Posts Tagged 'jack cover'

Underwater City: The Hustle and Bustle of Coral Reefs

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Bright, beautiful and overflowing with life, coral reefs are among the most incredible natural wonders in the world. 

national aquarium coral reef infographic

Often thought of as rocks or plants, corals are actually made up of invertebrates called polyps. These polyps can range in size from a millimeter to a foot in diameter. The polyps group together, forming a colony, and use calcium carbonate from the ocean to build a protective skeleton.

Generally, corals are classified as either hard or soft corals. Hard corals are the framework of the reef. As these corals grow in colonies, they create skeletons. Soft corals are soft and bendable, looking more like plants. These organisms form a visually stunning and biologically important foundation for many ocean inhabitants, from tiny fish to large apex predators like sharks.

Though coral reefs constitute less than one percent of the ocean floor, they support an estimated 25 percent of ocean life. They are incredibly bio-diverse, and provide critical spawning, nursery, breeding and feeding grounds for thousands of species. And, according to a report by the World Research Institute, 75 percent of the world’s reefs are considered threatened.

The Value of Coral Reefs

The loss of thriving coral reefs has real consequences, and not just to their many inhabitants. Besides being essential habitats for fish, coral reefs have a measurable value to those who live on land.

Because they essentially serve as mountain ranges for the ocean’s coastlines, they deflect the energy of brutal storms that might otherwise decimate coastal communities. In fact, in areas where we have experienced tsunamis, the areas with coral reefs fared much better than those without.

Chemical compounds unique to coral reefs are especially useful for medicinal purposes. Researchers have used coral amalgams to treat ailments including ulcers, skin cancers and heart disorders. Once the correct formula is identified, the medicines can be mass-produced synthetically.

And of course, the natural beauty of coral reefs makes them attractive for tourists, too. Visitors from all over the world flock to the Florida Keys, Barbados, Indonesia, Australia and other destinations to get a closer look. Most of these areas rely heavily on tourism for economic growth and sustainability, so preserving coral reefs is vital for their economies.

All told, the economic value of coral reefs has been estimated to be $375 billion per year.

Reef in Danger

Sadly, coral reefs are highly threatened. Storm damage, invasive species, climate change, coastal development and commercial use are just a few of the threats. Corals are extremely sensitive, so even small sifts in light, temperature and water acidity can be detrimental. Many of the choices that we make every day contribute to the devastation of coral reefs. Coral is able to grow and repair itself, but needs precisely the right environment to do so.

In order for many coral species to thrive, they must have exposure to bright sunlight. Clear-water environments are necessary for corals to receive the maximum amount of direct light. Pollution in our water from runoff and other chemicals can cause excessive amounts of algae to grow on its surface. This process, called eutrophication, clouds the water and prevents coral from getting the sun that it needs.

In addition to chemical pollutants, coral reefs are also threatened by ocean acidification caused by the burning of fossil fuels. This process sends a deluge of carbon dioxide into the air, forming carbonic acid. Destructive fish practices, such as the use of cyanide to attract specific types of fish, also contribute to the devastation of coral reefs.

To respond to the threat of ocean acidification, the XPRIZE Foundation launched the $2 million Wendy Schmidt Ocean Health XPRIZE last year. This new contest, developed with help from the National Aquarium and other leading ocean healthy organizations, aims to spur innovators to develop accurate and affordable ocean pH sensors that will ultimately transform our understanding of one of the greatest problems associated with the rise in atmospheric carbon dioxide.

While the future of coral reefs may appear bleak, there’s still a lot we CAN do to protect these aquatic treasures! 

Jack Cover

Adventures in Jellyfish Collecting

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When planning what species to display in Jellies Invasion: Oceans out of Balance, we knew it would be important to include species found in local waters. To keep our exhibits full of jellies, National Aquarium staff venture out to the Chesapeake Bay throughout the year to collect the following local species: Atlantic sea nettles (Chrysaora quinquecirrha), Leidy’s comb jellies (Mnemiopis leidyi) and Lion’s mane jellies (Cyanea capillata).

Our most frequented spot for jellyfish collecting is on the Eastern Bay, off the southeast end of Kent Island. This past weekend, we launched from my family’s waterfront property located in the southeastern region of the island. My nephew, Joe Cover, Jr., a resident of Kent Island and an avid fisherman, is my unofficial jellyfish monitor/assistant. He keeps me posted on when and where he is seeing groups of jellies.

Ideal jelly-collecting conditions include a moving tide (to raise jellies to the water’s surface), little to no wind and a cloudless sky (the mostly transparent Leidy’s comb jelly is almost impossible to spot when the sky is overcast). There are times when you believe the conditions are ideal, yet few or no jellies are found at the surface. When this happens, my standard line is, “You know, we have just been outsmarted by an animal that has no brain.”

jellies collecting trip 2013

We were glad to see calm waters and no clouds this past Saturday!

Equipped with collecting bags, five-gallon buckets, glass beakers and special plastic jelly-collecting nets, we motored out to the middle of Eastern Bay. The water was a bit choppy, but I stopped the boat as soon as I saw a “slick,” a narrow band or area of still water among the light waves. Natural slicks are sometimes formed when concentrations of microscopic diatoms gather at the surface and release natural oils that change the surface water’s density and retard the formation of ripples and small waves.

As we slowly drifted along with the wind and tide, we started to see Atlantic sea nettles and large Leidy’s comb jellies (a whopping 3 to 4 inches long) pulsing along the surface. We were in the right place at the right time! Upon further examination of the water’s surface, we saw thousands of tiny copepods (zooplankton) gathered – another great sign! Jellies continued to surface to feed on the copepods and, in some cases, each other. Yes, some jellyfish (like Atlantic sea nettles) include other jelly species (Leidy’s combs) in their diets.

I started filling collecting bags placed in five-gallon buckets with Bay water.

jellies collecting trip 2013

Jellyfish have no bones and little body structure. In fact, 96 percent of a jellyfish’s body is water! A delicate jelly can easily be injured if it is removed from the water or rubs against any abrasive surface. To avoid injuring our specimens, we used smooth-sided beakers to corral the jellies. The jelly is then moved, in water, to one of the water-filled plastic bags in a bucket. The beaker is submersed into the bucket and tilted to gently release the jelly.

jellies collecting trip 2013

Care must be taken to prevent the creation of air bubbles, which can get trapped in the jelly’s tissues and injure it. This is why beakers containing jellies are not poured in from above the water’s surface. Leidy’s comb jellies are especially fragile and must be transported with extra care.

In addition to their delicate body structures, quick temperature changes can be detrimental to jellyfish. It was relatively cool on this sunny afternoon, and the water in the buckets was staying close to the temperature of the Bay water. In a relatively short period of time, we filled six five-gallon buckets to capacity with jellies.

We headed back to the dock to prepare the buckets for transport to the Aquarium’s Jellies Lab. Prior to loading the buckets into the car, air is removed from each bag, which is then sealed with a rubber band. After loading up the car, I headed back over the Bay Bridge to the Aquarium. The car’s air-conditioning kept the jellies at their preferred temperature.

Once at the lab, the buckets of jellies are unloaded and the rubber bands are removed to allow gas exchange to the water.

The final leg of the jelly-collecting process is to slowly acclimate these jellies to the water in an exhibit or holding tank. I hand this part of the journey off to the Jellies staff. All incoming jellies need to be slowly acclimated to both the temperature and the salinity of our exhibit water. This process can take several hours or several days depending on how the salinity of the Bay and our exhibit waters compare.

Jellyfish continue to fascinate and amaze our visitors. We’re glad to provide our jellyfish gallery as a wonderful resource to connect people with our local jellies!

Jack Cover

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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