Glacier Bay National Park & Preserve National Park Service U.S. Department of the Interior The Kelp Forest

People who come to the Visitor Center at Glacier Bay National Park & Preserve are often surprised by the lush spruce-hemlock forest that surrounds them. It’s easy to see how important the forest is to its inhabitants as a home: squirrels, birds, bugs, even people! Kelp Forest

But, how many of us have actually explored an underwater forest? Instead of trees, bushes, and mosses, Glacier Bay’s underwater forests are composed of different types of algae that are just as important as homes for underwater creatures. Kelp Forest

So, what are algae? Algae are similar to plants in some ways, but different in others. Algae are generally more simple organisms than plants. However, both plants and algae make food using the sun with photosynthesis. Kelp Forest

The larger algae found in the underwater forest are kelps, or brown algae. In Glacier Bay, common types of kelp include Bull Kelp (Nereocystis leutkeana) and Giant Kelp (Macrocystis pyrifera). These organisms can grow to be over 100 feet in length! Kelp Forest

The structure of kelp can be compared somewhat to that of plants: they include a holdfast, a stipe, pneumatocysts, and fronds. Kelp Forest

The holdfast of kelp is similar to the roots of plants because it attaches the kelp to the surrounding environment, like rocks. Unlike roots, the holdfast does not funnel water and nutrients to the rest of the kelp Kelp Forest

Being less complex than plants, algae have no plumbing to transport nutrients. Instead, nutrients are absorbed by the entire organism directly from the water. Kelp Forest

Like a tree trunk, the kelp stipe allows it to reach up high to absorb sunlight. Algae use the sun to make food in the process of photosynthesis, just like plants. The stipe is hollow and filled with air, so that it can float to the surface of the water to reach the sun’s rays. And, because of the strong currents in the water, the stipe is flexible to allow for movement. Kelp Forest National Park & Preserve National Park Service U.S. Department of the Interior

In addition to having a hollow stipe, kelp often has pneumatocysts (pneu=air/cyst=ball), which are like balloons which hold the kelp up to get more sunlight. In contrast, plants are more solid and do not need anything like a pneumatocyst.

Finally, the fronds of the kelp are similar to leaves as they collect sunlight for photosynthesis. Fronds also release spores, the algal equivalent of seeds. Kelp Forest

In many ways, the underwater forests of Glacier Bay are very similar to forests on land. Both types of forests have a structure that includes a canopy, a middle layer and a forest floor Kelp Forest

The canopy of the underwater forest is a special place. It is where the kelp collects sunlight for photosynthesis (just like the plants in the forest). In Glacier Bay, birds like this Glaucous-winged gull can be found resting on top of the forest canopy as they search for food beneath the surface of the water. Kelp Forest

In the middle layer of the underwater forest, many creatures come to find food and hide to keep from becoming food! Long-lived fish like these rock fish, are always on the look out as they glide through on their search for food to eat, hoping not to be seen by the birds above or other creatures below. Kelp Forest

The forest floor is a busy place, crowded by crabs, urchins, and sea stars searching for food and shelter among the kelp holdfasts. In fact, several hundred creatures can be found living in and on one single holdfast! Kelp Forest

Sea urchins are like the cows of the ocean: they graze on kelp all through the day! In the past, urchins ate so much kelp that there weren’t many kelp forests in Glacier Bay, creating “urchin barrens”. But where urchin barrens once dominated the underwater landscape, kelp forests now flourish! Why? Glacier Bay is always changing, both above and below the water’s surface. Kelp Forest

No one was grazing on the urchins. But, now the urchin grazer has returned! This particular grazer will eat up to 25% of its body weight a day, because, unlike other marine mammals, this critter has no blubber to keep it warm. Who is this mystery creature? Kelp Forest

For many years, the sea otter was absent from Glacier Bay’s kelp forest, having been hunted by fur traders nearly to extinction. But, a repopulation project reintroduced them to the area in the 1960s. It wasn’t until the 1990s that sea otters were documented in Glacier Bay again. As of 2003, there were over 1,800!

So, what does that mean for the urchins? Researchers have been studying the effects that sea otters are having on the underwater forests of Glacier Bay, finding that kelp forests are increasing, while some of the inhabitants of kelp forests might decrease somewhat- including those sea urchins!

Sea otters aren’t the only creatures who affect the underwater forest in Glacier Bay. Sea stars are also voracious predators on the forest floor, consuming their share of sea urchins and affecting the growth of the kelp forest. Kelp Forest

Researchers are finding that the kelp forest is a much more diverse place when sea stars are the main predator than when sea otters are at the top of the heap. Which is better? Kelp Forest

Who knows! But, in a wild place like Glacier Bay, researchers and visitors alike have the opportunity to learn about how these changes occur- both under and above the water! Kelp Forest

Glacier Bay’s underwater forest is obviously an important place for creatures like gulls, urchin, sea otters and crabs. But, what about humans? People can’t live in the kelp forest like they can in forests on land. So, do kelp forests have any benefit for humans? Kelp Forest

Absolutely! For hundreds of years, people have been using the underwater forest of Glacier Bay. The Tlingit people who call Glacier Bay home knew that kelp forests were a great place to fish or to collect fish eggs on kelp fronds. Kelp Forest

Like Tlingit paddlers, modern kayakers also know that the kelp forest is a refuge from strong currents, and that kelp pickles are a great after-paddling treat! Kelp Forest

Outside of Glacier Bay, people harvest kelp to use as a thickener called “algin” in many common products like ice cream, toothpaste, paint, and lotion- items we use every day! Kelp Forest

Our journey through the underwater forest of Glacier Bay must come to an end for now. However, the National Park Service will be busy ensuring that this incredible place will continue to grow and change just like us! So, come visit us again one day to see what else is in store beneath the surface. Kelp Forest