DSpace Angular :: Browsing by Author "Broitman, Bernardo R."

Browsing by Author "Broitman, Bernardo R."

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Basal metabolism is correlated with habitat productivity among populations of degus (Octodon degus)
(2009) Bozinovic, Francisco; Rojas, Jose M.; Broitman, Bernardo R.; Vasquez, Rodrigo A.
Several competing hypotheses attempt to explain how environmental conditions affect mass-independent basal metabolic rate (BMR) in mammals. One of the most inclusive is the hypothesis that associates BMR with food habits, including habitat productivity. The effects of food habits have been widely investigated at the interspecific level, and variation between individuals and populations has been largely ignored. Intraspecific analysis of physiological traits has the potential to compensate for many pitfalls associated with interspecific analyses and serve as a useful approach for evaluating hypotheses regarding metabolic adaptation. Here we tested the effects of climatic variables (mean annual rainfall=PP, mean annual temperature=TA), net primary productivity (NPP) and the de Martonne index (DMi) of aridity on mass-independent BMR among four populations of the caviomorph rodent Octodon degus along a geographic gradient in Chile. BMR was measured on animals maintained in a common garden acclimation set-up, thus kept under the same environment and diet quality for at least 6 months. Mass-independent BMR was significantly different among degu populations showing a large intraspecific spread in metabolic rates. A very large fraction of interpopulational variability in mass-independent BMR was explained by NPR PP and DMi. Our results were conclusive about the effects of habitat productivity on setting the level of mass-independent BMR at the intraspecific-interpopulational level. (C) 2009 Elsevier Inc. All rights reserved.
CDOM dynamics in two coastal zones influenced by contrasting land uses in northern Patagonia
(2024) Curra-Sanchez, Elizabeth D.; Valerio, Aline de M.; Lara, Carlos; Garcia-Tunon, Wirmer; Broitman, Bernardo R.; Saldias, Gonzalo S.; Nimptsch, Jorge; Vargas, Cristian A.
Colored dissolved organic matter (CDOM) is an indicator and optical proxy of terrestrial processes such as land use with allochthonous material fluxes, biogeochemical cycles, and water quality in coastal zones influenced by rivers. However, the role of land use changes on the spatial and temporal availability of CDOM has been poorly explored in Chile. Here, we studied two watersheds with similar climates and contrasting land use patterns in northern Patagonia considering the sampling of CDOM in their estuarine and adjacent coastal ocean. An empirical algorithm with the coefficients adjusted to our study areas to estimate CDOM was applied to Landsat 7 and 8 images to examine temporal variability of CDOMest from 2001 to 2011 and 2013-2020. Our results showed an increasing trend of CDOMest in both areas. Different trends in land use patterns between the two watersheds showed a significant correlation with CDOMest and contrasting associations with environmental variables. Higher humification was found in Yaldad in comparison with Colu. In both areas, allochthonous materials predominated, especially during austral spring according to the low values of the Fluorescence Index (FI). Our results highlight the potential of CDOMest to parameterize biogeochemical cycling models and to further understand the dynamics of CDOM in coastal ecosystems.
Climate change in the coastal ocean: shifts in pelagic productivity and regionally diverging dynamics of coastal ecosystems
(2022) Navarrete, Sergio A.; Barahona, Mario; Weidberg, Nicolas; Broitman, Bernardo R.
Climate change has led to intensification and poleward migration of the Southeastern Pacific Anticyclone, forcing diverging regions of increasing, equatorward and decreasing, poleward coastal phytoplankton productivity along the Humboldt Upwelling Ecosystem, and a transition zone around 31 degrees S. Using a 20-year dataset of barnacle larval recruitment and adult abundances, we show that striking increases in larval arrival have occurred since 1999 in the region of higher productivity, while slower but significantly negative trends dominate poleward of 30 degrees S, where years of recruitment failure are now common. Rapid increases in benthic adults result from fast recruitment-stock feedbacks following increased recruitment. Slower population declines in the decreased productivity region may result from aging but still reproducing adults that provide temporary insurance against population collapses. Thus, in this region of the ocean where surface waters have been cooling down, climate change is transforming coastal pelagic and benthic ecosystems through altering primary productivity, which seems to propagate up the food web at rates modulated by stock-recruitment feedbacks and storage effects. Slower effects of downward productivity warn us that poleward stocks may be closer to collapse than current abundances may suggest.
Contrasting land-uses in two small river basins impact the colored dissolved organic matter concentration and carbonate system along a river-coastal ocean continuum
(2022) Curra-Sanchez, Elizabeth D.; Lara, Carlos; Cornejo-D'Ottone, Marcela; Nimptsch, Jorge; Aguayo, Mauricio; Broitman, Bernardo R.; Saldias, Gonzalo S.; Vargas, Cristian A.
Human activities have led to an increase in land use change, with effects on the structure and functioning of ecosystems. The impact of contrasting land uses along river basins on the concentration of colored dissolved organic matter (CDOM) reaching the coastal zone, and its relationship with the carbonate system of the adjacent coastal ocean, is poorly known. To understand the relationship between land use change, CDOM and its influence on the carbonate system, two watersheds with contrasting land uses in southern Chile were studied. The samples were collected at eight stations between river and adjacent coastal areas, during three sampling campaigns in the austral summer and spring. Chemical and biological samples were analyzed in the laboratory according to standard protocols. Landsat 8 satellite images of the study area were used for identification and supervised classification using remote sensing tools. The Yaldad River basin showed 82% of native forest and the Colu River basin around 38% of grassland (agriculture). Low total alkalinity (A(T)) and Dissolved Inorganic Carbon (DIC), but high CDOM proportions were typically observed in freshwater. A higher CDOM and humic-like compounds concentration was observed along the river-coastal ocean continuum in the Yaldad basin, characterized by a predominance of native forests. In contrast, nutrient concentrations, A(T) and DIC, were higher in the Colu area. Low CaCO3 saturation state (Omega(Ar) < 2) and even undersaturation conditions were observed at the coastal ocean at Yaldad. A strong negative correlation between A(T), DIC and Omega(Ar) with CDOM/fDOM, suggested the influence of terrestrial material on the seawater carbon chemistry. Our results provide robust evidence that land uses in river basins can influence CDOM/fDOM proportion and its influence on the carbonate chemistry of the adjacent coastal, with potential implications for the shellfish farming activity in this region. (C) 2021 Elsevier B.V. All rights reserved.
Coupled Biospheric Synchrony of the Coastal Temperate Ecosystem in Northern Patagonia: A Remote Sensing Analysis
(2019) Lara, Carlos; Cazelles, Bernard; Saldias, Gonzalo S.; Flores, Raul P.; Paredes, Alvaro L.; Broitman, Bernardo R.
Over the last century, climate change has impacted the physiology, distribution, and phenology of marine and terrestrial primary producers worldwide. The study of these fluctuations has been hindered due to the complex response of plants to environmental forcing over large spatial and temporal scales. To bridge this gap, we investigated the synchrony in seasonal phenological activity between marine and terrestrial primary producers to environmental and climatic variability across northern Patagonia. We disentangled the effects on the biological activity of local processes using advanced time-frequency analysis and partial wavelet coherence on 15 years (2003-2017) of data from MODIS (Moderate Resolution Imaging Spectroradiometer) onboard the Terra and Aqua satellites and global climatic variability using large-scale climate indices. Our results show that periodic variations in both coastal ocean and land productivity are associated with sea surface temperature forcing over seasonal scales and with climatic forcing over multi-annual (2-4 years) modes. These complex relationships indicate that large-scale climatic processes primarily modulate the synchronous phenological seasonal activity across northern Patagonia, which makes these unique ecosystems highly exposed to future climatic change.
Environmental and demographic factors influence the spatial genetic structure of an intertidal barnacle in central-northern Chile
(2019) Barahona, Mario; Broitman, Bernardo R.; Faugeron, Sylvain; Jaugeon, Lucie; Ospina-Alvarez, Andres; Veliz, David; Navarrete, Sergio A.
Understanding the multiplicity of processes producing genetic patterns in natural populations can shed light on the ecology and evolution of species, and help guide effective management and conservation strategies. Here we investigated the role of environmental, demographic, and geographic factors in shaping the spatial patterns of genetic diversity and differentiation of the intertidal barnacle Notochthamalus scabrosus along the central-northern coast of Chile (28-34 degrees S). We analyzed genetic data from 7 microsatellite loci genotyped for 300 individuals sampled from 10 sites and combined this information with 8 site-specific environmental (4), demographic (2), and geographic (2) variables using least squares linear regressions, generalized linear models, and matrix regression analyses. We found a strong association between the spatially structured genetic diversity of N. scabrosus and patterns of temporal variability in chlorophyll a, and among-site differences in seawater temperature and adult abundance. Our results illustrate that population size, partly driven by recruitment success, can leave a signal on genetic structure of this highly dispersive marine species. The significant effect of temperature and chlorophyll a stresses that local adaptation may be key to understanding the spatial genetic structure of our model species. Hence, the results of this work represent an advance towards understanding the usually complex causal relationships between environmental variables, gene flow, and genetic diversity patterns of coastal populations.
Environmental variability and larval supply to wild and cultured shellfish populations
(2022) Broitman, Bernardo R.; Lara, Carlos; Flores, Raul P.; Saldias, Gonzalo S.; Pinones, Andrea; Pinochet, Andre; Mejia, Alexander Galan; Navarrete, Sergio A.
Coastal upwelling ecosystems support some of the most productive fisheries of the planet together with a large shellfish aquaculture sector that depends on oceanographic processes to deliver planktonic larvae to replenish and feed the farmed stock. Coastal shellfish aquaculture operations in Chile and Peru have experienced large interannual fluctuations in larval supply over the past decade, yet the drivers of such variability remain unidentified. We focused on the effects of environmental variability on larval supply of the farmed Peruvian bay scallop Argopecten purpuratus in a bay in northern Chile (Tongoy Bay, 30 circle S) that accounts for over 90% of countrywide landings. We examined the hypothesis that the environmental processes governing larval supply were shared with wild benthic invertebrates with planktonic larval development and compared time series of larval abundance for the scallop with larval supply rates to benthic populations of two well-studied wild intertidal species: the Chthamalid barnacle Jehlius cirratus and the purple mussel Perumytilus purpuratus. To this end, we examined the cross-correlation of larval supply to environmental variability using MODIS satellite fields of sea surface temperature (SST) chlorophyll-a concentration (chl-a) and fluorescence line height (nFLH), together with three climate indices relevant for the south east Pacific sector: the Southern Oscillation index (SOI), the Pacific Decadal Oscillation (PDO) and the Antarctic Oscillation Index (AAO). Our results showed that over the five-year study period (2009-2013), patterns of larval supply to the scallop population were related to interannual variability in the environmental processes as captured by their Empirical Orthogonal Functions (EOFs), likely to adult condition before spawning. Surprisingly, larval supply for none of the wild species showed a clear association to the EOFs. In contrast, scallops and wild species showed significant association to lower frequency climate variability as captured by the SOI and the PDO, but not the AAO. Results suggest that larval supply patterns to Tongoy Bay may be modulated by regional patterns of climatic variability, particularly of tropical origin. Thus, changes in coastal oceanography associated with ongoing changes in global climate could have strong and lasting effects on the supply of seedstock for wild and cultivated species across this eastern boundary coastal system and argue for the establishment of long-term ocean observing and early warning systems along the region.
Geographic variation in diversity of wave exposed rocky intertidal communities along central Chile
(2011) Broitman, Bernardo R.; Veliz, Fredy; Manzur, Tatiana; Wieters, Evie A.; Randall Finke, G.; Fornes, Paulina A.; Valdivia, Nelson; Navarrete, Sergio A.
Along the coast of central Chile, geographic trends of diversity have been inferred from literature compilations and museum collections based on species range limits for some taxonomic groups. However, spatially-intensive field-based assessments of macrobenthic species richness are largely missing. Over the course of a multiyear study (1998-2005), we characterized latitudinal patterns of rocky intertidal diversity at 18 sites along the coast of central Chile (29-36 degrees S). At each site, the number of sessile and mobile macrobenthic species was quantified in 0.25 m(2) quadrats. Two estimators of local (alpha) diversity were used: observed local species richness, calculated from the asymptote of a species-rarefaction curve, and the Chao2 index, which takes into account the effect of rare species on estimates of local richness. We identified a total of 71 species belonging to 66 genera for a total of 86 taxa. The most diverse groups were herbivorous mollusks (27 taxa) and macroalgae (43 taxa). Diversity showed a complex spatial pattern with areas of high species richness interspersed with areas of low richness. In accordance with previous work, we found no trend in the number of herbivorous mollusks and an inverse and significant latitudinal gradient in the number of algal species. Our results highlight the need for taxonomically diverse assessments of biodiversity of the dominant taxa that conform intertidal communities.
Geographical variation of multiplex ecological networks in marine intertidal communities
(2020) Lurgi, Miguel; Galiana, Núria; Broitman, Bernardo R.; Kéfi, Sonia; Wieters Buchanan, Evie Ann; Navarrete C., Sergio
Independent Effects of Species Removal and Asynchrony on Invariability of an Intertidal Rocky Shore Community
(2022) Fica-Rojas, Eliseo; Catalan, Alexis M.; Broitman, Bernardo R.; Perez-Matus, Alejandro; Valdivia, Nelson
Ecological stability depends on interactions between different levels of biological organization. The insurance effects occur when increasing species diversity leads to more temporally invariable (i.e., more stable) community-level properties, due in part to asynchronous population-level fluctuations. While the study of insurance effects has received considerable attention, the role of dominant species that contribute with particular functional traits across different level of organizations is less understood. Using a field-based manipulative experiment, we investigated how species richness and different types of parameters at the population level, such as the invariability of dominants, population invariability, and population asynchrony, influence the community invariability. The experiment involved the repetitive removal of the canopy forming alga Mazzaella laminarioides (hereafter "Mazzaella") during 32 months in two rocky intertidal sites of northern-central Chile. We predicted that the invariability of dominants enhances community invariability, that the effect of multispecies population-level parameters on community invariability are dependent on species richness, and that subdominant algae are unable to fully compensate the loss of canopies of the dominant species. Biomass of algae and mobile invertebrates was quantified over time. We observed independent effects of Mazzaella removal and community-wide asynchrony on community invariability. While canopy removal reduced community invariability, population asynchrony boosted community invariability regardless of the presence of canopies. In addition, filamentous and foliose algae were unable to compensate the loss of biomass triggered by the experimental removal of Mazzaella. Canopy removal led to a severe decrement in the biomass of macrograzers, while, at the same time, increased the biomass of mesograzers. Asynchrony stemmed from compensatory trophic responses of mesograzers to increased abundances of opportunistic algae. Thus, further work on consumer-resource interactions will improve our understanding of the links between population- and community-level aspects of stability.
Oceanographical-driven dispersal and environmental variation explain genetic structure in an upwelling coastal ecosystem
(2024) Peluso, Livia; Faundez, Juan; Navarrete, Sergio A.; Broitman, Bernardo R.; Aiken, Christopher M.; Saenz-Agudelo, Pablo
The seascape comprises multiple environmental variables that interact with species biology to determine patterns of spatial genetic variation. The environment imposes spatially variable selective forces together with homogenizing and diverging drivers that facilitate or restrict dispersal, which is a complex, time-dependent process. Understanding how the seascape influences spatial patterns of genetic variation remains elusive, particularly in coastal upwelling systems. Here, we combine genome-wide SNP data, Lagrangian larval dispersal simulated over a hydrodynamic model, and ocean environmental information to quantify the relative contribution of ocean circulation and environmental heterogeneity as drivers of the spatial genetic structure of two congeneric intertidal limpets, Scurria scurra and S. araucana, along the central coast of Chile. We find that a genetic break observed in both limpet species coincides with a break in connectivity shown by the Lagrangian dispersal, suggesting that mean ocean circulation is an important seascape feature, in particular for S. scurra. For S. araucana, environmental variation appears as a better predictor of genetic structure than ocean circulation. Overall, our study shows broad patterns of seascape forcing on genetic diversity and contributes to our understanding of the complex ecological and evolutionary interactions along coastal upwelling systems.
Spatio-temporal variability of turbidity derived from Sentinel-2 in Reloncavi sound, Northern Patagonia, Chile
(2024) Garcia-Tunon, Wirmer; Curra-Sanchez, Elizabeth D.; Lara, Carlos; Gonzalez-Rodriguez, Lisdelys; Urrego, Esther Patricia; Delegido, Jesus; Broitman, Bernardo R.
Turbidity is associated with the loss of water transparency due to the presence of particles, sediments, suspended solids, and organic or inorganic compounds in the water, of natural or anthropogenic origin. Our study aimed to evaluate the spatio-temporal variability of turbidity from Sentinel-2 (S2) images in the Reloncavi sound and fjord, in Northern Patagonia, Chile, a coastal ecosystem that is intensively used by finfish and shellfish aquaculture. To this end, we downloaded 123 S2 images and assembled a five-year time series (2016-2020) covering five study sites (R1 to R5) located along the axis of the fjord and seaward into the sound. We used Acolite to perform the atmospheric correction and estimate turbidity with two algorithms proposed by Nechad et al. (2009, 2016 Nv09 and Nv16, respectively). When compared to match-up, and in situ measurements, both algorithms had the same performance (R-2 = 0.40). The Nv09 algorithm, however, yielded smaller errors than Nv16 (RMSE = 0.66 FNU and RMSE = 0.84 FNU, respectively). Results from true-color imagery and two Nechad algorithms singled an image from the austral autumn of 2019 as the one with the highest turbidity. Similarly, three images from the 2020 austral autumn (May 20, 25, 30) also exhibited high turbidity values. The turbid plumes with the greatest extent occurred in the autumn of 2019 and 2020, coinciding with the most severe storms and runoff events of the year, and the highest turbidity values. Temporal trends in turbidity were not significant at any of the study sites. However, turbidity trends at sites R1 and R2 suggested an increasing trend, while the other sites showed the opposite trend. Site R1 recorded the highest turbidity values, and the lowest values were recorded at R5 in the center of the sound. The month of May was characterized by the highest turbidity values. The application of algorithms from high-resolution satellite images proved to be effective for the estimation and mapping of this water quality parameter in the study area. The use of S2 imagery unraveled a predictable spatial and temporal structure of turbidity patterns in this optically complex aquatic environment. Our results suggest that the availability of in situ data and the continued evaluation of the performance of the Nechad algorithms can yield significant insights into the dynamics and impacts of turbid waters in this important coastal ecosystem.
Stability of rocky intertidal communities, in response to species removal, varies across spatial scales
(2021) Valdivia, Nelson; Lopez, Daniela N.; Fica-Rojas, Eliseo; Catalan, Alexis M.; Aguilera, Moises A.; Araya, Marjorie; Betancourtt, Claudia; Burgos-Andrade, Katherine; Carvajal-Baldeon, Thais; Escares, Valentina; Gartenstein, Simon; Grossmann, Mariana; Gutierrez, Barbara; Kotta, Jonne; Morales-Torres, Diego F.; Riedemann-Saldivia, Barbara; Rodriguez, Sara M.; Velasco-Charpentier, Catalina; Villalobos, Vicente, I; Broitman, Bernardo R.
Improving our understanding of stability across spatial scales is crucial in the current scenario of biodiversity loss. Still, most empirical studies of stability target small scales. We experimentally removed the local space-dominant species (macroalgae, barnacles, or mussels) at eight sites spanning more than 1000 km of coastline in north- and south-central Chile, and quantified the relationship between area (the number of aggregated sites) and stability in aggregate community variables (total cover) and taxonomic composition. Resistance, recovery, and invariability increased nonlinearly with area in both functional and compositional domains. Yet, the functioning of larger areas achieved a better, albeit still incomplete, recovery than composition. Compared with controls, smaller disturbed areas tended to overcompensate in terms of total cover. These effects were related to enhanced available space for recruitment (resulting from the removal of the dominant species), and to increasing beta diversity and decaying community-level spatial synchrony (resulting from increasing area). This study provides experimental evidence for the pivotal role of spatial scale in the ability of ecosystems to resist and recover from chronic disturbances. This knowledge can inform further ecosystem restoration and conservation policies.
The importance of having two species instead of one in kelp management: the Lessonia nigrescens species complex
(2011) Tellier, Florence; Alonso Vega, J. M.; Broitman, Bernardo R.; Vasquez, Julio A.; Valero, Myriam; Faugeron, Sylvain
Natural resource management requires extensive knowledge of the biology of the organisms and their responses to ecological and anthropogenic processes. While species are commonly used as management units, the presence of cryptic species morphologically indistinguishable, but with different biological characteristics may hinder the design of appropriate management and conservation measures. Thus, correctly assigning individuals to species is of particular importance and challenges current management approaches in seaweeds, which are highly plastic morphologically. After a synthesis of the species definitions, we show an example of the challenges of managing cryptic species with the Chilean kelp Lessonia nigrescens. We review phylogenetic, biological and ecological evidence indicating that this economically important intertidal species is composed of two cryptic species. In the face of increasing global demand for kelp, an intensified impact of harvesting pressure is observed around the region where both cryptic species find their northern and southern edge of their geographic distributions, around 30 S. We recommend special management strategies targeting harvested areas around such range edge populations. Our synthesis highlights the importance of having two species that are ecologically and genetically different. In addition, the cryptic species may diverge in biochemical composition, opening new perspectives for the alginates' industry. The capacity of conservation and management programs to correctly distinguish new species is of particular importance as numerous cryptic species are constantly being discovered in seaweeds, including kelps.
Transient species driving ecosystem multifunctionality: Insights from competitive interactions between rocky intertidal mussels
(2024) Betancourtt, Claudia; Catalan, Alexis M.; Morales-Torres, Diego F.; Lopez, Daniela N.; Escares-Aguilera, Valentina; Salas-Yanquin, Luis P.; Buchner-Miranda, Joseline A.; Chaparro, Oscar R.; Nimptsch, Jorge; Broitman, Bernardo R.; Valdivia, Nelson
Anthropogenic biodiversity loss poses a significant threat to ecosystem functioning worldwide. Numerically dominant and locally rare (i.e., transient) species are key components of biodiversity, but their contribution to multiple ecosystem functions (i.e., multifunctionality) has been seldomly assessed in marine ecosystems. To fill this gap, here we analyze the effects of a dominant and a transient species on ecosystem multifunctionality. In an observational study conducted along ca. 200 km of the southeastern Pacific coast, the purple mussel Perumytilus purpuratus numerically dominated the mid -intertidal and the dwarf mussel Semimytilus patagonicus exhibited low abundances but higher recruitment rates. In laboratory experiments, the relative abundances of both species were manipulated to simulate the replacement of P. purpuratus by S. patagonicus and five proxies for ecosystem functions-rates of clearance, oxygen consumption, total biodeposit, organic biodeposit, and excretion-were analyzed. This replacement had a positive, linear, and significant effect on the combined ecosystem functions, particularly oxygen consumption and excretion rates. Accordingly, S. patagonicus could well drive ecosystem functioning given favorable environmental conditions for its recovery from rarity. Our study highlights therefore the key role of transient species for ecosystem performance. Improving our understanding of these dynamics is crucial for effective ecosystem conservation, especially in the current scenario of biological extinctions and invasions.
Upper environmental pCO₂ drives sensitivity to ocean acidification in marine invertebrates
(2022) Vargas, Cristian A.; Cuevas, L. Antonio; Broitman, Bernardo R.; San Martin, Valeska A.; Lagos, Nelson A.; Gaitan-Espitia, Juan Diego; Dupont, Sam
The authors link the effects of pCO(2) on marine invertebrates to the localized pCO(2) conditions of their coastal habitats. They show that responses depend on the deviation from the locally experienced upper pCO(2) level, highlighting the importance of small-scale variability and adaptation.

Browsing by Author "Broitman, Bernardo R."

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