Chapter 16 - Oceans & Coastal Systems

Key Learning Concepts

  • After studying this material, you should be able to:

    • Describe the chemical composition and physical structure of the ocean.

    • Identify the components of the coastal environment and explain the actions of tides.

    • Describe wave motion at sea and near shore; explain coastal straightening and coastal landforms.

    • Describe barrier beaches and islands; their hazards related to human settlement.

    • Describe the nature of coral reefs and coastal wetlands; assess human impacts on these systems.

Inputs, Actions, Outputs, and Human-Earth Connections

Inputs

  • Solar energy

  • Wind

  • Earth materials

  • Living organisms

Actions

  • Tides

  • Waves

  • Currents

  • Biological processes

Outputs

  • Erosional landforms

  • Depositional landforms

  • Coral formations

Human-Earth Connections

  • Ocean acidification

  • Coral bleaching

  • Loss of mangroves and salt marshes

  • Coastal pollution

Open Material and Energy System

  • Beaches and shorelines are considered open systems because they are influenced by both land and sea, with continuous material and energy exchanges.

Coral Reefs in Decline

  • Health of coral reefs is declining due to climate change and human activities.

  • Corals: Simple marine animals related to jellyfish.

    • Each coral is a polyp, living in colonies.

    • Types of corals: Hard corals (build reefs) and soft corals.

  • Coral Relationship with Zooxanthellae:

    • 90% of coral nutrition provided by these algae through photosynthesis.

    • Coral Bleaching: Occurs when corals expel zooxanthellae due to heat stress.

Importance of Coral Reefs

  • Homes to over 25% of marine life.

  • Protect shorelines and provide economic resources via tourism and food.

  • Threats include climate change (mass bleaching events) and ocean acidification.

Coastal System Components

  • Coastlines are dynamic environments influenced by oceanic, atmospheric, and lithospheric processes.

  • Approximately 40% of Earth's population lives near coasts, increasing vulnerability to storms and sea level rise.

Properties of Seawater

  • Seawater is a solution with consistent chemical composition relating to salinity (concentration of dissolved salts).

  • Major components include chloride, sodium, sulfate, magnesium, calcium, and potassium.

Tides and Their Mechanisms

  • Tidal Action: Cyclical changes in sea level due to gravitational pull from the Moon and Sun.

    • Flood tides increase sea level; ebb tides decrease it.

    • Spring and neap tides affect the tidal range.

Wave Motion

  • Waves are generated by wind friction and move in wave trains.

    • In deeper water, waves consist of waves of transition.

    • In shallow water, waves form waves of translation, leading to breakers.

  • Coastal processes include longshore currents, which affect sediment transport.

Coastal Landforms

  • Erosional Landforms: Sea cliffs, arches, sea stacks formed by wave action.

  • Depositional Landforms: Beaches, barrier spits, bay barriers, lagoons created from sediment accumulation.

Barrier Beaches and Islands

  • Barrier islands protect the mainland and are formed by sediment deposition, but are vulnerable to storms and rising sea levels.

  • Development on these islands poses risks due to their dynamic nature.

Coral Reefs and Coastal Wetlands

  • Coral reefs formed by the accumulated calcium carbonate from coral polyps.

    • Critical ecosystems threatened by climate factors and human impacts.

  • Coastal wetlands include mangroves and salt marshes, vital for biodiversity and flood mitigation, but severely threatened by anthropogenic actions.

Conclusion - Human and Environmental Interactions

  • Human impacts on coastal systems: Including pollution, erosion, development, and climate change threats.

  • Importance of sustainable practices to preserve fragile ecosystems like coral reefs and wetlands.