Feeding ecology of the critically endangered Gobio Insuyanus (Gobionidae)

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 activity 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.