Felipe Alvarez’s research while affiliated with University of Santiago Chile and other places

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Publications (3)


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November 2024

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9 Reads

Benjamín Corvalan

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Felipe Alvarez

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Diego Landaeta

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[...]

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Combined effect of pesticide exposure and dehydration in a passerine bird
Impacts of an organophosphate pesticide and water restriction on physiology and immunity in the passerine Zonotrichia capensis

November 2024

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48 Reads

Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology

Climate change, specifically rising temperatures and increased frequency of droughts will increase the level of exposure of organisms to chemical pollution. Notably, the impact of increased frequency and duration of drought events and subsequent dehydration on pesticide toxicity remains largely unknown. We evaluated the combined effects of exposure to the pesticide Chlorpyrifos (CPF) and water restriction (WR) on the enzymatic activities of three plasma esterases (acetylcholinesterase, butyrylcholinesterase and carboxylesterase), basal metabolic rate (BMR), leukocyte profile (proportion of heterophils to lymphocytes; H:L ratio), and bactericidal capacity of plasma in the rufous-collared sparrow (Zonotrichia capensis), a common passerine bird in Chile. The activity of the enzyme carboxylesterase decreased in birds exposed only to CPF and birds exposed to both the CPF and WR. In the group exposed to both stressors, the butyrylcholinesterase activity was also reduced. The BMR exhibited an increase in both groups exposed to CPF, with a higher rise observed in the group exposed to both CPF and WR, while the group subjected to WR showed no change. The bactericidal capacity of the plasma decreased significantly in birds exposed to CPF and in those exposed to both the pesticide and WR, while a marginal effect was observed in the group only subjected to WR. The H:L ratio increased in all groups, with the most pronounced effect in birds exposed to both stressors. These results suggest a shift in the energy budget of Z. capensis, favoring the detoxification of the pesticide through esterase activities, at the expense of reduced immunocompetence.


(A) Mean (±SE) Δ’¹⁷O values of body water cryogenically distilled from blood plasma and (B) the estimated proportion of metabolic water to the total body water pool in two species of Cinclodes inhabiting a coastal environment in central Chile.
Estimated δ¹⁸O values (mean ± SE) of ingested pre-formed (drinking/food) water in two species of Cinclodes inhabiting a coastal environment in central Chile.
Positive and significant linear correlation between blood δ¹⁵N values and the estimated δ¹⁸O of ingested water based on Δ¹⁷O for two species of Cinclodes inhabiting a coastal environment in central Chile. The dotted line represents the relationship for data pooled across both species, while the solid line represents the relationship for only C. oustaleti.
A multi-isotope approach reveals seasonal variation in the reliance on marine resources, production of metabolic water, and ingestion of seawater by two species of coastal passerine to maintain water balance

February 2023

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166 Reads

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3 Citations

Tracing how free-ranging organisms interact with their environment to maintain water balance is a difficult topic to study for logistical and methodological reasons. We use a novel combination of triple-oxygen stable isotope analyses of water extracted from plasma (δ¹⁶O, δ¹⁷O, δ¹⁸O) and bulk tissue carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes of feathers and blood to estimate the proportional contribution of marine resources, seawater, and metabolic water used by two species of unique songbirds (genus Cinclodes) to maintain their water balance in a seasonal coastal environment. We also assessed the physiological adjustments that these birds use to maintain their water balance. In agreement with previous work on these species, δ¹³C and δ¹⁵N data show that the coastal resident and invertivore C. nigrofumosus consumes a diet rich in marine resources, while the diet of migratory C. oustaleti shifts seasonally between marine (winter) to freshwater aquatic resources (summer). Triple-oxygen isotope analysis (Δ¹⁷O) of blood plasma, basal metabolic rate (BMR), and total evaporative water loss (TEWL) revealed that ~25% of the body water pool of both species originated from metabolic water, while the rest originated from a mix of seawater and fresh water. Δ¹⁷O measurements suggest that the contribution of metabolic water tends to increase in summer in C. nigrofumosus, which is coupled with a significant increase in BMR and TEWL. The two species had similar BMR and TEWL during the austral winter when they occur sympatrically in coastal environments. We also found a positive and significant association between the use of marine resources as measured by δ¹³C and δ¹⁵N values and the estimated δ¹⁸O values of ingested (pre-formed) water in both species, which indicates that Cinclodes do not directly drink seawater but rather passively ingest when consuming marine invertebrates. Finally, results obtained from physiological parameters and the isotope-based estimates of marine (food and water) resource use are consistent, supporting the use of the triple-oxygen isotopes to quantify the contribution of water sources to the total water balance of free-ranging birds.

Citations (1)


... While the framework for calculating Δ 17 O has been understood for ∼ 50 years [27], interest in Δ 17 O has rapidly expanded in the last ∼ 25 years, particularly in paleoclimatology, geochemistry, and hydrology [25,[28][29][30]. In addition, Δ 17 O has recently been applied to animal samples in ecological and physiological studies [9,14,15,[31][32][33][34]. The two primary sources of water for animalspreformed (drinking/food water) and metabolic waterare expected to have unique and relatively consistent Δ 17 O values of 41 per meg (parts per million) and -441 per meg, respectively [9,35]. ...

Reference:

A protocol for distilling animal body water from biological samples and measuring oxygen and hydrogen stable isotopes via cavity ring-down spectroscopy
A multi-isotope approach reveals seasonal variation in the reliance on marine resources, production of metabolic water, and ingestion of seawater by two species of coastal passerine to maintain water balance