Oceanography 1 Quiz

Oceanography 1 (Physical Environment and Productivity)

• Oceanography studies the physical and chemical properties of the ocean, including waves, tides, currents, and the environment's impact on marine life.
• It's strongly connected to biology and meteorology.
• The physical environment is a major driver of patterns in marine life, impacting factors like temperature, chemistry, light intensity, nutrients, and currents.
• Similarly, the biological environment plays a part.
• Examples of factors within the biological environment: predators, competitors, mutualisms, and diseases.
• The physical marine environment is often defined by temperature stability which is influenced by water's high specific heat.
• Water resists large fluctuations in temperature.
• A high specific heat leads to stable conditions for chemical reactions in the water.
• Daily temperature fluctuations in the air and water are less than fluctuations over seasons.
• Daily temperature variations in air (31°C-28°C) and on rocks (62°C-28°C) are relatively smaller in comparison to seasonal changes in air (36°C - -2°C) and water (30°C-17°C).
• Water has differing temperatures across the globe.

Chemical Properties

• Water acts as a universal solvent, dissolving various solids and gases.
• Salinity is the total concentration of dissolved substances in seawater, typically ~35 ppt (~3.5% dissolved substances).
• Warmer water dissolves more solids, thus higher salinity.
• Temperature strongly affects the amount of dissolved gases, and colder water dissolves more gases.
• Gases such as carbon dioxide (CO2) are crucial for marine life, as well as oxygen (O2).

Oxygen & Carbon Dioxide

• Oxygen and carbon dioxide levels in the ocean are not at equilibrium as dictated by chemistry.
• The ocean's depth affects the concentrations of dissolved gases.
• Oxygen levels are comparatively lower at depth compared to the surface.
• The reverse is true for CO2 at depth.
• The oxygen minimum zone occurs at depths between 200 and 1000 meters, which is associated with the rapid decrease in oxygen concentration and increase in CO2
• This is often connected to respiration and less productivity with depth, which are related to photosynthesis and the organisms living there.
• The ocean acts as a significant carbon sink (60 times more CO2), absorbing carbon dioxide from the atmosphere.

Water Density and Stratification

• Water's density is affected by temperature and salinity.
• A unique characteristic of water is that its density peaks at approximately 4°C (39.2°F).
• Water density is inversely related to temperature in most cases.
• Regions with a high density often have colder temperatures.
• Water stratification is caused by the differences in temperature and salinity, creating layers (surface zone, thermocline, pycnocline, deep zone).

Primary Productivity

• The ocean's productivity in creating oxygen matches terrestrial production but is much less dense.
• Phytoplankton, mostly, are the key marine primary producers.
• They capture light energy and convert it to organic matter.
• Limiting factors for productivity include light extinction (depth) and nutrient availability.
• Light extinction occurs quickly in water, so primary producers are restricted to surface regions.
• Nutrients are taken up rapidly by photosynthetic organisms, making their concentration hard to measure.

Upwelling

• Upwelling is a significant factor in productivity. It brings nutrient-rich water to the surface.
• Upwelling helps create nutrient-rich areas, leading to rapid phytoplankton blooms.

Pelagic Food Chains

• The ocean's primary producers, like phytoplankton, form the base.
• Humans utilize the organisms in the ocean's food chains, making the productivity of phytoplankton crucial for human existence.

Summary (Oceanography)

• Physical and chemical properties define the nature of marine life.
• These properties fluctuate by region and time (season, depth).
• Increasing human activities are affecting ocean conditions.
• Primary productivity is critical for sustaining human existence.

Test your knowledge on the physical environment and productivity of the ocean in Oceanography. Explore how waves, tides, and currents influence marine life and understand the relationship between physical and biological factors affecting the oceanic ecosystem.