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The Biology of Sea Turtles, Vol. II
removing parasites and fouling epibiota such as barnacles. Sea turtles can withstand
short periods of freshwater (0 ppt) (Walsh, 1999). Freshwater treatments of up to 2
weeks have been used to treat floating–bloating problems with limited success, with
no observable detriment to the turtles’ health. A nonprescribed salinity of less than
14 ppt for a period of more than 2 weeks would require the addition of salt to the
storage tanks to increase salinity. Salinity should be measured with a refractometer
accurate to 1 ppt.
16.4.3 pH
pH is an indicator of water quality. As water quality degenerates from the accumulation of turtle waste products, pH decreases. Normal incoming NMFS STF
seawater has a pH of 7.9–8.2. A pH reading of less than 7.4 indicates that a raceway
is in need of cleaning. The normal pH of a clean raceway containing turtles ranges
from 7.5 to 8.1. pH is controlled by cleaning and changing water. Average pH
decreases as biomass and bioload increase in a raceway. Optimal pH for sea turtles
is 7.5–8.5 (FWC, 2002). pH is measured with a digital pH meter accurate to two
decimal places.
16.4.4 LIGHT
The majority of light in the NMFS STF comes from the translucent fiberglass panels
that make up a portion of the roof (15–1.2 m ¥ 2.4 m panels). Fluorescent lighting
(2 ¥ 40 W ¥ 15 fixtures) is used approximately 48 h/week to supplement sunlight.
The daily amount of light the turtles receive is dependent on the natural available
sunlight in Galveston, TX. The amount of actual ultraviolet (UV) light that reaches
the sea turtles in the NMFS STF through the fiberglass panels is unknown. No health
problems have been identified and associated with a lack of suitable light. Kemp’s
ridleys held in captivity for more than 1 year and loggerheads held in captivity for
more than 2 years tend to be lighter in complexion than their wild counterparts.
Sunlight is important in reptiles for the synthesis of vitamin D 3 . A lack of suitable
light may require dietary supplementation.
Experimentation with different quality and quantities of artificial light (both fullspectrum fluorescent lights, limited-spectrum lights [grow lights], and metal halide
lights [5000 K]) as treatments for carapace lesions or infections and floating–bloating
has been tried without success. Short periods of direct sunlight may help treat topical
fungal lesions of the skin (Fontaine et al., 1988). Natural diurnal light patterns should
be replicated for turtles housed in captivity. Excess light and nontherapeutic direct
sunlight should be avoided to control algae growth, and to prevent elevated water
temperature and sunburn.
16.5 HATCHLING SELECTION
Every attempt should be made to acquire captive stock bearing good genetic lineage,
ideally from many different nests. Avoiding physical deformities from the onset will
pay dividends in the end. Turtles with visible deformities may exhibit stunted and
1123_C16 Page 420 Tuesday, November 12, 2002 8:28 AM
The Biology of Sea Turtles, Vol. II
removing parasites and fouling epibiota such as barnacles. Sea turtles can withstand
short periods of freshwater (0 ppt) (Walsh, 1999). Freshwater treatments of up to 2
weeks have been used to treat floating–bloating problems with limited success, with
no observable detriment to the turtles’ health. A nonprescribed salinity of less than
14 ppt for a period of more than 2 weeks would require the addition of salt to the
storage tanks to increase salinity. Salinity should be measured with a refractometer
accurate to 1 ppt.
16.4.3 pH
pH is an indicator of water quality. As water quality degenerates from the accumulation of turtle waste products, pH decreases. Normal incoming NMFS STF
seawater has a pH of 7.9–8.2. A pH reading of less than 7.4 indicates that a raceway
is in need of cleaning. The normal pH of a clean raceway containing turtles ranges
from 7.5 to 8.1. pH is controlled by cleaning and changing water. Average pH
decreases as biomass and bioload increase in a raceway. Optimal pH for sea turtles
is 7.5–8.5 (FWC, 2002). pH is measured with a digital pH meter accurate to two
decimal places.
16.4.4 LIGHT
The majority of light in the NMFS STF comes from the translucent fiberglass panels
that make up a portion of the roof (15–1.2 m ¥ 2.4 m panels). Fluorescent lighting
(2 ¥ 40 W ¥ 15 fixtures) is used approximately 48 h/week to supplement sunlight.
The daily amount of light the turtles receive is dependent on the natural available
sunlight in Galveston, TX. The amount of actual ultraviolet (UV) light that reaches
the sea turtles in the NMFS STF through the fiberglass panels is unknown. No health
problems have been identified and associated with a lack of suitable light. Kemp’s
ridleys held in captivity for more than 1 year and loggerheads held in captivity for
more than 2 years tend to be lighter in complexion than their wild counterparts.
Sunlight is important in reptiles for the synthesis of vitamin D 3 . A lack of suitable
light may require dietary supplementation.
Experimentation with different quality and quantities of artificial light (both fullspectrum fluorescent lights, limited-spectrum lights [grow lights], and metal halide
lights [5000 K]) as treatments for carapace lesions or infections and floating–bloating
has been tried without success. Short periods of direct sunlight may help treat topical
fungal lesions of the skin (Fontaine et al., 1988). Natural diurnal light patterns should
be replicated for turtles housed in captivity. Excess light and nontherapeutic direct
sunlight should be avoided to control algae growth, and to prevent elevated water
temperature and sunburn.
16.5 HATCHLING SELECTION
Every attempt should be made to acquire captive stock bearing good genetic lineage,
ideally from many different nests. Avoiding physical deformities from the onset will
pay dividends in the end. Turtles with visible deformities may exhibit stunted and
1123_C16 Page 420 Tuesday, November 12, 2002 8:28 AM