Factors Affecting Aquatic Ecosystems

The general distribution of life in aquatic systems as a function of chemistry, geography, light, depth, salinity, and temperature.

​Sunlight

Sunlight reaches the upper 200 meters (650 ft). Below that, little to no light is present.

The sun provides 2 things:

Light à photosynthesis à plants grow.

Heat – Upper ocean à warm.

• All organisms have temperatures that are too warm or too cold to support life

• Shallow waters or surface water tend to be warmer due to sunlight

Equator = more direct sunlight; warmer temps

Poles = less direct sunlight; cooler temps

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Sunlight and Latitude

Remember, the photic zone is where the sunlight can reach ~200M

As we go deeper in the water

• Pressure increases

• No light/little light present

• Much colder temperatures

Organisms have adapted by:

• Having big eyes

• Some migrate to surface to feed

• Bioluminescent

River input = fresh à decrease salinity near coast

Middle of ocean à high salinity à high evaporation

Salinity is a measure of how much salt is in water

Most species can only live in freshwater or saltwater, not both

•But some have special adaptations that allow them to go back and forth

for Example:  Bull Shark

​Ocean water ph is 8.1-8.2 (slightly basic)

•Carbon Dioxide dissolved in water can cause the ocean water to become acidic

•Can damage coral reefs

•Affects the formation of shells (there are microscopic organisms that grow shells too)

•Causes changes in some fish behaviors

Think! What is the purpose of an aerator in an aquarium?

Yes! All marine organisms need oxygen to create energy

• Oxygen is dissolved in the water

• Surface water tends to have more oxygen present due to photosynthesis (remember, O2 is a product of that process)

​What about CO2, nitrogen, and phosphorus?

• CO2 is produced during cellular respiration (increased amounts affect PH)

• N and P are important nutrients for many autotrophs.

  • High concentrations near coastlines because of runoff

​Algae Blooms and the effect on Florida's waters

Rivers move materials from land to water

• Nutrients (like Nitrogen and Phosphorus)

• Sediment (like dirt)

• Pollution

Human activities are concentrated closest to land