Ecosystem Productivity & Seasonal Effects

Energy Flow & Productivity

• Producers (algae, plants) capture solar energy and convert it to glucose (photosynthesis).
• Energy transfers to consumers when they eat producers.
• Primary productivity = number/biomass of producers; more producers ⇒ higher ecosystem productivity.

Regional Productivity Patterns

• Polar Regions
  • Nutrient-rich waters.
  • Ideal season: Summer (extended daylight boosts photosynthesis).
• Temperate Regions
  • Nutrients + moderate light in spring create a productivity spike.
  • Summer: nutrient depletion lowers productivity.
  • Winter: limited light reduces productivity.
• Tropical Regions
  • Consistent light, but generally nutrient-poor.
  • Winter coastal upwelling adds nutrients, creating the annual productivity peak.

Seasonal Effects on Ecosystems

• Seasonal changes in sunlight & temperature alter nutrient availability.
• Phytoplankton blooms occur when light and nutrients coincide.
• Zooplankton, fish, and top predators migrate to follow these blooms.

Case Study: Shark “Katharine”

• Tracked path (late Oct.–early Nov.) follows waters from 0^{\circ}C to 31^{\circ}C.
• Likely follows prey concentrations tied to phytoplankton-driven food chains.