Oceanography Chp 10

• Pelagic Communities


  2 groups: Plankton, Nekton
• Phytoplankton


  The autotrophs
• Phytoplankton bind 35 billion tons of carbon into carbohydrates in a year
• Phytoplankton account for 40% of food made on earth
• Major types of phytoplankton

  • Diatoms
  • Dinoflagellates
• Nanoplankton


  Small plankton < 1cm
• Diatoms


  • More than 5600 species
  • Mostly rounded but can be elongated, branched or triangular
  • Perforated patterns through frustules
  • Extremely efficient at converting energy
  • Store energy as fatty acids and oils which allows floatation
• Diatoms


  Made up of two valves
• Diatoms are mostly single celled autotrophs
• Diatoms most have 2 whip like projections called flagella
• Zooplankton


  The heterotrophs
• Zooplankton are the most numerous primary consumers in the ocean
• Copepods (crustaceans) are the most abundant zooplankton
• Macroplankton


  Plankton larger than 1cm
• Holoplankton


  Spend whole lives as plankton
• Meroplankton


  Temporary visitors to plankton community
• Nekton


  Pelagic animals that swim actively
• Most nektonic animals are vertebrates with only few being invertebrates
• Bony Fish


  Lightweight skeleton, 90% of all living fish, contains cod, tuna, halibut, goldfish etc.

  
• Problems of Fish


  • Water is approx 1000 times denser than air
  • Water is 100 times more viscous than air

  
• Movement, Shape & Propulsion

  • Drag is resistance to movement
  • Drag is determined by frontal area, body contour and surface texture
  • Drag increases geometrically with speed
• Maintenance of Level


  • Density of fish tissue greater than water, so they should sink
  • Need to be offset by buoyant gas or fat filled swim bladder
  • Continuous swimming (cartilaginous fish i.e. sharks)

  
• Gas Exchange


  • Countercurrent flow
• Senses of Fish


  • Hearing
  • Sight
  • Smell
  • Schooling
  • Camouflage
  • Venom/poison
• Marine Reptiles


  Ectothermic, Breath air with lungs, Covered with scales, Impermeable skin, Have special salt glands, Most require warm water
• Marine Birds


  Endothermic, Evolved from small, fast running dinosaurs, All birds lay eggs on land, Salt excreting glands in their heads, Most live in Southern Hemisphere
• Common features of Marine Mammals

  • Streamlined body shape
  • Generate internal body heat
  • Respiratory system is modified
  • Osmotic adaptations
• Cetacea


  79 living species evolved from ungulates, Whales propelled by horizontal tail, Thick layer of oily blubber, One or two nostrils with special valves, Deeply convoluted brain
• Toothless Whales


  Filter feeders, Subsist on krill, Mouths have plates of baleen
• Toothed Whales


  Active predators, Large brains, Use echolocation
• Benthic Organisms


  Most common distribution pattern is clumped
• Seaweeds


  Large marine multicellular algae, Carry out 2-10% of ocean's primary productivity, Not technically plants, Classified as protistans, None live below euphotic zone
• Problems of Large Marine Autotrophs

  • Exposed to drying effects of air and sunlight when tide is out
  • Can be washed against rocks
  • Warm water can destroy proteins required for photosynthesis and respiration
  • Warm water may not have enough dissolved oxygen for respiration at night
• Seaweed Structure


  No vessels in seaweed, Thallus is the body which can be large or small, branching or tufted, sheet form or filamentous, encrusting or elongated, rounded or pointed
• Classification of Seaweeds


  • Chlorophyta-green algae
  • Phaeophyta-brown algae
  • Rhodophyta-red algae
• Vascular Marine Plants


  Have tissues for conducting water, minerals and photosynthetic products throughout the plant, Grow much larger because of this
• Salt marshes & Estuaries

  Salt marshes form in an estuary, Organisms tolerate varying salinity & extreme temperature range, Can get strong tidal currents, Highly productive
• Adaptations to Life in an Estuary/Salt Marsh

  • Plants trap silt with roots to stabilize them
  • Animals burrow or hide in vegetation
  • Produce nonplanktonic larvae
  • Lay eggs on firm objects or carry eggs in their bodies
• Rocky Intertidal Communities


  Intertidal zone is band between the highest high tide and lowest low tide marks in a rocky shore
• Rocky Intertidal Organisms


  • West Indian Top Shell
  • Chitons