Effects of seasonality and migratory prey on body condition of Cichla species in a tropical floodplain river

In this study we examine trends in body condition of three Cichla species native to the Cinaruco River, Venezuela. Specifically, we characterise the potential subsidy provided by migratory Semaprochilodus kneri to Cichla by comparing condition among species, hydrologic seasons and different size-classes (based on the ability to consume S. kneri assuming gape-limitation). All three species had lowest body condition during the rising-water season (following the reproduction period). Only Cichla temensis had greater body condition during the falling-water season than low-water season. During the falling-water season, C. temensis >300 mm SL had significantly greater condition than smaller conspecifics. Annual migration of S. kneri into the river during the falling-water season provides a resource subsidy to large C. temensis. Transfer of whitewater production into nutrient-poor rivers by migratory fishes appears to be a general phenomenon in the major Neotropical river basins and may partially account for high standing stocks of large piscivores in these unproductive ecosystems. D.J. Hoeinghaus*, K.O. Winemiller, C.A. Layman, D.A. Arrington, D.B. Jepsen Section of Ecology, Evolutionary Biology and Systematics, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, USA, Kansas State University, Division of Biology, Manhattan, KS, USA, Marine Biology Program, Department of Biological Sciences, Florida International University, North Miami, FL, USA, Loxahatchee River District, Jupiter, FL, USA, Oregon Department of Fish and Wildlife, Corvallis Research Lab, Corvallis, OR, USA