Posts Tagged 'science'

Saltwater Science at the National Aquarium

Just add salt? Not quite. Here’s the inside story on how we get our water just right: 

As vibrant fish residents swim gracefully in their aquatic habitats at the National Aquarium, the most important element of their exhibit homes – the water – often goes unnoticed.

national aquarium clown triggerfish

In total, more than 2 million gallons of water are perpetually pumped, filtered and re-pumped within the Aquarium’s nearly 200 water systems. For perspective, the average bathtub holds 50 gallons of water, making the National Aquarium’s water content roughly equal to 40,000 bathtubs!

Maintaining the quality of these millions of gallons of water is essential for healthy animals, and it is through the tireless work of dedicated aquarists and laboratory and life-support staff that we can provide the highest quality of water to the thousands of marine animals that call the Aquarium home.

Testing the Water

In every high school across the country, chemistry teachers illustrate water’s elemental simplicity by connection to Hs to one O. Sustaining life at the Aquarium, however, as in the oceans, is infinitely more complex. Salinity (the amount of salt), dissolved oxygen (the “air” fish absorb through their gills) and nitrates (waste product) all affect water chemistry.

That chemical balance, in turn, affects those plans and animals on exhibit, as well as fungi and bacteria that cannot be seen with the naked eye. Presenting a healthy environment by maintaining the absolute best water quality for each and every exhibit and backup tank requires a well-coordinated effort between staff across departments.

Each morning, aquarists, under the guidance of water quality expert Kim Gaeta, extract samples from select exhibit spaces. Those samples are then labeled and deliver to the lab, where they are test for ammonia, nitrite and salinity, as well as pH and alkalinity. If there’s a noticeable imbalance, staff, under the watchful eye of Laboratory Services Department supervisor Jill Arnold, diagnose the problem and prescribe a solution.

The Right Water

Nearly all of the water in our exhibits is homemade seawater. The National Aquarium, like most Aquariums, manufactures its own. The millions of gallons circulating through the exhibits are a combination of Baltimore City water and a house blend of salts.

Consequently, these salt solutions affect the pH, dissolved oxygen levels and hardness of the seawater, based on their own specific chemistry. Tons of salt is shipped to the Aquarium every year to be used in the manufacturing process. At a cost of about 7 cents per gallon, we spend roughly $150,000 every year to manufacture seawater.

“The Aquarium utilizes a variety of food-grade salts to prepare artificial seawater, using our proprietary formulation developed by our chemist,” says Arnold. “Our goal is to mimic natural ocean waters as closely as possible,” guaranteeing all of our animals a healthy place to call home!

Our hand-crafted saltwater is just one of the many things we do everyday to give our animals the best quality of care possible. Here’s how YOU can support our efforts this holiday season! 

New ‘Walking’ Shark Species Discovered in Indonesia!

A new species of epaulette (carpet) shark was recently discovered off the coast of an island in Indonesia!

New species of epaulette shark. Photo via Conservation International.

New species of epaulette shark. Photo via Conservation International.

The walking shark, Hemiscyllium halamhera, was first seen walking along the sea floor by divers in 2008. Only recently has it been officially recognized as a new species.

This is the third walking shark species found in Indonesia in the past six years! Walking sharks use their fins to navigate along the sea floor in search of small fish and crustaceans. Watch a walking shark do its thing: 

Although new species are discovered almost daily, this finding has given the conservation community new hope for the future of Indonesia’s elasmobranchs (sharks and rays). The local government and emerging dive tourism industry are excited by this discovery and have taken precautions to protect these sharks!

There are nine known species of walking shark in the world, all of which inhabit the shallow waters of very restricted ranges.

Got a question about this new discovery for our experts? Ask them in the comments section! 

Diane Rehm’s Environmental Outlook: Jellyfish And The Health Of The Ocean

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Earlier today, I spoke to NPR’s Diane Rehm about jellies and the impact that jellyfish population increases and expansion of some species’ geographic ranges are having on the health of our oceans.

Jack Cover at Diane Rehm show

With Bill Dennison and Diane Rehm at NPR.

Jellyfish first appeared around 560 million years ago (long before the time of dinosaurs). They’re 95 percent water, have no brains and no bones and no heart or blood, yet these gelatinous animals are among the worlds’ most resilient organisms.

The jellies simple body plan has remained relatively unchanged. But lately some scientists are concerned the animals are thriving too well – overrunning marine ecosystems, forcing nuclear power plants to shut down and filling the nets of commercial fisherman and shutting down fisheries around the world.

Some of the jellyfish species on exhibit here at the Aquarium.

Jellyfish species from top left (clockwise): blue blubber jelly, upside down jelly, spotted lagoon jelly, Leidy’s comb jelly

There are both ecological human-related issues causing an “explosion” of jellyfish populations around the world.

  • Over the years, climate change has raised the average temperature of the ocean. While this rise has negatively impacted organisms like coral, warm season jellies start breeding earlier and have longer active seasons.
  • Human activities, such as the over-fertilization of our lawns and farms, results in a runoff of excesses of nutrients into the Chesapeake Bay and ocean. This results in what’s known as an algal bloom. When the algae absorbs all of this nutrient run-off, it dies. Bacteria then feeds on the dead algae and removes all dissolved oxygen from the water – this process is called eutrophication and produces “dead zones.” Fish and crabs perish in these dead zones, but not the resilient jelly. Jellyfish can survive with low oxygen levels!
  • Jellyfish are opportunistic feeders. When food, like zooplankton, is abundant, they will grow rapidly and reproduce at a rapid rate. Excessively large jellyfish populations can out compete young fishes that also feed on zooplankton.
  • Some scientists speculate that the reproduction of jellyfish predators may also be giving jelly populations a boost. For example, all seven species of sea turtle will opportunistically feed on jellyfish when they are encountered. The largest species of sea turtle, the leatherback, feeds almost exclusively on jellies. Pacific populations of leatherbacks are currently at about 7 percent of their historic population levels. Human activities are the cause of sea turtle population declines. Overfishing has reduced fish populations that also feed on jellies.

To listen the full “Environmental Outlook” segment on Diane Rehm’s show, click here

Jack Cover


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