Does diet variation determine the digestive tract length of Capoeta banarescui Turan, Kottelat, Ekmekci and Imamoglu, 2006?

Abstract

This study tested the spatial variations in the digestive/intestine tract length of Capoeta banarescui, with regard to their diets in different habitats. Highly varied diets observed in a previous study within the same river system posed the question whether this flexibility is reflected in the digestive tract and intestine length of the species in the Yes ßilırmak River, Turkey. Totals of 382 specimens (standard length 4.6-19.1 cm) were captured by electro-fishing along the river in September 2012 at 11 locations spanning elevations from 34 to 992 m. The stomach, intestine and total digestive tract lengths were measured, and stomach contents analysed from 196 specimens. For statistical analyses, the stomach, intestine and total digestive tract length were expressed as percentages of total weight and standard length. The data provided evidence that the digestive tract and intestine lengths varied significantly among locations in association with the diet. Fish having dominantly carnivorous diets (e.g. chironomid larvae/ invertebrates) in two locations had significantly shorter intestines and digestive tracts than those with diets dominated by benthic algae and other plants. The data indicated that C. banarescui showed broad flexibility in their feeding habits. Feeding heavily on plant materials might lead to the development of longer digestive tracts, increasing the active surface area for digestion; alternatively, there may be less invested in development of the digestive tract when feeding primarily on carnivorous diets where the respective digestive enzymes are readily available. The data suggest that phenotypic plasticity in the digestive tract length of C. banarescui is associated more with the abundant protein-rich carnivorous food sources in the studied habitats. Whether this digestive tract plasticity has a genetic background remains to be verified in future studies.

Spatial and temporal variation in food web structure of an impounded river in Anatolia

“…In addition to rainbow trout, wels catfish (Silurus glanis), crucian carp (Carasssius carassius) and common carp (Cyprinus carpio) have been stocked in the Almus Reservoir. A cyprinid endemic to the Yes -ilırmak Basin, namely Capoeta banarescui, was recently described (Turan et al 2006). Unfortunately, we have no pre-impoundment data for fish assemblage composition.…”

“…Ϫ24 species (S. cephalus, C. banarescui, C. colchicum) were captured during every season. These omnivorous cyprinids consume a variety of aquatic invertebrates, as well as terrestrial and aquatic vegetation (Akin et al 2016;S. Akin, C. Sahin, B. Verep, D. Turan, A. M. Gozler, A. Bozkurt, K. Ç elik, E. Cetin, A. Aracı and I. Sargın, unpubl.…”

Unexpected Diversity of Feeding Modes among Chisel-Mouthed Ethiopian Labeobarbus (Cyprinidae)

“…The evolution of periphytonophagous adaptations probably occurred over millions of years. Specialized lineages of periphitonophagous scrapers can be found among a type of Asian cyprinids of a rather old origin (Miocene), e.g., Capoeta (Valenciennes 1842), Cyprinion (Heckel 1843), Garra (Hamilton 1822), Onychostoma (Günther 1896), Scaphiodonichthys (Vinciguerra 1890), Schizothorax (Heckel 1838), Schizopygopsis (Steindachner 1866) [28,32,33]; however, note the exceptions in feeding specialization for some members of these genera [17,26,69]. In the case of chisel-mouthed fish, periphyton feeding is accompanied by morpho-ecological adaptations, such as modified jaws, a long gut with thin walls, increased gill raker numbers, and often a black peritoneum ( [27,45], this study).…”

“…The other four scraper ecomorphs of more recent origin (probably of Pleistocene origin-see Beshera et al [70] are herbivores-detritivores or insectivores. Insectivory has not yet been reported for the Labeobarbus scrapers, although it is known for some representatives of evolutionarily distant lineages of scrapers, like Capoeta, Schizopygopsis, and Sarcocheilichthys (Bleeker 1860) [26,69,71,72]. It is noteworthy that the divergence of sympatric pairs of scrapers was confirmed in both the Genale and Gojeb rivers, not only by diet and stable isotope data but also by head morphology and gut length.…”