Homeostatic responses in the gut of Porcellio scaber (Isopoda: Oniscidea) optimize litter degradation |
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Authors: | M Zimmer W Topp |
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Institution: | Department of Zoology – Physiological Ecology, University of Cologne, Weyertal 119, D-50931 K?ln, Germany Fax: +49-221/470-5038, e-mail: mzimmer@mother.biolan.uni-koeln.de, DE
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Abstract: | In order to examine the influence of differences in food conditions on gut characteristics in Porcellio scaber, pH-manipulated and microbially inoculated leaf litter from three different tree species were offered. Microbial activity
was clearly influenced by the pH levels of the leaves. Analyses of the pH levels in the gut indicated the ability of P. scaber to buffer the pH value in the intestinal tract to about 5.5–6.0 in the anterior hindgut, and to about 6.0–6.5 in the posterior
hindgut. The pH levels of the gut sections remained in this range, within a range of food pH from 4.0 to 7.5, no matter what
kind of leaves the animals were fed. Homeostatic responses to changes in food pH guarantee optimized digestion of leaf litter.
However, when the pH level of the litter dropped below 3.5, P. scaber was not able to maintain the pH conditions in the gut. Furthermore, microorganisms colonizing the litter biased the pH level
in the anterior hindgut where digestive processes mainly take place. These results indicate a decline of litter quality with
regard to the nutrition of terrestrial isopods, caused by acidification and consequently reduced microbial activity.
Accepted: 19 July 1997 |
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Keywords: | Terrestrial isopods Acidification Gut pH Digestive enzymes Litter decomposition |
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