Tissue pH and gut ecomorphology in six freshwater teleosts occupying different trophic levels


Abstract: 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).

Keywords: Fish, pH, gastrointestinal tract, blood, muscle, gut length

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