James D Williams

Florida Museum of Natural History · Ichthyology and Malacology

Characterizing the mechanisms influencing the distribution of genetic variation in aquatic species can be difficult due to the dynamic nature of hydrological landscapes. In North America‘s Central Highlands, a complex history of glacial dynamics, long-term isolation, and secondary contact have shaped genetic variation in aquatic species. Although t...

Accurate taxonomic and distributional information are arguably the most critical components of conservation status assessments but can be greatly affected by misidentifications. The Louisiana pigtoe Pleurobema riddellii is a freshwater mussel proposed as threatened under the US Endangered Species Act. The species belongs to the tribe Pleurobemini,...

The Coosa Elktoe, Alasmidonta mccordi Athearn, 1964, was previously known only from the type specimen collected in the Coosa River, St. Clair County, Alabama. Based on the discovery of five previously misidentified specimens in three museum lots, we extend the distribution of A. mccordi into the Etowah and Conasauga Rivers, tributaries of the Coosa...

Aim Freshwater mussels share habitat and are parasites of freshwater fishes during the larval life stage. Therefore, models of fish biogeography may also explain the historical biogeography of freshwater mussels. We tested this assumption using predictions of three biogeographic models constructed for northern Gulf of Mexico drainages on a freshwat...

The bivalve Corbicula is one of the most successful aquatic mollusk invaders in the world. Since being introduced to North America from its native range in Asia, it has dispersed widely over a large portion of the continent from southern Canada to Panama. The first evidence of its introduction in the Western Hemisphere was discovered in 1924 in Bri...

Supplementary map for 'Status of Freshwater Mussels in the Ochlockonee River Basin of Georgia and Florida' depicting Toxolasma parvum (introduced) collections.

Abstract – Recent and comprehensive surveys of Ochlockonee River basin mussel fauna are lacking, particularly in the lower portion of the basin which historically has been undersampled. We present the results of surveys conducted between 2006 and 2017 to assess the status of freshwater mussels in the Ochlockonee River basin, and examine historical...

Abstract Objectively delimiting species boundaries remains an important challenge in systematics and becomes urgent when unresolved taxonomy complicates conservation and recovery efforts. We examined species boundaries in the imperiled freshwater mussel genus Cyclonaias (Bivalvia: Unionidae) using morphometrics, molecular phylogenetics, and multisp...

An important physiological constraint influencing distributions of coastal freshwater organisms is their tolerance for saline conditions. We experimentally evaluated salinity tolerance for three freshwater mussel species (Utterbackia imbecillis, Elliptio jayensis, and Glebula rotundata). Mussels were transferred abruptly from well water to one of f...

We present a revised list of freshwater mussels (order Unionida, families Margaritiferidae and Unionidae) of the United States and Canada, incorporating changes in nomenclature and systematic taxonomy since publication of the most recent checklist in 1998. We recognize a total of 298 species in 55 genera in the families Margaritiferidae (one genus,...

Accurate distribution data are critical to the development of conservation and management strategies for imperiled species, particularly for narrow endemics with life history traits that make them vulnerable to extinction. Medionidus walkeri is a rare freshwater mussel endemic to the Suwannee River Basin in southeastern North America. This species...

The Central Texas endemic freshwater mussel, Quadrula mitchelli (Simpson in Dall, 1896), had been presumed extinct until relict populations were recently rediscovered. To help guide ongoing and future conservation efforts focused on Q. mitchelli we set out to resolve several uncertainties regarding its evolutionary history, specifically its unknown...

An unknown population of Medionidus simpsonianus (Ochlockonee Moccasinshell) was discovered in the lower Ochlockonee River downstream of Jackson Bluff Dam in 2014. This discovery confirms that the species is extant, extends its known range by nearly 100 rkm, and represents only the second known collection of this species in the lower Ochlockonee Ri...

Freshwater Mussels of Florida by James D. Williams, Robert S. Butler, Gary L. Warren, and Nathan A. Johnson. University of Alabama Press, Tuscaloosa, Alabama. 2014. 498 pages. NOTE - This book is available from the University of Alabama Press Freshwater Mussels of Florida is a guide to all species of freshwater mussels in the state. The book cove...

The North America freshwater mussel fauna has suffered an inordinately high recent extinction rate, and the small size and isolation of many remaining populations portends a continued diminishment of this fauna. Causes of extinction and imperilment are varied but revolve around massive habitat loss, deterioration, and fragmentation. The National St...

Freshwater habitats of the southeastern U.S. support a high diversity of mussels in the families Margaritiferidae and Unionidae, order Unionoida. River systems of Florida and drainages contiguous with Alabama and Georgia are known to be inhabited by 65 mussel species, representing about 20% of the North American fauna north of Mexico. This diversit...

Reestablishment of locally extinct populations and augmentation of declining populations are management activities used with increasing frequency in the conservation of imperiled fishes in the United States. Unfortunately, these options were not always carefully or appropriately used in past cases, partly owing to a lack of guidelines that address...

A new species of unionid mussel, Anodonta hartfieldorum, is described from Coastal Plain streams of the eastern Gulf of Mexico drainages. It occurs in the Pearl River in Louisiana and Mississippi, Pascagoula River in Mississippi, Tombigbee River in Mississippi and possibly Alabama, Tensaw River in Alabama and the Escambia River drainage in Alabama...

article info Article history: Received 4 January 2008 Accepted 2 November 2008 Communicated by J. Ellen Marsden Index words: Control region Great Lakes Mitochondrial DNA Perca flavescens Population genetics Yellow perch Great Lakes populations of yellow perch have fluctuated throughout past decades to the present due to unstable recruitment pattern...

Accurate knowledge of an organism's distribution is necessary for conserving species with small or isolated populations. A perceived rarity may only reflect inadequate sampling effort and suggest the need for more research. We used a recently developed method to evaluate the distribution of a rare fish species, the blackmouth shiner Notropis melano...

Freshwater mollusks are highly imperiled, with 70% of the North American species extinct, endangered, or at risk of extinction. Impoundments and other human impacts on the Coosa River of Alabama, Georgia and Tennessee of the southeastern USA alone are believed to have caused 50 mollusk species extinctions, but uncertainty over boundaries among seve...

Two new species of freshwater sculpins are herein described from the Gulf Slope of the southeastern United States. The Tallapoosa Sculpin, Cottus tallapoosae, is restricted to the Tallapoosa River drainage, a tributary to the Mobile Basin, above the Fall Line in Alabama and Georgia, while the Chattahoochee Sculpin, Cottus chattahoochee, is restrict...

Three new species of Percina are described from upland drainages of the Mobile Basin. Two of the three species are nar- rowly 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 Bank...

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 Bankhea...

This study qualitatively surveyed freshwater mussel assemblages at 24 sites in the Choctawhatchee, Yellow, and Conecuh-Escambia river drainages of southeastern Alabama and northwest Florida in 2004. A specific focus of the study was to determine the current status of seven narrowly endemic candidate species: Margaritifera marrianae, Fusconaia escam...

The Mobile Basin historically supported one of the most diverse freshwater mussel (Bivalvia: Unionidae) assemblages in North America. More than 65 species of mussels are known from the Basin, but it is difficult to determine how many species were present historically. The drainage's unique physical habitat was largely destroyed between the late 180...

The non-marine mollusks of the late Pleistocene-Holocene boundary are virtually unstudied in Florida. Previous surveys of the fossil mollusk faunas of Florida have emphasized marine taxa of the middle to late Tertiary. Clearly, this is an artifact of the numerous marine exposures throughout much of the state, as well as the research interests of ea...

Carps of the family Cyprinidae, the largest family of freshwater fishes in the world (Nelson 1994), have long been introduced beyond their native ranges, a practice that continues today. Although carps have been introduced for several centuries, the widespread introduction of the genus Hypophthalmichthys, the bigheaded carps, is a relatively recent...

The current volume represents a reorganized and updated version of two earlier unpublished reports on black carp addressing the biology of the species as well as risks associated with its introduction. The first was completed in 1996 (see Nico and Williams 1996). In 2000, we were asked by the RAM Committee to re-examine our original risk assessment...