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

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

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

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

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

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

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

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

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.

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

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