Academic journal article The American Midland Naturalist

The Influence of Channelization on Fish Communities in an Agricultural Coldwater Stream System

Academic journal article The American Midland Naturalist

The Influence of Channelization on Fish Communities in an Agricultural Coldwater Stream System

Article excerpt

ABSTRACT.-

We characterized coldwater stream fish community response to habitat degradation and channelization for agriculture. Coldwater streams are not common in the lower midwestern United States, and these streams differ from warmwater streams with respect to their diversity and community response to degradation. Six sites were sampled on the coldwater Mac-o-chee Creek in Ohio. Three reaches were classified as geomorphically constrained (by a roadway) and three as recovering (unconstrained and not channelized or cleaned for more than 100 y). Within each reach 31 mesohabitat units were sampled and were delineated as riffles, runs, or pools. Our goals were: (1) to examine how habitat and geomorphic impairment influences the abundance and community structure of coldwater fishes; and (2) to test whether the constraints on recovery from channelization were more influential in structuring communities than mesohabitat types. Our hypothesis was that we would find lower species diversity overall in the recovering sites because they would be more indicative of a coldwater fauna. In contrast, we hypothesized that the sites that are not able to recover (geomorphically constrained) would be more indicative of a warmwater fauna, and thus more diverse. We found lower species abundances, diversity, and species richness in recovering stream reaches than impaired reaches. Mesohabitat types present are influenced by channelization and recovery but are also largely a product of geomorphologic setting of the study streams. The effects of habitat degradation on the biota and the resulting trophic structure are important for designing restoration targets for coldwater systems, which may be naturally less diverse than warmwater counterparts. For example, biometric scores like Index of Biotic Integrity (IBI) are often used as restoration targets, but this would be inappropriate unless a coldwater-specific IBI were used.

INTRODUCTION

Biota in fluvial systems are influenced by physical and chemical parameters as well as by the geographic and geological history of the systems that they inhabit (Allan, 1995; Poff, 1997; Williams et al, 2003). The environmental factors that shape a stream system are hierarchical in nature-from watershed, to reach, to microhabitat scale (Poff, 1997). Researchers have tested how hierarchical characteristics shape the way channel form influences habitat and fish communities (Schlosser, 1991; Smiley and Dibble, 2005; Parsons and Thorns, 2007). Landscape-scale features (e.g., geology, climate) structure reach-scale features like riffle-pool morphology and hydrology, which in turn structures fish communities (Frissell et al, 1986). Studies have confirmed that mesohabitat units (riffles, runs, and pools) in a stream are direcdy impacted by channel form and will support distinct biotic communities (Gorman and Karr, 1978; Beisel et al., 1998; Taylor, 2000). As habitat changes occur in lotie systems, mesohabitat units can become altered resulting in changes to natural aquatic communities, which are dependent on a less disturbed state of the stream system (Davies and Jackson, 2006).

Anthropogenic modification of stream channels to accommodate agricultural landuse is widespread in the United States and has led to changes in the types and amounts of mesohabitats within streams. When European settlers first encountered the fertile, relatively flat lands of the lower midwestern (defined here as Ohio, Indiana, Illinois, and Iowa) United States, many regions contained stream systems that regularly flooded interconnected wetland complexes (Schumm et al., 1984; Dameron-Hager, 2004). Early inhabitants converted large areas of these wetland complexes to agricultural fields by modifying existing streams and dredging new drainage channels, which have persisted in many areas. Wetland drainage and channel straightening caused geomorphic changes in stream systems that were well beyond the rate of change that would have occurred without human influence, and many of the headwater streams in the lower midwest have been channelized (Urban and Rhoads, 2003) . …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.