Introduction to Marine Biology

Discussion focus primarily on seaweeds (macroalgae and microalgae)
- Macroalgae: Larger seaweeds typically visible to the naked eye.
- Microalgae: Microscopic algae, viewed under a microscope.
Emphasis on ocean habitats, and while most discussion is about marine environments, there is a notable prevalence of freshwater green algae.

Oceans cover approximately 71% of Earth's surface, equating to almost three-quarters.
Seawater constitutes about 98% of all water on Earth; average ocean depth is about 3,700 meters (approximately 10,000 feet).
Below this depth is a zone where sunlight does not penetrate, resulting in the absence of photosynthetic organisms like seaweeds.
Some organisms near hydrothermal vents utilize sulfur for energy production instead of sunlight.
Important consideration: the distribution of species is not only about where they are found but also where they are absent, prompting inquiries about environmental factors influencing this.

Definition: Factors that are non-biological such as temperature, light, chemical composition and pressure that affect habitat.
Chemical Factors: Salinity, oxygen, carbon dioxide, and nutrient availability in marine environments.
Physical Factors:
- Light: Fundamental for photosynthesis, affecting seaweed growth.
- Direction and intensity of light are critical; species vary by light requirements.
- Temperature: Influences biological activities; coastal areas may be warmer and more moderate than inland regions.
- Humidity and Pressure: Vary with depth; certain organisms adapt to pressure changes and humidity levels.

Living organisms interact, influencing each species' distribution—some species may be excluded by predators or competition.
Example: Hiking into a forest shows stark transitions in biodiversity due to microhabitat changes just meters apart.

Water Composition: Water is comprised of H2O—two hydrogen and one oxygen atom, forming polar bonds important for various properties.
- Creates hydrogen bonding leading to stability and high heat capacity.
- Stability affects local temperature fluctuations—coastal areas experience moderate temperatures compared to deserts.
Solvent Properties: Water can dissolve many substances, including salts and gases, contributing to marine life (e.g., oxygen for fish and carbon dioxide for photosynthesis).
- Salinity of ocean water averages around 3.5% or 35 parts per thousand.
- Nutrients are primarily derived from land sources washed into the ocean, including nitrogen and phosphorus.

Primary nutrients required by seaweeds: carbon, oxygen, nitrogen, and phosphorus.
- Seaweeds grow effectively when fertilized; nutrients impact growth patterns just like in terrestrial plants.
- Different environmental processes recycle nutrients within oceanic habitats.

Seaweeds require light for photosynthesis.
- Quality: Different types of seaweeds absorb different wavelengths of light, influencing their color (e.g., green algae use green light poorly).
- Quantity: Refers to the intensity of light coming into the water, which affects photosynthetic efficiency.
Depth in the ocean affects light intensity; too shallow can lead to photo inhibition whereas too deep leads to insufficient light.
- Compensation Depth: The depth where light is sufficient for photosynthesis to meet the plant's energetic needs.
- Goldilocks Principle: A sweet spot exists for light intensity where conditions are optimal for seaweed growth.

Upwelling: Nutrient-rich water rising to the surface due to large-scale oceanic currents caused by wind patterns and Earth's rotation (Coriolis Effect).
- Upwelling zones, particularly on coasts, are critical for nutrient availability, supporting high primary productivity.
- Example: Cold waters along the coast of California yield rich ecosystems due to nutrient availability from upwelling.

Temperature affects regional biogeography, prompting distributions ranging from tropical to polar environments.
Variations in temperature along coastlines influence where different species can thrive (e.g., kelp forests predominantly reside in colder waters).
Temperature is linked to nutrient levels—when waters warm, nutrient levels often decrease which limits seaweed productivity.

Understanding the intricate balance of light, nutrients, chemical makeup, and ocean physical properties is key to studying seaweed ecology.
Concurrent themes include the importance of upwelling, distribution patterns based on abiotic factors, and the relationship between temperature changes and nutrient availability.
The course will delve deeper into the specifics of seaweeds, including examining pigments, photosynthesis processes, and ecological interactions.

The instructional approach emphasizes participant engagement, encouraging students to ask questions for clarity and deeper understanding as the subject matter unfolds.