OutdoorNebraska

40 Flat floater, Utterbackia suborbiculata Description: The Flat Floater has a distinctive shell that is almost as high as it is long. The shell is really thin and compressed. The shell has no pseudocardinal or lateral teeth. The nacre is white or pale pink. The epidermis is tan with dark growth rings. The beak area is flat and even with the dorsal edge while the beak sculpture consists of a several small bumps or pustules. Similar species: The Flat Floater would be hard to confuse with any other Nebraska species. The Giant Floater is most similar but their beaks with the double-looped sculpture and their inflated shell easily distinguishes them. Conservation status: G5, N5, S1. Prior to the 2010-11, this species was rarely found in the Missouri River. Construction of backwater habitat at mitigation sites as well as the construction of marinas coupled with the disturbance of the 2011 floods have greatly expanded the range and numbers of Flat Floaters in the Missouri River. If their populations hold up now that the river has returned to normal operations, their status could be upgraded. Hosts: Channel catfish, golden shiner, green sunfish, largemouth bass, white crappie. Habitats used: Ponds, lakes, sluggish mud-bottom pools of creeks and rivers (Cummings and Mayer 1992). Large rivers, backwaters, or sloughs in soft substrate (Seitman 2003). Lakes, sloughs, quiet segments of rivers with mud bottoms (Oesch 1995). Lakes, sloughs, shallow backwaters of larger rivers on mud (Parmalee and Bogan 1998). Soft stable sediment in pools, backwaters, and low flow reaches of large rivers (Watters et.al. 2009). Native range: The Mississippi River basin from Nebraska to Wisconsin and Ohio then down to Louisiana and Alabama Nebraska collection notes: In recent years, abundant numbers of Flat floaters have been collected from the Missouri River from off-channel quiet water areas between the Platte River and Gavins Point Dam. Comments: It has been noted in the literature that this species may be extending its range due to impoundment of large rivers. Its expanded presence in the Missouri river may be due to the construction of off-channel backwater habitats such as marinas and mitigation sites. The 2011 Missouri River flood was a two- edged sword. The flood may have helped them, via their fish hosts, to enter many new areas but huge numbers were stranded and died when the flood waters went down.

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