Water temperature in a stream gravel bed and implications for salmonid incubation

SUMMARY. 1. Water temperatures were recorded at hourly intervals in the gravel of a trout spawning area in a small stony stream at depths of 0–20 cm in 1985–86 and 0– 40 cm in 1987.
2. As depth within gravel increased, the size of the daily fluctuations reduced and their time of occurrence was delayed by about 12 min cm⁻¹' in 1985–86 and about 6 min cm⁻¹ in 1987.
3. From October to February mean temperatures at 20 cm depth were, on average, 0.5°C higher than those at the gravel surface. This reflected elevated daily minima more than it reflected elevated daily maxima.
4. From March to July daily minima were lower and daily maxima were higher in the stream than in the gravel. Consequences were: (a) an appreciable increase in mean daily range at all depths in the gravel during the summer, (b) higher daily means (by an average of about 0.4°C) in the water than in the gravel in May to August.
5. Some implications for the early development of salmonid fish are considered.     

Adult mortality and oviposition rates in field and captive populations of the blowfly Lucilia sericata

Abstract.  1. Adult mortality and oviposition rates were determined for populations of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae). This species is of economic importance as the primary agent of sheep myiasis throughout north-western Europe.
2. Populations of marked flies in six, 1 m³, outdoor field cages and unmarked wild flies at two farms in south-west England were studied simultaneously between May and September 1998.
3. In the field, wild female L. sericata were caught and aged using a combination of wing-fray and ovarian dissection techniques. Survivorship analysis gave estimates of mortality of 1.94% (± 0.037) and 2.09% (± 0.044) per day-degree and mean life expectancy of 51.5 and 47.9 day-degrees above a threshold of 11 °C, at the two farms studied. Mean lifetime reproductive output in the field was estimated to be 159.6 and 138.4 eggs per female at the two farms respectively.
4. The survivorship of cohorts of marked female flies in cages was followed by counting the number of dead individuals each day; the mortality rate of these flies was 0.81% per day-degree (± 3.49 × 10⁻⁴%) and the mean life expectancy was 123.1 day-degrees above a threshold of 11 °C. Mortality rate was shown to increase significantly with average ambient temperature and relative humidity lagged for two sample periods (approximately 10 days). Oviposition rate also increased with average temperature but declined with average relative humidity. A best-fit multiple regression model incorporating both ambient temperature and humidity explained 60.5% of the variance in the pattern of oviposition.
5. The differences between the field and cage populations highlight the caution required when extrapolating life-history parameters from artificial to natural habitats.     

Hatching time and growth of Nemurellapictetii (Plecoptera: Nemouridae) in the laboratory and a Lake District stream

SUMMARY. 1. Nemurella pictetii Klapæplek took 2 years to complete its life cycle in both the laboratory and a small stream in the English Lake District.
2. Hatching time (days after oviposition for 10%. 50% and 90% of the eggs to hatch) and hatching period (days between dates for 10% and 90% hatched) decreased with increasing water temperature in the laboratory, and the relationships were well described by a power-law. Estimates of the mean time for 50% hatching in the stream varied between 16 and 31 days after oviposition. depending on temperature.
3. Larval instars numbered fifteen for males and seventeen for females with a constant ratio of 1.18 between successive instars (conformed with Dyar's rule). Larval growth was exponential at four constant temperatures in the laboratory; mean instantaneous growth rates were 0.40±0.01% day⁻¹ at 5.9°C, 0.43±0.01% day⁻¹ at 8.2°C, 0.46±0.01% day⁻¹ at 12. 1°C. 0.56±0.02%day⁻¹ at 19.8°C. No larvae survived after instar XI at 19.8°C.
4. Larval growth was exponential in the stream and was scarcely affected by variations in water temperature (range 4.2 -14.0°C); mean growth rates for three year-classes were 0.41±0.02, 0.43±0.08, 0.54±0.05% day⁻¹. Their similarity to laboratory growth rates under optimum conditions suggests that the availability of resources, such as food and space, was not restricting growth in the stream.     

Life cycle and population dynamics of Trochosa terricola Thorell (Araneae: Lycosidae) in a Norfolk grass heath

Abstract. 1. The population of the lycosid Trochosa terricola Thorell was sampled from April 1973 to August 1975 at Weeting Heath NNR, a Breckland grass heath.
2. Four sampling methods were compared for efficiency. Hand searching gave density estimates between 38.3 and 70.1% of heat extraction.
3. The temperature range in the sward at +1 cm was –5°C to 39°C with January and July means of 3.2°C and 17.4°C.
4. Eight male and nine female instars were determined and the life cycle extended over 2 or 3 years.
5. Adults were nocturnal but the juveniles diurnal. An annual diplochrone activity pattern was observed for adult males.
6. The horizontal distribution within the sward was aggregated, the structure and microhabitat being important determining factors. The population density was greater in moist, young Festuca spp. tussocks. An equation relating population density to habitat characteristics was derived.
7. The overall population density ranged from 14.0 m^-2 to 76.0 m^-2 and was maximal in autumn after breeding. The population biomass was greatest during autumn (291.2 mg d.wt m^-2).
8. Mean number of juveniles emerging from an egg sac was 77.3 (first sac) and 38.0 (second sac). The natality in 1973 was 66.8 individuals m^-2.
9. The survivorship curve until maturity varied between types I and III in different years.
10. The population dynamics were compared and are discussed in the light of other data. The variable population characteristics suggested that Den Boer's "spreading of risk" theory applied to the T.terricola population.     

The affect of temperature on the metabolism and behaviour of an endemic amphipod, Hyalella montezuma, from Montezuma Well, Arizona, U.S.A.

1. Hyalella montezuma is endemic to Montezuma Well, Arizona, and is exposed to minimal diel and seasonal temperature fluctuations in the pelagic zone (21 ± 4 °C). Juvenile H . montezuma feed in the pelagic zone during the day and migrate into the littoral vegetation at night, while adults remain primarily in the littoral vegetation.
2. Oxygen consumption ( V O₂) of adult and juvenile H . montezuma was measured at 20, 25 and 30 °C. The V O₂ of both adult and juvenile H . montezuma increased with temperature. However, the V O₂ of juveniles was significantly greater than that of adults at all temperatures, with greatest divergence at 30 °C where mean juvenile V O₂ (6.31 μl mg^–1 dry weight (DW) h^–1) was almost twice that of adults (3.60 μl mg^–1 DW h^–1).
3. Survivorship of juveniles was significantly lower (54%) at 30 °C than at 27.5 °C (95%) after 4 h, whereas adults showed at least a 93% survivorship at both temperatures.
4. Our data suggest that temperature may have been the proximate cue that elicited the diel horizontal migration of juvenile H . montezuma in Montezuma Well, with the behaviour maintained and enhanced by intensive invertebrate predation in the pelagic and littoral zones.     

The affect of temperature on the metabolism and behaviour of an endemic amphipod, Hyalella montezuma, from Montezuma Well, Arizona, U.S.A.

1. Hyalella montezuma is endemic to Montezuma Well, Arizona, and is exposed to minimal diel and seasonal temperature fluctuations in the pelagic zone (21 ± 4 °C). Juvenile H . montezuma feed in the pelagic zone during the day and migrate into the littoral vegetation at night, while adults remain primarily in the littoral vegetation.
2. Oxygen consumption ( V O₂) of adult and juvenile H . montezuma was measured at 20, 25 and 30 °C. The V O₂ of both adult and juvenile H . montezuma increased with temperature. However, the V O₂ of juveniles was significantly greater than that of adults at all temperatures, with greatest divergence at 30 °C where mean juvenile V O₂ (6.31 μl mg^–1 dry weight (DW) h^–1) was almost twice that of adults (3.60 μl mg^–1 DW h^–1).
3. Survivorship of juveniles was significantly lower (54%) at 30 °C than at 27.5 °C (95%) after 4 h, whereas adults showed at least a 93% survivorship at both temperatures.
4. Our data suggest that temperature may have been the proximate cue that elicited the diel horizontal migration of juvenile H . montezuma in Montezuma Well, with the behaviour maintained and enhanced by intensive invertebrate predation in the pelagic and littoral zones.     

Helicobacter pylori Infection, Gastritis, and the Temperature of Choice for Hot Drinks

Background. The role of the temperature of the diet as a potential etiological factor for gastritis or peptic ulcer disease has been postulated since the beginning of the century. Animal studies have demonstrated damage to gastric mucosa caused by hot water at 60 to 80°C. In the pre- Helicobacter pylori era it was reported that the majority of ulcer patients preferred hot drinks. It also was reported that the temperature of choice for drinks increased with severity of histological grade of gastritis. We evaluated the association between the preferred temperature of hot drinks and the presence of H. pylori infection.
Methods. We tested the temperature of choice for hot drinking liquids among 12 H. pylori -negative and 43 H. pylori -positive volunteers. We also compared the effect of H. pylori therapy on hot drink temperature preference and, in 32 individuals, whether there was a relation between temperature and the degree of gastric atrophy.
Results. There was no difference in the preferred temperature for hot drinks between those volunteers with and without H. pylori infection (63.4°± 6°C compared to 61.3°± 7°C, respectively) (mean ± 1 SD, p =.3) There was no change in preferred temperature after successful therapy of the H. pylori infection compared to unsuccessful H. pylori therapy, nor was there a correlation between the preferred temperature and the presence, absence, or degree of gastric atrophy ( r ² < 0.001).
Conclusion. The temperature of preference for hot drinks was not influenced by H. pylori infection or by the presence of atrophic gastritis.     

Temperature-related fluctuations in the timing of emergence and pupation of Windermere alder-flies over 30 years

1. From 1966 to 1995, dates were recorded when adult alder-flies, Sialis lutaria L., were first seen (30-year range: 23 April – 25 May), 50% of the maximum density occurred (4 May – 4 June), and maximum density occurred (11 May – 17 June) along 200 m of Windermere shore. These emergence dates occurred at similar temperatures, estimated by mean values for both the emergence date and the week prior to emergence. The latter was the least variable at 10.1 °C (95% CL ± 0.37) for start of emergence, 11.2 °C (± 0.49) for 50% maximum density, 14.2 °C (± 0.51) for maximum density.
2. Final-instar larvae pupated in damp soil just above the water line. As laboratory temperatures were increased slowly from an initial 5 °C, the cumulative number of larvae leaving the water to pupate increased. A quadratic equation described this relationship from a threshold temperature of 7.2 °C to completion at 14.0 °C (50% point, 9.3 °C). The relationship between successful pupations and constant temperatures in the laboratory was well described by a quadratic equation with an optimum 14.9 °C (over 90% success) and no success outside the range 7–23 °C. A negative power-function described the relationship between days required for pupation and temperature, ranging from c . 28 days at 8.2 °C to c . 4 days at 22.1 °C.
3. Dates for larvae leaving the lake to pupate were back-calculated from dates for adult emergence, using the power-function for pupation time. Mean temperatures for estimated dates on which larvae left the lake to pupate were less variable than those for adult emergence, being 7.5 °C (± 0.20) for the start of pupation, 9.4 °C (± 0.16) for 50% maximum density, 13.7 °C (± 0.16) for maximum density. These values are similar to those obtained in the laboratory and can be used to predict pupation and adult emergence for different temperature regimes.     

Egg development of the stoneflies Siphonoperla burmeisteri(Chloroperlidae) and Dinocras cepùnalotes(Perlidae)

SUMMARY. 1. The duration of egg incubation ( Y ) in Dinocras cephalotes and Siphonoperla burmeisteri was related to constant temperatures from 4 to 24°C, by the regression equations Y=2382 T ^{− 1, 402}(r²=0.992, P<0.001) and y= 2683 T ^−1.667 ( r ²=0.994, P <0.001), respectively. No diapause was observed in either species.
2. Egg incubation in D. cephaloles was slow and took 784.9±92.7 (mean ± SD) degree days between 12 and 20°C. significantly more than in S. burmeisteri (445±76.17 degree days: t = 7.44. d.f.=13, P <0.001).
3. For D. cephalotes hatching occurred at temperatures between 12 and 24°C, and for S . burmeisteri between 8 and 20°C. The mean volume of the eggs of D. cephalotes was about 5 times greater than that of S. burmeisteri and the mean body lengths of the newly-hatched nymphs were 1.13 mm and 0.95 mm respectively.
4. This study shows that the freshwater fauna of northern Fennoscan- dia also contains species with warm stenotherm eggs. D. cephalotes. which is of a Mediterranean origin (Zwick, 1981a), may exist at the limit of its distribution in northern Fennoscandia.     

Effect of sampling interval and temperature on the accuracy of food consumption estimates from stomach contents

The effect of temperature and sampling interval on the accuracy of food consumption estimates based on stomach contents was studied using simulation. Three temporal patterns of feeding were considered (scattered throughout the day, one 5 h period or two 5 h periods) and gastric evacuation was modelled according to published values. Sampling intervals of 3 h gave reasonable food consumption estimates (2 to 19% error) at all temperatures. Comparably, sampling intervals as large as 12 h gave reasonable estimates of food consumption (1 to 20% error) when temperature was set to ≤10° C. At temperatures <5° C, even 24 h intervals (equivalent to one daily sampling) provided reasonable estimates of daily food consumption (2 to 19% error) for all but the highest gastric evacuation rate combined with one daily feeding period (47% error). The temperature effect on estimation error resulted from diminishing temporal fluctuations in stomach contents with slower gastric evacuation rates. It follows that sampling effort may be considerably minimized when estimating food consumption from stomach contents during periods with low temperatures such as the winter time experienced by temperate fishes.     

Thermoregulation and metabolism in the Cape golden mole (Insectivora: Chrysochloris asiatica)

The Cape golden mole, Chrysochloris asiatica is an insectivore which excavates superficial foraging burrows as it searches for its food. It has a mean (±S.D.) resting metabolic rate (RMR) when newly captured of 1–17±0.17 cm³ O₂g^-1 h^-1 ( n = 14), within the thermoneutral zone (TNZ) of 30–32°C.
The body temperature (Tb) of the mole in the TNZ is low 32.9 ± 0.36 ( n = 14) and remains stable at ambient temperatures (Tas) from 28–32°C. Above 32°C (range 34–37°C), Tb increases albeit slightly to 36 ± 1.75°C ( n = 14). The conductance is high 0.27 ± 006cm³ O₂g^-1 h^-l°C^-1 ( n = 46) at the lower limit of thermoneutrality. The mean RMR at 9°C (the lowest Ta tested) was 4.82±11 cm³ O₂g^-1h^-1, which is 4.1 times that of the RMR in the TNZ.
At an ambient temperature of 9°C, three of the golden moles entered a state of torpor where the RMR was reduced from 5.9±0.56 to 10 1.0 ± 0.69cm³O₂g^-1h^-1.     

The effects of temperature on the web-building behaviour of the common house spider, Achaearanea tepidariorum

1. Because spiders are ectothermic animals, the temperature regime of the microhabitat in which an individual finds itself may affect important performance traits of that individual. The present study examined the effects of temperature on attributes of webs spun by Achaearanea tepidariorum (C. L. Koch), as well as testing temperature preference in this species. The effects of temperature on the amount of silk per web produced by Achaearanea tepidariorum and the prey-capture efficiency of webs produced at different temperatures were determined by using webs constructed at 5, 10, 15, 20, 25 and 30°C. The temperature preferences of A. tepidariorum within a thermal gradient were also determined.
2. Web mass was related to temperature, exhibiting a quadratic relation with a maximum web mass occurring at approximately 20°C.
3. Number of strands per cm³ of webs varied directly with web mass; webs with greater strand densities were more efficient at capturing flies.
4. The number of spiders observed in each temperature range in the thermal gradient indicated a non-uniform distribution, with the spiders avoiding temperatures in the highest range (27·3±2·0°C).
5. These data suggest an optimal temperature for web construction at which webs produced are more efficient at capturing prey. The data also suggest that this species may avoid sites that do not provide an adequate thermal environment.     

Survival of the first stage larva of the metastrongyloid nematode Elaphostrongylus rangiferi under various conditions of temperature and humidity

First-stage larvae of E. rangiferi kept in water at 50°C died within 80 minutes, while at 6° the last larvae died between day 180 and 210. The time it took to reach 1_x= 0.5 (half of the larvae dead) at various temperatures between 6° and 50° was well described by the exponential function y = 614.6e^−0.15x, giving a value of 615 days to reach 1_x= 0.5 at 0°C. There was no clear decrease in the survival of larvae frozen at −20° in faeces and in water, and at −80° in faeces after 360 days. When subjected to repealed freezing and thawing, all larvae died within 77 days. When kept in air at RH = 20% and 22°C, all larvae died within 11 days, while when frozen (−20°C) in air at RH approx. 0%, 1_x stayed at approx. 0.5 from day 5 to day 16.     

THE EFFECT OF TEMPERATURE ON EGGS AND IMMATURE STAGES OF CULEX ANNULIROSTRIS SKUSE (DIPTERA: CULICIDAE)

Abstract
No immature stages of Culex annulirostris were found during field sampling in 1979–1980 when the average water temperature was < 17 °C; they reappeared when the average water temperature was 19 °C and reached the peak density (mean 107 immatures/cylinder) at 26.5 °C.
The effect of 6 temperatures (15–40°C) on egg hatching, development and survival of the immature stages of Cx annulirostris in the laboratory showed that at 15 and 40°C, eggs failed to hatch and larvae died in the first instars. The optimum temperatures for egg hatching and the survival of immature stages were 25 and 30°C. At these temperatures, 85 and 82% respectively of egg rafts hatched, the mean number of larvae per raft was 258 ± 9.8 and 260 ± 11.4 with immature survival of 83.5 and 79.0% respectively. Mean time to hatch at 20–35°C ranged from 1.2 d (35°C) to 2.9 d (20 °C). Developmental times from first instar to adult ranged from 7.1 d (35 °C) to 25.2 d (20 °C). The threshold for development of the immatures was 15.6 ± 2.5°C and the thermal constant was 142.9 ± 26.5 day—degrees (incubation temperatures 20–35°C). At less suitable temperatures of 20 and 35 °C, hatching (57.5 and 45%), number larvae per raft (mean 139.8 ± 9.8 and 102.6 ± 14.2) and survival were low.     

Seasonal change in the respiration of the dobsonfly larva, Protohermes grandis(Megaloptera: Corydalidae)

SUMMARY 1. Seasonal change in the respiration of the dobsonfly larva, Protohermes grandis ,was studied by measuring the oxygen consumption rate (resting metabolism) bimonthly for 2 years. The respiratory rate of the larva was significantly lower during the summer season when the stream temperature rose to 30°C.
2. Summer depression of respiration was confirmed by measuring the rate of carbon dioxide evolution. The mean value of the respiratory quotient was estimated to be 0.76 ± 0.05 SE. The larva is believed to conserve energy by this reduction in respiratory rate,
3. In other seasons, however, the larva maintained a higher respiratory rate and remained active even in the winter when the stream temperature decreased near to 0°C. In fact, significant growth in weight occurred from mid-October to late March.
4. This acclimation to temperature may enable the efficient allocation of energy during the long larval period (3 years) in streams which have large annual fluctuations in temperature.     

Daily ration estimates for yellowfin sole, Limanda aspera (Pallas), based on laboratory consumption and growth

Several estimates of minimal energy requirements for yellowfin sole were made. Energy expenditures of 1.6, 4.1 and 8.3 cal g⁻¹ day⁻¹ were obtained from starvation weight loss, standard metabolism and maintenance ration procedures, respectively, at 6° C. The temperature effect on energy requirement was reflected in the Q ₁₀ values for starvation weight loss (2.0), standard metabolism (6.3) and maintenance ration (6.5).
Both energy intake and weight of food were linearly related to, and good predictors of, laboratory growth. These relationships were used to estimate the food and energy intake necessary for yellowfin sole to achieve a year's growth in the natural environment. Based on a caloric value of 2.0 kcal g⁻¹ of food (herring fillets), yellowfin would require 0.35 to 0.39% body weight day⁻¹ at 3° C to achieve the mean growth rate exhibited in the Bering Sea. To achieve Gulf of Alaska growth rates at 5 to 6° C, yellowfin would require 0.63% body weight day⁻¹. Based on a caloric value of 0.57 kcal g⁻¹ of food (chopped octopus), yellowfin would require 0.83% body weight per day to achieve the Gulf of Alaska growth rate (6° C). These requirements based on the calorific value of herring fillets, which are three to five times higher than previous estimates of daily ration in this species, are probably conservative estimates since many of their prey species have a lower energy content.     

The upper critical thermal limits for alevins of Arctic charr from a Norwegian lake north of the Arctic circle

Mean values ±95% CL of the upper incipient (T_IL) and ultimate (T_UL) lethal temperatures, determined at five acclimation temperatures ( T_A ), increased for T_IL from 19.2 ± 0.4° C ( T_A 0.5° C) to 21.0 ± 0.4° C ( T_A 20° C), and for T_UL from 22.6 ± 0.1° C ( T_A 0.5° C) to 26.6 ± 0.4° C ( T_A 20° C). Mean values were close to those obtained for Arctic charr alevins from Windermere (north-west England). These comparative data for alevins, and previous data for 0+ year parr, indicate negligible geographical variation in the thermal limits of Arctic charr.     

Effect of long-term and rapid cold hardening on the cold torpor temperature of an aphid

Abstract.  The effect of long-term (seasonal) acclimation and rapid cold hardening is investigated on the cold torpor temperature ( CT _min) of adult grain aphids, Sitobion avenae, reared at 20 or 10 °C for more than 6 months before experimentation. Rapid cold hardening is induced by exposing aphids reared at 20 to 0 °C for 3 h and aphids reared at 10 to 0 °C for 30 min (acclimation regimes previously found to induce maximum rapid cold hardening). The effect of cooling aphids from the same rearing regimes from 10 to −10 °C at 1, 0.5 and 0.1 °C min⁻¹ is also investigated. In the 20 °C acclimated population, rapid cold hardening and cooling at 0.1 °C min⁻¹ both produce a significant decrease in CT _min from 1.5 ± 0.3 to –0.9 ± 0.3 and –1.3 ± 0.3 °C, respectively. Rapid cold hardening also results in a significant reduction in CT _min of the population reared at 10 °C from 0.8 ± 0.1 to –0.9 ± 0.2 °C. However, none of the cooling regimes tested reduces the CT _min of the winter-acclimated (10 °C) population. The present study demonstrates that rapid cold-hardening induced during the cooling phase of natural diurnal temperature cycles could lower the movement threshold of S. avenae , allowing insects to move and continue feeding at lower temperatures than would otherwise be possible.     

Embryogenesis of Dinocras cephalotes, Perla grandis and P. marginata (Plecoptera: Perlidae) in different temperature regimes

1. Temperature dependence of embryogenesis of the three perlid stoneflies Dinocras cephalots , Perla grandis and P. marginata was investigated by means of incubation experiments. Special emphasis was laid on the effect of fluctuating temperatures and on intraspecific differences between populations from two different field sites in the Swiss prealps (i.e. River Necker and River Thur).
2. Dinocras cephalotes embryos develop between 6.3 and 26.6 °C. The lower threshold temperature is lower than has been reported for more northern populations (i.e. from England and Norway), indicating the existence of a latitudinal gradient. Perla grandis eggs only developed between 9.9 and 18.4 °C. In P. marginata , successful embryogenesis was observed between 9.9 and 18.4 °C, but not enough eggs were available to explore the threshold temperatures.
3. Embryogenesis of D. cephalotes and P. grandis was significantly faster at a 12/16 °C daily fluctuating temperature regime than at a constant 14 °C. However, no significant difference was found between the development under simulated field temperature regimes (with less distinct daily amplitudes) and constant temperatures.
4. D. cephalotes , hatching of eggs from the Necker population was much less synchronous than that in the Thur population. Since the Necker discharge regime is harsher than the Thur regime, it is possible that this asynchrony spreads the risk of destruction during bed-moving floods.