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Effect of competitor abundance on feeding territoriality in a grazing fish, the ayu Plecoglossus altivelis

Effect of competitor abundance on feeding territoriality in a grazing fish, the ayu Plecoglossus... The grazing fish, ayu, Plecoglossus altivelis Temminck & Schlegel, establishes feeding territorialiry during the young stage. The population density fluctuates from year to year by more than a hundredfold, but the determinant of territory size is less well known. The feeding territoriality of ayu was examined under simulated habitat conditions where fish density was manipulated and food resources were renewable. Fish competed for algae attached to the substrata and were divided into residents with territories, and floaters without territories. By experimental alteration of fish density the number of residents increased with density and rerritory size decreased with density. Floaters intruded into territories in a school to feed on algae, which induced overt aggression of the resident and reduced the productivity of algae growing there. Both the intruding frequency of floaters over territorial areas and their feeding pressure on algae increased at higher floater density. Floaters functioned to shift cost‐benefit relationships for various territory sizes. They acted as food competitors to restrict territory size below a maximum through competitive interference. Although the growth rate of residents was inversely related to fish density, residents grew faster than floaters in each group. Under a given set of competitor abundances, economic defensibility determined territory size. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Ecological Research Wiley

Effect of competitor abundance on feeding territoriality in a grazing fish, the ayu Plecoglossus altivelis

Ecological Research , Volume 11 (2) – Aug 1, 1996

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References (46)

Publisher
Wiley
Copyright
© The Ecological Society of Japan
ISSN
0912-3814
eISSN
1440-1703
DOI
10.1007/BF02347682
Publisher site
See Article on Publisher Site

Abstract

The grazing fish, ayu, Plecoglossus altivelis Temminck & Schlegel, establishes feeding territorialiry during the young stage. The population density fluctuates from year to year by more than a hundredfold, but the determinant of territory size is less well known. The feeding territoriality of ayu was examined under simulated habitat conditions where fish density was manipulated and food resources were renewable. Fish competed for algae attached to the substrata and were divided into residents with territories, and floaters without territories. By experimental alteration of fish density the number of residents increased with density and rerritory size decreased with density. Floaters intruded into territories in a school to feed on algae, which induced overt aggression of the resident and reduced the productivity of algae growing there. Both the intruding frequency of floaters over territorial areas and their feeding pressure on algae increased at higher floater density. Floaters functioned to shift cost‐benefit relationships for various territory sizes. They acted as food competitors to restrict territory size below a maximum through competitive interference. Although the growth rate of residents was inversely related to fish density, residents grew faster than floaters in each group. Under a given set of competitor abundances, economic defensibility determined territory size.

Journal

Ecological ResearchWiley

Published: Aug 1, 1996

Keywords: ; ; ;

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