Geology topics

George H. Balazs

Publications and source records attributed to George H. Balazs.

31 records · Page 2Linked to original sources

USGS2014

Pink spot, white spot: the pineal skylight of the leatherback turtle ( Dermochelys coriacea Vandelli 1761) skull and its possible role in the phenology of feeding migrations

Leatherback turtles, Dermochelys coriacea , which have an irregular pink area on the crown of the head known as the pineal or ‘pink spot’, forage upon jellyfish in cool temperate waters along the western and eastern margins of the North Atlantic during the summer. Our study showed that the skeletal structures underlying the pink spot in juvenile and adult turtles are compatible with the idea of a pineal dosimeter function that would support recognition of environmental light stimuli. We interrogated an extensive turtle sightings database to elucidate the phenology of leatherback foraging during summer months around Great Britain and Ireland and compared the sightings with historical data for sea surface temperatures and day lengths to assess whether sea surface temperature or light periodicity/levels were likely abiotic triggers prompting foraging turtles to turn south and leave their feeding grounds at the end of the summer. We found that sea temperature was too variable and slow changing in the study area to be useful as a trigger and suggest that shortening of day lengths as the late summer equilux is approached provides a credible phenological cue, acting via the pineal, for leatherbacks to leave their foraging areas whether they are feeding close to Nova Scotia or Great Britain and Ireland.

Journal of Experimental Marine Biology and Ecology↗

USGS2013

A simple humane method to euthanize a sea turtle

Increased interconnectedness, communication, and demands of society require that wildlife professionals make every effort to consider animal welfare when handling animals. The challenge can be daunting, particularly when a wild animal needs to be euthanized. In some cases, biologists are in remote areas under conditions that may be less than ideal to properly and swiftly dispatch an animal, either because of a lack of proper supplies or veterinary training. Societal demands for consideration of animal welfare are not limited to wildlife professionals. Native cultures, fishermen and hunters have traditional methods of capturing or killing wildlife that are now under increasing public scrutiny. A current example is in Australia where aborigines were criticized for the practice of dispatching sea turtles by throwing a cement block at the animals’ heads resulting in negative public reaction (Queensland Times 2010).

Marine Turtle Newsletter↗

USGS2013

Tumors in sea turtles: The insidious menace of fibropapillomatosis

Early in July 2013, a colleague in New Caledonia reported the stranding of a green sea turtle on the far northwest of the island. The animal had washed up dead on a rocky beach with multiple large tumors on its neck and hind flippers. To all appearances, the turtle had fibropapillomatosis (FP), a tumor disease affecting marine turtles globally. This was the first known case of FP on the island—an alarming find, and another example of the creeping expansion of this disease in green turtles around the world.

The Wildlife Professional↗

USGS2012

The genome of Chelonid herpesvirus 5 harbors atypical genes

The Chelonid fibropapilloma-associated herpesvirus (CFPHV; ChHV5) is believed to be the causative agent of fibropapillomatosis (FP), a neoplastic disease of marine turtles. While clinical signs and pathology of FP are well known, research on ChHV5 has been impeded because no cell culture system for its propagation exists. We have cloned a BAC containing ChHV5 in pTARBAC2.1 and determined its nucleotide sequence. Accordingly, ChHV5 has a type D genome and its predominant gene order is typical for the varicellovirus genus within the alphaherpesvirinae . However, at least four genes that are atypical for an alphaherpesvirus genome were also detected, i.e. two members of the C-type lectin-like domain superfamily (F-lec1, F-lec2), an orthologue to the mouse cytomegalovirus M04 (F-M04) and a viral sialyltransferase (F-sial). Four lines of evidence suggest that these atypical genes are truly part of the ChHV5 genome: (1) the pTARBAC insertion interrupted the UL52 ORF, leaving parts of the gene to either side of the insertion and suggesting that an intact molecule had been cloned. (2) Using FP-associated UL52 (F-UL52) as an anchor and the BAC-derived sequences as a means to generate primers, overlapping PCR was performed with tumor-derived DNA as template, which confirmed the presence of the same stretch of “atypical” DNA in independent FP cases. (3) Pyrosequencing of DNA from independent tumors did not reveal previously undetected viral sequences, suggesting that no apparent loss of viral sequence had happened due to the cloning strategy. (4) The simultaneous presence of previously known ChHV5 sequences and F-sial as well as F-M04 sequences was also confirmed in geographically distinct Australian cases of FP. Finally, transcripts of F-sial and F-M04 but not transcripts of lytic viral genes were detected in tumors from Hawaiian FP-cases. Therefore, we suggest that F-sial and F-M04 may play a role in FP pathogenesis

Hawaii↗

USGS2011

Coastal habitat degradation and green sea turtle diets in Southeastern Brazil

To show the influence of coastal habitat degradation on the availability of food for green turtles (Chelonia mydas), we assessed the dietary preferences and macroalgae community at a feeding area in a highly urbanized region. The area showed low species richness and was classified as degraded. We examined stomach contents of 15 dead stranded turtles (CCL = 44.0 cm (SD 6.7 cm)). The diet was composed primarily of green algae Ulva spp. (83.6%). In contrast, the macroalgae community was dominated by the green alga Caulerpa mexicana. We found a selection for red algae, seagrass and Ulva spp., and avoidance for C. mexicana and brown alga Dictyopteris delicatula. The low diversity of available food items, possibly a result of environmental degradation, likely contributed to the low dietary diversity. The nutritional implications of this restricted diet are unclear.

Vitoria↗

USGS2010

Pathology and distribution of sea turtles landed as bycatch in the Hawaii-based North Pacific pelagic longline fishery

We examined the gross and microscopic pathology and distribution of sea turtles that were landed as bycatch from the Hawaii, USA–based pelagic longline fishery and known to be forced submerged. Olive ridley turtles ( Lepidochelys olivacea ) composed the majority of animals examined, and hook-induced perforation of the esophagus was the most common gross lesion followed by perforation of oral structures (tongue, canthus) and of flippers. Gross pathology in the lungs suggestive of drowning was seen in 23 of 71 turtles. Considering only the external gross findings, the pathologist and the observer on board the longline vessel agreed on hook-induced lesions only 60% of the time thereby illustrating the limitations of depending on external examination alone to implicate hooking interactions or drowning as potential cause of sea turtle mortality. When comparing histology of drowned turtles to a control group of nondrowned turtles, the former had significantly more pulmonary edema, hemorrhage, and sloughed columnar epithelium. These microscopic changes may prove useful to diagnose suspected drowning in sea turtles where history of hooking or netting interactions is unknown.

Journal of Wildlife Diseases↗

USGS2009

In vitro biology of fibropapilloma-associated turtle herpesvirus and host cells in Hawaiian green turtles (Chelonia mydas)

Fibropapillomatosis (FP) of green turtles has a global distribution and causes debilitating tumours of the skin and internal organs in several species of marine turtles. FP is associated with a presently non-cultivable alphaherpesvirus Chelonid fibropapilloma-associated herpesvirus (CFPHV). Our aims were to employ quantitative PCR targeted to pol DNA of CFPHV to determine (i) if DNA sequesters by tumour size and/or cell type, (ii) whether subculturing of cells is a viable strategy for isolating CFPHV and (iii) whether CFPHV can be induced to a lytic growth cycle in vitro using chemical modulators of replication (CMRs), temperature variation or co-cultivation. Additional objectives included determining whether non-tumour and tumour cells behave differently in vitro and confirming the phenotype of cultured cells using cell-type-specific antigens. CFPHV pol DNA was preferentially concentrated in dermal fibroblasts of skin tumours and the amount of viral DNA per cell was independent of tumour size. Copy number of CFPHV pol DNA per cell rapidly decreased with cell doubling of tumour-derived fibroblasts in culture. Attempts to induce viral replication in known CFPHV-DNA-positive cells using temperature or CMR failed. No significant differences were seen in in vitro morphology or growth characteristics of fibroblasts from tumour cells and paired normal skin, nor from CFPHV pol-DNA-positive intestinal tumour cells. Tumour cells were confirmed as fibroblasts or keratinocytes by positive staining with anti-vimentin and anti-pancytokeratin antibodies, respectively. CFPHV continues to be refractory to in vitro cultivation.

Hawai'i↗

USGS2009

Rise and fall over 26 years of a marine epizootic in Hawaiian green sea turtles

Estimates of chronic disease prevalence are needed to improve our understanding of marine disease epizootiology, which is poorly known for marine megafauna such as marine turtles. An emerging worldwide threat to green sea turtles ( Chelonia mydas ) is fibropapillomatosis (FP), which is a pandemic tumor-forming disease associated with herpesviruses. We report on a 26-yr FP epidemic in the Hawaiian Archipelago and show that apparent disease prevalence in the world's main endemic hot spot increased rapidly following a late 1980s outbreak, peaked during the mid-1990s, and then declined steadily ever since. While this disease is a major cause of sea turtle stranding in Hawaiian waters and can be fatal, we also show that long-term tumor regression can occur even for turtles with advanced FP. The endemic Hawaiian green turtle stock was severely depleted by overexploitation prior to protection under the US Endangered Species Act in 1978. This stock has increased significantly ever since, despite exposure to a major chronic disease epidemic that is currently declining.

Journal of Wildlife Diseases↗

USGS2008

Cause-specific temporal and spatial trends in green sea turtle strandings in the Hawaiian Archipelago (1982-2003)

We investigated cause-specific temporal and spatial trends in sea turtle strandings in the Hawaiian Archipelago. Five species of sea turtle were recorded in 3,861 strandings over a 22-year period (1982–2003). Green turtles comprised 97% of these strandings with size and gender composition reflecting the demographic structure of the resident green turtle population and relative green turtle abundance in Hawaiian waters. The cause of strandings was determined by necropsy based on a complete gross external and internal examination. Totally 75% of the 3,732 green turtle strandings were from Oahu where strandings occur year-round. The most common known cause of the green turtle strandings was the tumour-forming disease, fibropapillomatosis (28%) followed by hook-and-line fishing gear-induced trauma (7%), gillnet fishing gear-induced trauma (5%), boat strike (2.5%), and shark attack (2.7%). Miscellaneous causes comprised 5.4% of strandings whereas 49% of green turtle strandings could not be attributed to any known cause. Green turtle strandings attributable to boat strike were more likely from Kauai and Oahu while fibropapilloma strandings were more likely from Oahu and Maui. Hook-and-line gear strandings were more likely from Oahu due to higher per capita inshore fishing effort. The specific mortality rate (conditional probability) for fibropapillomatosis was 88%, 69% for gillnet gear and 52% for hook-and-line gear. The probability of a dead green turtle stranding increased from 1982 but levelled off by the mid-1990s. The declining mortality risk was because the prevalence and severity of fibropapillomatosis has decreased recently and so has the mortality risk attributable to gillnet gear. Despite exposure to disease and inshore fishing gears, the Hawaiian green turtle stock continues to recover following protection since the late 1970s. Nevertheless, measures to reduce incidental capture of sea turtles in coastal Hawaiian fisheries would be prudent, especially since strandings attributable to hook-and-line fishing gear have increased steadily since 1982.

Hawai'i↗

USGS2004

Retrospective pathology survey of green turtles Chelonia mydas with fibropapillomatosis in the Hawaiian Islands, 1993-2003

We necropsied 255 stranded green turtles Chelonia mydas with fibropapillomatosis (FP) from the Hawaiian Islands, North Pacific, from August 1993 through May 2003. Of these, 214 (84%) were euthanized due to advanced FP and the remainder were found dead in fresh condition. Turtles were assigned a standardized tumor severity score ranging from 1 (lightly tumored) to 3 (heavily tumored). Tumors were counted and measured and categorized as external, oral, or internal and tissues evaluated by light microscopy. Turtles in tumor score 2 and 3 categories predominated, and tumor score 3 turtles were significantly larger than the other 2 categories. More juveniles stranded than subadults or adults. Total cross-sectional area of tumors increased significantly with straight carapace length (SCL). Frequency distribution of total number of external tumors per turtle was significantly skewed to the right, and there were significantly more tumors at the front than rear of turtles. Eighty percent of turtles had oral tumors, and 51% of turtles with oral tumors had tumors in the glottis. Thirty-nine percent of turtles had internal tumors, most of them in the lung, kidney and heart. Fibromas predominated in lung, kidney and musculoskeletal system whereas myxofibromas were more common in intestines and spleen. Fibrosarcomas of low-grade malignancy were most frequent in the heart, and heart tumors had a predilection for the right atrium. Turtles with FP had significant additional complications including inflammation with vascular flukes, bacterial infections, poor body condition, and necrosis of salt gland. Turtles with oral tumors were more likely to have secondary complications such as pneumonia. Most turtles came from the island of Oahu (74%) followed by Maui (20%), Hawaii, Molokai, and Lanai (<3% each). On Oahu, significantly more turtles we necropsied stranded along the northwestern and northeastern shores.

Hawai'i↗

USGS2001

Immune status of free-ranging green turtles with fibropapillomatosis from Hawaii

Cell-mediated and humoral immune status of free-ranging green turtles ( Chelonia mydas ) in Hawaii (USA) with and without fibropapillomatosis (FP) were assessed. Tumored and non-tumored turtles from Kaneohe Bay (KB) on the island of Oahu and from FP-free areas on the west (Kona/Kohala) coast of the island of Hawaii were sampled from April 1998 through February 1999. Turtles on Oahu were grouped (0–3) for severity of tumors with 0 for absence of tumors, 1 for light, 2 for moderate, and 3 for most severe. Turtles were weighed, straight carapace length measured and the regression slope of weight to straight carapace length compared between groups (KB0, KB1, KB2, KB3, Kona). Blood was assayed for differential white blood cell count, hematocrit, in vitro peripheral blood mononuclear cell (PBMC) proliferation in the presence of concanavalin A (ConA) and phytohaemagglutinin (PHA), and protein electrophoresis. On Oahu, heterophil/lymphocyte ratio increased while eosinophil/monocyte ratio decreased with increasing tumors score. Peripheral blood mononuclear cell proliferation indices for ConA and PHA were significantly lower for turtles with tumor scores 2 and 3. Tumor score 3 turtles (KB3) had significantly lower hematocrit, total protein, alpha 1, alpha 2, and gamma globulins than the other four groups. No significant differences in immune status were seen between non-tumored (or KB1) turtles from Oahu and Hawaii. There was no significant difference between groups in regression slopes of body condition to carapace length. We conclude that turtles with severe FP are imunosuppressed. Furthermore, the lack of significant difference in immune status between non-tumored (and KB1) turtles from Oahu and Kona/Kohala indicates that immunosuppression may not be a prerequisite for development of FP.

Hawai'i↗

USGS1999

Relating tumor score to hematology in green turtles with fibropapillomatosis in Hawaii

The relationship between hematologic status and severity of tumor affliction in green turtles (Chelonia mydas) with fibropapillomatosis (FP) was examined. During 1 wk periods in July 1997 and July 1998, we bled 108 free-ranging green turtles from Pala'au (Molokai, Hawaii, USA) where FP is endemic. Blood was analyzed for hematocrit, estimated total solids, total white blood cell (WBC) count and differential WBC count. Each turtle was assigned a subjective tumor score ranging from 0 (no visible external tumors) to 3 (heavily tumored) that indicated the severity of FP. There was a progressive increase in monocytes and a decrease in all other hematologic parameters except heterophils and total numbers of white blood cells as tumor score increased. These data indicate that tumor score can relate to physiologic status of green turtles afflicted with FP, and that tumor score is a useful field monitor of severity of FP in this species.

Hawai'i↗

USGS1998

Morphologic and cytochemical characteristics of blood cells from Hawaiian green turtles

Objective - To identify and characterize blood cells from free-ranging Hawaiian green turtles, Chelonia mydas. Sample Population - 26 green turtles from Puako on the island of Hawaii and Kaneohe Bay on the island of Oahu. Procedure - Blood was examined, using light and electron microscopy and cytochemical stains that included benzidine peroxidase, chloroacetate esterase, alpha naphthyl butyrate esterase, acid phosphatase, Sudan black B, periodic acid-Schiff, and toluidine blue. Results - 6 types of WBC were identified: lymphocytes, monocytes, thrombocytes, heterophils, basophils, and eosinophils (small and large). Morphologic characteristics of mononuclear cells and most granulocytes were similar to those of cells from other reptiles except that green turtles have both large and small eosinophils. Conclusions - Our classification of green turtle blood cells clarifies imporoper nomenclature reported previously and provides a reference for future hematologic studies in this species.

Hawai'i↗