Corals in Glacier Bay

Juvenile pollock surround a red tree coral in Glacier Bay. Coral communities support a diverse range of marine life.

 

A sculpin rests on a large red tree coral in Glacier Bay.

Supporting a Diversity of Marine Life

Glacier Bay is home to many marine species including several coral species! One of those corals is the stunning red tree coral. Much like tropical corals, cold-water corals create important habitat for wildlife. Coral colonies like the red tree coral are made up of millions of individual polyps that build a soft flexible skeleton out of Calcium Carbonate and can live for hundreds of years. When Red Tree Coral are alive, their polyps are a bright peachy-orange color.

Scientists first documented red tree coral in Glacier Bay in 2010. They returned with a remotely operated vehicle (ROV) in 2016 to take a closer look! During that expedition they found thriving communities of Red Tree Coral in the deep waters of Glacier Bay, between 100 and 300 meters deep, as well as in shallower depths along the fjord walls. Red Tree Coral in the North Pacific exhibits “deep-water emergence” in several Southeast Alaskan fjords. “Deep-water emergence” is a phenomenon where marine species normally found at great depths can be found in significantly shallower depths, often in high latitude fjords, like Glacier Bay!

 

Immortal Coral?

Did you know? Coral is made up of individual organisms called polyps. If environmental conditions are good enough for coral to thrive, individual polyps may die, but corals can continue growing for thousands of years!
So, is coral immortal? In a way, it could be, but coral can be destroyed by human disturbance, geological events, and more.

 

Scientists observed a gradient of species diversity associated with Red Tree Coral in Glacier Bay, with higher diversity present in the Central Channel & lower diversity at the heads of glaciated fjords. This is due to a combination of physical and biological factors. Glacial sedimentation, nutrient availability, larval dispersal, and competition all factor into coral habitat.

Some of the marine life we found living among the corals were sculpin, schooling fish, nudibranchs (marine slugs), sea sponges, anemones, other species of corals like solitary cup corals and encrusting stoloniferous coral, brachiopods, octopuses, crabs and shrimp, the list goes on!

 

A large primnoa pacifica, aka red tree coral, on the sea floor.

Image courtesy of the NOAA Deepwater Exploration of Glacier Bay National Park expedition and UCONN-NURTEC.