OCEANS 100 Midterm #4

What are the main parts of the coastal region (from land → offshore)?

Coast → Shore → Beach → Nearshore → Offshore → Continental Shelf

If wave energy increases near the shore, which zone is most affected first?

The beach and nearshore zones.

How do waves erode coastal cliffs?

Hydraulic action + abrasion weaken rock, causing collapse over time.

Why are cliffs in Southern California constantly retreating?

Continuous wave attack + weak sedimentary rock

What is the main source of sand?

Rivers carrying sediment to the coast.

What happens if dams block rivers?

Less sand → increased beach erosion.

What is a berm?

A raised ridge of sand formed by wave deposition.

Why is building houses on berms risky?

Storm waves can erode/destroy them.

Difference between summer and winter beaches?

• Summer: wide, sandy (low-energy waves)

• Winter: narrow, eroded (high-energy storms)

Why do beaches shrink in winter?

Strong waves remove sand offshore.

What causes longshore drift?

Waves hitting shore at an angle.

Direction in Southern California?

Generally southward.

What happens if a jetty blocks longshore drift?

Sand builds on one side, erosion on the other.

Erosional coast characteristics?

Rocky cliffs, high wave energy.

Depositional coast characteristics?

Sandy beaches, low energy.

Why is the U.S. West Coast mostly erosional?

Active tectonics (plate boundary).

How do tectonics affect coasts?

• Active margins → erosional

• Passive margins → depositional

Why is the Atlantic coast sandy?

Passive margin → sediment builds up.

Causes of sea level change?

• Climate (melting ice)

• Tectonics (ridge activity)

What happens if all ice melts?

Major coastal flooding (Florida most affected).

Why are beaches eroding in San Diego?

• Reduced sand supply

• Rising sea levels

• Human structures

Why do seawalls worsen erosion?

They reflect wave energy → remove sand.

Do seawalls stop erosion?

No, they often increase it.

What happens to the beach in front of a seawall?

It disappears over time.

What is pollution?

Harmful substances entering the environment.

Difference between crude and refined oil?

• Crude: raw

• Refined: processed into products

Why does population growth increase oil pollution?

More consumption → more spills/runoff.

How is petroleum formed?

Buried organic matter under heat/pressure.

Effects on wildlife?

Smothering, poisoning, death.

• Exxon Valdez (1989)

• BP Gulf Spill (2010)

What is sewage pollution?

Wastewater entering oceans.

Why is Tijuana sewage worse in winter?

Storm runoff increases flow.

What are heavy metals?

Toxic elements like mercury.

What is Minamata disease?

Mercury poisoning.

What is bioaccumulation?

Toxins increase up the food chain.

Why should humans avoid large fish like tuna?

High mercury levels.

Why are plastics dangerous?

• Durable

• Not biodegradable

• Ingested by animals

What is the Pacific Garbage Patch?

Massive accumulation of plastic in ocean gyres.

Bio-degradation?

Breakdown by organisms.

Photo-degradation?

Breakdown by sunlight.

Ways to reduce pollution?

• Reduce plastic use

• Recycle

• Proper disposal

Which pollution-fighting action has the biggest impact personally?

Reducing single-use plastics.

What are the 3 domains?

Bacteria, Archaea, Eukarya

List the 6 animal kingdoms

Bacteria, Archaea, Protista, Fungi, Plantae, Animalia

Prokaryotes vs Eukaryotes

• Prokaryotes: no nucleus

• Eukaryotes: nucleus

Where do most organisms live?

Surface waters.

Why do most organisms live in surface waters?

• Sunlight

• Oxygen

• Nutrients

Vertebrates vs Invertebrates

• Vertebrates: backbone

• Invertebrates: no backbone

What is Cambrian Explosion

Rapid evolution of many life forms ~550 million years ago.

What is natural selection

Survival of best-adapted organisms.

Why are camouflaged fish more common?

Better survival → reproduce more.

Why fewer species despite size?

Less environmental variety than land.

Characteristics of plankton?

phytoplankton, zooplankton. Drift with currents.

Characteristics of Nekton?

Swim actively. fish, whales

Characteristics of Benthos?

Live on seafloor. crabs, clams

Pelagic?

Open ocean.

Benthic?

Ocean floor.

Which has more biodiversity? Pelagic or Benthic

Benthic.

What is Littoral Zone?

Area between high and low tide. High biodiversity + nutrient exchange