Reminder: HW3 Part II due Wednesday!
Midterm Thursday
Aquatic Ecosystems
Monday, August 22nd
Ecotone: the transition zone
between two diverse
communities
WHAT DID YOU FIND??????
Kelp Effect on Waves
Kelp forest ecosystem
Otters eat sea urchins
Kelp provides otter habitat
Sea urchins eat kelp
Kelp forest ecosystem & human
values
Kelp Effect on Waves
Impact of Kelp on Low Productivity
Terrestrial Env’ts
Example: Channel Islands
•Kelp detritus = nutrient input to intertidal communities
•Marine bird and mammals
feed on intertidal organisms
•Feces/guano provide nutrients
to terrestrial organisms
•Biggest impact where ratio of
shoreline to area is high
Kelp forest ecosystem
•30-40 m water depth
•Determined by light availability
•Require high concentrations of nutrients
•Occur mostly in areas of upwelling
•Provide primary production (food) and
habitat!
Selective Pressures in Intertidal Zones
Tides
Salinity
Waves
Rocky Intertidal Zonation
Where to snorkel, rocky shore or sandy beach? Why?
Aquatic Ecosystems
Oceans
• Lakes
Streams and Rivers
• Estuaries
Freshwater wetlands
•
•
•
Some General Questions:

Where does the energy to support aquatic life come from?

How productive are each of the aquatic environments?

What is the limiting factor in each aquatic environments?
How are nutrients cycled?

How have humans changed these environments?
The open ocean is most like…
A)
B)
C)
D)
a tropical rain forest
the boreal forest
the desert
chaparral
…with regard to productivity.
Where is the ocean most productive?
Where sunlight is available:
Top 100 meters (euphotic zone)
Where nutrients are
available:
 near the coast
From upwelling
rivers bring nutrients
 Polar upwelling
– Short, intense productivity
Net Primary Productivity (NPP) by Biome
Atmospheric/Ocean Coupling
surface currents are driven by wind
Ocean: surface currents
Ocean Primary Productivity
Coastal Upwelling
•Most upwelling occurs in response
to longshore winds.
•Upwelling: increased nutrients,
increased primary production
good fishing!
•El Nino brings warm water, shuts down
upwelling, bad for fisheries
Coastal Upwelling
Is Primary Production always
good for upper trophic levels?
Red tide
Harmful algal blooms: toxicity or increase in BOD
suffocation, starvation
LA Times:
Altered Oceans
Pulitzer Prize
The open ocean is most like…
A)
B)
C)
D)
a tropical rain forest
the boreal forest
the desert
chaparral
…with regard to productivity.
Coral reefs
Coral reefs are extremely productive
 Visibility is great!
 But we know that nutrient-rich water is murky

How is this possible?
Where are the nutrients?
What terrestrial biome does this remind you of?
Coral reefs
Efficient cycling of nutrients
 Complex relationships between
organisms

•
•
•
Corals: plants or animals?
zooxanthellae in coral
intricate food webs
Freshwater Ecosystems
Lakes, streams and rivers
Light Penetration in Lakes
Euphotic zone
Aphotic zone
Sediment
Secchi disk
eu: well or good
a: without
Oligotrophic vs. Eutrophic Lakes
Thermal Stratification of Lakes
Summer
Epilimnion
Hypolimnion
Sediment
Thermocline
Thermal Stratification of Lakes
(wind)
Summer
Fall
Epilimnion
Hypolimnion
Sediment
Thermocline
Well-mixed
profile
Sediment
Thermal Stratification of Lakes
(wind)
Cooling
Fall
Summer
Epilimnion
Hypolimnion
Sediment
Thermocline
Well-mixed
profile
Sediment
Cooling
Winter
Frozen
Warmer
Well-mixed
Hypolimnion
profile
Well-mixed
Sediment
Thermal Stratification of Lakes
(wind)
Cooling
Fall
Summer
Epilimnion
Hypolimnion
Sediment
Thermocline
Well-mixed
profile
Sediment
Warming
Cooling
Winter
Spring
Well-mixed
profile
Sediment
Frozen
Warming
Well-mixed
Hypolimnion
profile
(4°C)
Sediment
Summary

Aquatic Ecosystems
Limiting factors (light, nutrients, dissolved oxygen) and Temperature

Rocky Intertidal
Zonation and adaptations

Oceans
Productivity: euphotic zone/thermocline/nutrients/BOD/algal blooms
Open ocean vs. coast
– Nutrients: upwelling and coastal inputs
Coral Reefs (zooanthellae, coral bleaching, ocean acidification, dynamite fishing)

Lakes… seasonality of:
Light penetration (euphotic vs. aphotic zones)
Temperature (epilimnion vs. hypolimnion)
Oxygen (aerobic vs. anaerobic/anoxic)
Nutrients (oligotrophic vs. eutrophic)