Some factors affecting survival and oxygen uptake in a subtropical beach flea

The survival and oxygen uptake of the supralittoral amphipod Chroestia lota Marsden & Fenwick were investigated in humid air and sea water between 15 and 35°C. Seven-day exposure experiments were made on three size groups of amphipods at 6 constant temperatures (15, 20, 25, 30, 35, 40 °C) and three cyclic temperatures (15–25, 20–30, 25–35°C) in air and in sea water at 34 and 17%. salinity. Neither size, treatment nor temperature affected survival between 15 and 30°C. Mortality increased > 30°C with large individuals being consistently less tolerant than medium and small amphipods. While amphipods exposed to cyclic temperatures during submersion had reduced survival compared with constant temperatures, those individuals exposed to cyclic conditions in humid air showed the greatest resistance. Oxygen uptake of Chroestia increased with dry body wt and, over the range 15–35°C, this semi-terrestrial beach flea could maintain its aerial VO₂ following submersion. Oxygen uptake increased directly in proportion to gill area and the weight specific gill area was low, consistent with the need to reduce desiccation. It is suggested that total gill area does not limit oxygen uptake in Chroestia and that cutaneous respiration may be important especially in aquatic conditions.     

The combined effects of temperature,salinity, and declining oxygen tension on oxygen consumption in the marine pulmonate Amphibola crenata (Gmelin, 1791)

Oxygen consumption of Amphibola crenata (Gmelin) was measured in various salinity-temperature combinations (< 0.1‰ to 41‰ salinity and 5 to 30°C) in air, and following exposure to declining oxygen tensions. In all experimental conditions, respiration varied with the 0.44 power of the body weight (sd = 0.14). The aquatic rate was consistently higher than the aerial rate of oxygen consumption, although at 30 °C the two rates were similar. Oxygen consumption increased with temperature up to 25 °C in all salinities; the lowest values were recorded at temperatures below 10 °C and at 30 °C in the most dilute medium. At all exposure temperatures, the oxygen consumption of Amphibola decreased regularly with salinity down to 0.1 ‰, and following exposure to concentrated sea water (41‰). Salinity had the least effect at 15 °C which was the acclimation temperature. In general, all of the temperature coefficients (Q₁₀ values) were low, < 1.65. However, Q₁₀ values above 2.8 were recorded at a salinity of 17.8‰ between 10 and 15 °C. Oxygen consumption of all size classes of Amphibola was more temperature dependent in air than in water and small individuals show a greater difference between their aerial and aquatic rates than larger snails. The rates of oxygen consumption in declining oxygen tensions were expressed as fractions of the rates in air saturated sea water at each experimental salinity-temperature combination. The quadratic coefficient B₂ becomes increasingly more negative with both decreasing salinity and temperatures up to 20 °C. At higher temperatures (25 and 30 °C) the response is reversed such that O₂ uptake in snails becomes increasingly independent of declining oxygen tensions at higher salinities. On exposure to a salinity of 4‰, Amphibola showed no systematic response to declining oxygen tension with respect to temperature. The ability of Amphibola to maintain its rate of oxygen consumption in a wide range of environmental conditions is discussed in relation to its potential for invading terrestrial habitats and its widespread distribution on New Zealand's intertidal mudflats.     

The influence of some ecological factors on the metabolism—temperature curve of the larvae of Limnephilus rhombicus (Trichoptera, Limnephilidae)

SUMMARY. The oxygen uptake of Limnephilus rhombicus , a typical inhabitant of lentic waters, was measured in three different experimental situations: in still water with a plastic mesh as a substrate, in stirred water with a plastic mesh and in still water without any substrate. Water flow caused a small increase in oxygen uptake at all temperatures but principally above 15°C. The presence or absence of the plastic substrate had little influence on oxygen uptake; L. rhombicus can be active over the whole range of temperatures studied but its activity is always small. Its metabolism—temperature curve stands out in having a plateau between 5 and 10°C, with a steeper part between 10 and 20°C, the slope of which varies according to the conditions. Maximum oxygen uptake at high temperatures was relatively low (1235 ± 153 μl O₂g dry wt-1h-1 at 25°C).
The results are compared with those obtained previously for the larvae of Microptema testacea which inhabit flowing zones in brooks. L. rhombicus larvae appear both as cold-water animals and as animals from highly variable biotopes. They are in fact very ubiquitous and occupy all lentic biotopes from cold and mountainous districts to temperate lowlands.     

Gill ventilation and respiratory efficiency of Sacramento blackfish, Orthodon microlepidotus Ayres, in hypoxic environments

Respiratory and gill ventilatory responses of Sacramento blackfish to three environmental temperatures (12, 20 and 28°C) and four environmental dissolved oxygen concentrations (130, 90, 65 and 40 torr P_O2) were examined to determine physiological strategies of survival in eutrophic lakes and suitibility for culture conditions. Situated in van Dam-type respirometers, experimental blackfish showed increased gill ventilatory flows from increased ventilatory frequencies and stroke volumes to meet higher respiratory oxygen demands at increased temperatures. Ventilation volumes also increased at reduced environmental dissolved oxygen levels by increased ventilatory stroke volumes alone, except at 28°C where frequency increases were also measured. Oxygen consumption rates remained essentially constant with declining dissolved oxygen, except at 28°C where excitement elevated respiratory metabolism at 65 and 40 torr. Percentage utilization of oxygen increased with temperature from 12°C, but levels at 20 and 28°C were insignificantly different. Contrary to most studies on other species, there was no change in percentage utilization under hypoxic conditions even with 4.7-fold increases in ventilation volume in excited fish at 28°C. The ability of blackfish to survive in hypoxic waters is quantitatively compared with other species by calculation of a respiratory efficiency index (I), which includes the relationship between ventilation volume and percentage utilization of oxygen under normoxic and hypoxic conditions as well as the half-saturation value (P₅₀) of the species' blood with oxygen.     

Ventilatory mechanisms and the effect of hypoxia and temperature on the embryonic lesser spotted dogfish

Small, intermediate and large-sized embryos of the dogfish Scyliorhinus canicula utilize different ventilatory methods; small and intermediate embryos rely on body movement alone to stir either the jelly or sea water in the capsule, large embryos use conventional pharyngeal pumping to pump water through the case. The effects of environmental changes in O₂ tension (0.5–100% air saturation) and temperature (6–18°C) upon ventilatory mechanisms in the developing embryo in situ were studied using non-invasive ultrasonography. All three embryo classes increased ventilation rate with rising temperature: for small embryos, y=2.02x+3.295 ( P <0.01); for intermediate embryos, y=3.51x+0.395 ( P <0.01); and for large embryos, y=3.81x+9.39 ( P <0.01); where y=ventilatory frequency (tail beats min⁻¹ or pump cycles min⁻¹) and x=temperature (°C). Q ₁₀ (6–16°C)=5.0, 2.45, and 2.08 for small, intermediate and large embryos, respectively; corresponding Q ₁₀ (8–18°C) values were 2.09, 2.62, and 2.02. It is suggested that the extreme response of small embryos to 6°C is related to a different state of development in either chemoreceptors or muscle blocks. There was no significant change in ventilatory frequency induced by chronic (2 h) hypoxia. Dogfish embryos are oxyconformers at 8°C but oxyregulators at higher temperatures. Water flow through an eggcase occupied by a large embryo was studied also. Water enters the open eggcase of a large embryo, drawn in by the buccal/opercular pump of the respiring embryo, via holes at the posterior end of the eggcase. Expired water exits holes at the anterior end of the eggcase. The mean residence time for water in the case is 50 s at 8°C, giving a transit velocity of 1.36 mm s⁻¹.     

Respiratory mechanisms and metabolic adaptations of an intertidal crab,Chasmagnathus granulata (Dana, 1851)

• 1.1. The ventilatory mechanism, gill area, sites of oxygen uptake, oxygen consumption and activity of a crab from south Brazil, Chasmagnathus granulata, were investigated.
• 2.2. The oxygen uptake seems to be restricted to the gill lamellae.
• 3.3. The gill area varies with the wet body weight, being relatively higher in smaller animals. There is not a significative reduction of the gill area in relation to species of the infralittoral zone.
• 4.4. C. granulata presents a mechanism for recirculating the water of its branchial chamber when exposed to atmospheric air.
• 5.5. The oxygen consumption and activity are reduced when the animals are exposed to atmospheric air. The reduction in the oxygen consumption may be related to the poorly adapted respiratory system, while the decrease in activity may be a mechanism for saving energy during this hypoxic period.

     

Behaviour of Scrobicularia plana (Da Costa) in water of various salinities

Valve movements, heart and pumping rates have been recorded from Scrobicularia plana (Da Costa) when transferred stepwise from natural sea water to sea water of S = 30% (termed 100%) and then to 80, 60, 40, and 20% sea water, and after direct transfer from 100 to 20% Scrobicularia exhibits short periods of pumping alternating with short ventilatory pauses down to 40% sea water. These are termed activity cycles and contrast with periods of complete quiescence each ≈ 4–12 h long. The heart rate of animals in these salinities is fairly constant during activity cycles. When transferred to 20% sea water, either directly or gradually, short pumping phases alternate with long ventilatory pauses during the initial 72 h. At the same time the heart rate shows wide variation during activity cycles.On transference from 100 to 60% sea water, the valves opened and valve activity pattern returned to normal within 30 min and within 6 h of transfer from 60 into 40% SW. Transfer to 20%, whether stepwise or directly, resulted in valves remaining closed initially for ≈ 10 or 34 h, respectively before opening gradually to expose the mantle margin. The valve adductions were then of reduced frequency and extent.     

Respiratory and osmoregulatory responses of the hermit crab, Clibanarius vittatus (Bosc), to salinity changes

Intertidal hermit crabs were stepwise acclimated to 10, 20, and 30‰ salinity (S) and 21 ± 1 °C. Hemolymph osmolality, sodium, chloride, and magnesium were isosmotic (isoionic) to ambient sea water at 30‰ and hyperosmotic (hyperionic) at 20 and 10‰ S, while hemolymph potassium was significantly hyperionic in all acclimation salinities. Total body water did not differ significantly at any acclimation salinity. Oxygen uptake rates were higher in summer-than winter-adapted crabs. No salinity effect on oxygen consumption occurred in winter-adapted individuals. Summer-adapted, 30‰ acclimated crabs had a significantly lower oxygen consumption rate than those acclimated 10 and 20‰ S. Crabs exposed to 30 10 30‰ and 10 30 10‰ semidiurnal (12 h) and diurnal (24.8 h) fluctuating salinity regimes showed variable osmoregulatory and respiratory responses. Hemolymph osmolality followed the osmolality of the fluctuating ambient sea water in all cases, but was regulated hyperosmotically. Hemolymph sodium, chloride, and magnesium concentrations were similar to hemolymph osmolality changes. Sodium levels fluctuated the least. Hemolymph potassium was regulated hyperionically during all fluctuation patters, but corresponded to sea water potassium only under diurnal conditions. The osmoregulatory ability of Clibanarius vittatus (Bosc) resembles that reported for several euryhaline brachyuran species. The time course of normalized oxygen consumption rate changed inversely with salinity under semidiurnal and diurnal 10 30 10‰ S fluctuations. Patterns of 30 10 30‰ S cycles had no effect on oxygen consumption rate time course changes. The average hourly oxygen consumption rates during both semidiurnal fluctuations were significantly lower than respective control rates, but no statistical difference was observed under diurnal conditions.     

Effects of temperature and dissolved oxygen on heart rate,ventilation rate and oxygen consumption of spangled perch,Leiopotherapon unicolor (Günther 1859), (Percoidei,Teraponidae)

Summary Heart, ventilation and oxygen consumption rates ofLeiopotherapon unicolor were studied at temperatures ranging from 5 to 35°C, and during progressive hypoxia from 100% to 5% oxygen saturation. Biopotentials recorded from the water surrounding the fish corresponded to ventilation movements, and are thought to originate from the ventilatory musculature. Cardio-respiratory responses to temperature and dissolved oxygen follow the typical teleost pattern, with bradycardia, increased ventilation rate and reduced oxygen consumption occurring during hypoxia. However, ventilation rate did not increase at 15°C and below. Ventilation rate showed a slower response to increasing temperature (normoxic Q₁₀=1.39) than heart rate and oxygen consumption (normoxic Q₁₀=2.85 and 2.38).L. unicolor is unable to survive prolonged hypoxia by utilising anaerobic metabolism, but has a large gill surface area which presumably facilitates oxygen uptake in hypoxic environments. Periodic ventilation during normoxia in restingL. unicolor may improve ventilation efficiency by increasing the oxygen diffusion gradient across the gills.Abbreviations EBG electrobranchiogram - ECG electrocardiogram     

Effects of thermal stress on respiratory responses to hypoxia of a South American Prochilodontid fish, Prochilodus scrofa

Oxygen consumption (o₂) and respiratory variables were measured in the Prochilodontid fish, Prochilodus scrofa exposed to graded hypoxia after changes in temperature. The measurements were performed on fish acclimated to 25°C and in four further groups also acclimated to 25°C and then changed to 15, 20, 30 and 35°C. An increase in o₂ occurred with rising temperature, but at each temperature o₂ was kept constant over a wide range of O₂ tensions of inspired water ( Pi o₂). The critical oxygen tensions ( Pc o₂) were Pi o₂= 22 mmHg for 25°C acclimated specimens and after transfer from 25°C to 15, 20, 30 and 35°C the Pc o₂ changed to Pi o₂= 28, 22, 24 and 45 mmHg, respectively. Gill ventilation ( _G ) increased or decreased following the changes in o₂ as the temperature changed and was the result of an accentuated increase in breath frequency. During hypoxia the increases in _G were characterized by larger increases in breath volume. Oxygen extraction was kept almost constant at about 63% regardless of temperature and ambient oxygen tensions in normoxia and moderate hypoxia ( P o₂∼70 mmHg). P. scrofa showed high tolerance to hypoxia after abrupt changes in temperature although its survival upon transfer to 35°C could become limited by the capacity of ventilatory mechanisms to alleviate hypoxic stress.     

A Ca-activated ATPase in the mitotic apparatus of the sea urchin egg (isolated by a new method)

Steps in a new procedure for isolating the mitotic apparatus from sea urchin eggs (Strongylocentrotus purpuratus) are: (1) Cultivation of the eggs in sea water in which Na is replaced by Li, under which conditions the MA is stabilized in vivo and does not break down at the end of mitosis; (2) storage of the eggs containing the MA in 30% ethanol at −10 °C, preserving isolability and ATPase activity for several months; (3) isolation of the MA in the presence of ethanol and Triton X-100 at +10 °C by selective dispersal of the cytoplasm; (4) purification by washing in 30% ethanol, 0.1% Triton at low temperature. Because of the stabilization of the MA in the Li-sea water, the yield is large.     

Effects of experimental ventilation and ambient Po2 on O2 uptake of the isolated cutaneous tissue in the carp,Cyprinus carpio

Effects of experimental ventilation and ambient Po₂ on cutaneous O₂ uptake in vitro were studied in the carp, Cyprinus carpio. Oxygen uptake rate of the isolated cutaneous tissue was determined by ventilating the epidermis side of the skin with normoxic water in flow-through respirometers. Oxygen uptake rate of the skin increased with ventilation rate across the skin between 2.5 and 40 ml/min and became 3.2 nmol/cm²/min at a flow rate of 40 ml/min, which corresponds to an apparent water velocity of 1.1 cm/sec. At a ventilation rate of 10 ml/min, oxygen uptake rate of the skin increased with the ambient Po₂ between 115 and 230 Torr and became constant (3.8 nmol/cm²/min) between 230 and 295 Torr. When both sides of the skin were ventilated with normoxic water, oxygen uptake rate of the skin increased and became 3.7 nmol/cm²/min at a flow rate of 20–40 ml/min. These results suggest that the oxygen requirement of the skin is 3.7–3.8 nmol/cm²/min at 21.3°C and that cutaneous O₂ uptake in vitro depends on experimental ventilation and ambient Po₂, consistent with values measured in vitro in the carp (ref).     

Host-parasite relationship of Angiostrongylus cantonensis in Lymnaea palustris. III. Oxygen uptake of Lymnaea palustris.

Oxygen uptake rates by Lymnaea palustris infected with Angiostrongylus cantonensis and by noninfected controls were determined at 25, 30, and 35 C over 34-day periods. Significant decreases in oxygen uptake were noted from one day to the next for both infected and noninfected groups of snails. At 25 and 30 C groups of infected snails found to have high average larval recoveries frequently had significantly higher oxygen uptake rates than for corresponding groups of noninfected snails. At 35 C readings were less reliable due to an increase in mortality for both infected and noninfected snails. Respiratory rates were not significantly altered by increasing the temperature from 25 to 30 and 35 C.     

Aerial and aquatic oxygen consumption of Monodonta turbinata (Mollusca: Gastropoda)

The midlittoral trochid, Monodonta turbinata (Born) has a higher rate of oxygen consumption in air than in water at temperatures between 15 and 25°C. The temperature coefficient of its oxygen consumption is higher for the temperature interval 15 to 25°C than it is for the interval 5 to 15°C. The aerial oxygen consumption is increased by forced emersion or immersion for 24 hours. Immersion has the greater effect. It would appear that the trochid shows respiratory adaptation to zonation and environmental temperature.     

Hypometabolism in torpid goldsinny wrasse subjected to rapid reductions in seawater temperature

Goldsinny Ctenolabrus rupestris were subjected to rapid, environmentally realistic, reductions in temperature at 2° C increments from 10 to 4° C over a 3-day period in full-strength sea water. In separate experiments, oxygen uptake measurements and ultrasound recordings of heart rate and opercular motion were carried out at regular intervals over the same temperature regime. Mean oxygen uptake rates fell from 0.042 to 0.028 ml O₂ g⁻¹ h⁻¹ between 10 and 6° C respectively (Q₁₀=2.71). Between 6 and 4° C mean rates decreased from 0.028 to 0.008 ml O₂ g⁻¹ h⁻¹ (Q₁₀=542). Mean opercular motion and heart beat rates decreased from 49.5 and 60.3 beats min⁻¹ respectively at 10° C to 18.7 and 18.0 beats min⁻¹ respectively at 4° C. Most goldsinny subjected to 4° C were observed in a torpid state and would not react to external stimulation. Opercular motion was erratic at 4° C and would at times cease altogether for periods up to 1.3 min duration. Heart movement was diffcult to detect at 4° C and may also have ceased for prolonged periods. Q₁₀ values for opercular motion and heart beat rates recorded between 6 and 4° C were 6.39 and 24.52 respectively compared with values of 2.42 and 2.93 respectively recorded between 10 and 8° C. Such large depressions in metabolism appear not to have been reported previously for a marine fish species. No goldsinny mortalities were recorded at any temperature. The possibility that hypometabolic torpor is an adaptive strategy for goldsinny survival at low environmental temperatures is discussed.     

Gill ventilation and O2 extraction during graded hypoxia in two ecologically distinct species of flatfish,the flounder (Platichthys flesus) and the plaice (Pleuronectes platessa)

Synopsis Gill ventilation, breathing frequency, breath volume, oxygen extraction from the ventilatory water current and oxygen uptake through the gills were measured in flounder, Platichthys flesus, and plaice, Pleuronectes platessa, at water O₂ tensions ranging from 35 to 155 mm Hg at 10° C. Ventilation volumes were similar in the two species at high water O₂ tension. Exposure to hypoxic water elicited a larger increase in ventilation in the flounder. The per cent extraction of O₂ from water decreased slightly in both species as water O₂ tension was lowered. At comparable levels of ventilation O₂ extraction was higher in flounder. At the higher levels of water O₂ tension, O₂ uptake across the gills of flounder was stable, the critical O₂ tension being between 60 and 100 mm Hg. The plaice behaved as an oxygen conformer over the entire range of O₂ tensions investigated. The superior ability of the flounder in maintaining OZ uptake across the gills during a reduction in water O₂ tension may in part explain why the species, unlike plaice, inhabits very shallow waters with large fluctuations in dissolved oxygen.     

A comparison of carbon dioxide production and oxygen uptake in sediment cores from four south Swedish lakes

Carbon dioxide production and oxygen uptake were measured in undisturbed sediment cores taken during winter from four lakes of different trophic state. Respiration was measured at 5, 10, 15 and 20°C at high oxygen saturation (75–100%). The respiratory quotient, calculated from the mean values of carbon dioxide production and oxygen uptake at each temperature for each lake, was 0.83–0.96 with a mean value for the four lakes of 0.90. At very low oxygen saturations (<10%) carbon dioxide production was 21–42% of the production at 20°C and high oxygen saturations. The results indicate that under aerobic conditions, oxygen uptake and carbon dioxide production are closely-coupled processes in these lake sediments.     

An experimental study of the oxygen consumption,growth, and metabolism of the COD (Gadus Morhua L.)

The rate of oxygen consumption of cod in sea water at 12 °C containing MS222 (25 mg/l) can be expressed as: Q_o2 = 0.245 W^0,82(mg/h), where W is the lived weight of the fish (g). The maximum efficiency of conversion of assimilated food into growth was 24% during the feeding experiment. Digestion efficiencies were estimated at over 98% using fillets of plaice as food. The effect of increasing the rate of food intake was to increase liver weight and condition factor. The relative proportions of protein and lipid in the body did not change over the range of feeding levels used. The conversion efficiency had a maximum value at an intermediate feeding rate.     

Water loss and respiration of Lucilia cuprina during development within the puparium

The rate of loss of water and the rate of uptake of oxygen were measured continuously throughout the development of Lucilia cuprina within the puparium. Changes in these parameters were correlated with changes observed in morphology of cuticles and respiratory structures during development.In development at 26°C, there is, at 20–22 hr after puparium formation a major loss of water by mechanical expulsion of moulting fluid chiefly through the posterior larval spiracles after the severing of the posterior larval tracheae. This loss of water is essential to survival and is followed by an extremely low rate of water loss attributed to slow diffusion of water through the resulting air gap between the pupal cuticle and the puparium. There is an increase in oxygen consumption during the pupal movements associated with the casting of the larval tracheae followed by a sharp reduction in oxygen consumption until the pupal horns are everted a short time later. This combination of physiological events enables development to proceed over a wide range of conditions in the puparial environment.