418
The Biology of Sea Turtles, Vol. II
immersion heater (14,000 W). Each heater is connected to a temperature-control
unit, allowing the tanks to be adjusted independently. There is no active filtration
or treatment of any kind in the seawater system. The well points below the sand
remove large particles from the water. Settling in the sump and large holding tanks
removes most particulate matter, suspended algae, larvae, and some bacteria from
the seawater. Further settling in the eight smaller water storage tanks removes the
remainder of suspended sediment. The NMFS STF uses approximately
37,854–68,137-l of new seawater daily. Wastewater is discarded into the city of
Galveston sanitary sewer system.
From late September through April, the NMFS STF heats seawater. Seawater is
heated to approximately 38–43 ∞ C in three of the four 26,000-l storage tanks. Hot
water is mixed with ambient water 10–26 ∞ C by manipulating hot- and cold-water
valves to achieve an incoming water temperature of 26–30 ∞ C with a target of 28.5 ∞ C.
16.4 ENVIRONMENTAL PARAMETERS
The STF uses natural seawater in a static system where water is exchanged in each
tank three to six times per week. Three water quality parameters are monitored and
recorded daily: temperature, salinity, and pH.
16.4.1 T EMPERATURE
Maintaining a constant and acceptable temperature is critical for growth and for
preventing disease in sea turtles (Haines and Kleese, 1977; Leong et al ., 1989;
Caillouet et al ., 1997). Water temperature at the NMFS SFT is maintained within
the range of 26–30∞C (Figure 16.2). Water temperature is maintained by mixing
warm (heated) and cold (ambient) seawater to the desired temperature. Air temperature over the tanks is also controlled using forced-air heaters in cool months and
ventilation fans in hot months. The air temperature in the facility is 29–32∞C at night
(maintained by heaters in cool months) and is reduced to 24–26∞C during the day
to provide a more comfortable environment for captive rearing staff. In months where
heating the air is not required, the facility remains at a constant 28∞C day and night
with the assistance of exhaust fans and cross-flow ventilation. Temperature is measured with a thermometer, accurate to 0.5∞C.
When the temperature falls below 22°C, turtles that are normally maintained
at 26–30°C will slow or cease feeding. At temperatures above 32°C, water quality
becomes an issue because algae and bacteria populations can rapidly multiply in
the raceways. Sea turtles that are normally maintained at temperatures 24–25°C
may tolerate temperatures as low as 20°C before exhibiting signs of reduced
metabolic activity. Sea turtles should be maintained at 20–30°C (FWC, 2002),
preferably in the range of 25–30°C. Even short periods of water temperatures
below 22°C combined with shorter photoperiods in winter months can trigger
carapace lesions in loggerheads (Higgins, unpublished data). The carapace lesions
can be characterized by a white fluffy exudate that appears to grow from the
eroding neural and postmarginal scute spines. Outbreaks are directly related to
water temperature and water quality. The lesions, if left untreated, result in keratin
1123_C16 Page 418 Tuesday, November 12, 2002 8:28 AM
The Biology of Sea Turtles, Vol. II
immersion heater (14,000 W). Each heater is connected to a temperature-control
unit, allowing the tanks to be adjusted independently. There is no active filtration
or treatment of any kind in the seawater system. The well points below the sand
remove large particles from the water. Settling in the sump and large holding tanks
removes most particulate matter, suspended algae, larvae, and some bacteria from
the seawater. Further settling in the eight smaller water storage tanks removes the
remainder of suspended sediment. The NMFS STF uses approximately
37,854–68,137-l of new seawater daily. Wastewater is discarded into the city of
Galveston sanitary sewer system.
From late September through April, the NMFS STF heats seawater. Seawater is
heated to approximately 38–43 ∞ C in three of the four 26,000-l storage tanks. Hot
water is mixed with ambient water 10–26 ∞ C by manipulating hot- and cold-water
valves to achieve an incoming water temperature of 26–30 ∞ C with a target of 28.5 ∞ C.
16.4 ENVIRONMENTAL PARAMETERS
The STF uses natural seawater in a static system where water is exchanged in each
tank three to six times per week. Three water quality parameters are monitored and
recorded daily: temperature, salinity, and pH.
16.4.1 T EMPERATURE
Maintaining a constant and acceptable temperature is critical for growth and for
preventing disease in sea turtles (Haines and Kleese, 1977; Leong et al ., 1989;
Caillouet et al ., 1997). Water temperature at the NMFS SFT is maintained within
the range of 26–30∞C (Figure 16.2). Water temperature is maintained by mixing
warm (heated) and cold (ambient) seawater to the desired temperature. Air temperature over the tanks is also controlled using forced-air heaters in cool months and
ventilation fans in hot months. The air temperature in the facility is 29–32∞C at night
(maintained by heaters in cool months) and is reduced to 24–26∞C during the day
to provide a more comfortable environment for captive rearing staff. In months where
heating the air is not required, the facility remains at a constant 28∞C day and night
with the assistance of exhaust fans and cross-flow ventilation. Temperature is measured with a thermometer, accurate to 0.5∞C.
When the temperature falls below 22°C, turtles that are normally maintained
at 26–30°C will slow or cease feeding. At temperatures above 32°C, water quality
becomes an issue because algae and bacteria populations can rapidly multiply in
the raceways. Sea turtles that are normally maintained at temperatures 24–25°C
may tolerate temperatures as low as 20°C before exhibiting signs of reduced
metabolic activity. Sea turtles should be maintained at 20–30°C (FWC, 2002),
preferably in the range of 25–30°C. Even short periods of water temperatures
below 22°C combined with shorter photoperiods in winter months can trigger
carapace lesions in loggerheads (Higgins, unpublished data). The carapace lesions
can be characterized by a white fluffy exudate that appears to grow from the
eroding neural and postmarginal scute spines. Outbreaks are directly related to
water temperature and water quality. The lesions, if left untreated, result in keratin
1123_C16 Page 418 Tuesday, November 12, 2002 8:28 AM