GLY150: INTRODUCTION TO OCEANOGRAPHY University of North Carolina Wilmington

Back

Lecture Outline

Biological Productivity and Energy Transfer

I. Phytoplankton - Algae

• Microscopic
• Inhabit sunlit surface waters
• 50% of the biomass in marine environment
• Produce ~99% of the food supply for marine environment
  • Diatoms
    • Frustules of silica
  • Coccolithophores
    • Coccoliths of calcium carbonate
  • Dinoflagellates
    • Red Tide
    • Pfiesteria

II. Primary Productivity

• Photosynthesis
  • Sunlit waters, upper 100 m
  • carbon dioxide + water + Sunlight --> Glucose + Oxygen
• Chemosynthesis
  • Hydrothermal vent communities
  • Sulfur oxidizing bacteria
• Patterns of productivity
  • Tropical regions
    • Relatively low productivity
      • Coastal upwelling
      • Coral reefs
      • Equatorial upwelling
  • Temperate regions
    • Two peaks, spring and fall
  • Polar regions
    • One peak in summer

• Measuring primary productivity
  • Radioactive C¹⁴
  • Gran method
  • Coastal Zone Color Scanner

III. Biogeochemical/Nutrient Cycles

• Nitrogen
  • Complex cycle
  • Bacteria necessary to convert nitrogen to nitrates
    • Conversion can take up to three months
  • Nitrate essential in formation of proteins, amino acids
  • Availability can be limiting factor in productivity
• Phosphorus
  • Simple cycle
  • Phosphate essential in formation of nucleic acids, cell membranes
  • Availability not usually limiting factor in productivity

IV. Marine Ecosystems

• Producers - autotrophs
• Consumers - heterotrophs
  • Herbivores
  • Omnivores
  • Carnivores
• Decomposers

V. Trophic Levels and Biomass Pyramids

• Biomass
• Energy distributed within trophic level four ways
  • Respiration
  • Reproduction
  • Growth
  • Wastes
• Energy transfer between trophic levels inefficient (~10%)
• Food Chains
  • Terrestrial
  • Marine
  • Bioaccumulation/Biomagnification
• Symbiosis

VI. Fisheries

• Management
• Overfishing
• Incidental Catch

Some helpful links relevant to this lecture:
Measuring Primary Productivity with Satellites
Diatom Webpage
Pfiesteria Info
Harmful Algae

Top of Page