Virginia Shervette

University of South Carolina Aiken | USCA · Biology/Geology

Coastal Ecuador has lost 20–30% of mangrove wetlands over the past 30 years. Such habitat loss can impair the ecological functions of wetlands. A paucity of information exists concerning mangrove fish communities of Ecuador. In this study we identify the fish community of the remaining mangrove wetland in Palmar, Ecuador. Fish were sampled in the d...

The Black Drum Pogonias cromis is an estuarine-dependent fish that supports recreational and commercial fisheries throughout its range along the U.S. Atlantic coast and Gulf of Mexico (GOM) coast. We used nuclear microsatellite markers and samples collected from multiple locations along both the U.S. Atlantic and GOM coasts to evaluate the stock st...

Mercury (Hg) concentrations and nitrogen (δ¹⁵N) and carbon (δ¹³C) stable isotopic ratios were measured to assess differences in Hg bioaccumulation in four predatory fish species (Mycteroperca microlepis, Lutjanus campechanus, Caulolatilus microps, and Serioli dumerili) of high commercial and recreational importance in Atlantic waters of the southea...

Our understanding of fish life‐history strategies is informed by key biological processes, such as growth, survival/mortality, recruitment and sexual maturation, used to characterize fish stocks (populations). Characterizing the life‐history traits of fish populations requires the application of accurate age estimation for managed species. Grey tri...

Reef fishes support important fisheries throughout the Caribbean, but a combination of factors in the tropics makes otolith microstructure difficult to interpret for age estimation. Therefore, validation of ageing methods, via application of Δ¹⁴C is a major research priority. Utilizing known-age otolith material from north Caribbean fishes, we dete...

Cardinal snapper Pristipomoides macrophthalmus is a commercially important, but commonly misidentified, deepwater species in artisanal and semi-industrial fisheries throughout the Caribbean Sea. As with many tropical deepwater fishes, little is known about the biology or ecology of the species. Bomb radiocarbon (¹⁴C) dating was applied to cardinal...

Queen parrotfish Scarus vetula and stoplight parrotfish Sparisoma viride are widely distributed throughout the subtropical/tropical regions of the northwestern Atlantic, play important ecological roles in reef ecosystems, and contribute to small-scale commercial landings within several Caribbean management jurisdictions. Prior to this work, no comp...

For management efforts to succeed in Caribbean fisheries, local fishers must support and be willing to comply with fishing regulations. This is more likely when fishers are included in a stock assessment process that utilizes robust scientific evidence, collected in collaboration with fishers, to evaluate the health of fish stocks. Caribbean parrot...

Queen triggerfish Balistes vetula is an important reef-associated species for commercial fisheries in the U.S. Caribbean. It exhibits a relatively unique reproductive strategy as a nesting benthic spawner, investing substantial energy in territorial defense, building and maintaining nests, and caring for fertilized eggs during the reproductive seas...

Reef fishes have been utilized as food fish throughout the U.S. Caribbean and Gulf of Mexico waters for centuries, with increasing fishing effort in recent decades. As a result, many species have experienced declines in landings, including deepwater snappers such as queen snapper Etelis oculatus and blackfin snapper Lutjanus buccanella. However, li...

We investigated the relationship between aspartic acid d:l ratios and otolith-derived age estimates in Gulf of Mexico red snapper, Lutjanus campechanus (ages 1–26 years; R² = 0.89) and Caribbean yellowtail snapper, Ocyurus chrysurus (ages 2–17 years; R² = 0.84). The estimated racemization rate was 0.61 × 10⁻³ year⁻¹ for red snapper and 1.28 × 10⁻³...

***New version*** A photographic guide to extracting, handling, and reading otoliths from Balistes triggerfish species with max-age reported for Balistes vetula and Balistes capriscus

Ensuring the accuracy of age estimation in fisheries science through validation is an essential step in managing species for long-term sustainable harvest. The current study used Δ¹⁴ C in direct validation of age estimation for queen triggerfish Balistes vetula and conclusively documented that triggerfish sagittal otoliths provide more accurate and...

In fish consumption advisories pertaining to Hg, grouper species in the family Serranidae are often lumped together and labeled generically as Grouper. However, grouper species vary considerably in growth rate, maximum age, and maximum size. This study examined the variability of Hg concentrations and bioaccumulation rates (increase of Hg concentra...

Princess parrotfish Scarus taeniopterus is one of the top three parrotfish species landed in the Caribbean, and the top Scarus species targeted in commercial fishing efforts; however, a paucity of information exists concerning basic life history information for Caribbean parrotfish species. Prior to this work, no comprehensive life history informat...

Anthropogenic factors that negatively impact reef fishes can include changes in life‐history patterns of fisheries‐targeted species. Understanding these impacts on growth and population age structure is essential in the management of exploited populations of fishes. This is the first study to directly compare age and growth for a major fisheries sp...

The green porcelain crab Petrolisthes armatus is an abundant invader on intertidal oyster reefs along the southeastern coast of the United States. Its range expansion appears to be thermally limited and is predicted to shift poleward as water temperatures rise. Little is known about how P. armatus' seasonal residency patterns affect its reproductiv...

Vertebral number is adaptively important in fishes and is associated with body shape at broad taxonomic ranks. Less is known about this association within species. Rhoadsia is a deep-bodied characid genus endemic to western Ecuador and northwestern Peru. It includes two species differing in body depth (BD), described from different drainages and el...

Effective fisheries management requires a detailed understanding of the life history strategies of managed species. The Queen Triggerfish Balistes vetula supports productive fisheries in the western Atlantic, including the U.S. Caribbean. We utilized a combination of fishery-dependent and fishery-independent samples to assess the size structure, se...

Increasing ocean temperatures have led to poleward range expansions of many marine organisms. The green porcelain crab, Petrolisthes armatus, was first reported on intertidal oyster reefs near Charleston, South Carolina in the mid-1990s, an expansion from its tropical to sub-tropical native range. In order to investigate the relative abundances of...

Claw-only crab fisheries are often marketed as renewable because crabs are returned to the water after declawing to regenerate claws and re-enter the fishery. The challenge of managing a claw-only fishery for stone crabs (Menippe spp.) is compounded by varying regulations throughout their range that include the number of claws harvested from a crab...

Human population growth in coastal areas continues to threaten estuarine ecosystems and resources. Populations of Crassostrea virginica have declined across the USA due to water quality degradation, disease pressure, alteration of habitat, and other changes related to anthropogenic impacts. Metals that may be present in estuarine habitats can bioac...

Neotropical mountain streams are important contributors of biological diversity. Two species of the characid genus Rhoadsia differing for an ecologically important morphological trait, body depth, have been described from mountain streams of the western slopes of the Andes in Ecuador. Rhoadsia altipinna is a deeper-bodied species reported from low...

Water temperature at sampling sites measured during specimen collection. Temperature data for the Esmeraldas and Jubones sites were measured in July 2014 and for the Santa Rosa River in July 2013. (TIF)

Haplotype frequency of COI mtDNA gene for Rhoadsia samples. N is the number of specimens per sample. (DOC)

S7 intron allele frequencies for Rhoadsia samples. (DOC)

Catalog numbers for voucher specimens deposited in museums listed by drainage and site specimen number listed in parenthesis for sites with more than one lot examined. CAS: California Academy of Sciences, FMNH: Field Museum of Natural History, MECN: Museo Ecuatoriano de Ciencias Naturales (Ecuador), MUGT: Museo de Ciencias Naturales de la Universid...

Landmarks and linear measures used in the study. Insect pins were used to mark some of the landmarks that were difficult to see from a lateral perspective. SL is standard length and BD is body depth. The specimen in the photo is a male from the Santa Rosa River collected at the 31 m site. Scale bar is 10mm. (TIF)

Standard length variation among samples. E = Esmeraldas River, J = Jubones River, SR = Santa Rosa River, and GO = Guayas and other small neighboring drainages. (TIF)

Water quality data for the sampling sites in the Esmeraldas, Jubones, and Santa Rosa river drainages. (DOC)

Elevational gradients for the sampling sites in the Esmeraldas, Jubones and Santa Rosa rivers. Distances from ocean are approximate and were measured along river courses in Google Maps. (TIF)

Pairwise FST values between samples. COI gene below diagonal, S7i2 gene above diagonal. Significant FST values in bold with asterisks indicating the level of significance. (DOC)

The Gray Triggerfish Balistes capriscus supports fisheries on both sides of the Atlantic Ocean. We utilized fishery-independent samples to assess the age structure, growth, sex ratio, size and age at maturity, spawning season, and spawning frequency of the Gray Triggerfish population off the southeastern U.S. Atlantic coast. From1991 to 2012, 7,685...

Flooding can increase methylmercury production for uptake by predatory fish (Louis et al., 2005). As major weather events, such as storms and heavy rainfall, become more frequent and more intense in the future as a result of global climate change (Horton et al., 2015), understanding the impacts these events may have on Hg uptake in fishes is essent...

The Edisto River is the longest undammed blackwater river system in North America, flowing through 12 counties in South Carolina. Fishing is a common pastime, with many people consuming the fish they catch. Understanding Hg bioaccumulation in the commonly consumed fishes of the Edisto will provide insight into potential human health concerns. In ad...

Within a riverscape, fluvial dynamics cause shifting habitat mosaics at the spatial scale of the floodplain. Waterbodies are created by fluvial processes through lateral and vertical erosion and subsequent channel migration/abandonment. These waterbodies include side-arms, streams/creeks, cut-off channels, oxbow lakes, floodplain ponds, and marshes...

The genus Rhoadsia is endemic to western Ecuador and northern Peru and includes two described species that differ in body form, size, and the elevations at which they occur. Unfortunately, there is uncertainty about the number of species that should be recognized in the genus and the causes of the morphological variation documented within and betwe...

Measurements of age, growth, and reproduction are excellent tools for determining the ecological role and impact of a species within an ecosystem. Longnose Gar Lepisosteus osseus is a large, ubiquitous top predator in fresh and saline waters of the eastern United States. Even though the species is common, their basic biology has been largely unchar...

Mercury is found in fish species world-wide and since a large portion of the world depends on fish for protein, the concentrations and bioaccumulation rates of mercury in commonly consumed fishes is an important area of study. Reliable, up-to-date information on health concerns should be considered when choosing fish species and quantities to consu...

Longnose gar Lepisosteus osseus were collected from May 2012 to July 2013 in the Charleston Harbor and Winyah Bay estuaries (SC, U.S.A.). This study examined trends in stomach fullness, described major prey components and their importance in the diet of L. osseus, compared stomach content-based trophic level estimates with the stable-isotope-based...

Mercury (Hg) is found in fish species world-wide and since a large portion of the world depends on fish for protein, the concentrations and bioaccumulation of Hg in commonly consumed fishes is an important area of study The need to better understand Hg in the environment exists due to the vast amount of interspecific, intraspecific, temporal and sp...

Sixteen polymorphic, dinucleotide microsatellite loci were developed for Rhoadsia altipinna, a small characid fish from impacted rivers in south western Ecuador. None of the loci were in linkage disequilibrium or deviated significantly from Hardy–Weinberg equilibrium after sequential Bonferroni correction. Variability was relatively high with allel...

Though mercury (Hg) occurs naturally, anthropogenic emissions have increased atmospheric Hg levels by an estimated factor of three since the Industrial Revolution This has caused corresponding increases in Hg levels in terrestrial and aquatic ecosystems Wetlands contribute to the transformation of elemental mercury into its most toxic form, methylm...

Little to no peer-reviewed published research exists on basic life history parameters of queen triggerfish that occur in US Caribbean or other waters of the US. The 2013 SEDAR Stock Assessment for Queen Triggerfish indicated that the lack of current species-specific life history information greatly hindered the assessment and given the data limitat...

Fishes are an integral part of diets around the world, with approximately one billion people relying on fishes for their main source of protein. Eating fish provides an array of nutritional benefits; however the emerging concern of mercury exposure from the consumption of fish has led to much controversy concerning risks versus benefits. For this r...

Gray triggerfish has become a popular foodfish in many local fish markets throughout the southeastern United States. South Carolina commercial fishers and federal fisheries managers alike have expressed interest in sustainable harvesting of this species to ensure a productive and long-term future. Towards this end and in collaboration with commerci...

Understanding the impacts of contaminants such as mercury on fish species is an important step in the ultimate goal of conservation biology. Additionally, quantifying the temporal trends of contaminant concentrations within a potential source of exposure to humans will aid in future public health campaigns. Fish provide a nutritious source of prote...

The Black Drum Pogonias cromis is an estuarine‐dependent fish that supports recreational and commercial fisheries throughout its range along the U.S. Atlantic coast and Gulf of Mexico (GOM) coast. We used nuclear microsatellite markers and samples collected from multiple locations along both the U.S. Atlantic and GOM coasts to evaluate the stock st...

Though mercury (Hg) occurs naturally, anthropogenic emissions have increased atmospheric Hg levels by an estimated factor of three since the Industrial Revolution. This increase has caused corresponding increases in Hg levels in terrestrial and aquatic ecosystems. Wetlands contain anaerobic sulfur-reducing bacteria which contribute to transformatio...

Gray triggerfish Balistes capriscus is a commercially and recreationally valued reef fish species. Over the past five years, average annual landings approached 700,000 lbs in U.S. Atlantic waters. Gray triggerfish are managed by the South Atlantic Fisheries Management Council as part of the snapper-grouper complex fishery. Many of the other species...

Black drum is an estuarine dependent saltwater fish that supports important recreational and commercial fisheries throughout its range along US Atlantic and Gulf of Mexico coasts. A previous study examining genetic population structure of black drum, using mitochondrial DNA and limited samples from the Atlantic, reported distinct Gulf of Mexico and...

Little is known about the freshwater fishes of western Ecuador despite serious environmental threats including the creation of large artificial impoundments. Phenotypic and genetic divergence of populations of a large predatory fish, Hoplias microlepis, is examined in rivers and artificial impoundments of the Guayas River drainage in western Ecuado...

Few studies have compared oyster habitat use with adjacent vegetated and non-vegetated habitats. We investigated habitat use by six common, estuarine, invertebrate species. In order to better understand the species-specific use of oyster and adjacent habitats within the salt marshes of Grand Bay NERR, MS, we examined the abundance patterns and size...

A replicated pattern of habitat-associated morphology among different lineages may represent adaptive convergence. Deviation from the replicated (shared) pattern of diversification reflects unique (e.g. species specific) effects resulting from site- or species-specific selection, intrinsic factors (e.g. G matrix differences) or chance historical ev...

Government agencies, non-governmental organizations, commercial enterprises, and academic research programs have established a vast array of environmental databases for programmatic and research purposes. Most of these use different data management infrastructures that prevent repurposing or integrating information to serve other uses. Creating cap...

My research in coastal Ecuador and the northern Gulf of Mexico (GOM) elucidated differences in value of shallow estuarine habitats for fishes and invertebrates. I focused on mangrove and tidal river habitats in Ecuador, and oyster reef, vegetated marsh edge, and nonvegetated bottom habitats in the GOM. Coastal Ecuador has lost 20-30% of mangrove we...

Shallow estuarine habitats, including vegetated marsh edge (VME), oyster reefs (oyster), and nonvegetated soft bottom (NVB), provide important functions for estuarine resident and estuarine-dependent species. A paucity of information exists concerning relative nursery value of these habitats for juvenile fishes and invertebrates. In Grand Bay, MS a...

In Grand Bay National Estuarine Research Reserve (Grand Bay NERR), Mississippi, we used quantitative drop sampling in three common shallow estuarine habitats—low profile oyster reef (oyster), vegetated marsh edge (VME), and nonvegetated bottom (NVB)—to address the dearth in research comparing nekton utilization of oyster relative to adjacent habita...

Understanding how certain fish species utilize estuarine habitats is critical for future conservation and management efforts. Habitats with various types of structure, including seagrass, marsh, oyster reef, and nonvegetated bottom, provide transient juvenile fishes with food and refuge from predation. Relative growth rates and survival of species...

Natural and created Spartina brackish marsh habitats in the Guadalupe Estuary, adjacent to the Aransas National Wildlife Refuge, Texas, USA were surveyed during spring, summer, and fall 2004 to evaluate the equivalence of nekton assemblages in an old (>30 years) created marsh. During each season, six replicate samples were collected in each marsh t...

We investigated the effect of salinity on growth, survival, and condition of pinfish Lagodon rhomboides juveniles (36–80mm standard length) in two laboratory experiments in July 2003 and June/July 2004. Our results show that juvenile pinfish grown in laboratory conditions under a range of salinities experience rapid growth and high survival in typi...

Se recolectaron trece ejemplares juveniles de Sphoeroides rosenblatti Bussing, 1996 en un bosque pequeño y fuertemente impactado de mangle situado en Palmar, provincia de Guayas, Ecuador. Esta especie era conocida previamente solo de aguas costeras de Costa Rica y Panamá. Se contrastó la ocurrencia y morfología de S. rosenblatti con ejemplares de S...

In summary, we report the occurrence of a new species of pufferfish, S. rosenblatti, for the continental coast of Ecuador, which appears closely related to, and occurs, sympatrically with, the common pufferfish species S. annulatus in mangrove forests. The two species differ morphologically (although the differences are subtle among juvenile fish),...

We assess morphological diversity of species of the Cynoscion group in the Gulf of Guayaquil (GOG) using traditional morphometric methods. Five species from the GOG assemblage (C. albus, C. analis, C. phoxocephalus, C. squamipinnis, and Isopisthus remifer) are compared to four species from a relatively well-studied assemblage in the western Atlanti...

A greater understanding of population dynamics is essential in the management of any species. The Western Gulf stone crab, Menippe adina, is taken as incidental by-catch in the blue crab, Callinectes sapidus, fishery in Mississippi. However, there is a lack of information on the ecology of M. adina in estuaries of the northern Gulf of Mexico. We kn...

Shrimp viruses can remain infectious in frozen shrimp tissue and have been found in frozen commodity shrimp. Therefore, the threat of viral outbreaks in wild and cultured shrimp via frozen commodity shrimp exists. Because frozen shrimp are imported with and without the cephalothorax, more knowledge is needed concerning the infectivity of a cephalot...

Typescript. Thesis (M.S.)--University of Southern Mississippi, 2000. Includes abstract. Includes bibliographical references (leaves 28-31).