# Feeding Ecology of the Critically Endangered Gobio insuyanus (Gobionidae)

## TL;DR

This study explores the diet of the critically endangered Gobio insuyanus in Turkey, finding it to be an omnivore with habitat and seasonal feeding variations.

## Contribution

The paper provides the first detailed analysis of the feeding ecology of the critically endangered Gobio insuyanus.

## Key findings

- Gobio insuyanus is an omnivore, primarily consuming detritus, Gammarids, and Diptera larvae.
- Feeding intensity is higher in spring habitats, especially in summer, due to stable temperature and low turbidity.
- Mature individuals show an ontogenetic shift to larger prey, likely due to increased gape size and energy needs.

## Abstract

Despite the critical conservation status of the endemic gudgeon Gobio insuyanus, its feeding ecology remained unstudied. This research addresses this gap by investigating the diet of G. insuyanus in the Insuyu spring–stream system of Central Anatolia (Turkey) analyzing spatial, temporal, and intraspecific variations. We compared two distinct habitats: a stable spring and its continuum, a fluctuating stream. Results indicate that G. insuyanus is an omnivore, consuming primarily detritus, Gammarids, and Diptera larvae. Feeding intensity was higher in the spring habitat, particularly in summer, possibly related to its stable temperature and lower turbidity. Dietary diversity was higher in the stream, potentially reflecting its greater habitat complexity, but decreased in both habitats in autumn, suggesting a seasonal decline in prey availability. A significant ontogenetic shift in diet was observed; mature individuals exhibited a narrower niche and preferred larger prey, probably due to increased gape size, improved foraging ability, and higher energy requirements. No significant dietary differences were found between the sexes. The results have conservation implications, emphasizing the need to maintain the integrity of both habitats. Future research incorporating fish movement data with feeding ecology will further improve our understanding and inform more targeted conservation strategies.

This study investigates the diet of the critically endangered Gobio insuyanus in the Insuyu spring–stream system, revealing omnivorous feeding habits with a preference for detritus, Gammarids, and Diptera larvae. Ontogenetic dietary shifts were observed, with mature individuals specializing in larger prey, while habitat and seasonal variations influenced feeding activity and dietary diversity. These findings highlight the ecological importance of both habitats and emphasize the need for conservation efforts to preserve this endemic species.