Browsing by Author "Nimptsch, Jorge"

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    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.
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    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.
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    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.