摘要:

SUMMARY.Food evacuation in roach (total body length, range 75–150 mm) was studied at temperatures between 4.2 and 24.0 °C. The rate of food evacuation was described by an exponential function and was similar for two different food items (DaphniaandChaoborus). The relation between the instantaneous rate of food evacuation (R) and temperature was also described by an exponential function. A model developed for estimating food consumption rates in fish was tested in a simulation experiment and there was good agreement between estimated and actual values for food consumpti

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00615.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARY.Colonizing aquatic macroinvertebrates were collected from two kinds of artificial substrate placed on wing dams in Pool 13 of the Upper Mississippi River in September 1978. Thirty‐one taxa were collected from basket samplers containing cement spheres and twenty‐one taxa from multiplate samplers constructed from tempered hardboard. Hydro‐psychidae (Trichoptera), especiallyCheumatopsychesp.,Potamyla flavaandHydropsychesp., were the dominant macroinvertebrates which colonized both samplers. Basket samplers had a significantly greater macroinvertebrate density, biomass and number of taxa compared with multiplate samplers. Precision of the arithmetic mean for density, biomass and number of taxa was 19.9, 18.3 and 8.1% for basket samplers and 18.8, 18.7 and 8.5% for multiplate samplers. The number of sampling units required for a precision of 20% for macroinvertebrate density, biomass and number of taxa was 13, 11 and 2 for basket samplers and 11, 11 and 2 for multiplate samplers. Basket samplers with 7.5‐cm cement spheres are recommended for use instead of multiplate s

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00616.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARY.Pigments extracted in methanol, acetone and ethanol from three cultures of green algae and one blue‐green alga revealed different extraction efficiencies depending on the species, the extraction solvent used and the extraction time. Chromatographic identification and quantitative measurements of chlorophyllsaandbwere made from six green algae. When extraction of pigments was incomplete, chlorophyll‐bwas extracted faster than chlorophyll‐a.This effect was more pronounced for acetone extractions, whereas methanol extractions gave the stable ratios of chlorophyllb/aafter about 6–10 h. When green algae are frequent, a 6–10 h methanol extraction, without any extra manipulations, is sufficient to ensure reliable ratios of chlorophyllb/aand extraction of the major proportion of the chlorophylls without risk of induced destruction of the chl

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00617.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARY.The chironomid fauna of a chalk stream in southern England is described from 1 year's catches of emerging adults and 2 year's quantitative samples of larvae on Common Clubrush,Schoertoplectus lacustris.The number of species in eaeh higher taxon as adult males and larvae onSchoenoplectuswere: Tanypodinae, nine and three; Diamesinae, two for both; Orthoeladiinae, 26 for both; Chironomini. twelve and six; Tanytarsini, seven and five, respectively. A total of 66 species was recorded for both life stages. Adult Orthocladiinae were caught throughout the year. Tanytarsini were absent for a few weeks in winter, and Tanypodinae and Chironomini were caught for shorter periods in warmer months. Chironomids 93.5% of the total invertebrates onSchoenoplectus.Life histories are deseribed for seven speeies that formed 91% of the identified chironomids (32% of the total were unidentifiable first and second instar larvae). Four of these life histories appear for the first time. All seven species were multivoltine and had continuous recruitment for part of the year. The species diversity of larvae was mostly in the range 1.5–3.0 and it was determined more by equitability than by species richness. The numbers of chironomids through time were dependent on the weight of detritus on the leaves (r2= 0.69) and the availability of detritus therefore partly controlled their population siz

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00618.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARY.Odontocerum albicorne(Scopoli) took 1 year to complete its life cycle in a 3‐year study of this species in a small, stony stream in the English Lake District. Adults were present from May to August (1967, 1968) or from June to September (1969); most eggs were laid in July and August. There were five larval instarsand most larvae were in instars III, IV and V by October. Larvae usually overwintered in instar V or III and some third instars were in a resting state in sealed cases. Most fifth instars became male pupae in spring; most third instars grew rapidly to instar V in spring and then became female pupae. The duration of the pupal stage was short, and was shown in laboratory experiments to require 87.5 degree‐days (95% C L = 79–98 degree‐days) above a threshold temperature of 6.7±0.01°C. Pupation in the stream did not commence until temperatures exceeded 6.8°C.As the sample variance‐mean relationship followed a power‐law, the spatial distribution of larvae and pupae was density dependent. Relative clumping remained fairly constant between year‐classes but increased markedly between the larval and pupal stages. Although population density varied between year‐classes, it remained remarkably constant in each year‐class for about 9 months between the end of egg hatching and the start of adult emergence.The growth pattern was similar in each year‐class but growth rates varied between year‐classes. The mean instantaneous growth rate was highest (range 3.9–8.0% dry wt day‐1)in the first 3 months of the life cycle (August‐October), close to zero in winter (November‐February) and slightly higher than 1% day‐1(range 1.1–1.7%) for the rest of the life cycle (March‐August). Production varied considerably between years and year‐classes, and was closely related to growth rates for March‐August. Annual production estimates were 243, 160 and 257 mg dry wt m‐2in 1967, 1968 and 1969. respectively. The ratio of production to mean standing crop (P/B) also varied between year‐classes and the mean annual value was 3.9 (range 3.2–4.5).Life tables were similar for the 1966 (latter part only), 1967, 1968 and 1969 year‐classes. Losses were very high (c. 99%) in the egg stage and early instars. About 30% (range 27–31%) of the population in instars III‐V did not reach the pupal stage, and c. 25% (range 20–29%) of the pupal population died. Abou

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00619.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARY.Respiration ofAsellus aquaticuswas determined on tiine occasions throughout the year using a Gilson differential respirometer. On each occasion the determination was made at the lake temperature, which ranged from 2 to 18°C, Linear regressions were derived for log oxygen uptake against log dry weight. There was a significant difference between mean rates of oxygen uptake at the various temperatures but the slopes of the regression lines, which varied from 0,62 to O.85 with a mean of 0,76, were not significantly different.The temperature of the lake was monitored throughout the year. Using the relationship of oxygen uptake against temperature, and estimates of population density obtained previously, the total annual respiration of the population was calculated as 4571 ml O2m‐2, equivalent to an energy loss of 92.3 kj m‐2year‐1from a mean biomassof 752 mg m‐2.Consumption of decayedAlnus glutinosaleaves and faecal production rates, and thus assimilation efficiency, were determined by gravimetric methods in the laboratory at 10°C, close to the mean temperature of the lake (10.rC), In the four size classes investigated, larger animals consumed more food per individual, but less on a weight specific basis. However, it was shown that consumption was greater if the leaf material was more highly decomposed, Assimiliation efficiency was calculated as 23%.Using data for respiration, population density and the assimilation efficiency, the annual population energy budget was estimated as (kJ m‐2year‐1): consumption, 568.9 (100%); production, 38.5 (6.8%); respiration, 92.3 (16.2%); faeces, 438.1 (77%). The significance of these energy values, and the ecological efficiencies calculated from them, are discussed in relation to other p

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00620.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARY.Monthly changes in the biomassof Ranunculus, BerulaandCallitrichewere recorded on two 50‐m sites on the River Lambourn at Bagnor between March 1971 and October 1973. On the unshaded site.Ranunculuswas the dominant macrophyte and characteristically its biomass changed from 20–40 g dry wt m‐2in March to around 400 g dry wt m‐2at the end of the growing season. On the shaded site, whereBerulawas the dominant macrophyte. the biomass ofRanunculuswas lower than on the unshaded site. There was no significant difference between the mean biomasses ofBerulaon these two sites butCallitrichehad a signifieantly higher biomass on the shaded site. Estimates of the total biomass of macrophyte on each site were calculated and the biomass of macrophyte removed during cutting operations each summer was also a

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00621.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARY.The oxidation of 2, 5‐diniethylfuran (DMF) to cis‐1, 2‐ diacetylethylene (DAE) is a specific test for singlet oxygen (1O2). A method has been developed for the measurement of DAB by direct injection gas chromatography. By the use of this method, the photochemical generation of1O2 has been demonstrated in samples of two Canadian humic waters.Two other photochemical reactions probably mediated by1O2generation, the oxidation of histidine and the inactivation of a‐chymotrypsin, have been demonstrated in these waters.The possible ecological and environmental implications of these findings are di

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00622.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARY.Soluble reactive phosphorus (SRP) mass balances showed that phosphorus retention occurred during low summer flows in reaches of Duffin Creek and the Nottawasaga River, two phosphorus‐rich streams in southern Ontario. The average daily removal in Duffin Creek was 6.1 ± 1.6 kg SRP which represents the retention of about 92% of the phosphorus input. Approximately 5.3 ± 3.5 kg SRP (about 44% of the daily input) was removed from stream water in the Nottawasaga River. Laboratory experiments indicate that sorption by stream‐bed sediments is an important mechanism for phosphorus retention in both rivers. Uptake by benthic algae may also act as a temporary phosphorus sink in Duffin Creek. Major cation inputs and outputs are generally in balance, implying that these elements act in a relatively conservative manner in both r

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1982.tb00623.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY