Microhabitat estimation of an imperiled headwater fish, the Yazoo darter (Etheostoma raneyi), in Coastal Plain streams
Headwater fishes in the southeastern United States make up much of the fish biodiversity of the region yet many are imperiled. Despite this, the specific habitat requirements of imperiled headwater fishes in lowland Coastal Plain streams have rarely been quantified. Using data collected over three years of seasonal sampling we provide estimates of the microhabitat requirements
of the imperiled Yazoo darter (Etheostoma raneyi Suttkus and Bart), a small benthic insectivore. Our results indicate that the species is a microhabitat specialist and that optimum microhabitat within degraded contemporary streams consists of a narrow range of water depths (about 20–30 cm), current velocity = 0.25 m·s-1, complex stable debris piles, rooted macrophytes, and likely coarse substrate. No pronounced or generalized seasonal shifts in microhabitat use occurs, and no evidence exists for intraspecific partitioning of microhabitat. Though stable and complex instream cover is one of the most important variables explaining variation in microhabitat use by Yazoo darters, such cover is rare in the degraded streams within the range of the species. Current conservation classifications of the Yazoo darter by governmental agencies and nongovernmental organizations
as well as associated management plans that are based onthe assumption that Yazoo darters are habitat generalists should be reviewed in recognition of the increased risk of decline becauseYazoo darters aremicrohabitat specialists. These considerations should also be extended to other closely related imperiled species of snubnose darters.