Marine Ecosystems

Oceans Sunlight only penetrates 330 ft into the ocean (photic layer) Sunlight only penetrates 330 ft into the ocean (photic layer) Much ocean life is concentrated in shallow, coastal water Much ocean life is concentrated in shallow, coastal water The depths of the ocean are dark The depths of the ocean are dark Decomposers and filter feeders feed on organisms that fall from the surface (benthic layer) Decomposers and filter feeders feed on organisms that fall from the surface (benthic layer)

Coral Reefs Reefs are built by tiny animals called coral polyps and the symbiotic algae (zoozanthellae) that live inside them. Reefs are built by tiny animals called coral polyps and the symbiotic algae (zoozanthellae) that live inside them. Coral polyps secrete skeletons of calcium carbonate which accumulate to form reefs. Coral polyps secrete skeletons of calcium carbonate which accumulate to form reefs. Coral reefs are very diverse ecosystems Coral reefs are very diverse ecosystems Found only in warm salt water with enough light for photosynthesis Found only in warm salt water with enough light for photosynthesis

Why are reefs important? Reefs educe the impact of storms on shorelines They are carbon sinks Provide habitat for invertebrates and commercially important fish Potential source of pharmaceuticals Recreation and tourism

Threats to our reefs Human coastal development – excess sediment smothers reefs Oil spills Oil spills Polluting runoff – algal bloom smothers coral Polluting runoff – algal bloom smothers coral Destructive fishing practices (bottom trawling and dynamite) Destructive fishing practices (bottom trawling and dynamite) Use as bricks, road-fill, cement Use as bricks, road-fill, cement Destructive tourism Destructive tourism

Coral and climate change Increasing CO 2 levels result in warmer temps and warmer oceans – corals expel their algal symbionts and become bleached 1/3 of atmospheric CO 2 dissolves in the ocean CO 2 reacts with seawater to form carbonic acid (H 2 CO 3 ) By forming carbonic acid, more H + ions are present lowering the pH of the water At low pH fewer carbonate ions are available for corals to form their calcium carbonate skeletons At low pH calcium carbonate will start to dissolve

Bleached coral

Salt Marshes Found on temperate sandy/silty low energy coastlines Found on temperate sandy/silty low energy coastlines V. high primary productivity V. high primary productivity Important habitat for shorebirds and fish Important habitat for shorebirds and fish Filter pollution Filter pollution Stabilize shorelines Stabilize shorelines Threatened by reclamation for ag. urban development Threatened by reclamation for ag. urban development

Mangroves replace salt marshes in the tropics Distinctive roots absorb O 2 and hold plant in place Distinctive roots absorb O 2 and hold plant in place Important nurseries for fish Important nurseries for fish Diverse ecosystem Diverse ecosystem Erosion control Erosion control Slow runoff and filter pollutants Slow runoff and filter pollutants Storm protection Storm protection ½ world’s mangroves have been lost to coastal development, shrimp farming ½ world’s mangroves have been lost to coastal development, shrimp farming

Estuaries An area where freshwater from a river mixes with salt water from the ocean An area where freshwater from a river mixes with salt water from the ocean Highly productive: Highly productive: - constantly receive nutrients from the river - shallow so sunlight can reach to the bottom Large populations of rooted plants and plankton support diverse food chains Large populations of rooted plants and plankton support diverse food chains

Development on estuaries Many of the world’s cities were built on estuaries: Many of the world’s cities were built on estuaries: New York, Shanghai, Buenos Aires, New York, Shanghai, Buenos Aires,Bombay Estuaries are threatened by sewage, agricultural runoff and industrial waste, overfishing, habitat alteration Estuaries are threatened by sewage, agricultural runoff and industrial waste, overfishing, habitat alteration

Threats to the Ocean Pollution from nonpoint sources on land: chemicals, nutrients, trash, sewage, oil, plastic Pollution from nonpoint sources on land: chemicals, nutrients, trash, sewage, oil, plastic Runoff leads to algal bloom Runoff leads to algal bloom Mercury from coal burning bioaccumulates in animal’s tissues and biomagnifies up the food chain Mercury from coal burning bioaccumulates in animal’s tissues and biomagnifies up the food chain Mercury causes neurological damage Mercury causes neurological damage Avoid swordfish, shark and albacore tuna Avoid swordfish, shark and albacore tuna Oil, mineral and gravel extraction Oil, mineral and gravel extraction

Bioaccumulation Vs biomagnification Toxins which are fat soluble (DDT) or are stored in muscle (methyl mercury) build up in an animal over time This is termed bioaccumulation Toxins accumulated in one animal are transferred to another animal when a predator consumes its prey This is termed biomagnification Top predators end up with high concentrations of pollutants

# 1 threat is Overfishing Population of all the species we fish for today will collapse by 2048 (Science 2006) Population of all the species we fish for today will collapse by 2048 (Science 2006) Ecological systems with less genetic or species diversity are less able to withstand disturbances Ecological systems with less genetic or species diversity are less able to withstand disturbances We are currently fishing down the food chain We are currently fishing down the food chain TYowBo4&feature=related TYowBo4&feature=related TYowBo4&feature=related TYowBo4&feature=related