摘要:

SUMMARY.1Concentrations of seven metals in forty taxa of aquatic insects were determined in order to examine the influence of the insects’ feeding habits on their whole‐body metal content. Species were grouped into five feeding categories which reflected both the type of material the organisms ingested and their contact with sediments during feeding.2Species such as the burrowing mayflies (Ephemeridae) and some of the Chironomidae, which indiscriminately ingest sediment along with detritus, had the highest concentrations of most metals. Filter feeders (e.g. Hydropsychidae) had the next highest concentrations, followed by species which to some degree selectively ingest detritus and periphyton (e.g. many Ephemeroptera, Plecoptera and Trichoptera). Carnivores and surface feeding species, such as the Gerridae and Gyrinidae, had the lowest metal concentrations.3Analysis of metal concentrations of both gut contents and bodies of individuals from each of these feeding types explain these differences. Gut material was enriched in most metals (Co, Cr, Fe, Sb, Sc) relative to their concentrations in the organism's body and it often constituted a major proportion of an organism's whole‐body burden of a metal.4Both the concentrations of metals in the gut material and the proportion of the whole‐body burden of a metal that was associated with gut contents varied with the feeding habit of a species. This was because of differences in the amount of inorganic material ingested by the species in each feeding category, higher concentrations occurring in organisms which ingested relatively greater amounts of sediment.5Organism concentrations of K and Na were less affected by feeding habits since the majority of the whole‐body burden of these metals was associated with an organism's tissue and surface rather than with gut

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00682.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARY.1The influence of organism size on whole‐body metal concentrations of eight metals was examined in aquatic insects in field and laboratory studies. Information on the partitioning of metals between adsorbed, absorbed and gut content material was also obtained.2For Co, Cr, Fe, Sb and Sc, an exponential decrease in concentration with increasing organism size was observed, indicating surface adsorption as an important mode of metal accumulation.3No, or only a slight, concentration‐size relationship was found for K, Mn and Na. This is expected for metals with high absorption efficiencies and a low capacity to be adsorbed.4Clearing of the gut of the mayflyStenonema modestum(Ephemeroptera: Heptageniidae) did not significantly after the concentration size relationship for any of the metals studied.5Studies of Cr uptake withStenacron interpunctatum(Ephemeroptera: Heptageniidae) indicate that the concentration‐size relationship is not affected by variability in the concentration of available Cr.6About 52% of the whole‐body burden of Cr inS. interpunctatumwas associated with gut material while at least 33% was adsorbed to the organism's exoskeleton and at most 15% was internally a

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00683.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARY.1Mean tarnwater concentrations of CI‐and other ions (Na+, K+, Ca2+, Mg2+, SO42‐+ NO3‐) decrease with increasing distance from the sea and altitude but are also related to solid geology. Lowest concentrations occur on slow‐weathering igneous rocks (Borrow‐dale Volcanics); minima of c. 100 μequiv. CI‐I‐1are similar to the volume‐weighted mean for bulk precipitation. At least 10–20% of Na+is leached from upland catchments, giving Na+/CI‐ratios greater than the equivalent ratio (0.86) in seawater and precipitation. Evapotranspiration at 20–30% annual rainfall accounts for CI‐concentrations in many tarns on igneous rocks but not all; some CI‐may be leached from the rocks in upland catchments and come from groundwaters at low altitudes near the sea. Sea‐spray has little influence on tarnwaters near the coast.2On sedimentary rocks overall mean CI‐concentrations are 27–73% higher than equivalent means on Borrowdale Volcanics; concentrations of other ions are also higher. A 5‐fold to 10‐fold range of CI‐concentrations is not simply due to increased evapotranspiration. Na+/CI‐ratios are<0.86, especially on Skiddaw Slates where tarnwaters contain 10% or more excess CI‐balanced by Ca2+, apparently derived from groundwaters rich in CaCI2. On other sedimentary rocks (Silurian Slates and Carboniferous, Triassic and Permian series) tarn waters display a similar but less pronounced excess of CI‐and Ca2‐+relative to Na+. Some extra CI‐may be captured by dry deposition on vegetation but a portion, perhaps 15–30% of the total, apparently comes from the rocks or from groundwaters via deep aquifers in contact with seawater or connate water.3Anthropogenic sources on the catchments are also considered: deicing salt used on highways in winter accounts for a 27% increase of

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00684.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARY.1The physical limnology of Augher Lough, Northern Ireland (area=9.25 ha. z=5.5 m), including stratification pattern, heat budget, thermocline erosion rate, eddy diffusion rate in the thermocline and hypolimnion and areal hypolimnetic oxygen deficit is described.2Oxygen and temperature profiles, recorded at two sites during 1978 and four sites during 1979, showed that spatial variability of these quantities was low and allowed the following lake characteristics to be estimated. Heat budgel was 5.30 kcal cm‐2(standard deviation=s=0.26) in 1978 and 5.00 (s= 0.26) in 1979. The thermocline depth was 3.5–6.5 m with an erosion rate of 1.9X10‐7m s‐1in 1979. Eddy diffusion coefficients of heat in the thermocline and hypolimnion normally ranged from 0.48X 10‐2cm2s‐1(s=0.20X10‐2) to 5.4X10‐2(s=2.6X10‐2), but reached 10X10‐2cm2s‐l(s=9X10‐2) in early July 1978 after a cooling‐mixing episode in the epilimnion. The hypolimnetic oxygen deficit was 680 mg O2m‐2d‐1(s=76) and varied strongly with depth.3A cooling‐mixing episode in the epilimnion in June‐July 1978 caused the movement of heat down to 8 m, movement of oxygen down to 6 m and increased the eddy diffusion coefficients

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00685.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARY.1The microbial heterotrophic utilization of dissolved organic matter (DOM) was determined experimentally in microcosms using stream water and stream‐bed sediments from a third order reach of White Clay Creek (Pennsylvania, U.S.A.).2Sources of DOM for the experiments included White Clay Creek water at baseflow and stormflow and cold water extracts of jewel weed (Impatiens capensisL.) and spicebush (Linderu henzoin(L.) Blume).3The heterotrophic activity of the sediments was measured as uptake of the following: dissolved organic carbon (DOC), molecular weight fractions within the DOC pool, carbohydrates, amino acids and peptides, phenolics, and dissolved oxygen (DO), all in the overlying water.4Concentrations of adenosine triphosphate (ATP), and direct microscopic counts of bacteria were used to estimate bacterial biomass in the surface sediments.5The microcosm experiments showed that specific DOC molecular size classes and DOM functional groups were selectively removed from solution, exposure to one DOM source affected responses to a different DOM source and certain DOM sources were more readily utilized than others.6Continued exposure to a DOM source increased microbial heterotrophic activity (a condition which persisted even after removal of the DOM source for several days).7Rates of biotic DOC uptake ranged from 3.6 to 242.8 mg Cm‐2h‐1.8Indirect estimates of biosynthesis calculated from DOC and DO data ranged from 1.6 at baseflow and 2.6–61.2 at stormflow to as high as 192.6 mg C m‐2h‐1when the community was repeatedly exposed to enriched DOM sources.9The mean generation times of bacteria in sediments, determined from direct microscopy data, ranged from 12.5 to 46.

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00686.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARY.Size frequency distributions of larvae ofSimulium erythrocephalumsampled regularly throughout 1978 from the River Tiffey at Carlton Forehoe, Norfolk, revealed five generations per year. The number of larval instars could be determined for the second and fifth generations, being six and seven respectively. Individuals of the overwintering generation were of larger ultimate size, had more ovarioles and apparently laid larger eggs than those of the summer generations. Females were larger than males throughout the year.

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00687.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARY.1Phytoplankton primary production and biomass were compared with bacterial secondary production estimated by means of frequency of dividing cells (FDC) in eutrophic Lake Tystrup. Denmark.2In the upper part of the photic zone, bacterial secondary production constituted 12% of the carbon fixed by the phytoplankton. In vertical profiles, bacterial secondary production ranged from 7.6% (early spring) to 121% (during August) of the carbon fixed by the algae.3A close relationship was found between occurrence and activity of bacteria and algae, suggesting that released organic products are of primary importance to the bacteria.4The annual phytoplankton primary production was estimated as 227 g C m‐2compared to 102 g C m‐2assimilated by the bacteria, so 45% of the carbon fixed by the phytoplankton went through pelagic bacte

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00688.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Gulati, R.D.&Parma, S. (Eds.) (1982)Studies on Lake Vechten and Tjeukemeer, The Netherlands.Morgan, D.M. (Ed.) (1982)Ecology of Mysidacea.Furtado, J.I.&Mori, S. (1982)Tasek Bera: the Ecology of a Freshwater Swamp.

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00689.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0046-5070    

DOI:10.1111/j.1365-2427.1983.tb00690.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY