Aquatic Ecosystems Wednesday, November 1st Reminder: Problem Set due Friday!

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 have humans changed these environments?

The open ocean is most like… A) a tropical rain forest B) the boreal forest C) the desert D) chaparral … with regard to productivity.

Net Primary Productivity (NPP) by Biome

Coastal Upwelling

Atmospheric/Ocean Coupling surface currents are driven by wind

Ocean: surface currents

Where is the ocean most productive? Where nutrients are available:  near the coast From upwelling rivers bring nutrients  Polar upwelling –Short, intense productivity Where sunlight is available: Top 100 meters (euphotic zone)

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

Is Primary Production always good for upper trophic levels? Harmful algal blooms: toxicity or increase in BOD suffocation, starvation Red tide

Kelp forest ecosystem 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 ecosystem Kelp provides otter habitatSea urchins eat kelp Otters eat sea urchins

Kelp forest ecosystem

Kelp Forest Food Web

Kelp Dampens Waves

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 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

Rocky Intertidal Zonation

Selective Pressures in Intertidal Zones TidesSalinity Waves

Summary  Oceans Productivity: 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 Intertidal Zonation and adaptations