ISSN:1434-2944    

DOI:10.1002/iroh.19980830502

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

ISSN:1434-2944    

DOI:10.1002/iroh.19980830503

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

ISSN:1434-2944    

DOI:10.1002/iroh.19980830504

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractMany invertebrates react to the actual presence and/or to chemical cues from predators. However, there is lack of information on the interrelationship of different cues triggering the antipredator response. In a series of aquarium experiments we investigated to which extent the antipredator response of a freshwater amphipod (Gammarus roeseli), i.e. seeking refuge in coarse substrate, is influenced by the actual presence of a natural fish predator (the ruffe,Gymnocephalus cernuus) including mechanical and visual cues, purely chemical cues, as well as the thickness of the sediment layer. Presence ofGammarus roeselion the substrate surface and activity was videotaped under different conditions and evaluated according to a standard protocol. Even without fish present and without fish chemicalsGammarus roeselimoved into the substrate because of thigmotactic behavior. The presence of ruffe accelerated this phenomenon and fish odor elicited weaker responses.Gammarus roeseliwas able to recognize the approach of fish predators both visually and/or mechanically.

ISSN:1434-2944    

DOI:10.1002/iroh.19980830505

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractIn the Weidlingbach, a low‐order forest stream in the Wienerwald area near Vienna (Austria), hydraulic stress was measured at 112 locations from which benthic fauna (=33318 specimens of macro‐invertebrates) was collected between March and September 1995. For measuring hydraulic stress a set of FST hemispheres was used. The most abundant taxa studied (= 90.7% of the total) wereGammarus fossarumKoch (Amphipoda),Leuctraspp. (Plecoptera), the ephemeropteransBaetis rhodani(Pictet),B. vernus(Curtis),Habroleptoides confusaSartori and Jacob,Ecdyonurus starmachiSowa and the caddisflyHydropsyche instabilis(Curtis).Five mayfly, four stonefly and six caddisfly taxa significantly (p<0.05) preferred the lotic subsection of the research area, whereasEphemera danicaMüller significantly (p0.05) over the whole range of hydraulic stress, independent of disch

ISSN:1434-2944    

DOI:10.1002/iroh.19980830506

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractThe effect of the shredderKlapopteryx kuscheli(Plecoptera, Austroperlidae) on the breakdown ofNothofagus pumilioleaves was studied in field experiments. Decay rates due to leaching and shredder activity were measured on conditioned and unconditioned leaves. Two sizes of shredder were tested in order to establish if the consumption per unit of shredder biomass varied with insect development. In three days weight losses due to leaching were 8.5%, and decay rates due to shredders were significantly higher than in control replicates. There were no differences in decay rates between conditioned and unconditioned leaves. Small larvae consumed more leaf biomass per unit of insect biomass than large ones. Growth efficiencies ofK. kuschelilarva were low, but smaller larvae showed higher efficiencies than larger ones.

ISSN:1434-2944    

DOI:10.1002/iroh.19980830507

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractWe studied physical and chemical conditions and the crustacean communities in temporary ponds in a military area in South Germany. All ponds were formed by driving of tanks. They were turbid, without higher aquatic plants but contained a unique crustacean community with endangered species such as the anostracanBranchipus schaefferi, the copepodsCyclops furciferandMetacyclops minutusand the cladoceransDaphnia obtusa, MoinabrachiataandMacrothrix hirsuticornis. Branchipuswas only present in ponds which dried out and where driving occurred. Ponds which did not dry out and where driving events were rare or did not take place were devoid ofBranchipus. Physical and chemical conditions were similar in ponds with and withoutBranchipus. Day‐night fluctuations of temperature were up to 15 °C in summer. Conductivity was 200–300 μS cm−1, hardness ranged between 2 and 3.5 meq 1−1, alcalinity between 1 and 3 meq 1−1, pH between 7.5 and 9, dissolved phosphorus was<20 μg 1−1, concentration of nitrogen was60% in the ponds except one pond where concentrations of nutrients and conductivity were somewhat higher. When driving of tanks had been stopped the number and size of the ponds decreased and their character changed.Branchipus schaefferiand other endangered species disappeared and more but common, benthic species such as the cladoceranChydorus sphaericusand the copepodsMegacyclops viridisandEucyclops serrulatusgained importance.Branchipus schaefferiis now close to extinction. Conductivity, hardness, alcalinity increased while pH decreased probably because algae were replaced by marsh plants. We conclude that driving of tanks raised clay particles, prevented the growth of higher aquatic vegetation and condensed the bottom sediments. All this was necessary to keep the ponds in an early stage of succession thus providing conditions necessary to ma

ISSN:1434-2944    

DOI:10.1002/iroh.19980830508

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractThe population structure, abundance (ind m−2), biomass and reproduction ofCorophium curvispinum, an important element of the littoral fauna, have been studied at four sampling stations on the northern shoreline of Lake Balaton (Keszthely Bay, Szigliget Bay, Bozsai Bay and Paloznak Bay) three times a year (spring, summer and autumn) inPhragmitesgrowing period from May 1991 to October 1993 and in summer 1994. The sampling stations represent the trophic gradient of the lake.The environmental parameters (Chlorophyll‐acontent of the plankton and of the reed periphyton, and suspended solid content of the water) were significantly higher (ANOVA) in the western basin (Keszthely and Szigliget bays) than in the eastern basin (Bozsai and Paloznak bays). However, the population parameters (length of the animals, percentage of juveniles, length of ovigerous females, percentage of ovigerous females and fecundity) did not differ significantly between the two basins. Both the abundance and biomass were higher in the middle than in the westernmost and easternmost bays but the difference is not significant.The ovigerous females were significantly bigger in spring than in summer and autumn. The egg number per female was also significantly greater in spring than in summer and autumn. The length of ovigerous females and the fecundity in summer did not differ significantly from those of autumn data.There is a significant positive correlation (Spearman rank correlation) between both abundance and biomass and the above environmental parameters. The length of ovigerous females and the fecundity were inversely correlated with the plankton Chlorophyll‐aconcentrations.The abundance ofC. curvispinumin the reed belt of Lake Balaton is greater than in several parts of the Dnieper and Volga. However, it is much lower than in the Don, Oka, Danube and Rhine r

ISSN:1434-2944    

DOI:10.1002/iroh.19980830509

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

ISSN:1434-2944    

DOI:10.1002/iroh.19980830510

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractSimocephalus mesorostrisOrlova‐Bienkowskaja, 1995, previously recorded only in tropical regions was found in waterbodies of Uzbekistan. A short description of the female, the first description of the male and data on variability and distribution in Uzbekistan are give

ISSN:1434-2944    

DOI:10.1002/iroh.19980830511

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY