Academic journal article The American Midland Naturalist

Diurnal Habitat Associations of the Madtoms Noturus Albater, N. Exilis, N. Flavater and N. Flavus in Missouri Ozarks Streams

Academic journal article The American Midland Naturalist

Diurnal Habitat Associations of the Madtoms Noturus Albater, N. Exilis, N. Flavater and N. Flavus in Missouri Ozarks Streams

Article excerpt

ABSTRACT.-Few published studies detail the biology and natural history of the madtoms (Noturus spp.), and information about their habitat requirements is even more scarce. We described diurnal habitat use for N. exilis, N. albater and N flavater in Jacks Fork River and N. exilis and N. flavus in Big Piney River, Missouri. Madtoms were captured incidentally with a 1-m2 quadrat sampler while conducting quantitative crayfish sampling from June-Septemher 1995-2000. Sampling was stratified among five macrohabitats, and microhabitat measurements were recorded with each sample. A total of 2206 samples yielded 476 madtoms. Noturus exilis was most common in both rivers, occupied all macrohabitats and used a wide range of depths and current velocities. During late summer it increased use of backwater pools and emergent vegetation patches. Noturus albater was largely rheophilic and used shallow depths (0.06-0.57 in) and high current velocities (0.00-0.60 m/s). Noturus flavater was uncommon and associated with deep water (0.14-2.45 in). Noturus flavus was also largely rheophilic and associated with fairly shallow depths (0.03-0.46 in) and high current velocities (0.00-0.68 m/s). There were few apparent differences among madtoms with regard to associated substrate composition.

INTRODUCTION

Detailed studies on the biology and natural history of the Ictaluridae are scarce, particularly for the most speciose genus, Noturus (Burr and Stoeckel, 1999). Burr and Stoeckel (1999) recently provided a thorough review of madtom natural history and listed 14 aspects requiring further research; one of these was critical diurnal habitats. Chan and Parsons (2000) also noted that madtom research needs to concentrate on quantifying madtom habitat requirements. This is particularly important because the greatest risk to madtom conservation is habitat destruction (Robison and Harp, 1985; Chan and Parsons, 2000).

We described diurnal habitat use for four species of madtom collected in two Missouri Ozarks streams. The Jacks Fork River harbors Noturus albater, N. flavater and N. exilis. The Big Piney River contains N. exilis and N. flavus. Noturus albater and N. flavus. Noturus albater and N. flavater are endemic to the Ozarks region of Missouri and Arkansas (Pflieger, 1997). Noturus exilis ranges from eastern Kansas to east-central Tennessee and from southern Minnesota to northern Alabama (Taylor, 1969). Noturus flavus ranges throughout the north-central United States and southern Canada (Taylor, 1969). Only limited, primarily qualitative, information exists regarding habitat requirements for the above species we encountered (Taylor, 1969; Mayden et al., 1980; Burr and Mayden, 1984; Walsh and Burr, 1985; Vives, 1987; Pflieger, 1997).

METHODS

Study sites.-Jacks Fork and Big Piney rivers are spring fed, sixth order Ozarks streams in southern Missouri (Rabeni et al., 1995). Our study was conducted at four sites (2 per river), each between 0.8 and 1.3 km long, with well developed riffle and pool sequences. Water chemistry summaries and site descriptions are provided in DiStefano (2000).

Sampling design.-Madtoms were captured incidentally while conducting quantitative sampling of crayfish communities. Sampling protocols and gear are described by DiStefano (2000). We used a 1-m^sup 2^ quadrat sampler (Rabeni, 1985; Peterson and Rabeni, 2001) and stratified sampling effort among five macrohabitats (riffles, runs, pools, backwater pools and emergent vegetation patches). The amount of effort expended in each macrohabitat type was nearly proportional to the amount of that macrohabitat that existed in a study reach. However, sampling effort was partially determined by variance of mean crayfish densities (more effort where higher variance found) in each macrohabitat and cost (amount of physical effort) associated with sampling in each macrohabitat (see DiStefano, 2000). Sampling occurred at two sites in each of the two study rivers, but data within rivers have been pooled. …

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