As seasons change and temperatures shift outside, subtle changes are made inside the National Aquarium to ensure that the animals in our care feel right at home. By adjusting the lighting and temperatures in Aquarium habitats, as well as the food and materials available, staff members encourage animals to maintain natural rhythms and exhibit innate behaviors.
In Shark Alley, the water stays a steady 77.5 degrees throughout the year, but the exhibit lighting—which simulates dawn and dusk—changes with the amount of daylight hours outside. In the summer, the lights in Shark Alley start coming on at 7:30 am and powering down at 9:30 pm. By the time December comes around, the lights start coming on two hours later in the morning and power down 30 minutes earlier at night.
The lights take about 90 minutes to power up to full brightness and power down to full darkness. The light schedule is primarily geared to benefit the sand tiger sharks, which are typically found in temperate and tropical coastal waters. Unnatural changes in light and temperature are known to cause stress, so mimicking the changes that occur in these sharks’ natural environments is crucial.
Other Aquarium exhibits, such as Australia: Wild Extremes and Upland Tropical Rain Forest, do not allow for the same control over light because of the natural light that comes in through the glass ceilings—but that doesn’t mean that other seasonal changes cannot be created!
One of the birds in Australia: Wild Extremes, the fawn-breasted bowerbird, gets its name from the U-shaped tunnels—or bowers—made of twigs and sticks that males build in their natural habitats to attract mates. In the exhibit, our curators increase the available bower materials in May, June and July to help the male create his bower, even though he works on it all year long! Staff offer the bowerbird green craft paper, toy pieces and fake leaves to help him decorate his bower.
In Upland Tropical Rain Forest, seasonal changes can also be signaled through birds’ diets! After a wet season in the rain forest, there is an abundance of bugs present. Here at the Aquarium, staff mimic this change by offering the birds on exhibit—such as the red-capped cardinal—more insects, and a larger variety of them, to feed on.
In Dolphin Discovery, marine mammal staff have begun preparing the Aquarium’s colony of seven dolphins for its transition to an outdoor sanctuary by fluctuating the water temperature seasonally. In the winter, water temperatures are about 72 degrees, while the water in the summer is as high as 85 degrees.
Changing water temperatures as the seasons change helps prepare the dolphins for their future sanctuary home in a tropical habitat. Water temperatures in these habitats vary throughout the year, but bottlenose dolphins are very adaptable to a wide range of water temperatures—anywhere from 50 to 90 degrees.
Learn more about the exhibits at the National Aquarium!