magic import test CHAP 9

• Marine Ecology is the study of the interrelationships between the physical and biological aspects of marine environments
• Marine ecology is the study of how organisms adapt to and alter their marine environment
• Major marine provinces

  • Benthic (seabed)
  • Pelagic (water column)
• Pelagic environment zones

  • Neritic zone (continental shelves)
  • Oceanic zone (beyond the shelves)

  
• Oceanic zone subdivisions

  • Epipelagic zone (0-200m, illuminated)
  • Mesopelagic zone (200-1000m, trace of sunlight, no photosynthesis)
  • Bathypelagic zone (1000-2000m, no light)
  • Abyssalpelagic zone (2000-6000m, most of the ocean water column)
  • Hadalpelagic zone (>6000m, deep trenches)

  
• The pelagic environment makes up 3% of the epipelagic zone, 28% of the mesopelagic zone, 15% of the bathypelagic zone, 54% of the abyssalpelagic zone, and less than 1% of the hadalpelagic zone

  
• Benthic environment zones

  • Intertidal (littoral) zone (shore between high and low tides)
  • Sublittoral zone (beach to shelf break, 0-200m)
  • Bathyal zone (shelf break to 2000m)
  • Abyssal zone (2000-6000m)
  • Hadal zone (>6000m, deep ocean trenches)

  
• The benthic environment makes up 8% of the sublittoral zone, 16% of the bathyal zone, 75% of the abyssal zone, and 1% of the hadal zone
• Ocean zones by light

  • Photic zone (light sufficient for photosynthesis, 0-100m)
  • Dysphotic (twilight) zone (light too weak for photosynthesis, 100-450m)
  • Aphotic zone (no light from surface, >450m)
• The five major kingdoms of marine life

  • Eubacteria (bacteria, cyanobacteria)
  • Protista (single-celled organisms with nucleus)
  • Fungi
  • Chromista (plants, free-floating or attached)
  • Metazoa (multicellular animals)
• Kingdom Eubacteria

  • Bacteria, including cyanobacteria (blue-green algae), unicellular with no cell nucleus, important for decomposition
• Kingdom Protista

  • Single-celled organisms with a cell nucleus
• Kingdom Chromista

  • Plants, free-floating or attached to the seafloor
• Kingdom Fungi

  • Abundant in the intertidal zone and are important in decomposition
• Kingdom Metazoa (Animalia)


  • All multicellular animals in the ocean
• Marine organism lifestyles

  • Plankton (float, no propulsion)
  • Nekton (active swimmers)
  • Benthic (live on or in the seafloor)
• Some organisms cross between planktonic and benthic lifestyles during their life cycle
• Environmental factors in the marine environment

  • Temperature
  • Salinity
  • Pressure (water depth)
  • Nutrients
  • Dissolved gases
  • Currents
  • Light
  • Suspended sediments
  • Substrate (bottom material)
  • River inflow
  • Tides
  • Waves

  
• Ecosystem

  The total environment, including the biota (all living organisms) and the nonliving physical and chemical aspects
• Examples of marine ecosystems

  • Salt marshes
  • Estuaries
  • Kelp forest
  • Coral reefs
  • Abyssal sea bottom

  
• Ecologists study ecosystems to determine interrelationships and interconnections within the ecosystem
• Temperature


  • Can control aspects of an organism's life such as distribution, degree of activity, and reproduction
  • Many organisms are not able to regulate their body temperatures, which therefore vary with the temperature of the surrounding water
• Phytoplankton abundance

  Correlates with cool water temperatures
• Shellfish harvest in Maine

  Inversely related to mean annual sea-surface temperature
• The inverse relationship between shellfish harvest and temperature in Maine is actually due to increased green crab populations, which eat the clams, as temperature rises
• Salinity

  • Can affect marine organisms, with nearshore animals needing to be salinity tolerant due to changes in river discharge, and benthic animals needing high tolerances for changing salinity
• Diffusion

  The movement of substances from points of high concentration to points of low concentration, allowing nutrients to enter cells and waste to exit
• Osmosis

  Diffusion through a semipermeable membrane (cell wall)
• Osmoregulation

  How marine fishes counteract the osmotic diffusion of water out of their cells
• Hydrostatic pressure

  The pressure exerted by the water column above an organism, increasing by about 1 atm per 10 meters of depth
• Early biologists believed no life could exist at great ocean depths due to the high hydrostatic pressures, but we now know life can be found even in the deepest trenches
• Marine fishes

  • Counteract the osmotic diffusion of water out of their cells in various ways
• Freshwater fishes

  • Osmoregulate by not drinking water, urinating frequently, and absorbing salt ions through chloride cells in the gills
• Hydrostatic Pressure

  The pressure that the water column above an organism exerts
• Hydrostatic pressure increases with water depth at a rate of about 1 atm per 10 meters of the water column
• Early biologists believed that no life could live at depth due to the high pressures and lack of light
• Today we know life can be found even in the deepest ocean trenches, as organisms of the deep have no gases in their cells only water which can not be compressed
• Plants on land

  • Relatively large, multicellular, and rooted
  • Transfer nutrients and water to their leaves through a vascular system, generally from roots in the ground upward to the leaves
• Marine plants

  • Typically microscopic, unicellular, and free floating
  • Absorb nutrients from seawater through their cell walls
• More than 90% of marine plants are algae