摘要:

AbstractThis study is an attempt to quantitatively determine variables of significance for predicting colour in small glacial lakes. Lake colour is an important variable in many lake ecological contexts. The data emanate from two extensive data‐sets from Sweden, one of which concerns 1456 lakes, and the other 91 more well‐suited lakes. Four year average values of lake colour were compared to catchment and morphometric parameters to help identify the processes which influence variability in colour between lakes. Various hypotheses concerning the factors regulating colour in lakes were formulated and tested. Various statistical tests were used to separate random influences from causal influences. Those “map parameters” with the most significant influence on colour were the theoretical lake water retention time, the percent of rocks, lakes and mires of the drainage area, the ratio between lake area and drainage area and the lake mean depth. Each model parameter provides only a limited explanation (statistical) of the variability in colour between lakes. The predictability of colour by these models can not be markedly improved by accounting for the distribution of the characteristics in the drainage area. The stability of the final model, which gives anr2‐value of 0.74, has been tested with positive results. The model allows lake colour to be estimated from knowledge of “geological” characteristics of the lake and its drainage area. The variability between lakes from other factors, such as temperature, precipitation and/or contamination of acidifying substances and nutrients, may then be quantitatively differentiated from the impact of these “geol

ISSN:0020-9309    

DOI:10.1002/iroh.19930780112

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19930780113

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

摘要:

AbstractMesozooplankton samples were collected over a period of one year in five stations of the Ebrié lagoon and analysed for organic, carbon, nitrogen and phosphorus contents. When zooplankton was dominated byA. clausi, body composition was relatively stable compared with the broad variability of environmental factors (mainly salinity, food abundance and composition), although a negative hypothetic influence of salinity may have occurred. Body composition was comparable when zooplankton was dominated byPseudodiaptomus hesseiand freshwater species, but contents were significantly lower for assemblages dominated by more exclusively marine species (Paracalanusspp.,Oithonaspp., marine cladocerans, chaetognates, etc.)

ISSN:0020-9309    

DOI:10.1002/iroh.19930780114

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19930780115

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

摘要:

Effect of Diet on the Elementary Chemical Composition ofNebalia bipes(Crustacea, Leptostraca)Changes in carbon, hydrogen and nitrogen contents ofNebalia bipeswere studied under different artificial feeding conditions. Using a multifactor ANOVA, highly significant variations were observed according to diet. C:N ratio, which was 4.99 ± 0.31 in control animals, exhibited extreme values of 3.96 ± 0.09 and 5.52 ± 0.49. From a trophic point of view, the results demonstrate the large possibilities ofN. bipesto exploit very different resources. The variability of its elementary chemical composition expressed in C:N ratio is compared to other generalist speci

ISSN:0020-9309    

DOI:10.1002/iroh.19930780116

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19930780117

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

摘要:

AbstractSome typical and more frequent freshwater invertebrates of running waters were studied to examine the influence of styrene, xylene and benzene on their mortality. SnailsAmphimelania holandriFÉR.andLymnaea stagnalisL. and crustacenasAsellus aquaticusL. andGammarus fossarumKOCH., were used in the semi‐static test. Compounds were added in volume concentrations of 0.005 to 0.4%v/v.For all concentrations LC50was calculated by probit method, which demonstrated that mortality depends much more on increased concentrations (depending on the initial concentration) than on the length of exposure. Styrene was the most toxic, followed by xylene and then benzene. The speciesG. fossarumshowed marked sensitivity, followed byA. aquaticus, and the speciesA. holandriandL. stagnalisshowed less sensitivi

ISSN:0020-9309    

DOI:10.1002/iroh.19930780118

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19930780119

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

摘要:

AbstractA method is introduced to a) distinguish phytoplankton organisms from organic matter and b) ease its determination by staining protein structures with Coomassie Brilliant Blue G.

ISSN:0020-9309    

DOI:10.1002/iroh.19930780120

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19930780101

出版商:Akademie Verlag, Berlin    

年代:1993

数据来源: WILEY