active interaction between surface water and shallow groundwater, and a minor importance of local precipitation events, on the hydrological behavior in the study area. An exception is the Rinconada de Punitaqui zone where the results are consistent with the origin of the water being associated with local precipitation. Also, sources of sulfate, which is present in high levels especially in surface waters, have been assessed. The results of this study, based on an integrated use of chemical and isotopic tracers, provide sound and useful information to establish the level of interaction between surface water and groundwater, allowing the development of a hydrological conceptual model for the area.
Año: 2015
Palabras claves: Environmental isotopes, River−aquifer interaction, Flow conceptual model.
Referencia APA: Jofré, E., Morales, P., Maturana, H., Oyarzún, J., & Kretschmer, N. et al. (2015). A hydrogeochemistry and isotopic approach for the assessment of surface water–groundwater dynamics in an arid basin: the Limarí watershed, North-Central Chile. Environ Earth Sci, 73(1), 39-55.
A holistic picture of Austronesian migrations revealed by phylogeography of Pacific paper mulberry.
Chang, C., Liu, H., Moncada, X., Seelenfreund, A., Seelenfreund, D., & Chung, K.
The peopling of Remote Oceanic islands by Austronesian speakers is a fascinating and yet contentious part of human prehistory. Linguistic, archaeological, and genetic studies have shown the complex nature of the process in which different components that helped to shape Lapita culture in Near Oceania each have their own unique history. Important evidence points to Taiwan as an Austronesian ancestral homeland with a more distant origin in South China, whereas alternative models favor South China to North Vietnam or a Southeast Asian origin. We test these propositions by studying phylogeography of paper mulberry, a common East Asian tree species introduced and clonally propagated since prehistoric times across the Pacific for making barkcloth, a practical and symbolic component of Austronesian cultures. Using the hypervariable chloroplast ndhF-rpl32 sequences of 604 samples collected from East Asia, Southeast Asia, and Oceanic islands (including 19 historical herbarium specimens from Near and Remote Oceania), 48 haplotypes are detected and haplotype cp-17 is predominant in both Near and Remote Oceania. Because cp-17 has an unambiguous Taiwanese origin and cp-17–carrying Oceanic paper mulberries are clonally propagated, our data concur with expectations of Taiwan as the Austronesian homeland, providing circumstantial support for the “out of Taiwan” hypothesis. Our data also provide insights into the dispersal of paper mulberry from South China “into North Taiwan,” the “out of South China–Indochina” expansion to New Guinea, and the geographic origins of post-European introductions of paper mulberry into Oceania.
Año: 2015
Palabras claves: Broussonetia papyrifera, commensal approach, DNA of herbarium specimens, out of Taiwan hypothesis, Voyaging Corridor Triple I .
Referencia APA: Chang, C., Liu, H., Moncada, X., Seelenfreund, A., Seelenfreund, D., & Chung, K. (2015). A holistic picture of Austronesian migrations revealed by phylogeography of Pacific paper mulberry. Proceedings Of The National Academy Of Sciences, 112(44), 13537-13542.
Fungal endophytes associated with roots of nurse cushion species have positive effects on native and invasive beneficiary plants in an alpine ecosystem.
Molina-Montenegro, M., Oses, R., Torres-Díaz, C., Atala, C., Núñez, M., & Armas, C.
Facilitation has been proposed to be a fundamental mechanism for plant coexistence, being particularly important in highly stressful environments such as alpine environments. In this type of environment, species called “cushion plants” can ameliorate the stressful conditions, acting as nurses for other plants. Of the several mechanisms proposed in the positive-interactions framework, plant–microorganism interaction may be one of the most common, but least documented. Here we show that the presence of endophytes isolated from the roots of cushion plants Laretia acaulis can play a fundamental role in the establishment, performance and survival of both native and exotic plant seedlings that are known to be facilitated by the cushion species.
To test this, we measured survival and growth of two native and one invasive species at 3200 m in the Andes of Central Chile. Plants were grown inside artificial cushions filled with native soil, with or without sterilization, and with or without fungal endophytic inoculation to evaluate the role of fungal endophytes on survival and growth. In addition, we conducted a second experiment in a greenhouse with the invasive species to evaluate the effect of fungal endophytic infection/association on plant ecophysiological performance, dry biomass and seed output.
Overall, our results showed a strong positive effect of fungal endophytes on the survival and growth of both native and invasive species. Moreover, maximum quantum efficiency (Fv/Fm), biomass accumulation and seed production were enhanced in the invasive species when soils were inoculated with endophytes. Thus, facilitation by root endophytic fungi on native and invasive alpine plants could determine survival and establishment in this harsh environment.
Several studies have shown that direct facilitation by cushion plants in alpine environments improves the performance and fitness of both native and exotic plants. Our results suggest that there are indirect effects, mediated by microorganism associations that may also help to explain the successful establishment of native and invasive species in these environments. If indirect plant–plant facilitation through root fungal endophytes proves to be a widespread phenomenon in alpine ecosystems, it could be a key component in the structuring of plant communities in those stressful environments.
Año: 2015
Palabras claves: Cushion plants; Endophytic fungi; Facilitation; Invasive species; Positive interactions; Taraxacum officinale.
Referencia APA: Molina-Montenegro, M., Oses, R., Torres-Díaz, C., Atala, C., Núñez, M., & Armas, C. (2015). Fungal endophytes associated with roots of nurse cushion species have positive effects on native and invasive beneficiary plants in an alpine ecosystem. Perspectives In Plant Ecology, Evolution And Systematics, 17(3), 218-226.
Ecophysiological responses to drought followed by re-watering of two native Chilean swamp forest plants: Myrceugenia exsucca (DC.) O. Berg and Luma chequen (Molina) A. Gray
Bascuñán-Godoy, L., Alcaíno, C., Carvajal, D., Sanhueza, C., Montecinos, S., & Maldonado, A.
Myrceugenia exsucca (DC.) O. Berg and Luma chequen (Molina) A. Gray are two predominant species of Myrtaceae from the swamp forest which are strongly threatened by destruction of their habitat. Conservation programs include the creation of new protected areas which often have different environmental conditions respect their natural habitat. The drought tolerance and the capability to restore their physiological performance after stress relief are characteristic of great importance for the successful conservation programs on these kinds of plants. Understanding how these plants respond to episodic drought and watering pulse was the principal aim of this work. In this sense, water relations, soluble sugars, pigments and photosystem II (PSII) performance were studied. In general the water relationships were less affected by drought in L. chequen than in M. exsucca which was consistent with a higher maintenance of photochemical quenching (qP) in the first one. In addition, L. chequen exhibited complete recovery of water potential and maximum PSII efficiency and increasing the proportion of photochemical processes and soluble sugars related with a higher photosynthetic recovery. Contrastingly, M. exsucca was unable to recover its water potential and the proportion of open reaction centers of PSII under re-watering indicating a lower capacity of recovery. These results shown different capabilities to cope and reestablish physiological performance after water scarcity episode between these two native chilean swamp forest plants. We hope that these results will be important for conservation and re-vegetation managements programs.
Año: 2015
Palabras claves: Myrtaceae, photosynthetic performance, water deficit, re-watering.
Referencia APA: Bascuñán-Godoy, L., Alcaíno, C., Carvajal, D., Sanhueza, C., Montecinos, S., & Maldonado, A. (2015). Ecophysiological responses to drought followed by re-watering of two native Chilean swamp forest plants: Myrceugenia exsucca (DC.) O. Berg and Luma chequen (Molina) A. Gray. Gayana Bot., 72(2), 203-212.
Albedo variations and the impact of clouds on glaciers in the Chilean semi-arid Andes.
Abermann, J., Kinnard, C., & MacDonell, S.
Albedo variations are presented at two on-glacier sites in the semi-arid Andes, Chile, with >3 years of continuous measurements. Although <2 km apart and at similar elevations, the sites show significantly different albedo cycles. Whereas Toro 1 exhibits a clear seasonal cycle, Guanaco reveals a more complicated pattern, as exposed ice can occur in any month of the year. Daily albedo values are as low as 0.18 for debris-covered Toro 1, while minima are higher on Guanaco (0.38). A method is presented to discern cloud-free from cloudy conditions using measured incoming shortwave radiation only. A cloud climatology is provided showing very low cloudiness values. We see that effective cloud cover relates inversely to cloud occurrence (i.e. either more but thin or fewer but thick clouds). The cloud-free diurnal albedo cycle is pronounced, with lowest values around noon. Clouds increase albedo by 0.04 as a median hourly value, and 0.20 for the 95% quantile. There is a positive relationship between effective cloud cover and resulting albedo rise. Calculations as to whether the diurnal albedo cycle or the effect of clouds on albedo should be considered in energy-balance estimations show that the former is necessary whereas the latter can be neglected in the semi-arid Andes.
Año: 2014
Palabras claves: Energy Balance; Glacier Mass Balance; Glacier Meteorology; Ice/atmosphere Interactions
Referencia APA: Abermann, J., Kinnard, C., & MacDonell, S. (2014). Albedo variations and the impact of clouds on glaciers in the Chilean semi-arid Andes. Journal Of Glaciology, 60(219), 183-191.
Climatic drivers of tree growth in a swamp forest island in the semiarid coast of Chile.
Peña, M., Barichivich, J., & Maldonado, A.
Isolated patches of swamp forests surrounded by xerophytic vegetation occur along the semiarid coast of Chile. Supported by shallow groundwater, these unique ecosystems have endured a long-term aridity trend during the Holocene and historical land use change. In this study, we investigated the patterns and climate drivers of annual tree growth in a coastal swamp dominated by the hygrophilous tree Myrceugenia exsucca. A tree-ring width chronology spanning the period 1864–2007 was developed and compared with long-term precipitation, temperature and soil moisture dynamics. There is a general lack of significant climate response during the earlier part of the 20th century, but a time-dependent positive growth response to temperature and moisture variability took place following partial drainage of the forest (1930s). Furthermore, a shift from a concurrent to a lagged growth response to moisture occurred around 1980, coinciding with increased frequency of ENSO-related moisture extremes. These results suggest that the ecological functioning of swamp forests in this region is very resilient to short-term climate variability, but even slight drainage disturbance can trigger very dynamic growth responses to climate variability. The degree of anthropogenic disturbance of these ecosystems will likely influence their response to projected increases in regional aridity during the coming decades.
Año: 2014
Palabras claves: Dendrochronology; Drought; ENSO; Groundwater; Swamp forest.
Referencia APA: Peña, M., Barichivich, J., & Maldonado, A. (2014). Climatic drivers of tree growth in a swamp forest island in the semiarid coast of Chile. Journal Of Arid Environments, 109, 15-22.
Geographical Variation of Shell Thickness in the Mussel Perumytilus purpuratus Along the Southeast Pacific Coast.
Briones, C., M.m., Rivadeneira, M., Fernández, R., Guiñez.
At broad geographical scales, the variation in bivalve shell thickness can be modulated by environmental factors that vary with latitude, such as sea surface temperature (SST), seawater pH, or calcium carbonate availability. Mussels usually form multilayered beds, and shell thickness is also expected to be affected by density and layering due to intraspecific competition. In this work, we explored the geographical variation of shell thickness in the intertidal mussel Perumytilus purpuratus between 18° and 42°S along the southeastern Pacific coast. We tested the hypothesis that there was a positive relationship between shell thickness and SST, and then we explored other variables that could have an effect on thickness, such as density, number of layers, and others environmental variables (pH and calcite concentration). The expected positive linear relationship between shell thickness and sea surface temperature was not found, but when the other population variables were included in the analysis, an unexpected inverse SST-thickness relationships appeared as significant, probably because this species could be adapted to colder and more acid seawater as are those of the tips of South America. Thickness was also negatively affected by density, which was expected for a gregarious species howing high intraspecific competition.Finally, our results highlight the importance of including density and crowding effects when macroscale patterns are explored, particularly in gregarious species, since these patterns could also be modulated by density-dependent processes, which might then override latitudinal trends of shell thickness when they are not included in the analyses.
Año: 2014
Palabras claves:
Referencia APA: Briones, C., M.m., Rivadeneira, M., Fernández, R., Guiñez. (2014). Geographical Variation of Shell Thickness in the Mussel Perumytilus purpuratus Along the Southeast Pacific Coast. Biol. Bull. 227: 221–231.
How does spatial variability of climate affect catchment streamflow predictions?.
Patil, S., Wigington, P., Leibowitz, S., Sproles, E., & Comeleo, R.
Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distributed) meteorological inputs instead of spatially uniform (lumped) meteorological inputs. Both lumped and distributed versions of the EXP-HYDRO model are implemented at 41 meso-scale (500–5000 km2) catchments in the Pacific Northwest region of USA. We use two complementary metrics of long-term spatial climate variability, moisture homogeneity index (IM) and temperature variability index (ITV), to analyze the performance improvement with distributed model. Results show that the distributed model performs better than the lumped model in 38 out of 41 catchments, and noticeably better (>10% improvement) in 13 catchments. Furthermore, spatial variability of moisture distribution alone is insufficient to explain the observed patterns of model performance improvement. For catchments with low moisture homogeneity (IM < 80%), IM is a better predictor of model performance improvement than ITV; whereas for catchments with high moisture homogeneity (IM > 80%), ITV is a better predictor of performance improvement than IM. Based on the results, we conclude that: (1) catchments that have low homogeneity of moisture distribution are the obvious candidates for using spatially distributed meteorological inputs, and (2) catchments with a homogeneous moisture distribution benefit from spatially distributed meteorological inputs if they also have high spatial variability of precipitation phase (rain vs. snow).
Año: 2014
Palabras claves: Hydrologic model; Climate variability; Streamflow; Catchment.
Referencia APA: Patil, S., Wigington, P., Leibowitz, S., Sproles, E., & Comeleo, R. (2014). How does spatial variability of climate affect catchment streamflow predictions?. Journal Of Hydrology, 517, 135-145. http://dx.doi.org/10.1016/j.jhydrol.2014.05.017