Aquatic EcosystemsAquatic Ecosystems

Monday, August 22nd

Reminder: HW3 Part II due Wednesday!Midterm Thursday

Ecotone: the transition zone between two diverse communities

Ecotone: the transition zone between two diverse communities

WHAT DID YOU FIND??????WHAT DID YOU FIND??????

Kelp Effect on WavesKelp Effect on Waves

Kelp forest ecosystemKelp forest ecosystem

Kelp provides otter habitat Sea urchins eat kelp

Otters eat sea urchins

Kelp forest ecosystem & human valuesKelp forest ecosystem & human values

Kelp Effect on WavesKelp Effect on Waves

Impact of Kelp on Low Productivity Terrestrial Env’ts

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 ecosystemKelp 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 ZonesSelective Pressures in Intertidal Zones

Tides Salinity Waves

Rocky Intertidal ZonationRocky Intertidal Zonation

Where to snorkel, rocky shore or sandy beach? Why?

Aquatic EcosystemsAquatic Ecosystems

• Oceans • Lakes

• Streams and Rivers• Estuaries

• Freshwater wetlands

Some General Questions: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…The open ocean is most like…A) a tropical rain forestB) the boreal forestC) the desertD) chaparral

…with regard to productivity.

Where is the ocean most productive?Where is the ocean most productive?

Where nutrients are available:

near the coastFrom upwelling

• rivers bring nutrients Polar upwelling

– Short, intense productivity

Where sunlight is available:Top 100 meters (euphotic zone)

Net Primary Productivity (NPP) by BiomeNet Primary Productivity (NPP) by Biome

Atmospheric/Ocean CouplingAtmospheric/Ocean Coupling

surface currents are driven by wind

Ocean: surface currentsOcean: surface currents

Ocean Primary ProductivityOcean Primary Productivity

Coastal UpwellingCoastal Upwelling

•Most upwelling occurs in responseto longshore winds.

•Upwelling: increased nutrients, increased primary production good fishing!

•El Nino brings warm water, shuts downupwelling, bad for fisheries

Coastal UpwellingCoastal Upwelling

Is Primary Production always good for upper trophic levels?

Is Primary Production always good for upper trophic levels?

Harmful algal blooms: toxicity or increase in BOD suffocation, starvation

Red tide

LA Times:

Altered Oceans

Pulitzer Prize

The open ocean is most like…The open ocean is most like…A) a tropical rain forestB) the boreal forestC) the desertD) chaparral

…with regard to productivity.

Coral reefsCoral 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 reefsCoral reefs

Efficient cycling of nutrients Complex relationships between

organisms• Corals: plants or animals?• zooxanthellae in coral• intricate food webs

Freshwater EcosystemsFreshwater Ecosystems

Lakes, streams and rivers

Light Penetration in LakesLight Penetration in Lakes

Secchi disk

Euphotic zone

Aphotic zone

Sediment

eu: well or good a:

without

Oligotrophic vs. Eutrophic LakesOligotrophic vs. Eutrophic Lakes

Thermal Stratification of LakesThermal Stratification of Lakes

Epilimnion

HypolimnionSediment

Summer

Thermocline

Thermal Stratification of LakesThermal Stratification of Lakes

Thermocline

Epilimnion

HypolimnionSediment

(wind)

Summer Fall

Well-mixed profileSediment

Thermal Stratification of LakesThermal Stratification of Lakes

Hypolimnion

Thermocline

Well-mixed profileSediment

Epilimnion

HypolimnionSediment

(wind)

SummerFall

WinterFrozen

Warmer

Well-mixed

Well-mixed profileSediment

Cooling

Cooling

Thermal Stratification of LakesThermal Stratification of Lakes

Hypolimnion

Thermocline

Well-mixed profileSediment

Well-mixed profileSediment

Epilimnion

HypolimnionSediment

(wind)

SummerFall

WinterSpring Frozen

(4°C)

Well-mixed profileSediment

Cooling

Cooling

Warming

Warming

SummarySummary Aquatic Ecosystems

Limiting factors (light, nutrients, dissolved oxygen) and Temperature Rocky Intertidal

Zonation and adaptations Oceans

Productivity: euphotic zone/thermocline/nutrients/BOD/algal bloomsOpen 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)