1. Marine Ecosystems
Marine ecosystems
Why the Ocean Matters

2. Marine and coastal ecosystems
Regions of ocean water differ greatly
Some zones support more life than others
Photic zone = well-lighted top layer
Absorbs 80% of solar energy
Supports high primary productivity
Pelagic = habitats and ecosystems between the ocean’s surface and floor
Benthic = habitats and ecosystems on the ocean floor
Most ecosystems are powered by solar energy
But even the darkest depths host life
Deep Sea Life

4. Open ocean systems vary in biodiversity
Microscopic phytoplankton are the base of the marine food chain
Algae, protists, cyanobacteria
They feed zooplankton
Which then feed fish, jellyfish, whales, etc.
Predators at higher trophic levels
Larger fish, sea turtles, sharks, and fish-eating birds

5. Animals of the deep ocean
Animals adapt to extreme water pressure and the dark
Scavenge carcasses or organic detritus
Predators
Others have mutualistic relationships with bacteria
Some carry bacteria that produce light chemically by bioluminescence
Hydrothermal vents support tubeworms, shrimp, and other chemosynthetic species
bioluminescence
Hydrothermal vents

6. Kelp forests harbor many organisms
Kelp = large, dense, brown algae growing from the floor of continental shelves
Dense strands form kelp forests along temperate coasts
They provide shelter and food for organisms
They absorb wave energy and protect shorelines from erosion
People use it in food, cosmetics, paints, paper, soap, etc.
Kelp

7. Coral reefs are treasure troves of biodiversity
Coral reef = a mass of calcium carbonate composed of the skeletons of tiny marine animals (corals)
They may be an extension of a shoreline
Or exist along a barrier island, parallel to the shore
Or as an atoll (a ring around a submerged island)
Corals = tiny colonial invertebrate animals
Related to sea anemones and jellyfish
Attach to a rock or reef and capture passing food with stinging tentacles
Get food from symbiotic algae (zooxanthallae)
Coral video
coral

8. Most corals are colonial
Reefs consist of millions of densely packed animals
Reefs are located in shallow subtropical and tropical waters
Protect shorelines by absorbing waves
Innumerable invertebrates and fish species find food and shelter in reef nooks and crannies

9. Coral reefs are in worldwide decline
“Coral bleaching” = occurs when zooxanthellae leave the coral or die
Corals lose their color and die, leaving white patches
From climate change, pollution, or unknown natural causes
Nutrient pollution causes algal growth
Which smothers coral
Divers damage reefs by using cyanide to capture fish
Acidification of oceans deprives corals of carbonate ions for their structural parts
Coral bleaching
Acid sea

11. Deepwater coral reefs exist
They thrive in waters outside the tropics
On ocean floor at depths of 200–500 m (650–1,650 ft)
Occur in cold-water areas off the coasts of Spain, the British Isles, and elsewhere
Little is known about these reefs
Already, many have been badly damaged by trawling
Some reefs are now being protected
Deep water coral reefs

12. Intertidal zones undergo constant change
Intertidal (littoral) ecosystems = where the ocean meets the land
Between the uppermost reach of the high tide and the lowest limit of the low tide
Tides = periodic rising and falling of the ocean’s height due to the gravitational pull of the sun and moon
Intertidal organisms spend part of their time submerged in water and part of their time exposed to sun and wind
Surf the Dragon

13. A typical intertidal zone

15. Intertidal zones are a tough place to live
But they have amazing diversity
Rocky shorelines, crevices, pools of water (tide pools)
Anemones, mussels, barnacles, urchins, sea slugs
Starfish and crabs
Temperature, salinity, and moisture change dramatically from high to low tide
Sandy intertidal zones have slightly less biodiversity
tides
Intertidal zone

16. Salt marshes line temperate shorelines
Salt marshes = occur along coasts at temperate latitudes
Tides wash over gently sloping sandy, silty substrates
Tidal creeks = channels that rising and falling tides flow into and out of
Salt marshes have very high primary productivity
Critical habitat for birds, commercial fish, and shellfish
They filter pollution
They stabilize shorelines against storm surges a
Salt marsh 16

17. People change and destroy salt marshes
People want to live or do business along coasts
We lose key ecosystem services
Flooding (e.g., from Hurricane Katrina) worsens

18. Mangrove forests line coasts
In tropical and subtropical latitudes
They replace salt marshes along sandy coasts
Mangroves = salt-tolerant trees
Their unique roots curve up for oxygen and down for support
Nesting areas for birds
Nurseries for fish and shellfish
Mangroves provide food, medicine, tools, and construction materials

19. Mangrove forests have been destroyed
Half the world’s mangrove forests are gone
Developed for residential, commercial, and recreational uses
Shrimp farming
Once destroyed, coastal areas no longer:
Slow runoff
Filter pollutants
Retain soil
Protect communities against storm surges
National Geographic Mangrove Pic

20. Fresh and salt water meet in estuaries
Estuaries = water bodies where rivers flow into the ocean, mixing fresh and salt water
They are biologically productive
Have fluctuations in salinity
Critical habitat for shorebirds and shellfish
Transitional zone for fish that spawn in streams and mature in salt water
They have been affected by development, pollution, habitat alteration, and overfishing
NOAA Estuaries
EPA Estuaries

21. II Marine and Coastal Ecosystems
Where in the oceans are productive areas of biological activity likely to be found?
Describe three kinds of ecosystems found near coastal areas and the types of life they support.
Why are coral reefs biologically valuable?
How are they being degraded by human impact?
What is causing the disappearance of mangrove forests and salt marshes?

22. What you can do