Aquatic EcosystemsAquatic Ecosystems

Wednesday, November 1st

Reminder: Problem Set due Friday!

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 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.

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

Coastal UpwellingCoastal Upwelling

Atmospheric/Ocean CouplingAtmospheric/Ocean Coupling

surface currents are driven by wind

Ocean: surface currentsOcean: surface currents

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)

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

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

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!

Kelp forest ecosystemKelp forest ecosystem

Kelp provides otter habitat Sea urchins eat kelp

Otters eat sea urchins

Kelp forest ecosystemKelp forest ecosystem

Kelp Forest Food WebKelp Forest Food Web

Kelp Dampens WavesKelp Dampens Waves

Kelp Dampens WavesKelp Dampens Waves

Impact of Kelp Deforestation on Low Productivity Terrestrial Env’ts

Impact of Kelp Deforestation 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

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

Rocky Intertidal ZonationRocky Intertidal Zonation

Selective Pressures in Intertidal ZonesSelective Pressures in Intertidal Zones

Tides Salinity Waves

SummarySummary

OceansProductivity: euphotic zone/thermocline/nutrients/BOD/algal blooms

Open ocean vs. coast– Nutrients: upwelling and coastal inputs

Kelp Forest (keystone species: sea otter)

Coral Reefs (zooanthellae, coral bleaching, dynamite fishing)

Rocky IntertidalZonation and adaptations