Human alteration of marine environments: 45% of humans live within 100km of the ocean, (cid:883)(cid:882)% of humans live within . What"s a mangrove: a mix of shrubs and trees common in coastal areas of the tropics, can withstand having their roots in standing salt water. Human disturbance of marine systems at contact points: Where freshwater mixes with saltwater: large amounts of pollution, nutrients are discharged into ocean, anoxic (cid:494)dead zones(cid:495) are developing. At ocean-air interface, humans are: altering sea surface temperatures, altering marine chemistry, both are consequences of anthropogenic greenhouse gas emissions. Change in ocean acidity: barnacles, sea urchins, other organisms have difficulty in acidic sea water, contributes to coral bleaching. Along benthic margins, humans: dump solid waste, damage coral reefs, bottom-trawl for fish, shellfish, drill for oil. Coral reefs: dynamic, complex, but fragile ecosystems, grow slowly, as reef-building corals grow, die and grow on top of one another, develop in clear, shallow, salty waters where water temperatures is between.