US-Mexico Dissertation Enhancement: Changes in Community Structure and Ecosystem Processes in Response to Armored Catfish Invasion

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Although invasive grazing organisms have been introduced throughout the globe, little is understood about the effects of exotic grazers on nutrient cycling and other key ecosystem processes. The major objectives of this doctoral dissertation enhancement project are to examine whether exotic armored catfish alter nutrient cycling and primary productivity, decrease food quality and quantity for native species, and reduce native biodiversity of invertebrates and fishes in invaded tropical ecosystems. Graduate student Krista Capps, under the mentorship of Dr. Alexander Flecker, will study the impacts of armored catfishes on rivers systems in the Grijalva-Usumacinta watershed, a biologically and culturally diverse region in southern Mexico. The research will be done in collaboration with Dr. Rocío Rodiles-Hernández of the Colegio de la Frontera Sur (ECOSUR) in San Cristobal de las Casas, Mexico. The products generated by this study will include: 1) an experimental framework to assess the effects of invasive grazing organisms, 2) an understanding of how exotic armored catfish retain and process nutrients, 3) biological and chemical surveys of armored catfish invasion sites, and 4) enhanced biodiversity knowledge of the Grijalva-Usumacinta watershed through the creation and enhancement of biological collections.The introduction of non-native species is one of the greatest threats to species diversity and ecosystem function throughout the world. This study will directly contribute to the general understanding of exotic grazing organisms and their effects on ecosystem health. Since armored catfish invasion has been linked to the collapse of freshwater fisheries in the Usumacinta watershed region, knowledge derived from this study will also have extensive management implications. The research team will collaborate with the Mexican National Institute of Anthropology and History to promote management of exotic armored catfish populations, and will enhance the biodiversity knowledge of freshwater organisms in and around Palenque National Park, a UNESCO World Heritage Site.