Ocean Dynamics and Climate Science Fundamentals

Trophic Interactions and Food Webs

Trophic interactions are known as a food web. In a food web, herring typically receives about 0.68% of primary production, compared to 1% in a linear food chain. Ecosystems with fewer trophic levels often exhibit greater fish production.

The Biological Pump

The biological pump refers to the removal of organic matter (specifically organic carbon, fixed by phytoplankton during photosynthesis) from the euphotic zone to deeper waters and ultimately to the ocean floor (sediments).

Biogeochemistry and Trace Metals

Biogeochemistry involves the biological mediation of geochemistry. It encompasses major element cycles such as Carbon (C), Nitrogen (N), Phosphorus (P), and Sulfur (S). These cycles are intimately linked to both ecology and geochemistry. Key steps in these processes are often catalyzed by metals, leading to the study of trace metal biogeochemistry. The geochemical cycles of trace metals significantly impact the activities of various enzymes that catalyze these reactions.

Defining Trace Metals

A substance is considered a trace metal if it has a low concentration, typically less than 50 nM.

Mechanisms for Trace Metal Removal

• Biological removal
• Adsorption
• Organic complexation
• Internal recycling
• Benthic inputs

Impact of Excess CO2 on Oceans

When there is too much CO2 in the atmosphere, several oceanic changes occur:

• Oceans become more acidic.
• The concentration of carbonate ions decreases, impacting marine life.

Understanding the Greenhouse Effect

1. The greenhouse effect is essential for keeping our climate warm.
2. Without our atmosphere, the planet would be frozen, with an average temperature of about -20°C.
3. With our atmosphere, the average temperature is approximately 15°C (58°F).
4. CO2 absorbs outgoing radiation (heat), contributing to warming.
5. CO2 concentration is strongly correlated with global temperature.
6. Global temperatures are currently rising.

Oceanic Climate Phenomena

La Niña

La Niña is the opposite of El Niño-Southern Oscillation (ENSO), characterized by prolonged cold surface waters in coastal regions.

Upwelling

Upwelling occurs when wind from the south brings cold, nutrient-rich water to the surface. This phenomenon often creates optimal conditions for fishing year-round, leading to increased fish populations.

Key Dissolved Ions in Seawater

The four most abundant ions dissolved in seawater are:

1. Chloride
2. Magnesium
3. Sulfate
4. Sodium

Ocean Wave Formation

Ocean waves are primarily created by:

1. Wind
2. Catastrophic releases of energy into the ocean

Tsunamis

Tsunamis are created by abrupt vertical movements of the seafloor, typically caused by earthquakes. They spread as shallow water waves across vast ocean distances.

Earth's Climate Systems

Earth's climate system comprises three main components:

1. Atmosphere
2. Hydrosphere
3. Cryosphere

Natural Factors Influencing Earth's Climate

Several natural factors can alter Earth's climate:

1. Solar energy variations
2. Volcanic eruptions
3. Ocean acidification (can be natural or anthropogenic)
4. Melting of glaciers
5. Photosynthesis (CO2 absorption)
6. Methane emissions

Oceanic Changes Due to Global Warming

Global warming is causing significant changes in the ocean, including:

1. Ocean acidification
2. Coral bleaching
3. Decrease in ocean pH
4. Increase in dissolved CO2

Equinoxes: Sun Crossing the Equator

The sun crosses the equator twice a year, marking the equinoxes:

• March 21st
• September 21st