Chapter 16 - Oceans & Coastal Systems

Key Learning Concepts

  • After studying the chapter, you should be able to understand and describe:

    • The chemical composition and physical structure of the ocean.

    • The components of the coastal environment and the dynamics of tidal actions.

    • Wave motion both at sea and near shore, including the concept of coastal straightening and landforms.

    • Barrier beaches and islands, their formation, and associated hazards affecting human settlements.

    • The nature of coral reefs and coastal wetlands, along with human impacts on these vital ecosystems.

Oceans and Coastal Systems

Inputs

  • Insolation: Energy received from the sun, affecting temperatures and weather patterns in coastal regions.

  • Wind: Drives waves, currents and influences weather patterns.

  • Earth Materials: Geological materials that form coastal and ocean systems.

  • Living Organisms: Marine life that interacts with and shapes the coastal and ocean environments.

Actions

  • Tides: Regular fluctuations in sea level driven by gravitational forces of the moon and the sun.

  • Waves: Motion of water created by wind over the surface of the ocean; waves reshape coastlines through erosion and deposition.

  • Currents: Large scale water movements that transport heat and nutrients across oceans.

  • Biological Processes: Ecological interactions, such as those between coral and zooxanthellae.

Outputs

  • Erosional Landforms: Features created by the removal of material from coastlines, such as cliffs and sea stacks.

  • Depositional Landforms: Structures formed by accumulation of sediments, like beaches and barrier islands.

  • Coral Formations: Ecosystems formed by coral polyps providing habitat for diverse marine life.

Human-Earth Connections

  • Ocean Acidification: Resulting from increased CO2 absorption impacting marine life.

  • Coral Bleaching: Caused by elevated water temperatures leading to the loss of symbiotic algae in corals.

  • Loss of Mangroves and Salt Marshes: Due to human activities like development and pollution.

  • Coastal Pollution: Harmful substances that degrade coastal water quality and marine ecosystems.

Coral Reefs

Threats to Coral Reefs

  • Coral reefs are declining due to:

    • Climate change leading to increased water temperatures.

    • Ocean acidification affecting coral growth.

    • Overfishing, habitat destruction, and pollution.

Coral Anatomy and Type

  • Coral Polyps: Simple marine animals that form colonies; include hard (reef-building) and soft corals.

  • Zooxanthellae: Symbiotic algae providing corals with nutrients in exchange for protection.

Coastal Systems

Coastline Interaction

  • Coastal areas are dynamic, with landforms shaped by geological activity, tides, and human interventions.

  • Approximately 40% of Earth's population resides within 100 km of coastlines, highlighting the need for effective coastal management.

Sea Level Dynamics

  • Sea levels vary naturally and are influenced by climate change currently leading to global rises.

  • Changes include both eustatic shifts due to ice melt and isostatic changes from land subsidence.

Wave Dynamics

Formation and Types

  • Waves are generated through wind friction over water; they vary in scale from ripples to large storm-induced waves.

  • Wave energy is transferred to the shore, creating breakers when they hit shallow waters.

Coastal Erosion and Deposition

  • Erosional coastal features include cliffs and sea caves, while depositional forms comprise beaches and dunes.

  • Tsunamis: Large waves caused by geological disturbances that can inflict significant coastal damage.

Barrier Islands

Formation and Hazards

  • Long, narrow sandy islands that provide habitats and protect coastlines from storms.

  • These islands are vulnerable to storms, and development in these areas poses risks from erosion and flooding.

Coastal Wetlands

Importance and Threats

  • Wetlands support rich biodiversity and buffer coastal areas against storms and flooding.

  • Human activities, such as development and pollution, threaten the integrity of these ecosystems.

Harmful Effects of Oil Spills

  • The Gulf of Mexico oil spill illustrates the devastating impacts of human activity on marine and coastal ecosystems.

Conclusion

  • Understanding coastal and oceanic systems is essential for the sustainable management of these environments, focusing on the impacts of climate change and human activity.