Metabolic Cold Adaptation Research Articles

The Influence of Habitat and Altitude on Oxygen Uptake in Sub-Antarctic Weevils

Whole-organism oxygen uptake rate and its temperature sensitivity (determined using regression analyses and estimates of Q10) were examined in six closely related weevil species (Palirhoeus eatoni, Bothrometopus randi, Bothrometopus elongatus, Bothrometopus parvulus, Ectemnorhinus similis, and Ectemnorhinus marioni) from sub-Antarctic Marion Island over a short time period and using the same methods. Bothrometopus elongatus, B. parvulus, and the two Ectemnorhinus species have populations at both high and low elevations, and pairwise comparisons of these species were made. Regressions of the log of oxygen uptake rate on temperature and Q10 values revealed that the Ectemnorhinus species have a significantly greater thermal sensitivity than do species in the genera Bothrometopus and Palirhoeus. This may be considered an adaptation of the former to their moist lowland habitats and the requirements of angiosperm-feeding in E. similis. It is argued that elevated oxygen uptake rates and reduced slopes of the regression of the log of oxygen uptake rate on temperature in species and populations from high altitudes compared with those from low elevations provide evidence for metabolic cold adaptation. In addition, it seems likely that elevated oxygen uptake rates and their reduced thermal sensitivity within the genera Bothrometopus and Palirhoeus are an adaptation to the cold Neogene environments they evolved in. However, because data on the more basal taxa in the Ectemnorhinus group of weevils are not available, this temperature compensation could not be attributed conclusively to adaptation. Q10's of the lowland populations of all the species were negatively correlated with body water content, and it is suggested that the low temperature sensitivity of metabolism in P. eatoni and the Bothrometopus species may also be due to constraints imposed on them by their dry habitats.

Respiration of juvenile Arctic cod (Boreogadus saida): effects of acclimation, temperature, and food intake

Oxygen consumption (VO2) of juvenile Arctic cod (Boreogadus saida) was investigated at low tempera tures (six temperatures; range -0.5 to 2.7°C). Small (mean wt. 6–8 g) and large (mean wt. 14 g) fish were acclimated, or adjusted to a constant temperature (0.4°C), for 5 months and then tested for metabolic cold adaptation (elevated metabolic rates in polar fishes). Short-term (2 weeks) acclimated fish showed elevated VO2 similar to previously established values for polar fishes, but there was no such evidence after longterm acclimation. Long-term acclimation caused VO2 values to drop significantly (from 86.0 to 46.5 mg O2·kg−1·h−1, at 0.4°C), which showed that metabolic cold adaptation was a phenomenon caused by insufficien: acclimation time for fish in respiration experiments. We also measured the effects of temperature and feeding on VO2. A temperature increase of 2.3°C resulted in relatively large increases in VO2 for both longand short-term acclimated fish (Q10 = 6.7 and 7.1, respectively), which suggests that metabolic processes are strongly influenced by temperature when it is close to zero. Feeding individuals to satiation caused significant increases in VO2 above pre-fed values (34–60% within 1–2 days after feeding). Respiration budgets of starved and fed Arctic cod at ambient temperatures in Resolute Bay N.W.T., Canada, were used to model annual respiration costs and potential weight loss. Low respiration costs for Arctic cod at ambient temperatures result in high growth efficiency during periods of feeding and low weight loss during periods of starvation.

Estudo do metabolismo de rotina e excreção de amônia do antípoda antártico Waldeclàa obesa em duas temperaturas distintas

Realizaram-se estimativas, a 0ºC e a 3ºC, do consumo médio e específico de oxigênio e da excreção média e específica de amónia de anfípodas antárticos da espécie Waldeckia obesa, coletados na Baía do Almirantado, Ilha Rei George, Antártica. Os experimentos foram realizados na Estação Antártica Brasileira "Comandante Ferraz" e no Laboratório de Ecologia Polar do Instituto Oceanográfico da Universidade de São Paulo. Foram empregados animais entre 120 mg a 620 mg e entre 40 mg e 690 mg de peso úmido, nos experimentos a 0ºC e a 3ºC, respectivamente. Dentro dessas faixas de peso, o consumo médio de oxigênio, a 0ºC, variou de 2,22µl/h a 10,81µl/h e o específico de 0,011µl/mg/h a 0,018µl/mg/h. A 3ºC, o consumo médio de oxigênio variou de 1,83µl/h a 14,19µl/h e o específico de 0,033µl/mg/h a 0,022µl/mg/h. O Q10, calculado a partir das médias das classes, foi de 6,95. Por sua vez, a excreção média de amónia, a 0ºC, variou de 13,84 ng.at/h a 55,34 ng.at/h e a específica entre 0,090 ng.at/mg/h a 0,042 ng.at/mg/h. A 3ºC, a excreção média de amónia variou de 5,11 ng.at/h a 38,33 ng.at/h e a específica de 0,088 ng.at/mg/h a 0,059 ng.at/mg/h. A relação 0:N indica que uma mistura de proteínas e lipídios é utilizada como substrato para o catabolismo. A 3ºC, entretanto, há uma tendência a aumentar a contribuição dos lipídios nesse substrato. O consumo de oxigênio de Waldeckia obesa é bastante baixo estando de acordo com os valores encontrados, a 0ºC, por outros autores. Esses dados, juntamente com resultados recentes encontrados na literatura, indicam a fragilidade da hipótese de "adaptação metabólica ao frio", que supõe terem os animais marinhos ectotérmicos antárticos taxas metabólicas elevadas, como resposta adaptativa às baixas temperaturas. Os dados de consumo de oxigênio e excreção de amónia fornecem material básico para extrapolação a parâmetros populacionais, fornecendo subsídios para a avaliação do papel ecológico desses animais no ecossistema em que vivem.

Exercise metabolism in two species of cod in arctic waters

The northern range of Atlantic cod (Gadus morhua), overlaps the southern range of the Greenland cod (Gadus ogac), in the coastal waters of Western Greenland. The availability of a temperate water species (G. morhua) in the same area and oceanographic conditions as a polar species (G. ogac) presented us with the ideal circumstances to test the hypothesis of metabolic cold adaptation (MCA) since many of the problems associated with MCA studies (adaptation of the animals beyond their normal temperature range or mathematical extrapolation of data to common temperatures) could thus be avoided. We therefore used a swim tunnel to measure oxygen consumption in fish at 4°C over a range of swimming speeds and following exhaustion, monitored the size of the oxygen debt and time of oxygen debt repayment. There were no significant differences in standard (60–72 mg O2 kg−1· hr−1), routine (76 mg O2 kg−1·hr−1), active (137mg O2 kg−1·hr−1), or maximal (157 mg O2 kg−1·hr−1) metabolic rate, metabolic scope (2.5) or critical swimming speed (2.2 BL·s−1) between the two species. Following exhaustive swimming, however, the half-time for oxygen debt repayment in G. ogac (43 min) was almost twice that of G. morhua (25 min). Despite its circumpolar distribution, therefore, there was no evidence of MCA in G. ogac.

Oxygen consumption in four species of teleosts from Greenland: no evidence of metabolic cold adaptation

Standard metabolic rate of Greenland cod or uvak, Gadus ogac, polar cod, Boreogadus saida, Atlantic cod, Gadus morhua, and sculpin, Myxocephalus scorpius, caught in the same geographical area on the west coast of Greenland was measured at 4.5°C, the temperature at which the fish were caught. The present data does not support the Metabolic Cold Adaptation theory in the traditional sense of the standard metabolic rate being 2–4 times higher for Arctic fishes than for temperate species. The standard metabolic rate of the two exclusively Arctic species of teleosts was only 10% and 26% higher, respectively, than the two species that occur in temperate as well as Arctic areas. The critical oxygen tension, with respect to oxygen consumption, of resting uvak was between 50 and 60 mmHg, and the lethal oxygen tension 20–25 mmHg at 4.5°C, which is considerably higher than for Atlantic cod from a temperate area measured at the same temperature.

Metabolic rates of Calathus melanocephalus (L.) (coleoptera, carabidae) from alpine and lowland habitats (jeløy and finse, norway and drenthe, the netherlands)

1. 1. Metabolic rates (ml O 2/mg/hr) of three geographically separated populations of the carabid beetle Calathus melanocephalus L. (Finse and Je 10y, Norway and Drenthe, The Netherlands) were measured and compared by ANCOVA. 2. 2. No significant relationship ( P > 0.05) between metabolic rates and body weight or sex of the animals were found. 3. 3. Individuals mostly acclimated to low temperatures by increased metabolic rates and in the opposite direction to higher temperatures. Individuals collected in early summer also showed higher metabolic rates than those caught later in the autumn. 4. 4. Contradicting the theory of metabolic cold adaptation, beetles from The Netherlands had the highest metabolic rates, beetles from Finse intermediate rates and beetles from Jeløy the lowest rates. 5. 5. No significant relation were found between geographical origin of the beetles and their respective chill-coma temperature.

Some Pathways of Energy Metabolism Are Cold Adapted in Antarctic Fishes

Biochemical indices of metabolic cold adaptation were studied in muscular tissues of ecotypically similar Antarctic and Temperate Zone marine fishes. Pairwise comparisons were made between sluggish bottom-dwelling (polar: Notothenia gibberifrons; temperate: Myoxocephalus octodecimspinosus) and more active pelagic (polar: Trematomus newnesi; temperate: Tautoga onitis) species to ensure that results reflect differences in thermal habitats rather than life histories. Maximal activities of enzymes from central pathways of aerobic energy metabolism (citrate synthase, cytochrome oxidase) were 1.5-5-fold higher in oxidative muscles from polar species than from Temperate Zone counterparts when assayed at 1° C. Under similar conditions, enzyme markers for fatty acid oxidation (carnitine palmitoyltransferase, 3-hydroxyacyl-CoA dehydrogenase) were 1.3-27-fold higher in tissues from polar species, while those for both aerobic (hexokinase) and anaerobic (6-phosphofructokinase, pyruvate kinase, and lactate dehydrogenas...

Channels and pumps—determinants of metabolic cold adaptation strategies

1. 1. In all cells the passive diffusion of ions through transmembrane channels must be precisely balanced by the active transport of ions against concentration gradients, i.e., the ratio of ion channel/ion pump fluxes must be controlled at unity. 2. 2. One reason why some cells are cold sensitive is because temperature differentially affects these two processes and the necessary balance between them breaks down. 3. 3. Polar fishes apparently maintain channel/pump flux ratios at unity by upward adjustments in functional pump densities. 4. 4. That is presumably why their maintenance metabolic requirements are higher, which is an important cause of their higher-than-expected metabolic rates. This is the causal basis for the paradigm of metabolic cold adaptation in polar fishes. 5. 5. Channel/pump flux ratios of unity in principle also could be achieved in cold tolerant organisms by downward adjustments in functional channel densities of cell (and organelle) membranes. 6. 6. However, organisms utilizing this strategy would be expected to display profoundly reduced metabolic rates, reduced scopes for activity, and reduced osmoregulatory capacities. 7. 7. Deep sea fishes, also normally functional at low temperatures, display drastically reduced metabolic rates compared to other fishes and may well illustrate the latter strategy.

The physiology of McMurdo Sound fishes: current New Zealand research

1. 1. Peripheral nerve conduction and neurotransmitter release in Antarctic teleosts are partially temperature compensated near 0°C, but labile at higher temperatures. 2. 2. Synaptic currents are shortened, probably by increased membrane fluidity; effects on synaptic gain are postulated. 3. 3. Several stages of the vestibulo-ocular reflex pathway are characterized, showing high gain and enhanced low frequency performance. 4. 4. Lateral line receptors respond maximally to vibration frequencies emitted by swimming planktonic crustacea. 5. 5. Reductions in concentration and variety of Antarctic fish haemoglobins may be related to blood viscosity, circulatory energetics and oxygen availability. 6. 6. A small degree of metabolic cold adaptation is confirmed for some McMurdo Sound nototheniids.

The aerobic scope of an antarctic fish, Pagothenia borchgrevinki and its significance for metabolic cold adaptation

Resting weight-specific oxygen consumption of the cryopelagic Antarctic nototheniid Pagothenia borchgrevinki at 0°C was 39.6 ml kg-1 · h-1 for a 50 g fish, with oxygen consumption being described by the regression equation: log10 VO2(ml/h)=-1.104+0.825 log10 Mb (g). These values are considerably below those raported by Wohlschlag (1964a,b). VO2 max. in forced swimming was described by the regression equation: log10 VO2 max = -0.507+0.823 log10 Mb. Despite low basal metabolism, factorial aerobic scope is similar to that reported for most other teleost fish, as is the cost of net transport. Myotomal muscles were used only at the highest swimming speeds and once they were recruited the fish fatigued rapidly. After swimming, oxygen debt was repaid rapidly, with a half-time of 20 min.

Temperature and plankton

The relationship between temperature and metabolism was studied in Artic copepods with regard to the concept of metabolic cold adaptation of polar poikilotherms. Temperature tolerance and respiration rates of the dominant copepods Calanus finmarchicus (Gunnerus), C. glacialis (Jaschnov), C. hyperboreus (Kroyer) and Metridia longa (Lubbeck), collected in Fram Strait, Greenland Sea, in July 1983, were studied at different temperatures. Temperature tolerance in the boreal C. finmarchicus was slightly higher than in the three Arctic species. Respiration rates at lower temperatures followed the Arrhenius equation in all species, with values for μ (temperature characteristics) between 11.05 and 22.95, corresponding to a Q10 between 2.05 and 4.5. This increase in metabolic rate with rising temperature was not related to an increase of swimming activity, as was shown by videoanalysis. “Activity” was determined as average swimming speed and as frequency of certain locomotor patterns. Average swimming speed remained unchanged at all temperatures and was ca 1 cm s-1 for all species, when only periods of active swimming were considered. The time spent with active swimming did not change with temperature in M. longa and C. finmarchicus, but decreased in c. glacialis. In C. hyperboreus it increased at 5°C and decreased again at higher temperatures. It is suggested that the increase in oxygen consumption is fully accounted for by the basal metabolism.

Respiration of Antarctic fish from McMurdo Sound

1. 1. Resting rates of oxygen uptake were measured for nine species of unstressed fish living at − 1.8°C in McMurdo Sound, Antarctica (77–78°S). Interspecific differences in V́O 2 were correlated with the habits and activity of the fish. 2. 2. The cryopelagic Pagothenia borchgrevinki regulated oxygen uptake down to a critical PO 2 of ≈60mmHg. The inactive benthic species Trematomus centronotus extracted oxygen to lower PO 2 and appeared to have a lesser degree of oxyregulation when the data were analysed using a quadratic model. 3. 3. Cutaneous oxygen uptake in the nototheniids T. bernacchii and P. borchgrevinki amounted to 9 and 17% of total V́O 2 under normoxic conditions which is less than that reported for scaleless Antarctic fish. 4. 4. The contentious concept of metabolic cold adaptation in polar fish has been reviewed, and the opinion expressed that the phenomenon cannot be dismissed on the grounds of technically incompetent measurement, or through inappropriate extrapolation of data from fish at lower latitudes.

Cutaneous oxygen uptake in the antarctic icequab, Rhigophila dearborni (Pisces: Zoarcidae)

Total resting oxygen uptake (VO2) at-1.5°C in the scaleless antarctic icequab, Rhigophila dearborni (Fam. Zoarcidae), for fish with body mass (Mb) between 11.9 and 54.0 g may be summarized by the regression equation: log VO2=0.23+0.47 log Mb. Oxygen uptake by the skin accounts for ≈35% of total resting VO2 but cannot be increased to compensate for occluded branchial exchange. These data do not suggest that the species shows metabolic cold adaptation since the O2 uptake rates at -1.5°C are among the lowest recorded for fish.

Temperature and metabolism of plankton—I. Respiration of antarctic zooplankton at different temperatures with a comparison of antarctic and nordic krill

1. 1. Direct response of 6 common Antarctic zooplankters (the euphausiid Euphausia superba, the copepods Calanoides acutus and Euchaeta antarctica, the amphipods Parathemisto gaudichaudii and Hyperiella antarctica, and the polychaete Tomopteris carpenteri) to temperature changes was measured and their temperature tolerance tested. 2. 2. Respiration rates followed the Arrhenius equation in the range examined (generally − 1 to + 10°C). 3. 3. Temperature coefficients varied between 8.06 and 23.84, while Q 10 values from 1.64 to 5.24 were found. 4. 4. When krill data were compared with experiments on North Sea Meganyctiphanes norvegica, no significant difference was found for Arrhenius coefficients. 5. 5. No mortality occurred within 30 hr at temperatures from − 1 to 10°C. 6. 6. The results are discussed with regard to the concept of metabolic cold adaptation.

Metabolic cold adaptation and compensatory acclimation of respiration rate in polar arthropods

Metabolic cold adaptation and compensatory acclimation of respiration rate in polar arthropods

Respiratory metabolism of the antarctic tick, Ixodes uriae

1. 1. The respiratory metabolism of the Antarctic tick, Ixodes uriae White (Acari: Ixodidae) was investigated at Palmer Station, Anvers Island (64°46'S; 64°03'W) during the austral summer, January 1981. 2. 2. At 20°C the metabolic rate of females was 303 nl/mg live wt/hr, approximately three times that of males and engorged nymphs. 3. 3. Laboratory acclimation of females, males and nymphs to 0 and 10°C for 2 wk had no effect on respiration rates, suggesting that I. uriae lacks the ability for compensatory acclimation of respiration rate. 4. 4. Metabolic rates of temperate ixodids are similar to those for females of I. uriae. which suggests that metabolic cold adaptation is absent in this species.

Absence of metabolic cold adaptation and compensatory acclimation in the Antarctic fly, Belgica antarctica

The respiratory metabolism in larvae of the Antarctic fly, Belgica antarctica Jacobs (Diptera: Chironomidae) was investigated at Palmer Station, Anvers Island (64°46′S, 64°03′W). Oxygen consumption was linearly related to temperature from 0 to 20°C, respectively, 49 and 338 nl/mg live wt/hr. Maintenance at 0 and 10°C for 8 days had no differential effect on the metabolic rate, suggesting that larvae lack the ability for compensatory acclimation. A comparison of standard metabolism for polar and temperate chironomids revealed no elevation of metabolic rate in polar forms. However, polar species exhibited lower activation energies than temperate forms indicating that the respiratory metabolism of polar chironomids is relatively temperature independent.

Metabolic coping strategies in cold tolerant reptiles

The reality of metabolic cold adaptation in ectotherms is disputed. Reptiles differ in many important aspects of their thermal ecology from aquatic ectotherms, and their thermophysiology is therefore difficult to analyze in conventional terms. Evidence is presented in support of the view that both phenotypic metabolic cold acclimation and genotypic metabolic cold adaptation are important coping strategies in cold tolerant reptiles. Functional explanations of these paradoxical adaptations are discussed in the light of a multidimensional energetic model of the reptilian thermal niche.

A reappraisal of the concept of metabolic cold adaptation in polar marine invertebrates

The concept of ‘metabolic cold adaptation’, namely that polar marine ectotherms are adapted in having an elevated basal metabolic rate, has been examined in the light of recent biochemical, physiological and ecological data for Antarctic marine organisms. It is now clear that marine invertebrates from Antarctic waters are characterized by slow growth rates, low basal metabolism and reduced annual reproductive effort, and there is thus no clear evidence of the traditional view of an elevated metabolic rate. By analogy with fish, protein synthesis rates are probably also low. This suggests that the major feature of cold adaptation is a reduction in the individual total annual energy intake in comparison with ecologically similar organisms from warm water. This allows a high standing crop of suspension feeders to develop, and low temperature is thus a significant factor in the successful widespread adoption of typical K-strategies in Antarctic marine invertebrates.

Metabolic Cold Adaptation of Polar Fish: Fact or Artefact?

The purpose of this paper is to present new information about the metabolic rates of arctic fish suggesting that the concept of cold adaptation as applied to fish from high latitudes should be reevaluated critically. Although many types of organisms and their processes have been credited with cold adaptation, one of the most frequently cited examples is found with fish. Fish from the arctic and the ant-