1. Section 2: Marine Ecosystems
Unit 3: Aquatic Ecology
Section 2: Marine Ecosystems

2. Central Case Study: Collapse of the Cod Fisheries
Cod are groundfish, fish that live or feed along the bottom, eating small fish and invertebrates
Large ships and technology have overfished the cod
Cod populations shrank in the 1980s and crashed in the early 1990s
Some stocks dropped to just 10% of their former levels
2 Large populations off North East North American Coast

3. Central Case Study: Collapse of the Cod Fisheries
Because of decline, Fishing for cod was temporarily banned in numerous fisheries
Even with the fishing ban, stocks of cod were not recovering
Fish that had been cod prey were eating young cod
Bans were extended
A 2011 study showed that cod stocks were finally beginning to recover

4. Dem Oceans Ocean covers over 70% of the planet in water
Made up of 5 oceans – Atlantic, Pacific, Indian, Arctic, and Southern
Ocean is 96.5% water
Remainder is ions and dissolved salts
Sodium chloride (NaCl) makes up about 3% of the salts

5. Zones of the Ocean
Intertidal – where the ocean meets land; From top of high tide to bottom of low tide
Benthic – Underwater habitat on the sea floor
Pelagic – Between sea floor and ocean surface
Pelagic waters absorb over 80% of solar energy on Earth
ocean’s primary productivity occurs in top 10m (33ft) – Photic Zone

6. Estuaries Area where freshwater flows into ocean
Organisms here must be tolerant to major fluctuations in salinity
Major Examples: Chesapeake Bay, New York Harbor, San Francisco Bay
Ecosystem Services:
Habitat for shorebirds and commercially important shellfish
Filter Pollutants

7. Salt Marshes Brackish water – Mix of fresh and saltwater
High primary productivity!!! Mostly salt tolerant grasses and shrubs
Ecosystem Services:
Habitats for birds, fishes, and commercial shellfish
Stabilize shoreline
Filter pollutants
Destroyed by humans rapidly due to coastal development of homes and businesses

8. Mangrove Forests
In tropics, instead of salt marshes, mangrove forests fill this niche
Salt-tolerant trees
Ecosystem Services:
Nesting/Nursery areas for Fish, birds, and shellfish
Slow runoff into ocean
Shelter coastal communities from storm surges/tsunamis

9. Kelp Forests Large, dense areas of brown algae along Temperate coasts
Can reach 200 feet long and grow up to 18 inches a day
Ecosystem Services:
Shelter and food for organisms
Absorb wave energy and reduce coastal erosion
Used by humans as food, cosmetics, soap, etc.

10. Coral Reefs VERY HIGH BIODIVERSITY AND PRIMARY PRODUCTIVITY
Calcium carbonate structure formed by the skeletons of corals (animals) – related to jellyfish
Corals get nourishment through symbiotic relationship with zooxanthellae
Found mostly in shallow tropical waters
VERY HIGH BIODIVERSITY AND PRIMARY PRODUCTIVITY

12. Open Ocean Ecosystems
Surface productivity is focused in areas of upwelling
Areas where nutrients are moving to the surface via currents
Phytoplankton – Plants; Zooplankton – Animals
Deep pelagic organisms are accustomed to high pressure, cold temperatures, and very few food sources (mostly detritivores)
Hydrothermal vents are areas where life flourishes in the deep pelagic (APHOTIC)
Chemosynthesizers – Use hydrogen sulfide as an energy source