About

Gregory Lewbart is a faculty member associated with the College of Veterinary Medicine at NC State University. The page text does not provide specific details about his research focus, background, or key contributions. Therefore, no detailed biography can be extracted from the provided content.

Research topics

• Biology
• Fishery
• Anesthesia
• Medicine
• Chemistry
• Geography
• Anatomy
• Ecology
• Animal science

Selected publications

• Wild Freshwater Turtles as Bioindicators of Antimicrobial Resistance: An Exploratory Cross-sectional Study in Wake County, North Carolina

  Journal of Herpetological Medicine and Surgery · 2026-03-18

  article

  Abstract Wildlife can harbor and facilitate the spread of antimicrobial resistance (AMR) genes and antimicrobial resistant bacteria, including bacteria of public health concern (e.g., carbapenem-resistant Enterobacterales). However, the occurrence of and factors influencing AMR in wildlife are not well-understood. With their relatively long life spans and limited migration from human-impacted habitats, wild freshwater turtles could serve as bioindicators, or sentinels, of environmental AMR. During May-June 2024, we collected cloacal swabs and morphologic data from wild freshwater turtles across eight wetland locations in Wake County, North Carolina, USA, to explore their potential use as bioindicators of local environmental AMR. Among the 100 turtles (46 females, 44 males, 10 juveniles) humanely captured and released, six freshwater turtle species were represented, including 39 painted turtles ( Chrysemys picta ) and 24 yellow-bellied sliders ( Trachemys scripta scripta ). The median number of turtles captured per site was 11 (interquartile range: 7–18). Each cloacal sample was plated on MacConkey agar. Three morphologically distinct lactose-fermenting colonies per turtle were replated for purity. Among the 260 isolates identified to - and unique per turtle at - the genus-level, 14 genera were represented, mainly Citrobacter (n = 73; 28%), Enterobacter (n = 61; 23%), and Klebsiella (n = 36; 14%). A subset of 102 Enterobacterales isolates, namely Enterobacter , Escherichia , and Klebsiella spp., underwent antimicrobial susceptibility testing using microbroth dilution; of these, four Enterobacter spp. isolates demonstrated phenotypic resistance. Specifically, three Enterobacter spp. isolates, obtained from unique turtles captured at a single wetland location, exhibited resistance to an aminoglycoside and two folate pathway inhibitors; one resistant Enterobacter spp. isolate, obtained from a different wetland location, was multidrug resistant. Routine surveillance of freshwater turtles could further inform their potential use as bioindicators of environmental AMR and provide insight into environmental dynamics of AMR spread in aquatic and surrounding ecosystems.

  PublisherDOI

• First morphological description of the Galápagos pink iguana ( <i>Conolophus marthae</i> ) hatchling: a critical step for its conservation

  PeerJ · 2026-01-27

  articleOpen access

  The Galapagos pink iguana ( Conolophus marthae ) is endemic to Wolf Volcano on Isabela Island in the Galapagos archipelago. Due to its remote and hard-to-access habitat, the recently discovered and critically small wild population of the pink iguana has been extremely challenging to study. Herein we provide a first description of the morphology and behavior of six C. marthae hatchlings, and compare them with 12 hatchlings of the sympatric C. subcristatus . Morphometric measurements (snout–vent length = 10.9 ± 1.63 (SD) cm, tail length = 17.9 ± 3.05 cm, and weight = 47.8 ± 25.4 g) revealed a longer tail relative to its body size (ratio = 1.65 ± 0.23) compared to the sympatric Galápagos land iguana ( C. subcristatus ) hatchling of similar size (ratio = 1.42 ± 0.11). C. marthae hatchlings also displayed distinctive coloration with a bright green dorsal background with irregular black maculations and a pale, nearly unpigmented ventral surface. A comparative photograph of a subadult C. marthae revealed a directional, ontogenetic color shift: green dorsal areas became black while black maculations gave rise to pink patches, possibly a retained ancestral trait with implications for camouflage or signaling. These findings fill a knowledge gap in the early ecology of Galápagos pink iguana, providing information useful for monitoring recruitment in this Critically Endangered species.

  PublisherDOI

• Microplastic exposure and biological correlates in a key intertidal crab (Grapsus grapsus) from the Galápagos Islands

  Marine Pollution Bulletin · 2026-04-06

  article
  PublisherDOI

• Retrospective Analysis of Hatchling Success From Chelonian Eggs at a North Carolina Wildlife Clinic 2010 to 2023

  Zoo Biology · 2026-04-15

  articleOpen accessSenior authorCorresponding

  The success rate of deposited and harvested chelonian hatchlings between 2010 and 2023 were retrospectively reviewed by the North Carolina State University College of Veterinary Medicine Turtle Rescue Team. These data were analyzed to determine factors that may influence hatchling success including species, month of incubation, mother's status upon arrival, and the mother's presenting complaint. This study includes all wild chelonian species found in North Carolina that have presented as adult, gravid females over a 13-year period. These species include common snapping turtles (Chelydra serpentina), painted turtles (Chrysemys spp.), yellow-bellied sliders (Trachemys scripta scripta), cooters (Pseudemys spp.), eastern box turtles (Terrapene carolina carolina), eastern mud turtles (Kinosternon subrubrum), common musk turtles (Sternotherus odoratus), and red-eared sliders (Trachemys scripta elegans). Overall, there were a total of 2453 chelonian eggs and of those, 954 (38.9%) hatched. The greatest egg count numbers were recorded from common snapping turtles (703/2453, 28.7%), eggs collected in May (1300/2453, 53.0%), eggs that were collected from patients euthanized on arrival (1084/2453, 44.2%), and eggs that came from mothers presenting for vehicular trauma (1891/2453, 77.1%). Trauma did not significantly impact overall hatch rates, except for snapping turtles with vehicle-related injuries (p = 2.53e-08). Eastern Box Turtles had significantly lower hatch ratios (p = 0.000157), while aquatic turtles, such as musk and yellow-bellied sliders, fared better under current incubation protocols (p = 0.079 and p = 0.062, respectively). Results of this study represent opportunities to improve hatchling success and rearing under human care by understanding the major factors that contribute to their success.

  PublisherDOI

• Differences in PFAS exposure between Pacific pinnipeds: The Galapagos (Zalophus wollebaeki) and California (Zalophus californianus) sea lions

  Marine Pollution Bulletin · 2026-04-02

  articleOpen access

  Per- and polyfluoroalkyl substances (PFAS) are a class of man-made persistent chemicals that have been detected in both terrestrial and aquatic environments and thus impact humans, household pets, agricultural species, and wildlife. PFAS exposure is linked to a variety of adverse health consequences, including cancer and immune disruption. This study investigates differences in PFAS exposure between California (CSL, n = 69) and Galapagos (GSL, n = 65) sea lion pups and juveniles across various sampling locations within each species' habitat range. Whereas the GSL were all considered healthy, 17 of the 69 CSL were classified as malnourished. Comparing the two species, significantly higher serum concentrations of summed PFAS, perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) were detected in CSL than in GSL. This elevated PFAS exposure in CSL is likely related to historic pollution in their environment and close proximity to the urbanized coastline of Southern California. Within species, malnourished CSL had significantly higher PFNA than healthy CSL pups. GSL pups also tended to have higher PFAS levels than GSL juveniles. Within the Galapagos archipelago, PFAS exposure differed between rookeries, with PFOS exceeding its method reporting limit (0.5 ng/mL) in every sample, including GSL from islands uninhabited by humans. Summed PFAS, PFNA, PFDA, and perfluoroundecanoic acid (PFUnA) were all significantly higher in sea lions sampled on uninhabited than inhabited islands in the Galapagos archipelago. This study is the first comprehensive report of PFAS in CSL and the first archipelago-wide assessment of PFAS in GSL.

  PublisherDOI

• INVESTIGATION OF ANESTHESIA TECHNIQUES IN PAPER KITE BUTTERFLIES (IDEA LEUCONOE)

  Journal of Zoo and Wildlife Medicine · 2026-04-03

  article

  Despite the frequency of invertebrates in research, zoological, and personal collections, sedation and anesthesia in these species remains poorly studied. This study assessed anesthetic techniques in paper kite butterflies (Idea leuconoe). Thirty-six recently emerged butterflies were individually placed in 1.9 L air-tight containers and randomly exposed to one of six treatments (n = 6/group): 5% isoflurane via vaporizer (2 L min–1, fraction of inspired oxygen (FiO2) 1.0); (V), 0.5 mL (CB0.5) or 3.0 mL (CB3) liquid isoflurane on a cotton ball (FiO2 0.21); 100% carbon dioxide via flowmeter (2 L min–1) (CO2); cooling at 2.78°C, or no treatment (control) (CT). Three min (V, CB0.5, CB3, CO2) or 10 min (°C) following recumbency, butterflies were removed from exposure, manually manipulated, and monitored for return to upright posture. Times to recumbency, return to upright, and response to manipulation were recorded. Collected data were compared between groups (significance P < 0.05). Except in CT, all butterflies achieved recumbency. Median (range) time to recumbency was 1.3 (0.5–3.6), 2.8 (1.6–4.6), 1.7 (0.9–2.9), 1.2 (0.8–2.2), and 1.4 (1.0–3.5) min in V, CB0.5, CB3, CO2, and °C, respectively (P = 0.106). Median (range) time to upright was 9.3 (0.7–15.2), 13.8 (6.0–24.0), 14.9 (8.2–26.6), 1.3 (0.9–9.0), and 9.6 (3.6–30.0) min in V, CB0.5, CB3, CO2, and °C, respectively (P = 0.019). All butterflies recovered uneventfully. This is the first peer-reviewed evaluation of anesthetic techniques in butterflies.

  PublisherDOI

• Pathogen screening in adult frozen feeder mice commonly reveals zoonotic rodent-adapted Cryptosporidium spp.

  Journal of Exotic Pet Medicine · 2026-02-27

  article
  PublisherDOI

• PRELIMINARY HEMATOLOGY AND BIOCHEMISTRY REFERENCE INTERVALS IN JUVENILE BLACKTIP SHARKS (CARCHARHINUS LIMBATUS) IN THE GALÁPAGOS MARINE RESERVE

  Journal of Zoo and Wildlife Medicine · 2025-10-01 · 1 citations

  articleCorresponding

  Species-specific hematology and biochemistry reference intervals (RIs) provide a crucial diagnostic resource for veterinarians, researchers, and wildlife managers working with elasmobranchs. This study aimed to establish hematologic and biochemical RIs from a population of free-ranging, juvenile blacktip sharks (Carcharhinus limbatus) in the Galápagos Marine Reserve in Ecuador. Heparinized blood samples were collected from the ventral coccygeal vein in 36 juvenile blacktip sharks captured via beach seine and physically restrained. Manual CBCs were performed, and heparinized plasma was submitted to a reference laboratory for biochemistry analysis. Per American Society for Veterinary Clinical Pathology guidelines, preliminary hematology and biochemistry RIs were determined minus white blood cell differentials due to artifact following blood smear storage and transport. Juvenile blacktip sharks in the Galápagos Marine Reserve had similar PCV (median: 28%, RI: 18.6–35%) but higher WBC concentrations (median: 29.9 × 103/µL, RI: 9.5–52.4 × 103/µL) than wild adult sandbar sharks (Carcharhinus plumbeus). Furthermore, juvenile blacktip sharks had lower plasma concentrations of aspartate aminotransferase (AST, median: 6 U/L, RI: 4–13 U/L), creatine kinase (CK, median: 16 U/L, RI: 6–90 U/L), and glucose (median: 58 mg/dL, RI: 39–78 mg/dL) than wild Atlantic sharpnose (Rhizoprionodon terraenovae) and bonnethead sharks (Sphyrna tiburo) may have been due to different capture methods. Hematology and biochemistry reference intervals will aid blacktip sharks under managed care and support future comparative and longitudinal research of blacktip shark populations within the Galápagos Marine Reserve.

  PublisherDOI

• Marine iguanas have lower metabolic rates during El Niño

  Journal of Experimental Biology · 2025-08-21 · 2 citations

  articleOpen access

  The Galápagos marine iguana (Amblyrhynchus cristatus), the world's only marine lizard, feeds predominantly on algae. Owing to warming waters and reduced upwelling, algal abundance is reduced during El Niño events, causing high iguana mortality. During such periods, adult iguanas may shrink in size, a compelling phenomenon that has been suggested as an adaptation to reduce energetic needs. However, shifts in energy consumption have never been tested directly. We measured the body condition and metabolic rates of marine iguanas during an El Niño year and the subsequent neutral year. During El Niño, body mass relative to length was 17% lower, girth relative to length was 12% lower, and resting metabolic rates were 20% lower. This supports the hypothesis that marine iguanas partly offset the adverse effect of El Niño by an active response aimed at reducing their energy consumption, complementary to the energy-saving effect of body size reduction. Future ocean warming could force this endemic species to resort to such strategies increasingly often, and will likely exacerbate the already-high mortality rates caused by these events.

  PublisherOA PDFDOI

• Locating Nesting Sites for Critically Endangered Galápagos Pink Land Iguanas (Conolophus marthae)

  UNC Libraries · 2025-07-25

  articleOpen access

  Invasive alien species control is recognized worldwide as a priority action to preserve global biodiversity. However, a lack of general life history knowledge for threatened species can impede the effectiveness of conservation actions. Gal&aacute;pagos pink land iguanas (<em>Conolophus marthae</em>) are endemic to Wolf Volcano, Gal&aacute;pagos, Ecuador. These iguanas are threatened by invasive alien species, particularly feral cats, that may affect their small population size. To guarantee the long-term survival of <em>C. marthae</em>, the Gal&aacute;pagos National Park Directorate is considering, along with an ongoing campaign of feral cat control, the implementation of a head-start program. However, the success of this management strategy necessarily relies on the identification of pink iguana nesting grounds, which were still unknown at the onset of this study. We modeled the movement patterns of male and female iguanas during the reproductive season, using location data collected from custom-made remote tracking devices installed on adult pink iguanas in April 2021. We first calculated for each individual the vector of distances from its starting location, which was defined as net displacement. We then used net displacement as the response variable in a generalized additive mixed model with day of the year as the predictor. Based on the hypothesis that males and females may behaviorally differ after mating, we looked for female-specific migratory behavior suggesting females were moving toward nesting areas. The results obtained confirmed our hypothesis, as females exhibited a distinct migratory behavior, reaching a small plateau area inside of Wolf Volcano's caldera and ca. 400 m below the volcano's northern rim. Moreover, once inside the caldera, females displayed a more aggregated distribution pattern. The movement data obtained allowed Gal&aacute;pagos National Park rangers to locate individual pink iguana nests and subsequently to sight and collect the first observed hatchlings of the species. This work constitutes a necessary baseline to perform dedicated studies of pink iguana nests and emerging hatchling iguanas, which is an essential step toward the development of an effective head-start program.

  PublisherDOI

Frequent coauthors

• Juan Pablo Muñoz‐Pérez

  108 shared

• Diane Deresienski

  65 shared

• Craig A. Harms

  North Carolina State University

  65 shared

• Carlos A. Valle

  Universidad San Francisco de Quito

  60 shared

• Alice Skehel

  44 shared

• Catalina Ulloa

  Universidad San Francisco de Quito

  31 shared

• Maximilian Hirschfeld

  James Cook University

  30 shared

• Daniela Alarcón‐Ruales

  28 shared

Education

• VMD

  University of Pennsylvania

  1988

• MS, Biology

  Northeastern University

  1985

• BA

  Gettysburg College

  1981

Awards & honors

• Exotic DVM of the Year by Exotic DVM Magazine (2007)
• William Medway Award for Excellence in Teaching from the Int…
• ARAV/ZooMed RAVE Award for contributions to reptile and amph…