Browsing by Author "Farina, Jose M."

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    Establishment and formation of fog-dependent Tillandsia landbeckii dunes in the Atacama Desert: Evidence from radiocarbon and stable isotopes
    (2011) Latorre, Claudio; Gonzalez, Angelica L.; Quade, Jay; Farina, Jose M.; Pinto, Raquel; Marquet, Pablo A.
    Extensive dune fields made up exclusively of the bromeliad Tillandsia landbeckii thrive in the Atacama Desert, one of the most extreme landscapes on earth. These plants survive by adapting exclusively to take in abundant advective fog and dew as moisture sources. Although some information has been gathered regarding their modern distribution and adaptations, very little is known about how these dune systems actually form and accumulate over time. We present evidence based on 20 radiocarbon dates for the establishment age and development of five different such dune systems located along a similar to 215 km transect in northern Chile. Using stratigraphy, geochronology and stable C and N isotopes, we (1) develop an establishment chronology of these ecosystems, (2) explain how the unique T. landbeckii dunes form, and (3) link changes in foliar delta N-15 values to moisture availability in buried fossil T. landbeckii layers. We conclude by pointing out the potential that these systems have for reconstructing past climate change along coastal northern Chile during the late Holocene.
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    Experimental Evidence of the Tolerance to Chlorate of the Aquatic Macrophyte Egeria densa in a Ramsar Wetland in Southern Chile
    (2013) Palma, Alvaro T.; Schwarz, Alex O.; Farina, Jose M.
    In 2004, a massive die-off of the aquatic macrophyte Egeria densa occurred in a Ramsar wetland in southern Chile. In 2004, a pulp mill started its operations upstream from the wetland. Chlorate, a chemical compound found in pulp mill effluent, was one of the suspected causes of the observed ecosystem-level changes. The hypothesis was that high concentrations of chlorate in the wetland caused a massive die-off of the large populations of Egeria densa in this ecosystem. In this study several experimental efforts were aimed to understanding the potential effect of chlorate on E. densa. Plants were exposed to different doses of chlorate for variable periods in a large mesocosm array and several morphometric endpoints were quantified. Additionally, an ecotoxicological assay was implemented providing the first insight into the tolerance to chlorate of this aquatic plant. Both mesocosm and ecotoxicological evidences suggest that E. densa is tolerant to fairly high levels of chlorate (i.e. EC50 in the order of 1000 mg/L), at least three orders of magnitude larger than the highest concentration recorded in the wetland. Our results provide evidence that should guide the efforts of understanding the real causes of this environmental change.
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    Seasonal and geographic variation in thermal biology of the lizard Microlophus atacamensis (Squamata: Tropiduridae)
    (2008) Sepulveda, Maritza; Vidal, Marcela A.; Farina, Jose M.; Sabat, Pablo
    1. We studied physiological thermal adaptation in the lizard Microlophus atacamensis along a latitudinal range.
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    Time and behavioral adjustments to lactation: Insights from a marine predator
    (2023) Borras-Chavez, Renato; Goebel, Michael E.; Villegas-Amtmann, Stella; Huckstadt, Luis A.; Rivera-Rebella, Carla; Costa, Daniel P.; Farina, Jose M.; Bozinovic, Francisco
    The energetic costs of lactation have been studied in many marine mammals, but little is known about the behavioral adjustments needed to cope with this event. By simultaneously measuring foraging behavior of lactating and nonlactating Antarctic fur seal females, we estimate the behavioral changes necessary to cope with the constraints of lactation and include the first comparative record of dive behavior between lactating and nonlactating female otariids. Nonlactating females exhibited highly variable foraging trip durations and spent long times onshore between trips. In contrast, lactating females exhibited consistently shorter trips and spent half the time hauled-out compared to nonlactating females likely to maximize offspring provisioning. Lactating females show a reduced mean time per dive but greater percentage of time per trip spent diving compared to nonlactating animals. The reduction in time onshore and trip duration, together with modifications in dive performance suggests additional effort of lactating females to compensate for the constraints of rearing a pup, which has not been observed previously due to the lack of simultaneous comparison of lactating and nonlactating individuals. When possible, future studies of maternal investment should also include nonlactating individuals, since lactation may have a strong synergistic effect with other aspects shaping foraging behavior.