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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