Geography and Oceanography - Chapter 23 pps

Biolimiting NutrientsN, P, and Si are exhausted first in Eq.. surface waters during photosynthesis Essential to the growth of phytoplankton If these biolimiting nutrients increase in sea

Biological Productivity

Conditions for Life in the Sea

Consider the main biochemical reaction for life in the sea, and on earth in general:

6H 2 O + 6CO 2 + energy + nutrients = C 6 H 12 O 6 + 6O 2

Focus on left side of equation

What is in short supply in the sea and thus limits the amount of life in the ocean??

Open Ocean Food Webs

Pteropods

S in k in g O rg

molecules move from high to low concentrations

Which Nutrients are in Short

Phosphate and Nitrate in the Pacific

Silicate in the Pacific

Biolimiting Nutrients

N, P, and Si are exhausted first in Eq

surface waters during photosynthesis

Essential to the growth of phytoplankton

If these biolimiting nutrients increase in sea water, life increases

If these biolimiting nutrients decrease in sea water, life decreases

Where would you expect to find the

highest biomass in the Pacific??

CZCS Global Primary Production

O 2 is high in the surface and mixed layer

O 2 decreases to a minimum at base of thermocline

O 2 then steadily increases with depth

How Does Nutrient Distribution Compare w/

Dissolved Oxygen?

Dissolved O2 Reverse of

Nutrients

Why is the Concentration of Oxygen High in the Mixed Layer??

Hint #1: How and where is oxygen produced

How is Oxygen Removed from the Thermocline & Slightly Below??

Dead and decaying organic matter sinks

downward from surface waters

Rate of sinking decreases

as it encounters the cold,

dense water of the

thermocline

Material decays (oxidizes)

at the thermocline, which

strips O 2 out of the water

and returns nutrients to

CZCS Global Primary Production

Marine Ecology

Basic Ecology

physical and chemical parameters

affecting distribution and abundance

An ecosystem includes both the living (biotic) and non-living (abiotic) portions

of the environment.

– Examples include: salt marshes, estuaries,

coral reefs, the North Pacific Gyre.

Classification of Organisms

horizontal : neritic | oceanic

vertical :

– epi pelagic (top) / euphotic (good)

– meso pelagic (middle) / disphotic (low)– bathy pelagic (deep) / aphotic (without)– abysso pelagic (“bottomless”)

Divisions of the Marine Environment

Figure 9-1

Classification of Organisms

Scientists have established another

classification scheme to categorize biota

on the basis of lifestyle The major groups are:

– plankton (floaters)

– nekton (swimmers)

– benthos (bottom dwellers)

Distribution of Marine Lifestyles

16.7% of Earth’s animals are marine

2% inhabit pelagic environment (most of the oceans are cold and dark)

98% are benthic!

bottom.

Benthic plants - restricted to shallow

waters (light)

Benthic animals occur everywhere from shallow depths to the deep sea.

Research Video Clips:

“Live fast, die young ”

Hydrostatic Pressure

Pressure caused by the height of water

Function of water height and water density Pressure generally increases at a rate of 1 atm per 10 m of water.

( or 16 psi per 10 m depth)

Think You’re Under

Pressure Now?

Hydrostatic Pressure

(Cont.)

enormous in the deep sea yet animals live there

Animals do not contain gases

However, mesopelagic fish which have

gas-filled swim bladders to help maintain neutral buoyancy

– unable to move rapidly between depths

– pressure change could cause bladder explode.