Marine Ecosystems: Oceans & Estuaries

Marine Ecosystems: Oceans & Estuaries

Ocean

• Definition: A large open body of salt water that makes up significant portions of Earth's hydrosphere.

• Role: Oceans separate continents and are vital to global ecosystems.

Estuary

• Definition: A partially enclosed area where freshwater from rivers meets saltwater from the ocean.

• Example: The Outer Banks, NC.

Outer Banks, NC

• Fun Fact: The Outer Banks protect three large estuaries known as sounds: Pamlico Sound, Currituck Sound, and Albemarle Sound.

Importance of Oceans & Estuaries

• Recreation: Activities such as swimming, boating, fishing.

• Food Sources: Includes fish, shellfish, crab, lobster, and seaweed.

• Habitat: Essential for various animals and plants.

• Weather Influence: Oceans play a critical role in weather patterns.

• Climate Regulation: Oceans help to absorb excess heat from greenhouse gases.

• Transportation and Trade: Over 90% of international trade is conducted via ship; critical for the economy.

• Economic Significance: Approximately one in six U.S. jobs is marine-related; over 66% of the world’s population resides near coastlines.

Ecosystem Services from Oceans & Estuaries

• Ecological Services:

  • Climate moderation

  • Provide habitats for marine life

  • Reduce storm impact on coastlines

  • Support great biodiversity

  • CO2 absorption helps mitigate climate change

• Economic Services:

  • Food production

  • Job creation

  • Medicines development

  • Shipping and transportation facilitation

  • Recreational opportunities

  • Offshore oil and natural gas extraction

Similarities and Differences: Oceans vs. Estuaries

Similarities

• Both are aquatic environments that support diverse life forms.

• Both are related to water ecosystems.

Differences

• Salinity Levels: Estuaries have variable salinity due to the mixing of freshwater and saltwater, while oceans typically have a consistent higher salinity.

• Organisms: Different organisms inhabit oceans and estuaries, each adapted to their specific salinity levels.

Salinity

• Definition: Concentration of salt in water.

• Measurement: Salinity is measured in parts per thousand (ppt).

  • 1 gram of salt in 1,000 grams of water = 1 ppt.

• Salinity Levels:

  • Oceans: Average around 35 ppt (range: 25-40 ppt).

  • Estuaries: Variable salinity ranging from >0.5 ppt to <25 ppt.

  • Freshwater: Less than 0.5 ppt.

Factors Influencing Ocean Salinity

• Influenced by:

  • Evaporation rates

  • Precipitation rates

  • Freshwater runoff

Characteristics of Estuaries

• Nutrient-rich environments due to fast-moving rivers that carry nutrients.

• High productivity and biodiversity are common.

• Example: Chesapeake Bay serves as an important estuary.

Flora and Fauna in Estuaries

Estuary Plants

• Adapted to salty conditions and play a key role in soil retention.

Estuary Animals

• Comprise a vast variety of species; example includes many birds such as the Great White Egret.

Ecosystem Services of Estuaries

• Grasses stabilize soil and prevent erosion, acting as a protective barrier between land and ocean.

• They mitigate flood impacts by absorbing excess water during heavy rains.

• Serve as a major food source for marine life.

• Filtration Role: Estuaries filter out sediments and pollutants before they reach the ocean, resulting in cleaner water.

  • Fun Fact: An oyster can filter 180 liters of water daily.

Economic Benefits of Estuaries

• Contribute economically via:

  • Tourism

  • Fisheries

  • Recreational activities

  • Providing protected coastal areas for boating and shipping.

"Nurseries of the Sea"

• Estuaries support fish and wildlife breeding and growth due to sheltered waters.

• Many species of fish and shellfish, including salmon and herring, rely on estuaries during their life cycles.

• Unique Life Cycle of Salmon: Salmon transition between freshwater and saltwater; estuaries provide necessary environments for this transition.

Human Impact on Estuaries

• Human activities contributing to estuary health decline:

  • Coastal development

  • Invasive species introduction

  • Overfishing

  • Dams affecting water flow

  • Climate change impacts

  • Pollution affecting water quality.

Summary

• Understanding the significance of oceans and estuaries is critical for ecological balance and human reliance on marine resources.