1. Marine Life

2. Plankton – drift with ocean currents (zooplankton, phytoplankton)
Nekton – animals that move independently of currents (swim)
Benthos – organisms on or in sea floor
Classification

3. Life Zones Availability of Sunlight
Photic zone – where sunlight penetrates
Varies with water clarity, atmospheric conditions, time of day, latitude, & season.
Euphotic zone – where light is strong enough for photosynthesis (up to 100m)
Aphotic zone - dark

4. Life Zones Distance from shore
Intertidal – between high and low tides (harsh)
Neritic Zone – from low tide mark across continental shelf. (high nutrients, biomass)
Oceanic Zone – beyond Neritic Zone – deep, low nutrients
Life Zones

5. Life Zones
Water Depth
Pelagic Zone – surface to moderate depth, has zooplankton, phytoplankton, & nekton.
Benthic Zone – sea floor – crabs, sea stars, burrowing worms.
Abyssal Zone – deep ocean floor, abyssal plains, trenches – nutrient poor

6. Life Zones
Hydrothermal Vents – sea water seeps into cracks along midocean ridge, gets ejected hot & saturated with minerals.
Heat provides energy for chemosynthesis, minerals provide building blocks.

7. Productivity
Primary Productivity – using light energy (photosynthesis) or chemical energy (chemosynthesis) to make organic compounds from inorganic.
Photosyntheis influenced, limited by availability of nutrients & sunlight.

8. Productivity in Polar Oceans
Temp. & density vary little, plenty of mixing between surface & deeper, nutrient-rich water.
Limited by solar radiation
Phytoplankton peaks in May, stays near surface (melting ice)
Zooplankton peaks in June
Productivity in Polar Oceans

9. Productivity in Tropical Oceans
Limited by lack of nutrients.
Permanent thermocline, no mixing, so cold, nutrient-rich water locked deep, away from phytoplankton.
Productivity in Tropical Oceans

10. Productivity in Temperate Oceans
Determined by shifting nutrient supply & sunlight throughout seasons.
Winter – low, because solar energy is limited.
Days short, sun angle low.
Plenty of nutrients, but little growth.

11. Productivity in Temperate Oceans
Spring – fair.
More sun & nutrients, but seasonal thermocline traps algae in euphotic zone.
Algae bloom uses
up nutrients, productivity stops.

12. Productivity in Temperate Oceans
Summer – low
High sun angle, much solar radiation, surface warms, strong thermocline prevents mixing.

13. Productivity in Temperate Oceans
Fall – fair
Sunlight decreases, thermocline breaks down, mixing begins.
Algae bloom, not as much as in spring.

14. Estuaries Where freshwater rivers empty into ocean.
Lower salinity, shallow warm water, nutrient rich.
HIGH productivity.

15. Salinity Total amt. solids dissolved in water
Comes from earth’s interior (volcanic) & weathering of rocks.
Sea water about 3.5% salinity

16. Processes Affecting Salinity
Usually pretty constant.
Variations come from processes that affect water content (add or remove water).

17. Salinity Salt concentration determines what can live in it.
Brine – highest conc., fewest species
Brackish – mixture of fresh & saltwater

18. Ocean Temperatures
Surface temperature most affected by amount of solar radiation received.
Solar radiation mostly a function of latitude.

19. Temperature & Depth Thermocline – layer between 300 & 1000 m
where temperature
decreases rapidly.
Below 1000 m, remains constant just above freezing
High latitude – cold at surface, no thermocline

20. Ocean Density Affected by salinity and temperature Saltier = denser
Colder = denser
Temperature has greater affect on density because it varies more.
Pycnocline – layer between 300 & 1000 m where density increases rapidly.
No pycnocline at high latitudes.

21. Ocean Layering Deterimined by density
Shallow surface mixed zone – 300 m, mixed by waves, tides, currents, uniform temp., 2%
Transition zone – includes thermocline & pycnocline, temp drops, 18%
Deep zone – temp constant (low), density constant (high),80%