1. The Marine Ecosystem

2. Ocean Overview
Oceans cover three quarters of the Earth's surface, and they are as diverse as they are large.
The ocean is a complicated ecosystem, with very complex food chains and animals that have adapted to a variety of conditions.
The ocean is home to the smallest plankton and the largest creature on earth, the blue whale.

3. Ocean Zonation
Because sunlight powers life on Earth, one way the ocean is subdivided is based on the amount of light present. The light zones are:
The Euphotic (Sunlit) zone
The Disphotic (Twilight) zone
The Aphotic (Midnight) zone

4. The Sunlit Zone The ‘top layer’ of the ocean Goes down to about 600ft
Is the only zone where photosynthesis can occur
More than 90% of all marine life is in this zone

5. The Twilight Zone 600-3000 feet below surface
Light decreases and pressure increases
No plants in this zone (not enough light)
Animals have adapted to dark waters
Bioluminescence

6. The Midnight Zone 90% of ocean water is in this zone NO LIGHT
Very high pressure
Temperatures near freezing
Small amount of life in this zone thrives near thermal vents in the ocean floor

7. Life of the Sunlit Zone (Euphotic)
Many types of aquatic plants and algae
Marine mammals, such as seals, whales and dolphins
A variety of fish
Lots of invertebrates
Plankton, which make up the basis of the marine food chain
Most things you think of living in the ocean are in this zone

8. Life of the Twilight Zone (Disphotic)
Lantern fish
Viperfish
Hatchet fish
Mid-water jellyfish
Oarfish(some can grow as long as a school bus!)
Some squid and fish can use their own bodies to make light
This is called bioluminescence

9. Life of the Midnight Zone (Aphotic)
Angler fish
Sea cucumber
Gulper Eel
Opposum shrimp
Vampire squid
Everything in this zone is nourished by bacteria that live by nutrient rich thermal vents in the ocean floor

10. Other important terms
Pelagic: The water part of the ocean (not near the bottom or shore)
Neritic: water from high tide to 600 ft (coastal)
Oceanic: water deeper than 600 ft (open water)
Benthic:ocean bottom
Intertidal:area that is exposed to air at low tide
Subtidal:area of shore covered by water at high or low tide

11. Alaska’s Marine Life
Alaska is surrounded by a lot of water, and the coast line of Alaska is longer than that of the rest of the United States!
There are many types of animals that live in Alaska’s waters or on the coastlines, but the three main classes we will talk about are:
Birds, mammals and fish 

12. Coastline Birds
Alaska is widely recognized as a global center for shorebirds
Ninety percent of the migratory species in the Western Hemisphere have breeding populations in Alaska
Examples are: sandpipers, terns, plovers and puffins.

13. Marine Mammals Cetaceans: Whale, dolphins and porpoises
completely aquatic mammals
body is streamlined
breathe through nostrils (blowhole) on top of the head
grouped into two suborders
Baleen whales
Toothed whales

14. Marine Mammals Baleen Whales Toothed whales Right whales, rorquals,
gray whales
Toothed whales
Sperm whales, beaked whales,
dolphins, beluga whales and porpoises

15. Marine Mammals Pinnipeds: Seals, Sea Lions and Walruses
Pinniped means ‘flipper foot’
carnivores that have adapted to an amphibious marine niche
come ashore or onto ice at some time of the year to mate, give birth, nurse their young
four webbed flippers used to propel their spindle-shaped bodies
many are capable of long, deep repetitive dives (to 4500 ft depths and 2 hours).

16. Marine Mammals Crabeater Seal Bearded seal Northern fur seal
Stellar Sea Lions
Walrus

17. Marine Mammals Fissipeds: Sea otters and polar bears
Fissiped means ‘split foot’
more closely related to terrestrial carnivores
lack many of the physiologic adaptations to marine life seen in pinnipeds and cetaceans
Both species are considered marine mammals under U.S. laws because of the roles they play in the marine environment.

18. Marine Mammals Polar bears (bear family Ursidae)
spend most of their lives associated with marine ice and waters
competent swimmers, but they are the marine mammal least adapted to aquatic existence
rest, mate, give birth, and nurse their young on the ice

19. Marine Mammals Sea otters (weasel family, Mustelidae)
live a primarily marine life
they rest, mate, give birth, and nurse their young in the water
hind limbs are webbed for swimming, but their front paws are padded with separate, clawed digits
lack blubber, but are insulated by air trapped in their thick fur, which is densest among all mammals.

20. Ocean Fish/Crustaceans
Many types of fish play an important role in Alaska’s marine environments.
Many are economically important, including halibut, salmon, pollock, and crustaceans such as crab and shrimp.

21. Mariculture Mariculture: farming or ranching of marine organisms
Most commonly farmed in AK is the Pacific oyster
Others are littleneck clams, mussels, scallops, sea cucumbers, and seaweed
Most commonly ‘ranched’
are salmon--hatcheries

22. Threats to the Marine Ecosystem
Pollution
Overfishing
Climate change