摘要:

SummaryForty‐three species of Plecoptera were collected from emergence traps in an Oregon woodland stream. Adults occurred during every month of the year, but the largest numbers and most species emerged from April to June. Temporal separation of con‐generic species occurred within the suborder of Filipalpia, but not in Setipalpia. Some species of Nemoura had split emergence periods.The onset of emergence for a species from year to year generally varied by less than 2 weeks. Peak emergence occurred at least 1‐2 weeks after the start ofthe emergence p

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00090.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryA survey ofthe macro‐invertebrate fauna in the River Tamar revealed that a division ofthe catchment can be made which separates an organically enriched upper region from a more stable environment in the lower tributaries and reaches. Invertebrate species normally associated with organic pollution were found immediately downstream from farm waste and sewage effluent outfalls. Invertebrate species normally associated with an unpolluted condition were widely distributed throughout the catchment, and revealed that the Tamar is essentially free from gross pollution causing the continuous elimination of stream fauna. Systems used by pollution control organizations to codify biological results are reviewed and applied comparatively to the results. The Diversity index was found to be the most consistent method in assessing the biological state of the river. The Trent, Lothian, Chandler and Carpenter indices were found to give either anomalous figures or proved insensitive to conditions beyond a certain qualit

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00091.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00092.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00093.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Summary1The vertical distribution of the benthic fauna of the Speed River, Ontario, was studied over a 13‐month period from October 1970 to October 1971. Various physical and chemical parameters of this interstitial environment were also measured.2Several new techniques for sampling the interstitial environment of rivers wert devised. These methods and their relative efficiencies are considered.3The validity of the terms ‘hyporheal’ and ‘hyporheic’ are discussed and the term ‘hyporheos’ is offered to replace the former.4A brief resume of interstitial sampling methods is given with comments on their limitations for sampling deep heterogeneous substrates.5Chemical parameters are thought to be more important in the control and distribution ofthe fauna than physical parameters.6It is suggested that many larvae of stream‐dwelling chironomids have over‐wintering stages when they penetrate deep into the substrate to: (a) actively feed on the trapped organic detritus; (b) follow an optimum temperature for development.7It is suggested that the shape of an organism determines its success as a hypo‐rheic form and examples are given.8The numbers of animals oecurring in the sub‐benthic populations are shown to be very large indeed. For the Speed River, estimates of between 184,760 and 797,960 animals/m^ are made for different times of the year. Dry weight biomass is estimated o t vary between 30 9 g and 253‐2 g/m^ throughout the year.9Sub‐benthic or hyporheic populations are shown to exist in at least three other Canadian rivers. Some ofthe animals found are shown to be common to two or more of these rivers.10The inefficiencies of many conventional benthic samplers in sampling the total biomass of certain streams with hyporheic

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00094.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryDistribution and abundance of C. quadrangula (O. F. Muller) has been studied in two small lakes in the southern part ofthe English Lake District. Esthwaite Water (maximal depth 15 m) was sampled from 1958 to 1969 and Blelham Tarn (maximal depth 12 m) from 1961 to 1963. Samples in both lakes were taken with a 5‐1 water bottle at a fixed station in deep water.No difference in vertical distribution between day and night samples was observed. The majority of individuals were located below 7 m in Esthwaite Water and above 8 m in Blelham Tarn. The seasonal cycle in the open water was from May to December with maximal abundance in September and October. Males and ephippial females regularly appeared in early October, irrespective of population density, water‐temperature or the time of the overt

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00095.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryWater samples collected weekly from the rivers Yare, Tud, Wensum and Tas in Norfolk, England, displayed marked depletions in the spring and summer of the concentration of dissolved silicon. These were unconnected with any hydrological event and were assumed to be due to the assimilation of silicon by diatoms. Equilibrium concentrations were maintained in the Yare and Tud during the weeks prior to and following the spring bloom. It was estimated that 35 Mg (51%) of the predicted load were removed from the Yare during the 11 weeks of this depletion and 6‐0 Mg (45%) from the Tud. The lowest observed concentration (0‐4 mg/l) occurred during the first week in May when over 90% of the silicon had been removed. However, the maximum amount of removal and hence maximum diatom productivity occurred earlier at a time of higher water discharge. A similar pattern was observed in the Yare during the spring of 1971. Two small blooms occurred later in the summer of 1970 in the Yare and Tud. It was estimated that 15% ofthe Yare's dissolved silicon load of 263 Mg was in the assimilated form and 12‐5%of the Tud's output of 56‐6 Mg. The weathering of silicate minerals was probably the source of almost all the silicon and the outputs represented a silicon erosion rate of 1‐15 Mg/km2/year for the Yare and 0‐77 Mg/kmVyear

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00096.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryThe effects of eleven chosen feeding levels ranging from 0 to 198 mg damp dry (plant) Ceratophyllum/g live snail/day on the absorption, conversion and metabolism of the snail Pila globosa (of 1 ‐9 g body weight) have been studied. Absorption rates increased from 3‐0 to 21‐0 mg dry food/g live snail/day in snails fed 3‐4‐28‐8 mg dry food/g live snail/day. In these snails, absorption efficiency decreased from 87.5 to 73.0%. Conversion rates increased from 0‐3 mg/g/day for snails receiving 23‐4 mg/g/day to 2‐7 mg/g/day for those fed maximum amounts, and the efficiency (K2) also increased from 1‐9% to 130%. When compared to other gastropods, Pila globosa appears to be a poor convertor. During 30 days' starvation, the test individuals lost 4.4 mg dry body substance/g/day i.e. the maintenance cost was 14‐7 cal/g live snail/day. The SDA increased by four times for those feeding on maximum rations in comparison to those receiving about 5 mg/g/day, i.e. the energy cost for converting food was

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00097.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryCalorific values of thirty‐three species of aquatic invertebrates, representing various life stages, from small prairie wetlands are given. The values for twenty‐seven species are new to the literature. Percentage crude protein for fifteen species and the amino acid composition for eleven taxa are presented. The majority of the species dealt with are eaten by waterf

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00098.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummarySieving efficiency, defined as the percent increase in yield of numbers or biomass of organisms, obtained by use of a sieve with 0‐25‐mm mesh openings instead of a 0‐50‐mm meshed sieve, was investigated in a lotic habitat over a 12‐month period. Greatest elficiencies obtained were 300 to 600% for mayflies, chironomids, simuliids, ‘other dipterans,’ water mites and plecopterans and 90 and 190% for trichopterans and coleopterans, respectively. For the fauna as a whole, efficiency varied from 95 to 325% over the study period.Efficiency in estimating biomass was not as great as that with numbers and generally was below 10% for trichopterans. mayflies, ‘other dipterans’, coleopterans and the fauna taken as a whole. For chironomids, simuliids and water mites efficiencies generally were higher than 10% and reached as high as 174%, 60% and 80%, respectively. In all groups efficiency varies throughout the year with lowest occurring during winter months.The findings are compared with data found in the literature and discussed in relation to structural, behavioural, and life h

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1974.tb00099.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY