Dietary‐morphological relationships of fishes in Liangzi Lake, China

Species in Liangzi Lake were clustered into four trophic groups:Hemiramphus kurumeusandHemiculter bleekeri bleekerifed predominantly on terrestrial insects;Carassius auratus auratusandAbbottina rivularison non‐animal food;Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva and Toxabramis swinhonison cladocerans or copepods;Culterichthys erythropteruson decapod shrimps. Gut length, mouth width, mouth height, gill raker length and gill raker spacing, varied widely among species. With the exception of three species pairs (H. swinhonis, C. giurinus; C. erythropterus, H. kurumeus; T. swinhonis, H. bleekeri bleekeri), principal components analysis of morphological variables revealed over‐dispersion of species. Canonical correspondence analysis of dietary and morphological data revealed five significant dietary‐morphological correlations. The first three roots explained > 85% of the total variance. The first root reflected mainly the relationship of gut length to non‐animal food, with an increase in gut length associated with an increase in non‐animal food. The second root was influenced strongly by the relationship of the gill raker spacing to consumption of copepods, with an increase in gill raker spacing associated positively with copepods in the diet. The third root was influenced by the relationship of mouth gape to consumption of fish and decapod shrimps, with an increase in mouth gape associated with more fish and decapod shrimps in the diet. These significant dietary‐morphological relationships supported the eco‐morphological hypotheses that fish morphology influence food use, and morphological variation is important in determining ecological segregation of co‐existing fish species.