Behavioral temperature regulation by aquatic ectotherms during hypoxia

1988 ◽  
Vol 66 (12) ◽  
pp. 2649-2652 ◽  
Author(s):  
R. Keith Dupré ◽  
Stephen C. Wood

Terrestrial animals lower their body temperature by behavioral and (or) physiological means in response to environmental or anemic hypoxia. Because hypoxia is common in some aquatic environments, temperature selection by two aquatic ectotherms, paedomorphic tiger salamanders (Ambystoma tigrinum) and crayfish (Procambarus simulans), was examined during environmental hypoxia in an aquatic thermal gradient. Both species selected lower temperatures when exposed to an environment with a [Formula: see text] of about 37 Torr (4.9 kPa). These data suggest that the lowering of body temperature, and thus oxygen demand, in the face of a low oxygen availability may be an adaptive response in heterothermal aquatic environments. The available data for diverse species show that the hypothermic response to hypoxia is a taxonomically widespread phenomenon occurring in both water- and air-breathing animals.

Author(s):  
James W. E. Dickey ◽  
Neil E. Coughlan ◽  
Jaimie T. A. Dick ◽  
Vincent Médoc ◽  
Monica McCard ◽  
...  

AbstractThe influence of climate change on the ecological impacts of invasive alien species (IAS) remains understudied, with deoxygenation of aquatic environments often-overlooked as a consequence of climate change. Here, we therefore assessed how oxygen saturation affects the ecological impact of a predatory invasive fish, the Ponto-Caspian round goby (Neogobius melanostomus), relative to a co-occurring endangered European native analogue, the bullhead (Cottus gobio) experiencing decline in the presence of the IAS. In individual trials and mesocosms, we assessed the effect of high, medium and low (90%, 60% and 30%) oxygen saturation on: (1) functional responses (FRs) of the IAS and native, i.e. per capita feeding rates; (2) the impact on prey populations exerted; and (3) how combined impacts of both fishes change over invasion stages (Pre-invasion, Arrival, Replacement, Proliferation). Both species showed Type II potentially destabilising FRs, but at low oxygen saturation, the invader had a significantly higher feeding rate than the native. Relative Impact Potential, combining fish per capita effects and population abundances, revealed that low oxygen saturation exacerbates the high relative impact of the invader. The Relative Total Impact Potential (RTIP), modelling both consumer species’ impacts on prey populations in a system, was consistently higher at low oxygen saturation and especially high during invader Proliferation. In the mesocosm experiment, low oxygen lowered RTIP where both species were present, but again the IAS retained high relative impact during Replacement and Proliferation stages at low oxygen. We also found evidence of multiple predator effects, principally antagonism. We highlight the threat posed to native communities by IAS alongside climate-related stressors, but note that solutions may be available to remedy hypoxia and potentially mitigate impacts across invasion stages.


Genome ◽  
2013 ◽  
Vol 56 (7) ◽  
pp. 407-414 ◽  
Author(s):  
Jacqueline M. Doyle ◽  
Gregor Siegmund ◽  
Joseph D. Ruhl ◽  
Soo Hyung Eo ◽  
Matthew C. Hale ◽  
...  

Historically, many population genetics studies have utilized microsatellite markers sampled at random from the genome and presumed to be selectively neutral. Recent studies, however, have shown that microsatellites can occur in transcribed regions, where they are more likely to be under selection. In this study, we mined microsatellites from transcriptomes generated by 454-pyrosequencing for three vertebrate species: lake sturgeon (Acipenser fulvescens), tiger salamander (Ambystoma tigrinum), and kangaroo rat (Dipodomys spectabilis). We evaluated (i) the occurrence of microsatellites across species; (ii) whether particular gene ontology terms were over-represented in genes that contained microsatellites; (iii) whether repeat motifs were located in untranslated regions or coding sequences of genes; and (iv) in silico polymorphism. Microsatellites were less common in tiger salamanders than in either lake sturgeon or kangaroo rats. Across libraries, trinucleotides were found more frequently than any other motif type, presumably because they do not cause frameshift mutations. By evaluating variation across reads assembled to a given contig, we were able to identify repeat motifs likely to be polymorphic. Our study represents one of the first comparative data sets on the distribution of vertebrate microsatellites within expressed genes. Our results reinforce the idea that microsatellites do not always occur in noncoding DNA, but commonly occur in expressed genes.


Author(s):  
Andrew J. Watson ◽  
Timothy M. Lenton ◽  
Benjamin J. W. Mills

The major biogeochemical cycles that keep the present-day Earth habitable are linked by a network of feedbacks, which has led to a broadly stable chemical composition of the oceans and atmosphere over hundreds of millions of years. This includes the processes that control both the atmospheric and oceanic concentrations of oxygen. However, one notable exception to the generally well-behaved dynamics of this system is the propensity for episodes of ocean anoxia to occur and to persist for 10 5 –10 6 years, these ocean anoxic events (OAEs) being particularly associated with warm ‘greenhouse’ climates. A powerful mechanism responsible for past OAEs was an increase in phosphorus supply to the oceans, leading to higher ocean productivity and oxygen demand in subsurface water. This can be amplified by positive feedbacks on the nutrient content of the ocean, with low oxygen promoting further release of phosphorus from ocean sediments, leading to a potentially self-sustaining condition of deoxygenation. We use a simple model for phosphorus in the ocean to explore this feedback, and to evaluate the potential for humans to bring on global-scale anoxia by enhancing P supply to the oceans. While this is not an immediate global change concern, it is a future possibility on millennial and longer time scales, when considering both phosphate rock mining and increased chemical weathering due to climate change. Ocean deoxygenation, once begun, may be self-sustaining and eventually could result in long-lasting and unpleasant consequences for the Earth's biosphere. This article is part of the themed issue ‘Ocean ventilation and deoxygenation in a warming world’.


2004 ◽  
Vol 82 (9) ◽  
pp. 1477-1483 ◽  
Author(s):  
Matthew J Parris ◽  
Alison Davis ◽  
James P Collins

Pathogens can alter host behavior and affect the outcome of predator-prey interactions. Acute phase responses of hosts (e.g., a change in activity level or behavioral fever) often signal an infection, but the ecological consequences of host behavioral changes largely are unexplored, particularly for directly transmitted (i.e., single-host) pathogens. We performed three experiments to test the hypothesis that a pathogen, Ambystoma tigrinum virus (ATV), alters host behavior of Sonoran tiger salamanders (Ambystoma tigrinum stebbinsi Lowe, 1954) and enhances predation. In the first experiment, salamander larvae exposed to ATV experienced 48% lower mortality from dragonfly Anax junius (Drury, 1773) larvae than those in controls. Second, uninfected and infected larvae exposed to the nonlethal (caged) presence of predators did not significantly differ in their distance from the predator. Infected salamanders significantly increased their activity level relative to those in controls in predator-free conditions. Finally, ATV-infected larvae preferred significantly warmer temperatures than uninfected larvae, but larvae reared at the thermal maximum for the virus all died. High host activity level yet retention of effective antipredator responses likely benefits ATV because this single-host pathogen relies on host survival for transmission. Preference for warmer temperatures may be associated with the host response to pathogens and may help fight infection.


2021 ◽  
Vol 21 (2) ◽  
pp. 640-646
Author(s):  
Beril Ozdemır ◽  
Sıddıka Songül Yalçın

Background: The World Health Organization (WHO) recommends the use of tachypnea as a proxy to the diagnosis of pneumonia. Objective: The purpose of this study was to examine the relationship between body temperature alterations and respiratory rate (RR) difference (RRD) in children with acute respiratory infections(ARI). Methods:This cross-sectional study included 297 children with age 2-60 months who presented with cough and fever at the pediatric emergency and outpatient clinics in the Department of Pediatrics, Baskent University Hospital, from January 2016 through June 2018. Each parent completed a structured questionnaire to collect background data. Weight and height were taken. Body temperature, respiratory rate, presence of the chest indrawing, rales, wheezing and laryngeal stridor were also recorded. RRD was defined as the differences in RR at admission and after 3 days of treatment. Results: Both respiratory rate and RRD were moderately correlated with body temperature (r=0.71, p<0.001 and r=0.65, p<0.001; respectively). For every 1°C increase in temperature, RRD increased by 5.7/minutes in overall, 7.2/minute in the patients under 12 months of age, 6.4/minute in the female. The relationship between body temperature and RRD wasn’t statistically significant in patients with rhonchi, chest indrawing, and low oxygen saturation. Conclusion: Respiratory rate should be evaluated according to the degree of body temperature in children with ARI. How- ever, the interaction between body temperature and respiratory rate could not be observed in cases with rhonchi and severe pneumonia. Keywords: Fever; tachypnea; pneumonia; respiratory rate difference; children.


Copeia ◽  
2003 ◽  
Vol 2003 (3) ◽  
pp. 601-607 ◽  
Author(s):  
Elizabeth W. Davidson ◽  
Matthew Parris ◽  
James P. Collins ◽  
Joyce E. Longcore ◽  
Allan P. Pessier ◽  
...  

1999 ◽  
Vol 141 (1) ◽  
pp. 124-139 ◽  
Author(s):  
KJERSTEN L. LARSON ◽  
WALTER DUFFY ◽  
ERIN JOHNSON ◽  
MICHELE F. DONOVAN ◽  
MICHAEL J. LANNOO

2014 ◽  
Vol 70 (4) ◽  
pp. 729-735 ◽  
Author(s):  
Ganapathy Ramanathan ◽  
Christopher M. Sales ◽  
Wen K. Shieh

The occurrence of autotrophic denitrification and nitrification activities by ammonia-oxidising bacteria and nitrite-oxidising bacteria is studied in a bioreactor system operable at low-dissolved oxygen (DO) and at variable oxygen influx rates. At a loading of 3.6 mg NH4+–N/h into the bioreactor, simultaneous autotrophic denitrification and nitrification contributed to NH4+–N removal over oxygen influxes of 2–14 mg O2/h and DO &lt;0.5 mg/L. The maximum autotrophic denitrification (or total-N removal) rates were achieved in a narrow oxygen influx band of 3–5 mg O2/h, where it accounted for up to 36% of NH4+–N removal. At oxygen influx &gt;16 mg O2/h and DO &gt;2 mg/L, autotrophic denitrification ceases and roughly 90% of feed NH4+–N is oxidised to NOX−–N. The stability of total effluent chemical oxygen demand (COD) over the range of oxygen influxes tested confirms the absence of heterotrophic denitrification in the bioreactor. The long solids residence time of the stable biomass zone (21 days) led to production of effluent COD as a result of cell decay, and thus effluent COD was used to calculate more accurately the mean cell residence time.


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