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N.M. Burkhead

Publications and source records attributed to N.M. Burkhead.

17 recordsLinked to original sources
USGS2008

A new species of Percina (Perciformes: Percidae) from the Apalachicola River drainage, southeastern United States

Percina crypta, the Halloween Darter, is described as a new species endemic to the Chattahoochee and Flint River systems in Georgia and Alabama. Percina crypta differs from sympatric Percina nigrofasciata in having narrowly separated dorsal saddles (inter-saddle spaces typically less than or equal to saddle width, compared to frequently wider than saddle width in P. nigrofasciata), in usually possessing a single modified scale between the pelvic bases (compared to two or more in P. nigrofasciata), and in having dark wide bands on pectoral-fin rays (versus pectoral fin clear, or with irregular dark marks or weak tessellations on fin rays in P. nigrofasciata). Phylogenetic relationships of P. crypta to other species of Percina are obscure. Percina crypta occurs in shoal and riffle habitats in the Chattahoochee and Flint River mainstems and in a few tributary systems, with the known extant range comprising four disjunct areas separated by mainstem impoundments and altered river reaches.

Zootaxa↗
USGS2008

Conservation status of imperiled north American freshwater and diadromous fishes

This is the third compilation of imperiled (i.e., endangered, threatened, vulnerable) plus extinct freshwater and diadromous fishes of North America prepared by the American Fisheries Society's Endangered Species Committee. Since the last revision in 1989, imperilment of inland fishes has increased substantially. This list includes 700 extant taxa representing 133 genera and 36 families, a 92% increase over the 364 listed in 1989. The increase reflects the addition of distinct populations, previously non-imperiled fishes, and recently described or discovered taxa. Approximately 39% of described fish species of the continent are imperiled. There are 230 vulnerable, 190 threatened, and 280 endangered extant taxa, and 61 taxa presumed extinct or extirpated from nature. Of those that were imperiled in 1989, most (89%) are the same or worse in conservation status; only 6% have improved in status, and 5% were delisted for various reasons. Habitat degradation and nonindigenous species are the main threats to at-risk fishes, many of which are restricted to small ranges. Documenting the diversity and status of rare fishes is a critical step in identifying and implementing appropriate actions necessary for their protection and management.

Fisheries↗
USGS2007

Red shiner invasion and hybridization with blacktail shiner in the upper Coosa River, USA

Human disturbance increases the invasibility of lotic ecosystems and the likelihood of hybridization between invasive and native species. We investigated whether disturbance contributed to the invasion of red shiner (Cyprinella lutrensis) and their hybridization with native blacktail shiner (C. venusta stigmatura) in the Upper Coosa River System (UCRS). Historical records indicated that red shiners and hybrids rapidly dispersed in the UCRS via large, mainstem rivers since the mid to late 1990s. We measured the occurrence and abundance of parental species and hybrids near tributary-mainstem confluences and characterized populations at these incipient contact zones by examining variation across morphological traits and molecular markers. Red shiners represented only 1.2% of total catch in tributaries yet introgression was widespread with hybrids accounting for 34% of total catch. Occurrence of red shiners and hybrids was highly correlated with occurrence of blacktail shiners, indicating that streams with native populations are preferentially colonized early in the invasion and that hybridization is a key process in the establishment of red shiners and their genome in new habitats. Tributary invasion was driven by post-F1 hybrids with proportionately greater genomic contributions from blacktail shiner. Occurrence of red shiners and hybrids and the relative abundance of hybrids significantly increased with measures of human disturbance including turbidity, catchment agricultural land use, and low dissolved oxygen concentration. Red shiners are a significant threat to Southeast Cyprinella diversity, given that 41% of these species hybridize with red shiner, that five southeastern drainages are invaded, and that these drainages are increasingly disturbed by urbanization. ?? 2007 Springer Science+Business Media B.V.

Biological Invasions↗
USGS2007

Three new percid fishes (Percidae: Percina) from the Mobile Basin drainage of Alabama, Georgia, and Tennessee

Three new species of Percina are described from upland drainages of the Mobile Basin. Two of the three species are narrowly distributed: P. kusha , the Bridled Darter, is currently known only from the Conasauga River drainage in Georgia and Tennessee and Etowah River drainage in Georgia, both tributaries of the Coosa River, and P. sipsi , the Bankhead Darter, which is restricted to tributaries of Sipsey Fork of the Black Warrior River in northwestern Alabama. The third species, P. smithvanizi , the Muscadine Darter, occurs above the Fall Line in the Tallapoosa River drainage in eastern Alabama and western Georgia. In a molecular analysis using mitochondrial cytochrome b sequence data, P. kusha and P. smithvanizi were recovered as sister species, while Percina sipsi was recovered in a clade consisting of P. aurolineata ( P. sciera + P. sipsi ). Two of the three species, P. kusha and P. sipsi , are considered to be imperiled species and are in need of conservation actions to prevent their extinction. Description of these three darters increases the number of described species of Percina to 44. Sixteen are known to occur in the Mobile Basin, including nine that are endemic.

Alabama, Georgia, Tennessee↗
USGS2005

Status and conservation of the fish fauna of the Alabama River system

The Alabama River system, comprising the Alabama, Coosa, and Tallapoosa subsystems, forms the eastern portion of the Mobile River drainage. Physiographic diversity and geologic history have fostered development in the Alabama River system of globally significant levels of aquatic faunal diversity and endemism. At least 184 fishes are native to the system, including at least 33 endemic species. During the past century, dam construction for hydropower generation and navigation resulted in 16 reservoirs that inundate 44% of the length of the Alabama River system main stems. This extensive physical and hydrologic alteration has affected the fish fauna in three major ways. Diadromous and migratory species have declined precipitously. Fish assemblages persisting downstream from large main-stem dams have been simplified by loss of species unable to cope with altered flow and water quality regimes. Fish populations persisting in the headwaters and in tributaries to the mainstem reservoirs are now isolated and subjected to effects of physical and chemical habitat degradation. Ten fishes in the Alabama River system (including seven endemic species) are federally listed as threatened or endangered. Regional experts consider at least 28 additional species to be vulnerable, threatened, or endangered with extinction. Conserving the Alabama River system fish fauna will require innovative dam management, protection of streams from effects of urbanization and water supply development, and control of alien species dispersal. Failure to manage aggressively for integrity of remaining unimpounded portions of the Alabama River system will result in reduced quality of natural resources for future generations, continued assemblage simplification, and species extinction.

Book chapter↗
USGS2005

Status and conservation of the fish fauna of the Alabama River system

The Alabama River system, comprising the Alabama, Coosa, and Tallapoosa subsystems, forms the eastern portion of the Mobile River drainage. Physiographic diversity and geologic history have fostered development in the Alabama River system of globally significant levels of aquatic faunal diversity and endemism. At least 184 fishes are native to the system, including at least 33 endemic species. During the past century, dam construction for hydropower generation and navigation resulted in 16 reservoirs that inundate 44% of the length of the Alabama River system main stems. This extensive physical and hydrologic alteration has affected the fish fauna in three major ways. Diadromous and migratory species have declined precipitously. Fish assemblages persisting downstream from large main-stem dams have been simplified by loss of species unable to cope with altered flow and water quality regimes. Fish populations persisting in the headwaters and in tributaries to the mainstem reservoirs are now isolated and subjected to effects of physical and chemical habitat degradation. Ten fishes in the Alabama River system (including seven endemic species) are federally listed as threatened or endangered. Regional experts consider at least 28 additional species to be vulnerable, threatened, or endangered with extinction. Conserving the Alabama River system fish fauna will require innovative dam management, protection of streams from effects of urbanization and water supply development, and control of alien species dispersal. Failure to manage aggressively for integrity of remaining unimpounded portions of the Alabama River system will result in reduced quality of natural resources for future generations, continued assemblage simplification, and species extinctions. ?? 2005 by the American Fisheries Society.

American Fisheries Society Symposium↗
USGS2001

Effects of suspended sediment on the reproductive success of the tricolor shiner, a crevice-spawning minnow

Excessive sedimentation of rivers and creeks has been linked to increasing levels of imperilment in the diverse fish fauna of the southeastern United States. In particular, benthic-spawning fishes have decreased in both numbers and range. The tricolor shiner Cyprinella trichroistia is a crevice-spawning minnow that is widespread in the eastern Mobile River drainage above the Fall Line. While they are less sensitive to perturbation than the federally threatened blue shiner C. caerulea, tricolor shiners have decreased in numbers and range during the past few decades. This experiment examined the effects of 0 (control), 100, 300, and 600 mg/L initial concentrations of suspended sediment on the reproductive success of the tricolor shiner. Increasing levels of suspended sediment caused decreasing levels of reproductive success (fewer spawns and fewer eggs laid when spawning occurred). Increasing levels of suspended sediment also delayed the onset of spawning, resulting in distinct frequency distributions of clear eggs, eyed eggs, and larvae across treatments. Mortality of eggs and larvae was not a factor in the experiment. We examined daily sediment concentration data recorded at three sites in the upper Coosa River over the April-August spawning season of 1963. By weighting our experimental results by the number of days above each sediment concentration, we estimated that 20% fewer eggs were laid than would have been laid if conditions had been like those of the controls. Albeit our model is simplistic, it provides insight into how excessive sedimentation contributes to population extirpation. Mitigation of suspended sediments is an important management action for the conservation of southern Appalachian fishes that spawn in benthic habitats.

Transactions of the American Fisheries Society↗
USGS1993

First collection of rudd, Scardinius erythrophthalmus (Cyprinidae), in the New River, West Virginia

We collected the first rudd, Scardinius erythrophthalmus (Cyprinidae), from the New (Kanawha) River drainage, West Virginia. The rudd has now been reported from 12 states (Arkansas, Kansas, Illinois, Massachusetts, Maine, Missouri, New York, Oklahoma, Virginia, Wisconsin, and West Virginia) and several major river systems. The rapid spread of the rudd has apparently been facilitated by bait dealers. Despite its widespread distribution, there have been no investigations of potential interactions with native aquatic fauna.

Journal of Freshwater Ecology↗
USGS1991

An intergeneric hybrid of a native minnow, the golden shiner, and an exotic minnow, the rudd

The hybrid golden shiner Notemigonus crysoleucas × rudd Scardinius erythrophthalmus is the first known nonsalmonid, intergeneric hybrid of an exotic species and a North American native species. The cross is also the first valid record of a viable hybrid involving the native golden shiner. Meristic and mensural characters of 30 artificially produced hybrids of male golden shiners and female rudds were analyzed. Forty-seven percent of the meristic traits exhibited character states intermediate between those of parents. Twenty-seven percent of the meristic characters were supernumerary, suggesting developmental instability of the hybrid genome. Mensural hybrid characters were significantly skewed to the golden shiner phenotype. The skewed mensural inheritance and other skewed patterns of morphological inheritance also suggest problems in canalization of the hybrid phenome or atypical patterns of dominance. All hybrids were identifiable by intermediate squamation of the cultrate abdomen: the keel was mostly scaled but exhibited a small fleshy ridge posteriorly. This minnow hybrid allows general inferences to be made about the phylogenetic affinity of the golden shiner to other cultrate cyprinids of Eurasia. The hybrid cross has important management and conservation implications for fishes in North America. The hybrid is an example of how an exotic species may negatively affect a native species.

Transactions of the American Fisheries Society↗