Dietary overlap and selectivity among silver carp and two native filter feeders in the Wabash River.

Silver carp (Hypophthalmichthys molitrix) are a potential threat to native filter feeders and larval fish due to dietary overlap. To test for dietary overlap and selectivity, we collected diet samples from invasive silver carp and two native filter feeders (gizzard shad Dorosoma cepedianum and bigmouth buffalo Ictiobus cyprinellus), and river plankton samples at three sites on the Wabash River during the spring and summer of 2015. Contents of diet items were identified to major group and quantified. Diet proportions were compared among seasons, sites and species. Diet selectivity was calculated using the Manly–Chesson diet selectivity index. The results of our diet analysis showed that silver carp had significantly dissimilar diets among seasons and displayed dietary overlap with native fishes. We did not find a significant difference among sample sites. While silver carp diets overlapped with native fishes, the impact of this possible source of competition requires further study to confirm impacts on native fish abundances and body conditions.

[1]  L. Williams.  DOMINANT PLANKTONIC ROTIFERS OF MAJOR WATERWAYS OF THE UNITED STATES , 1966 .

[2]  M. Cremer,et al.  Food habits and growth of silver and bighead carp in cages and ponds. , 1980 .

[3]  J. M. Bates,et al.  Ecological assessments of effluent impacts on communities of indigenous aquatic organisms (symposium), 1979 , 1981 .

[4]  Jean Chesson,et al.  The Estimation and Analysis of Preference and Its Relatioship to Foraging Models , 1983 .

[5]  G. Bitterlich.  Digestive enzyme pattern of two stomachless filter feeders, silver carp, Hypophthalmichthys molitrix Val., and bighead carp, Aristichthys nobilis Rich. , 1985 .

[6]  G. Bitterlich.  Digestive processes in silver carp (Hypophthalmichthys molitrix) studied in vitro , 1985 .

[7]  Feeding experiments with silver carp (Hypophthalmichthys molitrix Val.) fry , 1989 .

[8]  L. Page,et al.  Non-native fishes inhabiting the streams and lakes of Illinois. , 1996 .

[9]  P. Xie.  Gut contents of silver carp, Hypophthalmichthys molitrix, and the disruption of a centric diatom, Cyclotella, on passage through the esophagus and intestine , 1999 .

[10]  P. Fuller,et al.  Spatial and Temporal Patterns of Nonindigenous Fish Introductions in the United States , 1999 .

[11]  A. Huusko,et al.  Varying Resistance of Zooplankton Prey to Digestion: Implications for Quantifying Larval Fish Diets , 2000 .

[12]  M. Gophen,et al.  Feeding behaviour of silver carp Hypophthalmichthys molitrix Val. and its impact on the food web in Lake Kinneret, Israel , 2004, Hydrobiologia.

[13]  D. Allen,et al.  Trophic relationships and seasonal utilization of salt-marsh creeks by zooplanktivorous fishes , 2004, Environmental Biology of Fishes.

[14]  M. Belk,et al.  Complex interactions between native and invasive fish: the simultaneous effects of multiple negative interactions , 2004, Oecologia.

[15]  I. Domaizon,et al.  Experimental study of the impacts of silver carp on plankton communities of eutrophic Villerest reservoir (France) , 1999, Aquatic Ecology.

[16]  J. Garvey,et al.  Growth, Fecundity, and Diets of Newly Established Silver Carp in the Middle Mississippi River , 2005 .

[17]  G. Sass,et al.  Reduced condition factor of two native fish species coincident with invasion of non‐native Asian carps in the Illinois River, U.S.A. Is this evidence for competition and reduced fitness? , 2007 .

[18]  J. Chick,et al.  Diet overlap among two Asian carp and three native fishes in backwater lakes on the Illinois and Mississippi rivers , 2009, Biological Invasions.

[19]  P. Willink,et al.  Bigheaded Carps: A Biological Synopsis and Environmental Risk Assessment , 2009, Copeia.

[20]  J. Chick,et al.  Underestimation of rotifer abundance a much greater problem than previously appreciated , 2010 .

[21]  Francis K C Hui,et al.  The arcsine is asinine: the analysis of proportions in ecology. , 2011, Ecology.

[22]  A. Coulter,et al.  Phenotypic plasticity in the spawning traits of bigheaded carp (Hypophthalmichthys spp.) in novel ecosystems , 2013 .

[23]  M. Pyron,et al.  Shift in a Large River Fish Assemblage: Body-Size and Trophic Structure Dynamics , 2015, PloS one.

[24]  A. Coulter,et al.  Invasive Silver Carp movement patterns in the predominantly free-flowing Wabash River (Indiana, USA) , 2015, Biological Invasions.