Tissue pH and gut ecomorphology in six freshwater teleostsoccupying different trophic levels

This study investigated the gastrointestinal (GI) tract, blood, and muscle pH, and explored the characteristic of gut morphology (relative gut length) associated with trophic level in 6 freshwater teleosts. The results showed that GI pH differences among species and significant differences occurred in GI segments (P < 0.05). The lowest pH values were observed in the stomach of 2 typical carnivorous fish. An increased pH from proximal intestine to distal intestine was found in 4 species. A positive relationship was observed between blood and muscle pH values for these species (P < 0.05). Additionally, relative gut length revealed the trend of divergence depending on the feeding habits (in planktivores > omnivores > carnivores). A robust link was negatively found between relative gut length and trophic level (P < 0.05).

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