About

Craig Harms is associated with the College of Veterinary Medicine at NC State University, which is dedicated to shaping the future of veterinary medicine and preparing the next generation of veterinarians. The college emphasizes a collaborative and inclusive culture, fostering student achievement, well-being, and extracurricular engagement, including research projects conducted in world-class labs. While specific details about Dr. Harms's research focus, background, or key contributions are not provided in the page text, his association with the college suggests involvement in veterinary education, research, or related activities within this academic environment.

Research topics

• Zoology
• Biology
• Fishery
• Environmental chemistry
• Ecology
• Animal science
• Biochemistry
• Chemistry

Selected publications

• Noise-Induced Hearing Loss in Turtles: Recent Insights and Research Needs

  2026-01-01

  book-chapterOpen access

  Both freshwater and marine turtles are vulnerable to anthropogenic noise, an increasingly large component of underwater soundscapes. While there is a growing understanding of turtle sound use, there are few data on the potential auditory impacts of underwater sound exposure. This review summarizes recent studies that demonstrated that sound can induce underwater temporary threshold shifts (TTS) in two species of freshwater turtles [red-eared sliders (Trachemys scripta elegans) and Eastern painted turtles (Chrysemys picta picta)], with frequency-dependent shifts as high as 40 dB for both species. The TTS onset data and empirical models of TTS growth are vital to address auditory noise impacts for protected freshwater and sea turtle taxa. Overall, these results underscore that turtle ears are surprisingly susceptible to sound exposure with shifts higher than originally predicted, upward frequency shifts similar to mammals, and indicate that intermittent noise may mitigate TTS. The chapter then considers gaps in understanding the susceptibility of sea turtles to sound exposure and outlines future data needs. The noted TTS susceptibility emphasizes the importance of understanding auditory impacts to turtles from different noise types, reflecting the varied sound characteristics of underwater noise, and the goal of developing empirically based noise pollution guidelines for turtles.

  PublisherOA PDFDOI

• Underwater hearing sensitivity of the Kemp's ridley sea turtle ( <i>Lepidochelys kempii</i> )

  The Journal of the Acoustical Society of America · 2026-02-01

  articleOpen accessSenior author

  Anthropogenic noise may pose a threat to Kemp's ridley sea turtles in nearshore and offshore waters of the western North Atlantic and Gulf of America, where shipping and energy industries are widespread. Understanding hearing sensitivity is necessary for the development of effective noise impact mitigation strategies. However, data gaps currently exist. Therefore, in this study, we measured auditory evoked potentials (AEP) to determine the underwater hearing sensitivities of 13 juvenile Kemp's ridley sea turtles using hearing test frequencies ranging from 50 to 1600 Hz. We detected AEPs for hearing test signals between 50 and 800 Hz. Peak hearing sensitivity occurred between 200 and 300 Hz, followed by a decline in sensitivity above 400 Hz. The lowest hearing threshold averaged across all test subjects was 100 dB re 1 μPa at 300 Hz. No responses were detected at 1200 Hz (max received level = 143 dB re 1 μPa) and 1600 Hz (max received level = 143-165 dB re 1 μPa). Our results averaged across multiple individuals at 100 Hz (n = 9), 200 Hz (n = 8), 300 Hz (n = 5), and 400 Hz (n = 8) reveal lower hearing thresholds (greater sensitivity) than those reported in a previous study of two Kemp's ridley sea turtles at these frequencies. The results presented here should be considered a conservative estimate of hearing sensitivity, as perceptual hearing thresholds are likely lower than what can be determined with AEPs.

  PublisherDOI

• Blood gas and lactate analysis in nesting loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles from southeastern Florida, USA

  PLoS ONE · 2026-03-02

  articleOpen access

  High-energy demands and transition to a catabolic state pose physiological challenges for sea turtles during the nesting season. The objectives of this study were to assess venous blood gas analytes and lactate in loggerhead (Caretta caretta) and green turtles (Chelonia mydas) nesting in southeastern Florida to establish species-specific reference intervals, examine correlations between blood analytes, and investigate differences between species. For each species, the goal was to identify associations of analytes with morphometrics, nest deposition date, and, in loggerheads, duration of emergence from the water to blood sampling. The agreement of lactate concentrations between two point-of-care analyzers (i-STAT and Nova Lactate Plus) was also compared. In total, 49 loggerheads and 30 green turtles were sampled over portions of two nesting seasons. Reference intervals were established for clinically normal nesting turtles for each species. Partial pressure of oxygen was higher in loggerheads, while partial pressure of carbon dioxide and bicarbonate were higher in green turtles. In loggerheads, lactate positively correlated with curved carapace length, while pH declined and lactate increased across the nesting season, and there were no relationships between blood analytes and time from emergence to blood collection. No morphometric or seasonal trends were observed for green turtles. There was a strong association between lactate concentrations determined by i-STAT and Nova Lactate Plus, with the i-STAT yielding higher results. The mild trend toward relative lactic acidosis across portions of the nesting season in loggerheads suggests that physiological strategies to manage periods of high-energy utilization during nesting activities vary between species. These results provide insight into the variability of blood analyte data of two species of nesting sea turtles, allow for understanding physiological and metabolic changes during nesting, and provide relevance for clinical evaluations during health assessment studies, stranding response, and rehabilitation.

  PublisherDOI

• Direct Hearing Measurements in a Small Mysticete Whale, The Common Minke (Balaenoptera acutorostrata)

  2026-01-01

  book-chapterOpen access

  The hearing abilities of baleen whales have long been a mystery that has in recent decades impeded understanding of how anthropogenic noise might affect them. Because of their large size and difficulty maintaining them under human care, the use of behavioral audiometry to test their hearing has been impractical. Knowledge of baleen whale hearing has historically been inferred from the frequency range of their vocalizations, although this is known to be a poor predictor of the full range of hearing in mammals and provides no information on hearing thresholds. Additional information on sound sensitivity in baleen whales has been obtained through behavioral response studies, anatomical modelling, and most recently, the use of electrophysiological methods. Collectively, these approaches demonstrated or predicted that baleen whale hearing ranges exceed the range of vocalization frequencies, which is a common feature of mammalian hearing. Within the last 2 years, a modified behavioral observation audiometry study with free-ranging humpback whales and an electrophysiological study with temporarily held common minke whales suggest higher-frequency sensitivity than previously predicted. These approaches provide information on sound sensitivity, and the approaches may potentially be combined to permit a baleen whale audiogram to be obtained.

  PublisherOA PDFDOI

• Histochemical indications for a chemically complex signal produced by the cervical gill slit gland of the pygmy sperm whale (<i>Kogia breviceps</i>)

  The Anatomical Record · 2025-01-09 · 1 citations

  articleOpen access

  The pygmy sperm whale (Kogia breviceps) possesses an exocrine gland associated with its false gill slit pigmentation pattern. The cervical gill slit gland is a compound tubuloalveolar gland that produces a holocrine secretion and displays maturational changes in size and secretory histology. While the morphology of the cervical gill slit gland has been described in detail, to date, the chemical composition of its secretion remains uncharacterized. This study used histochemical staining techniques and quantitative lipid analysis to identify and characterize the constituents expressed in the secretory cells and secretion of the cervical gill slit gland. Results demonstrate that the secretion, like those of terrestrial artiodactyls that function in chemical communication, includes a complex mixture of carbohydrates, proteins, and lipids. Differences in staining intensity across germinal and secretory epithelial layers demonstrate differential expression, or maturation, of mucins and proteins. Additionally, a highly unusual and primary constituent of the secretion is uric acid. Uric acid was identified within the secretion using histochemical stains and polarized light imaging, and chemically verified using scanning electron microscopy with energy dispersive spectrometry. While uric acid is not a common constituent of mammalian exocrine glands, urate-based compounds are abundant in the secretions of marine organisms used in chemical communication. Thus, uric acid may contribute to the chemical message produced by K. breviceps in its marine environment. We hypothesize that the chemical signals produced by the gill slit gland may be shared at close-range by conspecifics, and that the mode of sensory reception is likely gustation.

  PublisherOA PDFDOI

• Meningeal Lymphatic and Glymphatic Structures in a Pelagic Delphinid (Delphinus delphis)

  UNC Libraries · 2025-04-02

  articleOpen access

  The glymphatic system, an analog of the peripheral lymphatic system in the brain, and the meningeal lymphatic system are critical to central nervous system health. The glymphatic system functions to distribute cerebrospinal fluid and important compounds throughout the brain and to remove metabolic waste. The flow of cerebrospinal fluid through this system is affected by changes in cerebral blood flow, intracranial pressure, and vascular tone. Cetaceans experience profound cardiorespiratory alterations while diving that can directly affect cerebrospinal fluid and blood flow and, thus, glymphatic function. Our goal was to investigate glymphatic and lymphatic system structures, including perivascular spaces, aquaporin-4 water channels, meningeal lymphatic, and dural venous sinus vessels in the common dolphin (Delphinus delphis), using immunofluorescent labeling, histochemical staining, and postmortem computed tomography (CT) angiography. We highlight perivascular spaces and aquaporin-4 water channels surrounding blood vessels in the parenchyma and demonstrate evidence of meningeal lymphatic vessels and associated dural venous sinuses. These results demonstrate that common dolphins possess the key anatomical structures required for functional glymphatic and meningeal lymphatic systems. Future studies can build upon these anatomical discoveries to study the function and role of these systems in brain health in this species.

  PublisherDOI

• Mycobacterium ulcerans ecovar infection in wild Kemp’s ridley Lepidochelys kempii and loggerhead Caretta caretta sea turtles

  Diseases of Aquatic Organisms · 2025-10-09

  article

  Mycobacteria infections are sporadically documented in wild sea turtles and are generally regarded as opportunistic pathogens. This case series describes infections by a Mycobacterium ulcerans ecovar in 2 imperiled species of sea turtle, the Kemp's ridley Lepidochelys kempii (n = 5) and loggerhead turtle Caretta caretta (n = 1). Most cases were stranded animals that presented with neurological abnormalities resulting from severe mycobacterial meningoencephalitis. In 4 instances, infected turtles were found in relative proximity to one another and without evident predisposing conditions, suggesting the potential for broader population health significance. Lesions were predominantly heterophilic and histiocytic, and were characterized by extensive leukocytic necrosis, absence of organized granuloma formation within the nervous system, fibrinoid vascular necrosis, and myriad extracellular and intrahistiocytic acid-fast bacilli. Except for one severely bacteremic animal, involvement of visceral organs was relatively mild and often paucibacterial. Multiple genetic loci were 100% identical in all 6 affected turtles and to multiple reported M. ulcerans ecovars; an ITS2 sequence amplified from each turtle was 100% identical only to M. pseudoshottsii, a pathogen of wild and farmed fish. The genetic relatedness of the organism to M. ulcerans ecovars known to produce mycolactones (polyketide toxins) suggests that the distinct pathological features among these cases are the result of a mycolactone-producing species of mycobacteria. This is the first report of M. ulcerans ecovar infection of a reptile. Mycobacterial meningoencephalitis should be considered as a differential etiological diagnosis for neurological disease in wild sea turtles.

  PublisherDOI

• DEREGULATION OF GLUCOSE HOMEOSTASIS AND MATERNAL GALECTINS SHAPES OBESITY PROFILE EARLY IN PREGNANCY

  Journal of Reproductive Immunology · 2025-01-24

  article
  PublisherDOI

• Invertebrates

  2025-01-17 · 1 citations

  otherOpen access
  PublisherOA PDFDOI

• Temporary threshold shifts in the Eastern painted turtle (<i>Chrysemys picta picta</i>) in response to narrowband underwater noise exposures

  The Journal of the Acoustical Society of America · 2025-09-01 · 1 citations

  article

  Sound is important to many turtle species, emphasizing the need for data-driven predictive models of acoustic impacts of noise pollution. Freshwater turtles experience temporary threshold shifts (TTSs) and data of the specific frequencies and duration inducing hearing loss are critical for TTS modeling. Three adult female Eastern painted turtles (Chrysemys picta pica) were exposed to 1/6-octave-narrowband noise centered at 200 or 400 Hz at varying durations and amplitudes (received sound exposure levels, 136-174 dB re 1 μPa2 s). Underwater auditory thresholds were measured at each band's center frequency and 1/2 octave above these frequencies using auditory evoked potential methodology. A comparison of post-exposure to control thresholds revealed that all turtles experienced TTS at all four test frequencies. Turtles showed greater susceptibility to the 400-Hz centered narrowband, a frequency of higher auditory sensitivity. Greater TTS and a lower TTS onset was observed at 570 Hz compared to 400 Hz, revealing an upward frequency shift in TTS compared to the exposure frequencies. Auditory sensitivity recovered within <1 h or by two days post-exposure, but one turtle showed TTS lasting multiple weeks. Narrowband TTS growth aligned with broadband empirical models, suggesting TTS predictions may be similar for these two noise types.

  PublisherDOI

Frequent coauthors

• Lori H. Schwacke

  Marine Mammal Commission

  108 shared

• Forrest I. Townsend

  Auburn University

  104 shared

• Eric D. Jensen

  Naval Information Warfare Center Pacific

  104 shared

• Larry J. Hansen

  104 shared

• Teresa K. Rowles

  NOAA National Marine Fisheries Service

  101 shared

• Emily F. Christiansen

  North Carolina Aquarium

  100 shared

• Sara K. Rosenkranz

  Kansas State University

  74 shared

• Gregory A. Lewbart

  North Central State College

  65 shared

Education

• Ph.D., Comparative Medicine

  North Carolina State University

  2001

• M.S., Comparative Medicine

  University of California, Davis

  1997

• B.S., Animal Science

  University of California, Davis

  1995

Awards & honors

• Diplomate, American College of Zoological Medicine