Theses and Dissertations

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Defense Date

4-1989

Document Type

Dissertation - NSU Access Only

Degree Name

Ph.D. Oceanography/Marine Biology

Department

Oceanographic Center

First Advisor

Curtis M. Burney

Second Advisor

Harold Haines

Third Advisor

Max Bree

Fourth Advisor

David Woodbridge

Fifth Advisor

Julian McCreary

Abstract

The culture of sea turtles provides a means for reestablishing depleted natural populations through restocking and, at the same time, alleviates pressures of over-exploitation on existing populations. A major problem in the rearing of sea turtles is disease control, particularly skin-disease. Necrotic skin lesions develop within the initial months of raising hatchlings and usually result in death, if not treated. Unfortunately, most treatments for controlling skin diseases in sea turtles have proven to be ineffective and labor intensive.

The primary objective of this study was to determine the effectiveness of an iodophor compound (Vanodine™) and standard treatment (KMnO4) in the prevention and treatment of developing skin lesion disease observed in sea turtle aquaculture. Samples of skin lesions encountered in the culture of sea turtles were described and identified. Bacteria associated with these skin lesions were isolated, cultured, and identified.

To test the prophylaxis of the treatments three study groups (N=35) of Caretta caretta (loggerhead sea turtles) were randomly selected from a mixed group of hatchlings, from six egg clutches. One group served as a “control" and remained untreated. The other two groups were treated with (1) Vanodine at a final concentration of 1:10,000 (100 ppm) and (2) Potassium permanganate (KMnO4) at a concentration of 1:1,000 (1,000 ppm). In both treatment groups, chemicals were added directly to the water of the holding tanks and maintained for 8-10 hour intervals.

To confirm the prophylactic effect, the initially untreated and KMnO4 treated groups were switched to Vanodine treatment on the seventh week of the study and the turtles in the initially Vanodine treated group were removed from treatment. This cross-over experiment followed the same experimental protocol as the initial phase of the prophlactic study. In order to determine the effectiveness of Vanodine on already established skin lesions, untreated loggerhead sea turtles of approximately 4 months of age were ramdomly divided into two groups. One group remained untreated and another group was treated with Vanodine at a final concentration of 1:10,000 (100 ppm) for 8 to 10 hours daily. This procedure continued for seven weeks, at which time the untreated group was treated with Vanodine and treatment in the initially Vanodine treated group was terminated. This cross-over experiment was identical in procedure and duration to the initial treatment study.

The susceptibility for natural skin lesion development in hatchling loggerhead sea turtles had been reported to occur during the third to fourth month after hatching. In this study, skin lesions developed in the Vanodine and untreated groups during the fifth week of life: however, skin lesions occurred during the second week on the turtles exposed to KMnO4.

Vanodine inhibited skin and scute lesion development in sea turtle hatchlings. Turtles which had previously developed skin lesion disease were successfully treated with Vanodine. It is important to note that Vanodine did not inhibit all lesions but was significant in reducing lesions when compared to the untreated and KMnO4 treated groups.

More and larger skin lesions occurred in the KMnO4 group than in the untreated group. KMnO4 had been used as a standard treatment for skin lesion disease in sea turtles and is effective on some skin lesion types, if administered topically. In this study, the addition of KMnO4 to the water of the holding tank was not successful in the prevention of skin and scute lesions in newly hatched loggerhead sea turtles when compared to the untreated group of turtles.

Switching the KMnO4 group to Vanodine (week 7) resulted in a highy significant (P>0.9995) decreasing trend in skin lesion number and area. After the KMnO4 turtles were exposed to Vanodine, lesion number first increased for initial two weeks of treatment, but then declined at a substantial rate thereafter. Skin lesion area decreased throughout the study period. Visible KMnO4 staining and matting of necrotic tissue around established lesions persisted for about two weeks after treatment was switched. The flushing of residual KMnO4 in conjunction with regeneration of stain damaged tissue appeared to be required before Vanodine could effectively treat existing skin lesions.

Scute lesions, especially those associated with Salmonella sp., were eliminated by the exposure to Vanodine. Number and area of scute lesions in the prophylactic study, became significantly (p>0.9995) lower in the Vanodine treated group compared to the untreated group after six weeks of treatment and remained significantly different throughout the cross-over experiment.

Scute lesion number and area were greater in the KMnO4 group compared to the untreated group, with the difference becoming highly significant (P>0.9995) by week six. KMnO4 was not effective in controlling scute lesions when compared to the untreated and Vanodine treated groups.

Vanodine seems to have two important roles in controlling skin lesion disease in sea turtle culture. First, the biocidal properties of the iodophor cause a possible reduction in the microbial load infiltrating the lesions. Second, Vanodine treatment of the water in the holding facility permits sufficient time for lesion healing by inhibiting the invasion of “opportunistic” pathogens. It appears that “opportunistic” pathogens which invade the already open lesion cause the high morbidity and mortality associated with skin lesion diseases in hatchling sea turtles.

The procedure developed in this study for treating an entire group of sea turtles by administering the iodophor directly 'into the water of the holding facility is very efficient when compared to the labor intensive practice, utilized by many previous methods, in which turtles were treated individually. Vanodine's application to raising sea turtles affords a one-step procedure for administering the iodophor to the entire stock, and enhancing the hatchling survival rate.

Comments

Research supported by Nova University.

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