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  • 1
    Electronic Resource
    Electronic Resource
    Number of meals in a day, maximum weight of food consumed in a day and maximum rate of feeding for brown trout, Salmo trutta L. (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 5 (1975), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Brown trout (live weight 9–302 g) were fed to satiation in each of four meals at seven different water temperatures (range 3.8–18.1°C). The period (Ih) from the start of one meal to the start of the following meal was not significantly affected by the weight (Wg) of the trout, but was negatively correlated with water temperature (T°C). A regression equation described the exponential relationship between I and T, and also estimated the number of meals {N) in a day. Values ranged from one meal at about 4°C t o three meals at about 18°C, The greatest increase in appetite occurred at the end of the period I.The maximum weight offood (Drng) eaten in a day was positively correlated with both W and T, a relationship which was well described by a multiple regression equation. The maximum rate of feeding (Fmg h−1) was not significantly affected by W, but increased from 3.8 to 6.8°C, was fairly constant from 6.8 to 19.3°C, and decreased markedly above 19.3°C. Estimates of D and F(with 95% confidence limits) were applicable to a wide variety offood organisms with the exception of mealworms. From comparisons with the results of other workers, it was concluded that the upper limit ofthe daily energy intake determines the optimum temperature for growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1975.tb00142.x
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  • 2
    Electronic Resource
    Electronic Resource
    Rates of gastric evacuation in piscivorous brown trout, Salmo trutta (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 25 (1991), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. The dry weight of food remaining in the stomachs of piscivorous trout decreased exponentially with time. Gastric evacuation rates increased exponentially with increasing temperature but were unaffected by predator size, meal size or type of fish prey.2. Mathematical models were developed to estimate both the rate and time for the gastric evacuation of different meal sizes (expressed as dry weight), and were applicable to piscivorous trout of different sizes (length range 10–32 cm) feeding on trout fry or sticklebacks at different temperatures (range 5–18°C).3. The wet weight of food in the stomachs also decreased exponentially with time, but evacuation rates both increased with temperature and decreased with increasing meal size; the latter relationship occurred because relative rates of water loss from a meal also decreased with increasing meal size. Use of wet or dry weights can therefore lead to different conclusions about the effect of meal size on evacuation rates.4. When piscivorous trout were fed three consecutive meals of varying size, the models predicted the total dry weight of food left in the stomach, but not the weight remaining for each individual meal. Interactions between meals led to an increase in evacuation rates for meals consumed early in the series and a decrease in evacuation rates for later meals.5. Evacuation rates for piscivorous trout were compared with those for trout feeding on invertebrates in an earlier study, and were close to those for caddis larvae as prey, higher than those for mealworms and lower than those for a variety of invertebrate prey. Although a great deal is now known about the daily food intake and growth rates of trout feeding on invertebrates, there is little comparable information for piscivorous trout.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1991.tb00492.x
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  • 3
    Electronic Resource
    Electronic Resource
    Interspecific and intraspecific variations in egg hatching for British populations of the stoneflies Siphonoperla torrentium and Chloroperia tripunctata (Plecoptera: Chloroperiidae) (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 20 (1988), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. The objective was to compare variations in egg hatching between the two species (interspecific variations) and between populations of the same species (intraspecific variations). There were significant interspecific, but not intraspecific, differences in female size, adult life-span, egg production, hatching success, incubation periods and hatching periods.2. The optimum temperature for hatching success within the range 3.8–22.1°C in the laboratory and the range over which at least 50% of the eggs hatched were lower for Chloroperia tripunctata (Scopoli) (8.5°C, 4.2–17.3°C) than for Siphonoperla torrentium (Pictet) (12.8°C, 6.1–19.4°C). Few eggs hatched at 22.r°C.3. The relationship between incubation period (d days) and water temperature (T°C) was given by: d=1219/T1.368 for S. torrentium, d=253/T0.459 for C. tripunctata. Both equations successfully predicted incubation periods for eggs placed in a stream. The period over which eggs hatched was much longer for C. tripunctata than for S. torrentium at all temperatures.4. The shorter incubation period (at r〉5.6°C) and shorter hatching period for S. torrentium ensure that larvae of this species are already growing when eggs of C. tripunctata start to hatch, but the prolonged hatching period of the latter species ensures a long period of larval recruitment to the population. These differences in egg hatching may reduce competition between the two closely-related species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1988.tb01712.x
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  • 4
    Electronic Resource
    Electronic Resource
    The effects of temperature, atmospheric pressure and season on the swimming activity of the medicinal leech, Hirudo medicinalis (Hirudinea; Hirudinidae), in a Lake District tarn (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 16 (1986), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. The chief objective was to determine the major environmental factors affecting the swimming activity of Hirudo medicinalis L. because the latter will affect the feeding and growth periods. 841 leeches were caught in samples taken every 2 weeks in 1982, 1983 and 1984.2. There were four major size groups, probably corresponding to year-classes. Only nine leeches were in their fourth year (Group IV), most leeches found on stones were in their first year (Group I) and most swimming leeches were in their second or third year (Groups II, and III). Size groups I-III overlapped considerably and could not be treated separately in subsequent analyses.3. Water temperature appeared to be the dominant factor affecting swimming activity, the threshold for activity being 7°C (range 5–9°C). A curvilinear regression provided the best description of the relationship between temperature and catches of swimming leeches; 62% (range 50–75%) of the catch variation could be explained by temperature.4. Atmospheric pressure at the time of sampling and its rate of change over 24 h preceding sampling had no significant effect on catches of swimming leeches, not even on the residuals of catches after the dominant effect of temperature had been removed. Similar analyses showed that there were no significant seasonal effects on swimming activity.5. From a discussion of the implications of this study, it is concluded that the absence of the medicinal leech from many water bodies may be due partially to the relatively high temperatures required for swimming activity in a large proportion of the population (11.9°C, 19.0°C, 22.7°C for 10%, 50%, 90% active respectively).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1986.tb00981.x
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  • 5
    Electronic Resource
    Electronic Resource
    Hatching time and growth of Nemurellapictetii (Plecoptera: Nemouridae) in the laboratory and a Lake District stream (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 14 (1984), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1984.tb00169.x
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  • 6
    Electronic Resource
    Electronic Resource
    Prey switching in four species of carnivorous stoneflies (2004)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 49 (2004), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Previous studies compared the functional responses to their prey, and both intraspecific and interspecific interference, in mature larvae of Dinocras cephalotes, Perla bipunctata, Isoperla grammatica and Perlodes microcephalus. The present study examines switching by larvae of the same species presented with different proportions of two contrasting prey types; larvae of Baetis rhodani and Chironomus sp. In each experiment, 200 prey were arranged in nine different combinations of the two prey types (20 : 180, 40 : 160, 60 : 140, 80 : 120, 100 : 100, 120 : 80, 140 : 60, 160 : 40, 180 : 20). Prey were replaced as they were eaten. A model predicted the functional response in the absence of switching and provided a null hypothesis against which any tendency for switching could be tested.2. No evidence for prey switching by Dinocras and Perla was obtained, both species showing a slight preference for Baetis over Chironomus. Prey switching occurred in Isoperla and Perlodes. As the relative abundance of one prey type increased in relation to the alternative, the proportion eaten of the former prey changed from less to more than expected from its availability, the relationship being described by an S-shaped curve. Isoperla and Perlodes switched to a preference for Baetis when its percentage of the total available prey exceeded 57 and 42%, respectively. Equivalent values for Chironomus were 43 and 58% for Isoperla and Perlodes, respectively. Switching was strongest in Perlodes.3. Non-switching in Dinocras and Perla was related to their feeding strategy, both species being more successful when using a non-selective ambush strategy at dusk and dawn rather than a search strategy during the night. Both Isoperla and Perlodes used a search strategy. The smaller Isoperla fed chiefly at dusk and dawn, and preferred Chironomus larvae, whereas most of the larger Perlodes fed continuously from dusk to dawn and preferred Baetis larvae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01222.x
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  • 7
    Electronic Resource
    Electronic Resource
    Temperature-induced changes in the life cycle of Leuctra nigra(Plecoptera: Leuctridae) from a Lake District stream (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 18 (1987), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. The life cycle of Leuctra nigra (Olivier) took 2 years in a small stream in the English Lake District and the exponential growth of the larvae was scarcely affected by variations in water temperature (range 4.2-14.0°C). Mean growth rates for three year-classes were 0.43±0.01, 0.42±0.01, 0.39±0.05% body length day−1. There were thirteen or fourteen larval instars for males and fourteen or fifteen for females. The ratio between successive instars was a constant 1.20 (conformed with Dyar's rule).2. Larval growth and mortality were exponential at six constant temperatures (5.9, 8.2, 12.1, 15.8, 18.2, 19.8°C) in the laboratory. Mean growth rates (% body length day−1) increased directly with temperature from 0.37 (5.9°C) to 0.55 (19.8°C). Mean mortality rates (% day−1) increased directly with temperature from 0.20 (5.9°C) to 0.26 (12.1°C) and then markedly increased to 0.54-0.58 at the three higher temperatures. Only 7-10% of animals completed their life cycle at the three higher temperatures compared with 23–27% at the three lower temperatures. Egg production also decreased considerably at the higher temperatures.3. As growth rates in the stream and laboratory were similar at similar temperatures (〈14°C), the optimum conditions for growth in the laboratory were probably similar to those in the stream; therefore resources such as food and space were not restricting growth in the stream.4. The implications of the temperature-induced changes in growth and mortality are discussed and it is concluded that although the life cycle can change from semivoltine to univoltine with increasing temperature, the costs of a univoltine life cycle are high in terms of survival and egg production, both of which decreased markedly between 12.1 and 15.8°C. Therefore the optimum habitat for this species appears to be a summer cool stream (maximum temperature 〈14°C) and the optimal life cycle appears to be about 2 years from egg to adult.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1987.tb01305.x
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of temperature on the hatching time of eggs of Ephemerella ignita (Poda) (Ephemeroptera:Ephemerellidae) (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 8 (1978), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. Eggs of Ephemerella ignita (Poda) were kept at eight constant temperatures (range 5.9–19.8°C) in the laboratory. Over 85% of the eggs hatched in the temperature range 10.0–14.2°C but the percentage decreased markedly to 39% at 5.9°C and 42% at 19.8°C. Hatching time (days after oviposition) decreased with increasing water temperature over the range 5.9–14.2°C and the relationship between the two variables was well described by a hyperbola. Therefore, the time taken for development was expressed in units of degree-days above a threshold temperature. Mean values (with 95%CL) were 552 (534–573) degree-days above 4.25°C for 10% of the eggs hatched, 862 (725–1064) degree-days above 3.57°C for 50% hatched and 1383 (1294–1486) degree-days above 3.14°C for 90% hatched. These values can be used to predict hatching times at temperatures below 14.68°C for 10% hatched, 14.54°C for 50% hatched and 14.45°C for 90% hatched. At higher temperatures, the hatching time and the number of degree-days required for development both increased with increasing temperature. Equations were developed to estimate the number of degree-days required for development at these higher temperatures.Eggs were also placed in the Wilfin Beck, a small stony stream in the English Lake District. Maximum and minimum water temperatures were recorded in each week and the summation of degree-days was used to predict the dates on which 10%, 50% and 90% of the eggs should have hatched. There was good agreement between these estimates and the actual hatching times. Only 10–15% of the eggs hatched between October and late February with most of the eggs hatching in March, April and May. Nymphs hatching in October and November probably did not survive the winter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1978.tb01425.x
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  • 9
    Electronic Resource
    Electronic Resource
    Haementeria costata (Hirudinea: Glossiphoniidae), a leech new to Britain (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 9 (1979), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. The European leech Haementeria costata is recorded in Britain for the first time and is described in detail. A key is provided to distinguish H. costata from other species of leeches in Britain, and the literature on the ecology of H. costata is summarized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1979.tb01530.x
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  • 10
    Electronic Resource
    Electronic Resource
    Weight of food and time required to satiate brown trout, Salmo trutta L. (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 5 (1975), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Brown trout of different weights (range 8-358 g) were fed to satiation at fifteen different water temperatures (range 3.8–21.6°C. Both the weight of the trout (Wg) and the water temperature (T°C) affected the maximum weight of food (Q mg) consumed in a meal, and the relationship between the three variables was well described by a multiple regression equation which can be used to estimate the value of Q (with 95% confidence limits) for trout of different weights at different temperatures between 3.8°C and 21.6°C. The satiation time (with 95% confidence limits) can also be estimated from a multiple regression equation for trout of different weights at temperatures between 6.8°C and 18.1°C. Estimates from the multiple regression equations were applicable to a wide range of food organisms with the exception of larvae ofTenebrio molitor (mealworms). Appetite (measured by voluntary food intake) varied with temperature and was greatest between 13.3°C and 18.4°C. From comparisons with the results of other workers, it was concluded that the maximum amount of food consumed in a meal may provide sufficient calories for both the daily metabolic requirements and the daily maintenance requirements of a trout at temperatures between 3.8°C and 18.4°C, but not at temperatures above 18.4°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1975.tb00120.x
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