Oceanography Chp 9

• Living organisms


  • Can capture, store & transmit energy
  • Can reproduce
• 1 part in 2000 of light reaching the Earth's surface is captured for photosynthesis
• Chemosynthesis


  • Production of usable energy directly from energy rich inorganic molecules
  • Available in the environment not from the sun
  • Very few organism carry out chemosynthesis
  • Only simple forms of life

  
• Primary Productivity


  • Synthesis of organic material from inorganic material
  • Expressed in grams of carbon bound into organic material per square meter of ocean surface area per year

  
• Diatom


  • Single celled phytoplankton
  • Most abundant
  • Made of silicon
• Autotrophs


  Make their own food
• Heterotrophs


  Eat other things to obtain energy
• Trophic Pyramid
• Physical Factors Affecting Marine Life

  • Light
  • Temperature
  • Dissolved nutrients
  • Salinity
  • Dissolved gases
  • Acid-base balance
  • Hydrostatic Pressure
• Light


  • Most sunlight approaching at a low angle reflects off of the water surface
  • Blue light penetrates the deepest
  • Red light is absorbed near the surface
  • Light energy absorbed by water turns to heat
  • # of particles affects amount of penetrating light
• Photic Zone


  Uppermost layer of seawater lit by sun (approx 100m/330ft)
• Aphotic Zone


  Permanently dark layer of seawater beneath the photic zone
• Euphotic Zone


  Upper most part of the photic zone (70m/230ft)
• Disphotic zone


  Where light is present but not bright enough to allow photosynthesis
• Temperature


  • Rate of chemical reactions in living organisms is dependent on heat
  • Metabolic rate is the rate at which energy releasing reactions proceed within an organism
  • The metabolic rate approximately doubles with a 10 oC (18 oF) temperature rise
• Ectotherms


  • Cold Blooded organisms
  • Have internal temperature that stays close to their surroundings
• Endotherms


  • Warm Blooded organisms
  • Have stable, high internal temperatures
• Dissolved Nutrients


  • Nutrient is a compound required for the production of organic matter
  • Nitrogen in form of nitrate (NO3-) and Phosphorus as phosphate (PO43-) are main inorganic nutrients for primary productivity
• Salinity


  • Changing salinity can cause physical damage of membranes, Alter protein structure, Affect specific gravity, density and buoyancy of organism
  • Most simple marine organisms are isotonic i.e. salinity inside their bodies is equal to salinity of the seawater
• Dissolved Gases


  • Marine organisms primarily require oxygen and carbon dioxide to stay alive
  • Oxygen is not easily dissolved in seawater
  • Carbon dioxide is more soluble and essential to primary productivity

  
• Acid-Base Balance


  • Seawater is slightly alkaline at pH 8
  • Dissolved substances in seawater act as a buffer
  • Acids or bases distort the shapes of enzymes/proteins
• Hydrostatic Pressure


  • Pressure is maintained inside and outside an organism
  • Same in ocean and at bottom of atmosphere
  • Marine organisms do not need heavy shells to keep from being crushed
  • At great depths high pressure makes gases more soluble, Inactivates some enzymes, Metabolic rates for similar temperatures are higher
• Classifications of Marine Environment

  Divided into zones based on homogeneous physical features like Light, Temperature, Salinity, Depth, Latitude, Water Density, Location (primary division between water and ocean bottom)
• Community


  Assemblage of all interacting species of organisms in an area
• Population


  A group of organisms of the same species in a specific area
• Ecosystem


  System of all interacting organisms, including their non-living surroundings
• Habitat


  Space an organism inhabits; defined by biological requirements of each particular organism
• Niche


  Includes all ways an organism affects organisms with which it interacts as well as how it modifies its physical surroundings
• Competitive Exclusion Principle


  No two species can occupy the same ecological niche in the same place at the same time
• Less fit species must evolve into a slightly different niche
• Communities can modify the physical aspects of their environment
• Coral reefs alter current patterns, ocean temperature, and change proportion of dissolved gases
• Climax Community is a long established, stable community
• Aquatic Succession