scholarly journals Determining the density dependence of immigration and emigration of benthic stream invertebrates: theoretical considerations

Hydrobiologia ◽  
1984 ◽  
Vol 108 (1) ◽  
pp. 49-55 ◽  
Author(s):  
William Y. B. Chang ◽  
Daniel W. Sell
Keyword(s):  
Density Dependence ◽  
Stream Invertebrates ◽  
Immigration And Emigration ◽  
Benthic Stream ◽  
Theoretical Considerations

scholarly journals Assessing density-dependent establishment and dispersal: an example using caddisfly larvae

2000 ◽  
Vol 57 (6) ◽  
pp. 1190-1199 ◽  
Author(s):  
B L Kerans ◽  
Peter L Chesson ◽  
Roy A Stein
Keyword(s):  
Density Dependence ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Laboratory Data ◽  
Population Level ◽  
Model Fit ◽  
Low Flow ◽  
Density Dependent ◽  
Caddisfly Larvae ◽  
Benthic Stream

Density dependence in colonization is poorly understood. We studied colonization by a benthic, stream-dwelling caddisfly, Hydropsyche slossonae, through experiments varying conspecific densities and environmental conditions. A model of larval acceptance or rejection of a locality (dispersal from the locality) was developed and fitted to the data to estimate the relative strengths of density-dependent and density-independent processes underlying dispersal. In spring and fall, we varied density, substrate size, and current velocity in laboratory experiments and varied density in field experiments. In the laboratory, dispersal of fifth instars was always density dependent, but the strength of density dependence was highest in spring when the proportion dispersing was lowest. Dispersal in field experiments was density dependent only in spring. Proportion dispersing was highest under low flow. The model fit to laboratory data suggested that stronger density dependence in spring occurred because of a reduction in density-independent dispersal stimuli with no change in density-dependent stimuli. In contrast, a change in density-dependent stimuli did appear to cause differences between the proportions dispersing under the two flow regimes. The model reveals the potential for density-independent dispersal stimuli to modify the strength of density dependence detectable at the population level.

Seeking shelter from the storm: responses of benthic stream invertebrates to natural and experimental floods

2015 ◽  
Vol 34 (3) ◽  
pp. 897-908 ◽  
Author(s):  
Jonathan T. Fingerut ◽  
Dina M. Fonseca ◽  
James R. Thomson ◽  
David D. Hart
Keyword(s):  
Stream Invertebrates ◽  
Benthic Stream

scholarly journals Quantitative hydrological preferences of benthic stream invertebrates in Germany

2017 ◽  
Vol 79 ◽  
pp. 163-172 ◽  
Author(s):  
Karan Kakouei ◽  
Jens Kiesel ◽  
Jochem Kail ◽  
Martin Pusch ◽  
Sonja C. Jähnig
Keyword(s):  
Stream Invertebrates ◽  
Benthic Stream

The Biological Clock and Sleep in the Elderly

2006 ◽  
Vol 19 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Myriam Juda ◽  
Mirjam Münch ◽  
Anna Wirz-Justice ◽  
Martha Merrow ◽  
Till Roenneberg
Keyword(s):  
Circadian Rhythms ◽  
Biological Clock ◽  
The Elderly ◽  
Early Morning ◽  
Behavioral Changes ◽  
Older Age ◽  
Age Related ◽  
Theoretical Considerations ◽  
Sleep Difficulties ◽  
Circadian Biology

Abstract: Among many other changes, older age is characterized by advanced sleep-wake cycles, changes in the amplitude of various circadian rhythms, as well as reduced entrainment to zeitgebers. These features reveal themselves through early morning awakenings, sleep difficulties at night, and a re-emergence of daytime napping. This review summarizes the observations concerning the biological clock and sleep in the elderly and discusses the documented and theoretical considerations behind these age-related behavioral changes, especially with respect to circadian biology.

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