RESEARCH ARTICLE Predicting Species ’ Vulnerability in a Massively Perturbed System: The Fishes

Background and Trophic Diversity Study Lake Turkana is an understudied desert lake shared by Kenya and Ethiopia. This system is at the precipice of large-scale changes in ecological function due to climate change and economic development along its major inflowing river, the Omo River. To anticipate re-sponse by the fish community to these changes, we quantified trophic diversity for seven ecological disparate species (Alestes baremose, Hydrocynus forskalli, Labeo horie, Lates niloticus, Oreochromis niloticus, Synodontis schall, and Tilapia zillii) using stable isotopes. Based on their marked morphological differentiation, we postulated that dietary niches of these species would be similar in size but show little overlap. The degree of trophic diversity varied greatly among the species studied, refuting our hypothesis regarding dietary niche size.Oreochromis niloticus and L. niloticus had the highest trophic diversity and significant-ly larger dietary niches than T. zillii, A. baremose and H. forskalli. Low overlap among the di-etary niches of the seven species, with the exception of the synodontid catfish S. schall, is consistent with our second hypothesis