Abstract

This is a retrospective study examining the frequency and location of live Atlantic Ridley (Lepidochelys kempi) and Loggerhead (Caretta caretta) turtle strandings in the region of Cape Cod, Massachusetts over the last ten years. In the 1993 stranding season of November and December, we have noted an increase in live turtle strandings.

We will also discuss pertinent clinical chemistry and hematology results and the utility of diagnostic tests such as plain radiographs, magnetic resonance imaging and computer aided tomography scans. Gross pathology and histology results from some of this season's turtles will be presented.

Introduction

The New England Aquarium (NEA) is the northern-most institution in the East Coast Stranding Network. The NEA responds to all strandings of sea turtles from the Boston area and points north. The Massachusetts Audubon Wellfleet Bay Wildlife Sanctuary and the NEA responds, with the help of volunteers and local organizations (C­MARC) to all turtle strandings in Massachusetts south of Boston and on Cape Cod. All live turtles from this area are transported to the NEA for treatment and short term holding. Once stabilized, the turtles are transported to Marineland of Florida for further rehabilitation and release.

Three species of turtles strand most frequently in this area. Leatherback turtles, Dermochelys coriacea, generally strand in mid-summer through fall, primarily on the ocean facing beaches of Cape Cod with a few randomly distributed exceptions. Kemp's Ridley, Lepidochelys kempi, and Loggerhead, Caretta caretta, strand in Cape Cod Bay predominantly during the months of November and December.

The purpose of this retrospective study was to examine the locations, frequencies, and sizes of Kemp's Ridley and Loggerhead turtles that stranded alive on Cape Cod, Massachusetts from 1985-1993. Summaries of blood tests and post mortem evaluations of animals that died during rehabilitation in 1993 are discussed as well as survival rates for the 1993 season.

Methods and Materials

Since 1987, all live turtles found stranded on Cape Cod were transported to the New England Aquarium for treatment. Upon arrival, physical examinations were performed, blood was drawn and radiographs were taken. Subsequent diagnostic tests and treatment were performed as necessary to guide treatment.

Blood was analyzed either by using in-house instrumentation or sent-out to Tufts Diagnostic Laboratories, Grafton MA. At Tufts a Hitachi 747 was used to perform all chemistry analyzing, while CBCs are analyzed on a Coulter Counter with a manual differential. In-house blood was analyzed on the following instrumentation: Nova Stat profile 3 blood gas analyzer, Kodak Extachem Dt60II (1993 to present), Orion Na+ and K+ analyzer (pre 1993), Lytening 5 instant ISE (1993 to present), Fiske One-Ten Osmometer HemoCue B-hemoglobin analyzer and a HemoCue B-Glucose analyzer.

After initial assessment, all turtles received treatment according to the same procedure. To alleviate presumptive pressure lesions received while laying on the beach, turtles were placed on blankets in dry "kiddie" pools. Subsequent treatments included the application of beta-dyne to scrapes and external wounds, and administration of fluids for turtles that appeared to be severely dehydrated. Following a 12 hour period of dry acclimation to room temperature a small amount of warm water (approximately 60 degrees F) was added to the pools. The addition of water continued provided the turtles could support themselves and swim. The turtles were then transferred to a temporary 3000 gallon holding pool heated to a constant temperature of approximately 67.5° F.

Once in the pool, food (live rock/green crabs, previously frozen Ilex squid and capelin) was introduced to the turtles in the pool. Depending on the severity of injury or disease, turtles began to feed as early as 24 hours after being introduced into the 3000 gallon pools. During this time, the turtles were observed for signs of dehabilitating effects of either sickness or cold exposure.

If the turtles continued to be non-responsive despite warm-up procedure, further diagnostics were performed. Radiographs were performed to suggest areas for further examination with CAT and MRI scans.

The CAT and MRI scans produced hard tissue and soft tissue images respectively. Upon review of the images, further steps could be taken to assist the turtles through this critical period including but not limited to; antibiotic treatments, vitamin treatments, cloacal ravage (to remove any blockage) or tube feeding.

Recovered turtles that died at NEA were necropsied to determine the cause of death. Gross necropsy findings were recorded and microbial samples were taken and sent out for culture. Tissue samples for histology from necropsies were preserved in 10% non buffered formalin; however histological examinations were performed only in cases where autolysis was minimal (9 out of 15 cases). In some cases autolyses appeared advanced at the time of death. Histopathology exams were performed at John Hopkins University.

Blood values for stranded Loggerhead turtles were compared to normal blood values, collated by Dr. Robert George D.V.M., from samples collected on juvenile Loggerhead turtles in the Chesapeake Ray.

Results

During the years of 1989-1993, Kemp's Ridley turtles stranded most frequently on the Eastern shore of Cape Cod Bay (Figure 1). The Loggerhead turtles stranded most commonly on the southern shore of Cape Cod Bay, but with a more even distribution as compared with Kemp's Ridleys over this same time period (Figure 2). Most live Kemp's Ridley turtle strandings Occurred in the months of November and December, while the vast majority of Loggerheads stranded in December (Figure 3). For both species, strandings usually followed severe storm fronts and high northeast winds.

During the 1985-1993 stranding seasons, the live Kempts Ridley stranding frequency ranged from 0-16 individuals per year, while the live Loggerhead strandings ranged from 0-9 individuals per year (Figure 4).

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

The average straight lengths, straight widths and weights for live stranded Kemp's Rid leys were 28.15 cm, 27.32 cm, and 4.27 kg respectively; Loggerheads were 47.95 cm, 42.44 cm and 27.35 cm respectively (Figure 5 and Table 1).

Table 1. Showing lengths, straight widths, and weights

Blood analysis showed a marked increase or decrease from recognized normal values in almost all parameters examined. Tests that showed a marked increase were: WBC, glucose, creatinine, phosphorus, total protein, Alk, phosphate, AST, LDH and CPK. Tests that show a marked decrease in value were: BUN, calcium, sodium, chloride, and potassium. Standard deviations were large for blood parameters indicating a high degree of variation or small "n" size in the parameters tested (see Table 2).

Table 2. Showing average and standard deviations of selected blood values

The percentages of the most commonly seen gross necropsy results are seen as follows; shell discoloration was found in 100% of the cases seen, lung lesions were found in 80% of the cases, while dilated intestines were seen in 60% of the cases.

The most common pathologies found on histological exam were; fatty changes to the liver in 88% of the cases, lungs showed either fungal or bacterial infection in 66% of the cases; and the kidneys showed the following three maladies in 22% of the cases: Glomerulonephritisinterstitial nephritis, mineralization and casts.

If plain radiographs suggested the presence of lesions, a further work up was pursued with MRI and CAT scans. The NEA 1993 survival rate for the Lepidochelys kempi was 12.5% and Caretta caretta survival rate was 100%. (see Figure 6).

Figure 6

Discussion

The Kemp's Ridley Sea Turtle (Lepidochelys kempi) is the most endangered of the Atlantic sea turtles. (Early, Carr) These turtles have a unique and unusual distribution that includes the Gulf of Mexico, ranging from Texas to the West Coast of Florida, with areas of abundance along the northern half of the Florida peninsula and an odd absence from Melbourne south to Miami. There are records of turtles as far north as Nova Scotia, Great Britain and the Azores (Early). During the months of November and December, immature Ridleys and Loggerhead turtles are often washed ashore on the west coast of Cape Cod Bay. (See Maps).

The turtles collected are all reported to be "cold stunned" or dead. This refers to a condition used to generally describe turtles suffering from differing stages of hypothermia, ranging from mild hypothermia to frozen below critical temperatures.

Turtles often showed high enzyme values suggesting damage to the muscles or major organs. Low values may be related to malnutrition.

In spite of aggressive diagnostic and treatment procedures, mortality rates of Lepidochelys kempi are high, even after apparent short term recovery from cold effects. Caretta caretta, though they are normally recovered in December, tend to recover uneventfully. This leads us to suggest that the Ridley turtles are sick before they are "cold stunned" and once they are warmed up they quickly succumb. Turtles that start to eat on a regular basis are supplemented with Osteo Avicon (manufactured by Vet a Mix) twice a week for the remaining time spent at NEA. The usual amount of time NEA rehabilitates turtles in-house is 2-3 months. They are then shipped to Marineland Park, Marineland FL, where they are further monitored and treated in outdoor pools, by the Marineland Vet staff until their eventual release back into the wild.

Upon evaluation of the data from turtles at NEA, some general conclusions can be made. The size of the turtles are small enough to assume that these are all juveniles. Mass of the turtles may play a role in surviving the effects of exposure The Loggerhead turtles weighing more, have a significantly higher survival rate. Ridley turtles appear to be afflicted with other diseases at the time of cold stunning.

There seems to be no significance to stranding distribution. However, if maps are overlaid, a line of demarcation becomes evident. Lepidochelys kempi strand from Eastham to Provincetown, Ma, while Caretta caretta are more varied in location but primarily strand along the southern half of Cape Cod. This may be a weather effect reflecting the "drift" of turtles too cold to swim.

Distended bowels and fungus appear to be important in the health of the turtles. Further investigation is necessary to more clearly illustrate the role.

CAT and MRI scans may play an important part in the enhancement of the diagnostic routine, but should only be used in special cases to enhance, not replace normal diagnostic and treatment routines. The use of these scans, the possible benefits of cloacal flushes, and the use of a fungicidal antibiotic produced significant improvements in the care and survival of the stranded turtles treated in 1993.

It should also be noted that there is a absence of data on Caretta sp. that have died from cold stunning. Histology on freshly dead Caretta caretta would provide significant insight into the role fungal pathogens may play in association with cold stunning when compared with Lepidochelys kempi.

References

1.  Carr, A. 1987. New Perspectives on the Pelagic Stage of Sea Turtle Development. Conservation Biology, Volume 1, No 2, August 1987. 18pp.

2.  Early, G.E.. Personal Correspondance.1994. Early, G.E., Burke, A.. Unpublished IMS Grant, 1993. 2pp.

3.  Kemps Ridley Recovery Team. Draft Recovery Plan for Kemp's Ridley Turtle (Lepidochelys kempi)

4.  Synopsis of the Biological Data on the Loggerhead Sea Turtle Caretta caretta (Linnaeus 1758). Biological Report 88(14). May 1988.