intertidal zone

  1. What is the tidal range of Gulf of Mexico and why?
    low tidal range: 2ft due to Wind effect
  2. Intertidal Zone
    Between highest tide level and lowest
  3. Tidal range
    Distance between highest and lowest tide levels
  4. What have the most extreme tidal range; give example
    long, narrow bays have most extreme tidal range ex East Canada- Bay of Fundy-25ft tidal range
  5. Tide tables
    list high and low tides etc
  6. what tide is desired for field trips? launching boat/scuba?
    • Field trip-low tide
    • Boat/scuba-high tide
  7. Tides are measured from the ?
    Zero mark
  8. What is the zero mark?
    Its set by observation-they keep record of highest and lowest tide for year; avg measurement=> ?
  9. What is the intertidal zone?
    Area with tidal effects
  10. What is the subtidal area?
    Area below intertidal to deepest wave effects
  11. Why do we have tides?
    • earth rotates around sun, moon rotates around earth; Moon pulls at water on earth on same side of it=>high tide
    • Opposite side of earth has low tide
  12. What is spring tide? What causes it?
    • When tide seems to "spring" up: Higher highs and lower lows
    • Occurs was EATH->moon-> sun in that order=>higher tidal range
  13. What is neap tide? Cause?
    • Lesser tidal range
    • Occurs when sun and mood are perpendicular
  14. Why may tides table be off by couple hours?
    Gradually move as earth rotates
  15. Diurnal tides; where do they occur?
    • 1 high and 1 low tide per day
    • Tropics
  16. Semidurnal
    • 2 highs and 2 lows per day at 6 hour interval
    • Pacific coast of USA
    • Higher High(HHT) 6ft
    • Lower low (LLT) -2ft
    • Lower high(LHT) 4ft
    • Higher low(HLT) 2ft
  17. Seiches
    • Waves of tidal flow tends to raise water level on 1 side of basin
    • Occurs in semi enclosed areas
    • Ex Gulf of Mexico
  18. Physiological challenge on marine life at low tide
    • Respiration-low water levels or water retreats
    • Desiccation: drying out
    • Exposure to wind and rain
    • Exposure to land-based predators: birds are major danger, mammals(coyotes/racoons)
    • Trampling &crushing and sand compaction
    • When little rain=> higher salt=> when dry out -salt formation= BAD
    • Especially at extreme high tide
  19. Challenges at high tide: COMPETITION
    • Surf-wave banging on tiny organisms can crush or rip away from perch
    • Cope by hide, rubbery body, flexible; hang on tight
    • Sand abrasion-act like sand paper
    • Exposure to Sea water predators-fishes, morays, crabs, octuopus, starfishes
    • Ex baracuda into shallow water in search of food
  20. How to cope w/ low life
    • Leave-fish will swim offshore or go into deeper pools
    • Dig in-burrow into sediment
    • Cause problems b/c less oxygen
    • Store water
    • Stay in a shady place
    • Body color: light ,pale or camouflaged
    • Helps against predators and heat
    • Seasonal cycles
    • Some species are strictly intertidal
    • Ghost crab: ocypode-only live in intertidal b/c they can't compete
  21. Microhabitats
    • Can be refuges
    • Rock jetties with overhang
    • May form microhabitats
    • At low tide may go under and will see things only seen when diving normally
    • Can also have BAD microhabitats-hypersaline, or dead, rotted seaweed or human caused
  22. Effects of Sea Spray at very highest levels
    • Moisture and salt-causes problems with rooted plant
    • Salt gets on leaves=>desiccation of leaves
    • Some things can handle that
Card Set
intertidal zone
marine biology intertidal zone