Dietary changes in an allochthonous sea catfish species from Panama

Biologie de l'organisme
jeudi 19 déc. 09:15 AM (15 minutes)
Salle EFG

Invasion of a new habitat can lead to rapid adaptation of a species. The coastal brackish sea catfish species Cathorops tuyra (Ariidae, Besudo sea catfish) from the Eastern coast of Panama has repeatably been found in the freshwater rivers and lakes of the Panama Canal. Habitat transitions require various adaptations to different environmental conditions including changes in feeding ecology. Stomach content analysis is the most convenient and often the only way available of researching the feeding habits of a particular species. We collected 101 C. tuyra specimens from two different habitats that differed in salinity and ecology, the freshwater Rio Chagres and the brackish Rio Santa Maria. Fish were dissected and information was collected on various other internal and external features. A stomach content analysis was carried out identifying prey to the lowest possible taxonomic group then categorized into fish, bivalves, crustaceans, gastropods, insects, other invertebrates, and plants. In Rio Chagres individuals had a higher mean size than in Rio Santa Maria and there was also a bias towards catching females. Additionally, there were many more fish that had entered the breeding cycle in the Rio Chagres than in the Rio Santa Maria. The prevalence of parasites was low in Rio Chagres and there were none at all in Rio Santa Maria. While the diets were very similar between populations, the main difference in diet was due to the increase in predation of crustaceans in Rio Santa Maria. Gastropods, bivalves and insects were the most important prey items in both rivers representing a fairly diverse omnivorous diet that is similar to that of other catfishes.


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