Reproductive Ecology of Two Sympatric Cyprinids in the Rio Grande Basin, Texas

The genus Dionda (family Cyprinidae) consists of at least 12 species, all of which inhabit groundwater-dominated streams within the western Gulf slope drainages of North America.  Purposes of this study were to quantify reproductive characters of two sympatric Dionda (D. argentosa and D. diaboli) and to assess relationships among life-history traits and habitat adaptations.   From September 2009 to August 2010, D. argentosa and D. diaboli were collected monthly from the Devils River, Rio Grande Basin, Texas, and D. diaboli from Pinto Creek, Rio Grande Basin, Texas.  Population structure (number of age groups, longevity, growth rates) and reproductive effort (spawning season, spawning periodicity, batch fecundity estimates) were determined for each species by drainage.  Dionda argentosa had a protracted spawning season, from January through November, whereas D. diaboli spawned from January through July.  Differences in life history were related to seasonal temperature and photoperiod associated with different habitat selection strategies.