Chapter 12

Chapter 12 - Chapter 12 Coastal Waters and Marginal Seas...

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Unformatted text preview: Chapter 12: Coastal Waters and Marginal Seas Coastal waters are disproportionately important to humans:-95% of fish consumed by humans and domesticated animals are obtained within 200 miles of the shore.-Coastal water support 95% of the total biomass found in the oceans.-Coastal waters support most modern-day shipping routes; are primary sites of oil and gas exploration -Estuaries and wetlands are among the most biologically productive ecosystems on Earth Freshwater is less dense than saltwater; therefore, when fresh river water enters the sea, it usually floats on the surface, creating a strong halocline. Intense evaporation driven by hot, dry wind can also cause a halocline to develop in the reverse direction (i.e., saltiest waters on top). Wind-driven mixing + runoff will cause the river and ocean water to mix, forming a isohaline (constant In high and low latitude regions, uniformly cold and warm temperatures (respectively) cause isothermal conditions to prevail. In the mod latitude seas, strong seasonal differences in temperature cause surface waters to cool in the winter warm in the summer. These seasonal effects diminish with depth, where temperature is more stable throughout the year. These seasonal fluctuations in surface water but not deeper water cause steep isoclines to develop in mid-latitude oceans. Wind blowing parallel to the coast piles water up along coast, forming a saltwater wedge. This water flows back down slope toward the open ocean and is deflected by the Coriolis Effect to the right (northward on west coast of US and southward on the east coast) in the Northern hemisphere, and to the left in the Southern hemisphere. This “geostrophic flow” is compounded by freshwater running down the slope of the saltwater wedge into the open ocean. Off the coast of Washington and Oregon, this combined geostrophic current + freshwater runoff is called the Davidson Current. Estuaries: partially enclosed coastal body of water in which freshwater runoff dilutes seawater. Most commonly occurring estuaries are the mouths of large rivers, where fresh river water mixes with ocean water. are the mouths of large rivers, where fresh river water mixes with ocean water....
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Chapter 12 - Chapter 12 Coastal Waters and Marginal Seas...

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