Bluehead chub nesting activity: a potential mechanism of population persistence in degraded stream habitats

Abstract

Aquatic biodiversity continues to decline as humans modify the landscape, mainly because of stream habitat alterations and loss caused by urban development. Bluehead chubs may mitigate some effects of instream habitat degradation by providing clean gravel substrate via their spawning nests. We used path analysis, an extension of multiple linear regression, to explore the relationships among instream habitat degradation, adult chub abundance, chub nesting activity, and chub reproductive performance. Age-0 chub abundance was best explained by small adult abundance and nest abundance. Habitat disturbance indirectly and negatively influenced age-0 chub abundance through adult chubs and nest abundance. Percentages of pool and run habitat also had indirect negative effects on age-0 chub abundance. Several metrics of chub nesting activity (nest density [proportion of substrate occupied by nests], average nest size, and number of nests) were explained by both adult chub abundance and nesting site conditions. Variability among stream systems described significant variation in adult chub abundance and nesting characteristics and, if unaccounted for, would have resulted in large unexplained variability. Chub nesting activity served as a link between habitat degradation, adult chub abundance, and their reproductive performance. Our study provides preliminary evidence that bluehead chubs' nesting activity may be a mechanism of their persistence in degraded stream reaches. We recommend confirmatory studies through in-stream manipulative experiments.

Lotic cyprinid communities can be structured as nest webs and predicted by the stress‐gradient hypothesis

“…This method is effective because length‐frequency histograms of short‐lived temperate fishes such as cyprinids show distinct modal breaks. This method typically agrees well with age estimation based on hard structures (Reid, Jones & Yunker ; Peoples, Tainer & Frimpong ). The purpose of the binary age classification was not to quantify actual age structure, but to partition demography into indices of reproductive success (juvenile abundance) and a major cause of reproductive output (adult abundance).…”

“…the positive relationship between adult and juvenile abundance of a reproductive group). For example, models predicting nest abundance must contain large adult male abundance and gravel availability (Peoples, Tainer & Frimpong ). Because they reproduce almost exclusively on Nocomis nests, models predicting juvenile Nocomis and strong associate abundance must always contain nest abundance.…”

A survey of macroinvertebrates colonizing bluehead chub nests in a Virginia stream

“…Additionally, 38 of 48 macroinvertebrate families recorded in the section of stream studied were found on chub nests, which is a significant concentration of macroinvertebrate families in the small area represented by nests in the stream. There is some preliminary evidence that chub nests may allow nestassociate fish species to persist in degraded streams, offering support to increasing consideration of Nocomis as keystone species (Vives 1990;Peoples et al 2011;Pendleton et al 2012). Dedicated research on interactions of stream macroinvertebrates with chub nests may find that chubs also facilitate the persistence of some members of macroinvertebrate communities.…”

“…We found the nests in pairs at each site, likely because multiple males put their nests in the most suitable conditions of flow and depth located at pool tails (Sabaj et al 2000;Bolton et al 2015). Our study did not examine stream flow, presence of riffles and pools, or other environmental conditions because these nest site conditions have already been studied in detail (Peoples et al 2011;Bolton et al 2015). We sampled the nests by first measuring the depth of the water at the nest location and two diameters of the nest.…”

Linking hydrologic, physical and chemical habitat environments for the potential assessment of fish community rehabilitation in a developing city

“…Successful implementation of these methods depends critically on connecting the underrepresented taxa with the mechanisms responsible for their reduction/ elimination but often requires substantial scientific expertise. Although many previous studies have related human activities to resident species assemblages, few have confirmed or determined mechanisms (Peoples et al, 2011;Kemp, 2014). Common bioindicators often include benthic macroinvertebrates, fish, benthic diatoms, macrophytes and birds (Feld and Hering, 2007;Vaughn et al, 2007;Hughes et al, 2010).…”