Imagine a world were darkness reigns.
Where a strange snow perpetually falls.
Where the whimsy of swirling currents determinine the patterns of life
and yet...life flourishes.
It is a world seen by few.
The Underwater World of Glacier Bay.
Glacier Bay National Park and Preserve
encompasses 3.3 million acres of fjords,
mountains, and ice.
it is a place where the earth still chafes
under the lingering effects of the Little Ice Age.
An evolving landscape partially released
from the grip of glaciers within the past three hundred years.
Every year thousands of visitors come to the bay for the scenery,
the wildlife
and the solitude.
Yet few will venture beyond the reflections of the landscapes
to the world beneath.
Join us as we travel into the underwater world of Glacier Bay
to discover some of its secrets.
Glacier Bay is a fjord. A valley carved by glaciers
now flooded by ocean water.
It is here in the mountains that the glaciers that carved the bay were born.
These rivers of ice flow down the mountainsides carving deep valleys in the bedrock.
Then in the 1700s
the glaciers began to retreat pulling back sixty miles into the interior
in the fastest glacial retreat in recorded history.
Seawater flooded the deep trench where the ice had been
leaving a long fjord
that exhibits some of the most complex oceanographic processes on earth.
The shallow uneven bottom left by the retreating glaciers at the narrow
entrance to the bay
and the extreme tides in Southeast Alaska combined to create a complex and
powerful system of
currents in the waters that flush into the bay from the Gulf of Alaska.
The underwater landscape mimics the contours of what we see on land.
the massive glaciers scoured the bay in some areas leaving depths of over
fourteen hundred feet.
Surface and deep water currents
and the nutrients they carry help determine just where
and how much life can be found these waters.
Glacier Bay is perhaps one of the most productive
fjord ecosystems on the planet.
This richness is due in large part to the presence of tiny plant-like organisms called
phytoplankton.
Smaller than a pinpoint, phytoplankton fuels virtually all life in this marine environment.
From the smallest copepod to giant humpback whales.
Some parts to the bay are much more hospitable to life than others.
Glacier Bay extends like a "Y" 65 miles into the surrounding mountains
in the upper reaches of the bay,
ice meets the sea.
as it moves
a glacier pulverizes the rock beneath it.
The resulting silt and clay are carried away by the streams and calving ice
that flow from the glacier.
This fresh water and ice release huge amounts of sediments
Underwater, it's a challenging world.
Here only a few hardy species can cope
with the harsh conditions.
any light penetration is limited by the extreme sediment
but phytoplankton reproduce in a thin rich surface layer
providing food for dense populations of barnacles and mussels that colonize the
few rocky areas available.
As we move into the depths,
the dim sunlight gives way to total darkness.
Visibility becomes obscured by a perpetual blizzard
of marine snow.
Made up of glacial silt and organic materials that clump together and
eventually sink to the bottom
marine snow transports nutrients from the surface
to deeper waters. The snow and years of sediment accumulation
blanket the bottom in powdery soft layers
that could be hundreds of feet thick
To survive in this moonscape, location is everything.
Considered prime real estate,
the few existing rocky outcroppings are colonized if conditions are right.
This lone soft coral
drifted in on circulating currents during its larval stage
and found the surface and food it needed to live.
A prickleback uses the deep sediments to make a home.
A basket star is well-suited to this environment.
Spreading its far-reaching tentacles
it collects plankton from the water.
This unique setting dominated by darkness is a place of biological
catastrophes.
For creatures that live attached to the bottom
there is no guarantee that conditions will not change.
A sudden increase in the freshwater runoff,
or sudden drop in the water temperature can doom whole groups of organisms.
Once a thriving colony,
all that remains of this group of barnacles is their now empty
exoskeletons which provide homes for shrimp and other small creatures.
If an animal can move it has more options.
A sculpin glides through the darkness
in search of its next meal.
The occasional Tanner Crab must keep on the prowl to find food.
Halibut prefer a silty bottom where they can lie partially buried
waiting for unsuspecting small prey.
If nothing comes along they will move on.
Born with a vertical orientation this flatfish
begins life with one eye on each side its body.
As it matures, one eye migrates to join the other.
And it develops a horizontal attitude, giving it a "Picasso-like" quality.
The silt-laden waters in this area teem with small schooling fish
and microscopic animals called zooplankton.
Obscured visibility makes it hard for predators to find them,
but shockwaves created during glacial calving
and the massive freshwater runoff
flush these creatures up from deaths where they become easy prey
for hungry seabirds.
What spells doom for some, provides sanctuary for others.
Over 4,000 harbor seals congregate each spring during pupping season on the glacial ice floes
their prime predator, killer whales
are seldom seen venturing into these ice- choked waters.
moving down bay
away from the glaciers changes in the landscape are apparent.
Plants begin to reclaim the land.
Beneath the reflections life has more opportunity
Throughout spring and summer
sunlight
penetrates the water surface
to a depth of 100 feet, sometimes more.
There is less sediment in the water making feeding easier.
filter feeders like these cloud sponges which must strain the water
through their cells. They have grown to enormous size.
Some reach more than three feet across.
Their Swiss cheese-like structure makes a perfect home
for this eelpout.
Currents deliver a constant supply of nutrients
which diffuse with the calm, sunlit surface waters of the mid-bay.
This is an ideal environment for phytoplankton
that need the sun and nutrients to photosynthesize.
They reproduce in such profusion that the water becomes
green due to the chlorophyll in their bodies.
The massive amount of phytoplankton will fuel large numbers of zooplankton
like these copepods.
This microscopic nutrient soup
is the basis for Glacier Bay's renowned productivity
Though odd in appearance at this phase, many of these larval zooplankton will develop
into more familiar creatures.
This larva will eventually mature into a Dungeness crab.
The hermit crab larvae which bears no resemblance to the adult
becomes the colorful crab.
After going through a complicated life cycle jellyfish larvae will develop
into beautiful jellies, provided they are not eaten first.
Everywhere you look in the mid-bay, it's dinner time
As if eager to gobble as much as it can, this sea cucumber barely takes time to
wipe its bushy tentacles before waving them around to gather more plankton.
Barnacles begin life as free-swimming larvae
and then settle in large colonies where they use their specialized legs to strain
nutrients from the water.
This sea pen unfurls its polyps in search of food.
Described by some as a roving stomach,
A comb jelly searches for zooplankton.
It propels itself through the water with a rhythmic movement of its cilia.
Tiny plates arranged like teeth of a comb
that run the length of its body.
The rippling cilia reflect all available light
outlining this predator like a neon sign.
The underwater world becomes a colorful mosaic of life.
Tubeworms, sponges, and chitons
compete for surfaces.
Triton snails continuously lay spirals of eggs.
Unable to build its own shell,
this hermit crab acquired an abandoned snail shell
and unwittingly picked up a group of hitchhiking barnacles in the process.
A forest of anemones marks an especially rich location.
By pumping water into their central cavities,
they can stretch their bodies to an incredible length
and be flexible in the currents.
At four feet high these animals tower over the seafloor.
Like a true eccentric, the decorator crab creates a
bold ensemble drawn directly from the world around it.
In its passion there is function.
This outfit helps the crab blend into its surroundings
keeping it safe from predators.
This is an "eat or be eaten" world.
A sunflower seastar, the largest of the seastars
reaching more than three feet across, prowls for its next meal
and settles for a sea urchin.
Mussels seek sanctuary from the voracious seastars in the intertidal zone
that area between high and low tides.
Though they are exposed to air twice daily,
mussels survive by taking in moisture
before closing their shells.
Their predators, the seastars, can only lurk beneath the waterline.
The readily visible browse line marks the extent of their hunting
forays into the mussels territory.
the intertidal zone hosts an extraordinary diversity of life
but like mussels, the organisms that live here
must cope with spending long periods out of the water when the tide is low.
Such exposure has its risks.
Almost every land creature that lives in Glacier Bay
has been seen eating here.
The native people of Glacier Bay, the Huna Tlingit have a saying.
---Tlingit Voice--
"When the tide is out, the table is set."
The lower bay is where the power of the tidal current plays its most dominant role.
The water here is never placid due to the strong tidal currents
passing over a shallow ridge left by the retreating glacier.
Swift currents keep the waters churning,
thoroughly mixing and distributing nutrients.
Zooplankton thrive, as do small schooling fish
that feed on them.
The abundance of these small schooling fish is staggering.
It is enough to draw humpback whales to the bay
each spring from their wintering waters near Hawaii.
An adult whale will eat about 2,000 pounds of these small fish every day throughout the summer.
And whales aren't the only things that eat them.
Gulls and phalaropes are ready to snatch up schooling fish that loiter at the surface.
Other animals such as sea anemones
allow the currents to bring food to them, cleaning up the scraps
Here in the lower bay the land has had the most time to recover from the
effects of the glaciers.
The streams run clear and are used by salmon as a nursery.
Two to four years ago these fish emerged from the streams as fingerlings
and fed on the zooplankton of the bay before finding their way
to the open ocean.
They have now returned to complete their life's journey.
The coves of the lower Bay provide the habitat of choice for Dungeness crabs.
The sandy bottoms prove ideal for these females brooding eggs.
After coupling with the males
females carry the fertilized eggs on their abdomens
and bury themselves by the scores in the loose sand as their eggs develop.
Many eyes watch for predators like the sea otter. When an otter gets too close for comfort
the crabs explode from the sand creating a confusion
that allows some to escape.
Glacier Bay National Park and Preserve also includes the 150-mile coastline
that stretches from Cape Spencer in the south to the Alsek River in the north.
It is a twisting shore.
Rugged and wild that must endure the full brunt
of storms that blow in off the Gulf of Alaska.
What forces rage above the surface contrast with the relative calm
of the underwater world.
Wave action scour the bottom of soft sediments
allowing the bull and giant kelp to readily find purchase.
After establishing a rock anchor
kelp, a brown algae, begins to photosynthesize and grow.
Its long hollow body
can grow over 5 inches per day reaching more than
30 feet in length.
Bull kelp is held aloft by a gas filled float.
The long blades streaming off the float form a canopy
creating a world of light and shadow
for creatures beneath.
The blades of the giant kelp grow along the stalk all the way to the bottom
creating an underwater forest that provides habitat for a myriad of animals.
Small snails and colonies of animals called bryozoans live on the blades.
This orange peel nudibranch grows to a length of seven inches.
it foils potential predators by secreting a toxic chemical
Rockfish hide in the maze from predators
Some, like this quillback exhibit highly territorial behavior.
Others such as the dusky rockfish form large schools.
The ling cod favors the dense kelp forest
to ambush its prey.
Kelp greenling add a splash of color to the scene.
On the surface, sea otters float among the kelp canopy.
In rough weather they may even wrap themselves in the blades
to keep from being washed ashore.
The presence of kelp forests and other algae depends in part
on the presence of sea otters.
Otters feed on sea urchins which are grazers.
The urchins move about the bottom in search of algae to eat.
Where urchins are plentiful, kelp does not flourish.
The return of the sea otter from near extinction in the late 1800s is responsible
for the lush kelp forests we see today.
Steller sea lions
patrol rocky reefs looking for fish and octopus.
these large predators can weigh up to one ton
and have formidable strength and speed.
The extremely large eye has tremendous light gathering capacity
so they can find prey in deep and dim waters.
The Giant Pacific Octopus leaves its den at night to feed.
Its camouflage is even more effective in the dark
helping it to avoid sea lions and other predators.
During the day it is rarely seen outside its rocky den.
Jellies are commonly found in these waters.
Their beautiful translucent bodies disguise the fact that these animals are
efficient predators
that come in an assortment of strange shapes and sizes.
Their tentacles contain stinging cells that immobilize and capture prey.
Some like this tiny stalk jelly
resemble plants and live attached to the kelp blades.
Each of its eight sets of tentacles
capture zooplankton that drift by.
The lion's mane jelly can grow to over six feet in diameter
with tentacles 30 feet long.
Its elegance belies its deadly sting.
Yet somehow the small medusa fish has earned a reprieve.
Immune to the jelly's poison it seeks protection
behind this curtain of death.
Humans have long enjoyed the richness of Glacier Bay and its outer coast.
It is the homeland of the Huna Tlingit
who celebrate its sea life in their art and legends.
Passed down from generation to generation
the strongman totem story tells of a sea lion
killing a village hunter whose death was then avenged by a nephew.
The nephew thought to be lazy and weak
grabbed the sea lion and ripped it in half became the village strongman
Local residents still bring the bay's bounty to many tables.
For still more it provides a feast for the eyes
and the mind
as only wildness can.
Even before its designation as a National Monument in 1925
the bay captured the imaginations of scientists
Today this national park, Biosphere Reserve, World Heritage Site, and Marine Reserve
continues to intrigue.
It is a living laboratory for researchers
trying to unlock it many mysteries and understand the delicate role
humans can play in balancing the use and preservation
of this very complex ecosystem.
The waters and the organisms that live here
know nothing of the designations bestowed upon them.
Currents and the life they carry swirl beyond boundaries and borders.
They connect to an ocean
that encircles the globe.
We cannot see nor do we understand all the intricate workings of the underwater world
But as we watch nature's dramas unfold each day
or as we marvel at the whales that return to the bay each summer
perhaps we can agree that there is something precious
in that mystery.
We can also acknowledge that what happens here and in the far reaches of the world's oceans
can touch us in ways that we can not yet fathom.
The choices we make today will determine
what our children will discover beneath the reflections tomorrow.
For what they find, will be a reflection
of ourselves.