Characteristics of Woody Cover Used by Brown Madtoms and Pirate Perch in Coastal Plain Streams

We measured or described microhabitat characteristics of woody debris accumulations (i.e., structural complexity, cavity space, stein diameter, suspended and benthic leaves, depth, inside and outside flow, undercut bank, and lateral position) found in headwater coastal plain streams of central Louisiana. Debris characteristics at sites used as diurnal cover by adult brown madtoms Noturus phaeus and pirate perch Aphredoderus sayanus were compared with characteristics at unoccupied debris sites. Woody debris used by brown madtoms was characterized as having greater cavity space, structural complexity, and suspended leaves. Additionally, brown madtoms more frequently occupied debris areas located beneath undercut banks or next to areas of high flow. Of all the habitat variables, undercut bank and cavity space showed the strongest relationship with the presence of brown madtoms in woody debris. Brown madtoms demonstrated no significant difference in use of debris characteristics between small (34–83 mm TL), medium (84–101 mm TL), and large (102–140 mm TL) size‐groups. Relative to unoccupied sites, pirate perch more frequently occupied sites with benthic leaves and leaves suspended within the debris. Debris in deep water with undercut banks and slow inside flows were also used more by this species regardless of its size‐group. The structural complexity of debris at sites occupied by large and medium size pirate perch (59–95 mm TL) was significantly greater than that at unoccupied sites and at sites occupied by small pirate perch (27–58 mm TL). Overall, submerged debris tended to have specific physical characteristics that acted as important determinants in diurnal habitat use of these two structure‐associated fishes.