Marine Bio: Abiotic Factors

What are the 4 major abiotic factors that influence ocean life?

Light, salinity, temperature, and oxygen

What is seawater temperature influenced by?

Solar input and mixing of water sources

What does the difference in solar energy create?

A latitudinal temperature gradient of surface seawater

Where is there a net capture of heat from solar energy?

At lower latitudes

Where is there a net loss of heat?

Higher latitudes

Define salinity

The measure of inorganic solids in seawater (ppt or psu)

What is the difference between marine and aquatic?

Marine = ocean dwelling organisms in salt water

Aquatic = organisms that live in freshwater

What is residence time?

The average time a substance spends in the ocean before it settles which allows elements to be found in constant concentrations

What does a longer residence time mean?

The more likely constant proportions will exist in the worlds oceans

What are the major elements?

Cl & Na

What are the minor elements?

Carbon and silicon

What are the trace elements?

N, P or Fe

How is oxygen added to seawater?

By mixing with the atmosphere and photosynthesis

Where is oxygen concentration the highest in the ocean?

At the surface

What happens to dissolved O2 with increasing salinity?

Dissolved O2 decreases

How is underwater dissolved oxygen removed?

By respiration and decomposition (decomposers are respiring organisms which use O2)

Is oxygen concentration vertically structured in the ocean?

Yes due to the thermocline

What is the thermocline?

A zone of great increase of water density with depth; transition between warmer and colder water

What is the oxygen minimum layer?

At the thermocline where particulate matter settles and microbial decomposition depletes O2

What are the characteristics of the water below thermocline?

Cold, O2 rich water from poles with higher O2 concentrations

What is the sunlight (euphotic) zone?

Where sunlight rarely penetrates beyond this zone

What is the twilight (dysphotic) zone?

Where sunlight decreases rapidly with depth and photosynthesis is not possible

What is the midnight (aphotic) zone?

Where sunlight does not penetrate at all; bathed in darkness