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Abstract: Aerobic respiration is the main energy source for most eukaryotes, and efficient mitochondrial energy transfer greatly influences organismal fitness. To survive environmental changes, cells have evolved to adjust their biochemistry. Thus, measuring energy metabolism at the subcellular level can enhance our understanding of individual performance, population dynamics, and species distribution ranges. We investigated three important metabolic traits at the subcellular level in five lacertid lizard species sampled from different elevations, from sea level up to 2000 m. We examined hemoglobin concentration, two markers of oxidative stress (catalase activity and carbonyl concentration) and maximum rate of metabolic respiration at the subcellular level (potential metabolic activity at the electron transport system). The traits were analysed in laboratory acclimated adult male lizards to investigate the adaptive metabolic responses to the variable environmental conditions at the local sampling sites. Potential metabolic activity at the cellular level was measured at four temperatures – 28 °C, 30 °C, 32 °C and 34 °C – covering the range of preferred body temperatures of the species studied. Hemoglobin content, carbonyl concentration and potential metabolic activity did not differ significantly among species. Interspecific differences were found in the catalase activity, Potential metabolic activity increased with temperature in parallel in all five species. The highest response of the metabolic rate with temperature (Q10) and Arrhenius activation energy (Ea) was recorded in the high-mountain species Iberolacerta monticola.
Keywords: physiology, lacertids, aerobic respiration, interspecific variability, hemoglobin, zoology
Published in DiRROS: 03.09.2024; Views: 18; Downloads: 852
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Keywords: thermal remote sensing, Landsat, forest canopy
Published in DiRROS: 03.09.2024; Views: 28; Downloads: 7
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Abstract: Purpose Hyporheic biofilms are the central site for biogeochemical cycling in streams and rivers. In view of global warming and increasing human pressures, this study aimed to compare the response of hyporheic biofilm biomass and activities from an unpolluted reference stream reach surrounded by forest with those from a stream reach exposed to agricultural and urban land use using a mesocosm experiment in which the water temperature and dissolved organic carbon (DOC) contents were manipulated. Methods Hyporheic sediments collected in the field from the two study reaches (i.e. reference and impacted) were incubated in the laboratory at two different temperatures (10 °C, 14 °C) and wetted with three types of synthetic water (control [C] – 0 mg L−1; low DOC – 5 mg L−1; high DOC – 30 mg L−1) for four weeks. The responses of the hyporheic biofilms were measured weekly using structural (total protein content [TPC] as a proxy for biofilm biomass) and functional measures (electron transport system activity [ETSA] and community-level physiological profiling [CLPP]). Results The response of hyporheic biofilms to temperature changes and DOC enrichment was site-specific for all studied measures (TPC, ETSA and CLPP, including measured average well colour development [AWCD]). The addition of DOC to biofilms from the pristine stream reach significantly heightened the responses at 10 °C, a temperature within the normal environmental temperature ranges of the reference location, but not at 14 °C, which was here, a temperature outside normal environmental range. On the other hand, biofilms from the impacted stream reach exhibited increased responses following DOC enrichment under both temperature regimes, with a particularly pronounced response at 14 ºC, in this case, both experimental temperatures were within the normal environmental temperature ranges of the study locations. Conclusion Hyporheic biofilms were shown to be, like benthic biofilms, sensitive to temperature changes and organic enrichment, but their response to temperature changes and enrichment caused by climate change and/or other anthropogenic pressures (i.e. point and non-point pollution, removal of the riparian zone, hydromorphological modifications, etc.) was not simply linear but site-specific. The intensity of the response, characterized by increased activity and biomass production, appears to be constrained within the temperature ranges prevalent in the environment from which the biofilms originate. These findings emphasize the importance of site-specific considerations in predicting the impacts of climate change and anthropogenic pressures on these critical components of river and stream ecosystems.
Keywords: sediments, respiration, enzymes, functional indicators, interactions
Published in DiRROS: 05.08.2024; Views: 180; Downloads: 186
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Abstract: The size and composition of fish eggs are related to female’s characteristics, such as age, size and individual conditions, and they have an impact on the properties of offspring that are important for their fitness. Electron transport system (ETS) activity and respiration rate (R) of early life history stages (i.e. non-fertilized eggs, eggs at eyed stage and larvae with yolk sac) of 13 females of marble trout (Salmo marmoratus) were measured separately in order to determine their metabolic properties in relation to size. The results showed that larger females produced larger eggs in higher numbers. Growth experiments on the survival of offspring of a single female revealed that the survival rate of early embryos was higher for smaller eggs during the earliest stages, but ultimately the percentage of surviving larvae did not correlate with egg size. The ETS activities and respiration rates of non-fertilized eggs, eyed eggs and larvae differed significantly between 13 females. Both parameters increased with increasing dry mass of the early life history stages, but the increase of respiration rate was greater than that of ETS activity. The lower ETS/R ratios in larger individuals therefore indicate that their energy metabolism was less adaptable to environmental changes than that of smaller ones. Larger egg size could be an advantage under favourable conditions, whereas smaller size could be optimal under stressing circumstances in which the higher metabolic potential enables production of the energy required for metabolism. This is first report on the relationship between ETS activity and respiration rate of the early life history stages in salmonids.
Keywords: Salmo marmoratus, fitness, metabolism, ETS activity, ETS/R ratio, fishes
Published in DiRROS: 29.07.2024; Views: 182; Downloads: 96
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Abstract: Purpose Increased sedimentation due to land use intensification is increasingly affecting carbon processing in streams and rivers around the globe. This study describes the design of a laboratory-scale flow-through incubation system as a tool for the rapid estimation of sediment respiration. The measurements were compared with those obtained using an in situ closed chamber respiration method. The influence of sediment size on respiration rates was also investigated. Materials and methods Measurements were conducted on a pre-alpine gravel-bed river sediment separated into the following grain size fractions: > 60 mm (14.3%), 60–5 mm (60.2%), 5–2 mm (13.7%), 2–0.063 mm (11.1%) and <0.063 mm (0.6%). Concurrently, in situ and laboratory measurements were carried out on a naturally heterogeneous sediment. In situ respiration was determined in closed chambers as O2 consumption over time, while in the laboratory, respiration was determined using flow-through respiration chambers. Oxygen concentrations were measured using a fibre-optic oxygen meter positioned at the inflow and outflow from the chamber. Results and discussion The mean respiration rates within naturally mixed riverbed sediments were 1.27 ± 0.3 mg O2 dm−3 h−1 (n = 4) and 0.77 ± 0.1 mg O2 dm−3 h−1 (n = 3) for the flow-through chamber system and closed chamber system, respectively. Respiration rates were statistically significantly higher in the flow-through chamber system (t test, p < 0.05), indicating that closed chamber measurements underestimated the oxygen consumption within riverbed sediments. Sediment grain size was found to significantly affect respiration rates in both systems (ANOVA, p < 0.001) with the fine sediment fraction (particle size <0.063 mm) having the highest respiration rate (rflow-through = 51 ± 23 mg O2 dm−3 h−1). The smallest fractions (2–0.063 and <0.063 mm), which represent approximately 12% of total sediment volume, contributed 60% of total respiration. Conclusions The study demonstrated that flow-through respiration chambers more accurately estimate the respiration rate within riverbed sediments than in situ closed chambers, since the former experiment imitates the natural conditions where continuous interstitial flow occurs in the sediments. We also demonstrated that fine sediments (<5 mm) substantially contribute to heterotrophic respiration in the studied gravel-bed river.
Keywords: carbon fluxes, freshwaters, geomorphology, hyporheic zone, respiration, sediments
Published in DiRROS: 24.07.2024; Views: 172; Downloads: 111
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