OVERVIEW OF THE ECOLOGICAL BACKGROUND

      This Data Set grew out of a similar one on lizards (Huey et al. 2001) in which proportion of animals with empty stomachs was used as an index of instantaneous energy balance. In that case, researchers wanted to know whether lizards alternate between states of feast or famine in contrast to keeping a positive energy balance.

     In the present study Arrington et al. (2002) selected fish because these animals display a wide range of trophic specializations. The scientists measured the number of fish with empty stomachs in 36.875 individual fish of 254 species collected from Africa, South America, Central America, and North America. They only included samples with >10 individuals in the study; mean sample size was 145.

     Arrington et al. found that percentage of piscivores with empty stomachs was significantly higher than percentages for omnivores, invertivores, and algivores/detritivores in each geographic location (ANOVA, P< 0.005). Invertivores had next highest proportions with empty stomachs followed by the other two categories, which were not statistically different from each other. Within the piscivores a disproportionate number provided parental care (e.g. mouth brooding).

      Arrington et al. conclude that animals able to put surplus energy into lipids and other storages can tolerate the energy costs associated with high-cost reproduction and also survive stress periods. They state that their results "reveal a potential influence of feeding frequency and energy balance on life history evolution".

     In the Ecology paper Arrington et al. also include figures on Nocturnal/diurnal fishes (nocturnal fishes had more empty stomachs); African/Central & South/North American fishes (same pattern); and piscivore "biters"vs."engulfers" (biters had fewer empty stomachs).


References:

Arrington, D. A., K. O. Winemiller, W. F. Loftus, and S. Akin. 2002. "How often do fishes "run on empty"? Ecology 83 (8): 2145:2151.

Huey, R. B., E. R. Pianka, and L. J. Vitt. 2001. How often do lizards "run on empty"? Ecology 82: 1-7.