Addition of spurs to stone toe protection for warmwater fish habitat rehabilitation

Longitudinal stone toe is one of the most reliable and economically attract ive approaches for stabilizing eroding banks in incised channels. However, aquatic habitat provided by stone toe is inferior to that provided by spur dikes. In order to test a design that combined features of stone toe and sp urs, eleven stone spurs were placed perpendicular to 170 m of existing ston e toe in Goodwin Creek, Mississippi, and willow posts were planted in the s andbar on the opposite bank. Response was evaluated by monitoring fish and habitats in the treated reach and an adjacent comparison reach (willow post planting and standard toe without spurs) for four years. Furthermore, phys ical habitats within the treated reach were compared with seven reaches pro tected with standard toe on a single date three years after construction. O verall results indicated that spur addition resulted in modest increases in baseflow stony bankline, water width and pool habitat availability, but ha d only local effects an depth. These relatively small changes in physical h abitat were exaggerated seasonally by beaver dams that appeared during peri ods of prolonged low flow in late Summer and Autumn. Physical changes were accompanied by shifts in fish species composition away from a run-dwelling assemblage dominated by large numbers of cyprinids and immature centrarchid s toward an assemblage containing fewer and larger centrarchids. Biological responses were at least partially due to the effects of temporary beaver d ams.