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TheScientificWorldJOURNAL
Volume 8, Pages 169-175
http://dx.doi.org/10.1100/tsw.2008.37
Research Article

Phenotypic Plasticity in Gut Length in the Planktivorous Filter-Feeding Silver Carp (Hypophthalmichthys molitrix)

Donghu Experimental Station of Lake Ecosystems, State Key Laboratory for Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, China

Received 12 October 2007; Revised 15 January 2008; Accepted 26 January 2008

Academic Editor: Micheal S. Allen

Copyright © 2008 Zhixin Ke et al.

Abstract

Phenotypic plasticity widely exists in the external morphology of animals as well as the internal traits of organs. In the present study, we studied the gut length plasticity of planktivorous filter-feeding silver carp under different food resources in large-net cage experiments in Meiliang Bay of Lake Taihu in 2004 and 2005. There was a significant difference in stocking density between these 2 years. Under a low stocking density and abundant food resources, silver carp increased their energy intake by feeding on more zooplankton. Meanwhile, silver carp adjusted their gut length to match the digestive requirements of food when exposed to different food resources. In the main growth seasons (from April to October), silver carp significantly increased their relative gut length when feeding on more phytoplankton in 2005 (p < 0.01, 9.23 ± 1.80 in 2004 and 10.77 ± 2.05 in 2005, respectively). There was a nearly significant negative correlation between zooplankton proportion in the diet and the relative gut length when silver carp were stocked in a high density (p = 0.112). It appears that silver carp might have evolved plasticity to change their gut length rapidly to facilitate efficient utilization of food resources. Such resource polymorphisms in the gut may be a good indication of temporal adaptation to resource conditions. Our work provided field evidence for understanding the functional basis of resource polymorphisms and the evolution of phenotypic plasticity in planktivorous filter-feeding fish.