1. Nutrients, Blooms, & Dead Zones: Abiotic Factors
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2. Abiotic Factors in Ocean Ecosystems
Depth (pressure, light availability, oxygen availability)
Salinity
Temperature
Nutrient availability

3. Depth and Pressure
At sea level, there is 1 atmosphere (atm) of pressure.
Each 10 meters of depth, you gain another 1 atm of pressure.
Human bodies can only withstand around 3 to 4 atm of pressure.

4. Light Availability
In the ocean, the amount of light that penetrates through depends on the depth and the color of the light.
Blue light penetrates the farthest, which is why the ocean appears blue.
Red light penetrates the least.
Light is needed for photosynthesis, but it can only be done in the first 200 meters of the ocean.

5. Salinity
Salt is added to the oceans by the eroding of rocks and rainfall bringing soils from land.
The average salinity of the ocean is 35 parts per thousand.
Ocean animals are equipped to handle salt and can not live outside of saltwater environments.
Freshwater animals can not handle salt and will die if too much is introduced to their ecosystem.

6. Nutrient Availability
In order for photosynthesis to take place in the ocean, certain nutrients must be available to the phytoplankton (plant plankton), algae, and seagrasses.
The most important nutrients in the ocean are nitrates (NO3-) and phosphates (PO43- ) as they are both needed by plants and algae.

7. Eutrophication
Eutrophication - excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land
Causes algal blooms (such as red tide)
All the floating algae cuts off sunlight to other plants, halting photosynthesis and depleting the oxygen
Anoxic zones (also known as dead zones) form, causing massive die-offs of fish