HR: 16:00h
AN: NB24D-03    [Abstracts]
TI: Do spates determine species? The influence of altered hydrology on stream fish assemblages.
AU: * Helms, B
EM: helmsbs@auburn.edu
AF: Auburn University, Department of Biological Sciences, Auburn, AL 36849 United States
AU: Schoonover, J
EM: schooje@auburn.edu
AF: Auburn University, School of Forestry and Wildlife Sciences, Auburn, AL 36849 United States
AU: Feminella, J
EM: feminjw@auburn.edu
AF: Auburn University, Department of Biological Sciences, Auburn, AL 36849 United States
AB: We investigated the influence of short-term hydrologic regimes on fish assemblages in 18 watersheds (500-2500 ha, Lower Piedmont ecoregion) along an urbanization gradient north of Columbus, Georgia, USA. We monitored stream hydrology continuously with pressure-transducers for 1 y and also quantified fish and habitat variables in representative 100-m reaches in each watershed. We characterized each stream's hydrograph using a suite of 44 metrics, broadly characterized as Magnitude, Frequency, Duration, Flashiness, or Predictability measures. Fish species richness, diversity, health, proportion of lithophilic spawners (sensitive guild) and overall assemblage integrity (IBI) declined with an increasing number of spates (Frequency). In addition, the proportion of sunfish species, primarily Lepomis auritus and L. macrochirus, increased with increasing numbers of spates, suggesting that hydrologically altered streams are numerically dominated by tolerant species. Overall, Frequency measures were the most informative of all hydrological predictors, suggesting spate frequency is potentially a strong driver of fish assemblage structure. Interestingly, not all watersheds exhibiting a high number of spates were highly urbanized, thus factors other than % impervious surface, which was highest in the urban watersheds, influence the hydrologic regime. Overall, our data suggest a functional connection between land use change, altered stream hydrology, and shifts in fish assemblages.
DE: 1800 HYDROLOGY
DE: 1803 Anthropogenic effects
DE: 1821 Floods
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly