Riparian and landscape disturbance effects on stream fish community composition in an agriculturally-dominated drainage

Abstract

We compared historical stream fish community sampling and remote sensing data from 1993–2011 in an agriculturally-dominated drainage basin to determine the effects of varying levels of riparian and landscape disturbances on fish communities. Stream fish guilds were analyzed with National Land Cover Database and aerial imagery products to quantify disturbance levels at a local and watershed scale. Insectivores and benthic insectivores were associated with intact riparian areas, whereas environmentally tolerant and omnivorous species were found in environments with degraded riparian areas. Riparian disturbances had the greatest effect near the stream (0–10 m), and the effects diminished with increasing distance from the stream. This spatial scale corresponds with those reported in the literature whereby allocthonous inputs and riparian filtering influenced stream fish communities and water quality. The landscape disturbance was not a strong predictor for any fish guild, indicating that local riparian conditions were more biologically meaningful. Considering the rapid rates of land conversion to production agriculture across the midwestern United States, ensuring adequate riparian buffering of streams may help protect specialist aquatic species and their habitat. Given the broad temporal and spatial nature of our data, these results suggest that targeted conservation of the 10-m scale of intact riparian vegetation directly adjacent to streams is a sound practice and should be considered the minimum conservation goal for watershed restoration in low-gradient landscapes historically dominated by agricultural land-use practices.

Keywords:

• riparian buffers
• land use
• fish guilds

Acknowledgements

The authors thank Aaron Larsen, North Dakota Department of Health, and Scott Gangl, North Dakota Game and Fish Department for data sharing. Two anonymous reviewers provided valuable feedback and comments.

Funding

This study was funded by the University of North Dakota Department of Biology, Stella Fritzell and Joe K. Neal Memorials, and North Dakota View.