The Upland Tropical Rain Forest exhibit is temporarily closed through Fall 2022.


Winter 2021

Welcome to Watermarks

In this issue of your exclusive multimedia National Aquarium member magazine, we are taking a look at the unique species and places that make our region—and the Aquarium itself—such a special place.

In This Issue

From the scenic shores of Assateague Island to the waters lapping at our very own piers, this issue of Watermarks offers a closer look at special places and species that shape the National Aquarium's work and mission.

Birds of a Feather

The birds in our Sea Cliffs exhibit have drastically different appearances depending on the time of year, thanks to a process called molting...

Learn More

VP of Conservation Programs Laura Bankey...

Floating Wetlands: Five Lessons Over Ele...

Kai's Kids

Amazing Alcids

The National Aquarium's amazing alcids—puffins, black guillemots and razorbills—display fascinating and significant seasonal molting patterns. With the help of our gifted staff photographers, we're ruffling some feathers and taking a closer look.

Aquarium Inside Out: Laura Bankey

The latest installment of our Aquarium Inside Out series follows National Aquarium VP of Conservation Programs Laura Bankey to Assateague Island National Seashore where she explores the incredible biodiversity of a protected mid-Atlantic barrier island in fall.

Photo: Sanderlings are small shorebirds that migrate from the Arctic Tundra to Assateague Island National Seashore and other mid-Atlantic beaches during fall and winter.

Reading the Reef: Sharks, Climate Change and You

Biodiversity—like the numerous species teeming around our Blacktip Reef exhibit—is an important indicator of ocean ecosystem health. See what sharks mean to a reef system and how their presence or absence relate to climate change, and how our choices can make all the difference within these fragile blue spaces.

Five Lessons Learned from Our Floating Wetlands

The Aquarium's thriving floating wetland prototype is far more than a grassy raft. In fact, this cutting-edge island has proven to be both a return to our region's pre-industrial habitat and a look at what the future might hold.

Photo: For eleven years, our floating wetland prototypes between Inner Harbor Piers 3 and 4 have taught Aquarium experts about the health of the Inner Harbor.

Internationally Renowned Oceanographer Sylvia Earle

"I consider aquariums to be an essential part of educating the public at large. I hope this place is like a halfway house to get to the BIG Aquarium—the ocean itself—to let people see what they otherwise would not see. I thank you for being ambassadors for the ocean."

Sylvia Earle addressing our staff and volunteers during her visit on December 1, 2021.

Kai's Kids

Meet thoughtful local brothers making a run for the money to support our cross-team efforts to help green sea turtle Kai find some balance as we work to perfect a shell prosthetic that will allow her to dive naturally.

Photo: Kai, a rescued green sea turtle, is receiving cross-team attention to manage buoyancy issues resulting from an injury.

Ask the Expert

Lizzie S. Asked:

"Sometimes when we visit the National Aquarium, the water in the Inner Harbor is a cloudy green color. Other times, it looks normal. What causes this?"

We Answered:

Sulfur bacteria live happily on the bottom of the harbor where there's a tiny bit of sunlight and no oxygen. When we experience a really hot day followed by a cold night, like we often see in September and October, the sharp temperature change affects the density of brackish salt water. This causes surface water to sink rapidly, displacing the water at the bottom, which is then brought to the surface. When the sun rises the next day, the bacteria harvest sunlight to perform anoxygenic photosynthesis—or photosynthesis without the production of oxygen. The waste product of this process is hydrogen sulfide, which has a characteristic smell of rotten eggs. The chemical reaction between the sulfur bacteria and sunlight also results in a bright green color, which is why this bloom is often referred to as a "pistachio tide."

-Charmaine Dahlenburg, National Aquarium Director of Field Conservation

Do you have a science, animal or conservation question for National Aquarium experts? Email us at, use the subject line "Ask the Experts" and you might see your question in our next issue of Watermarks.

Support the National Aquarium Together, we can change the way humanity cares for our ocean planet.

Interactive 3D Aquarium Tour

Whether you’d like to relive your most beloved National Aquarium moments, plan your next visit or just explore from the comfort of your couch, check out our interactive 3D tour. Click-by-click, you can navigate your way from our front door to your favorite exhibits and everyplace in between. What are you waiting for? Hop in and take a look around!

National Aquarium President & CEO John Racanelli

"While 2021 was indeed a challenging year, we shifted from surviving the present to once again planning the future. Now, our attention can turn to thriving in 2022. None of this optimism would be possible without the support of our members. I applaud your loyalty and continued dedication to supporting our vision to change the way humanity cares for our ocean planet. We wish you a joyful holiday season and look forward to seeing you often in the new year!"

More from Past Watermarks

News 40th Facts: How Well Do You Know the National Aquarium?

News Our Evolution

Animals Rare Turtle Hatchlings Grow, Learn—and Teach

Online Gift Shop Apparel & Gifts

Browse our online gift shop for tees, hats and more featuring commemorative 40th anniversary artwork, sea turtles and sharks! Plus, all sales support our important field conservation and animal welfare efforts.