sandy beaches

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sandy beaches
2011-10-05 16:57:31
marine sandy beaches

sandy beaches marine and birds
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  1. Gulf of Mexico:
    exposed sandy beach->barrier island->bay->mudflats, salt marsh->mainland
  2. Waves
    • result of winds blowing across surface of ocean
    • Smaller scale than tide
    • Size depends on strength of wind
  3. Fetch
    • Distance wind blows
    • Longer=higher waves
    • Worst winds around Antartica
    • Texas doesn't get the high wind or the fetch=> don't get big waves
  4. Wave can what with each other
    Augment or cancel each other
  5. Swell
    • Mostion of waves
    • Will move up and down; doesn’t have Break
  6. Waves break when?
    • when wave height /wave length =1/7
    • Break at 10000lbs/square inch
  7. Period
    seconds for crest to travel 1 wave length
    • Eye level=wave height
    • Better think about it
    • Look at where wet seaweed is in relation to you
    • If high up, then shouldn't enter water
  9. Shallow water wave:
    depth=1/2 wave length
  10. Surge
    Back and forth wave motion in shallow water
  11. Breakers
    Can be spilling or plunging
  12. Spilling breaker
    Wave curls over and doesn’t break immediately, but curves over long line (water tunnel)-surfers use
  13. Plunging breaker
    • comes up on a steep beach
    • Just goes splat
    • Doesn't feel bottom until already on beach
  14. Wave breaks
    • In TX and most of gulf coast; waves break in series over sandbars
    • Some troughs can be 5 ft deep
    • So rule of thumb-don't go more than knee deep
  15. Once Waves finally run up on beach then?
    Water can sink into sand and go back to sea Or backwash
  16. backwash
    • water runs back to sea
    • 1 inch isn't big deal-strong backwash can knock you off your feet
    • Hissing noise indicates strong backwash
  17. Longshore currents
    • Run along beach, carry water to RIP channels-go 900 to beach out to sea
    • Usually weak
    • Fish sit in rip channel b/c if something gets knocked off beach, it gets into rip channel
    • Looks calm-interruption in waves then with foam
  18. Primary Productivity of sandy beach
    • Phytoplankton present
    • No attached algae, seagrasses etc
    • Animals rely on debris, dead stuff or predation for food
    • Lots of dead sargassum
    • Affected by surf-scraping, movement
    • Sand grain size important what causes sand to be more coarse
    • stronger surf=> ?
  19. Wentworth scale:
    • silt (less than 1mm) on upp
    • Primarily medium sand in TX
    • Most animals prefer medium and thin sand
  20. Coarse sand doesn't have much fauna b/c ?
    they have to deal with wave action
  21. Coarse sand characteristics
    • Wave action LOTS=> lots of O2 and stuff cast ashore,
    • BUT sand doesn’t retain water at low tide; much abrasion
    • Greater porosity
  22. FINE SAND characteristics
    • Less wave action
    • Retains better water at low tide
    • Also allows decomposition of particles in it=>can be stagnant
    • Allows burrow formation-sticks to itself
    • Low porosity b/c sandgrains essentially glued together by silt
    amount of space between sand grains
  24. Thixotrophy-
    • ability of sand to hold water under certain amount of pressure
    • Causes water puddle in footprint
    • Makes burrows b/c can put water about themselves
  25. BEACH (farthest-closest to water) topography
    Sand dune; backshore; berm(dry beach); front beach; bars and troughs
  26. Sand dune characteritics
    • Affected by salt spray
    • Anything lives there will get salt on it
    • Little fresh water, scant soil
    • Plants have deep roots or spread out across sand by runners
    • Can excrete salt or have hairs, to catch salt
  27. Sand dune flora
    • Sea oats-deep
    • Beach morning glory
    • Runners
    • Beach tea-hairs
    • Location varies by season
    • Insects, lizards, ground squirrels also live there
  28. Backshore
    Zone of driftwood and storm debris
  29. Berm(dry beach): ghost crabs and small beetles
    • Ghost crabs eat just about anything
    • Can even burrow down deep
    • Move FAST 6ft/sec.
    • Even baby sea turtle
  30. Front beach
    • Beach face
    • Intertidal
    • Palp worms, amphipods, mole crabs(Emerita); clam(Donax)
  31. Bars and troughs
    • Ghost shrimp, small fishes, speckled crab (Arenaeus), sand dollars (Mellita) and sea pansy
    • Some starfishes in surf zone
  32. Eating habits of BEACH BIRDS
    • Usually 3rd level consumers
    • So common, they are the major 3rd level consumer on beach ecosystem
    • Help w/ TX economy-rare bird
    • Eating small fish, crabs etc
    • At low tide; birds are most likely the predators that need to be considered
    • If ignore, you will only have a small picture of what is going on
  33. GULLS
    • Scavengers;Live along just about any big body of water-Move inshore if big storm
    • Strong bill
    • Eat just about anything-fritos; chips; baby sea turtle; small fish/crabs; anything fisherman catches
    • Rounded wings]
    • Found on open and closed beaches
    • Most common in TX
    • Characteristic cry
    • Black heads in summer And white heads with black dot in winter
  35. TERNS
    • Sharp wings
    • Forked tail
    • Dive for fish
    • Very adroit fliers
  36. SAND PIPER family
    • Shore birds
    • Pecking at things in the sand
    • Feeding on polyket worms, SMALL clams etc
    • Lot of members; extremely difficult to tell apart
    • Make peep noise
    • Type of sandpiper
    • found at low tide level, hunts among the incoming water
    • White; Very common-cute
    • Found on open beach
  38. Plover
    • Small bill, but Larger than sandpiper
    • Short bill
    • Feed on small invertebrates
    • Very good fliers: Doesn’t glide/hover
  39. Willet
    • Wading bird or on beach, long legs, gray, wings black and white
    • Make lot of noiseMake big racket if disturbed
    • Eat very small crab
    • Have long bill
    • more surf vs less surf
    • more surf less surf
    • grain size larger Grain size smaller (more silt)
    • Greater porosity Less-more compact sediment
    • More O2 in sediment Less except at surface
    • More abrasion No abrasion
    • Difficult to create burrows Burrowing is easy, burrows last for long time
  41. Stratification occurs in sediment-describe layers
    • MAINLY OCCURS IN LESS surf b/c more surf=> mixing and oxygenization of sand
    • Water
    • Oxygenated-"GRAY" sand
    • No/low free O2-"BLACK" sand
    • Full of bacteria-anaerobic
    • Decomposition occurs
    • H2SO4
    • Animals -are low and slow and only if able to survive ACIDIC and anaerobic environment
    • REDOX layer: between gray and black layer
    • Very distinct; often red
  42. PROTECTED SANDY BEACHES characteristics
    • No surf b/c On bay sides of barrier islands
    • Sandy: wind blows sand into bay
    • Very flat =>Wide tidal range
    • HARSH environment
    • Hot and dry @ low tide
    • Can be soaked by rain-problems b/c marine orgs. Will have hard time with fresh water
  43. Fauna of protected sandy beaches
    • Animals tend to move up and down; in and out
    • Primary production from phytoplankton
    • Sometimes also benthic microalgae
    • Many small animals rely on detritus for food
    • Detritus= decaying organic matter with a coat of bacteria (protein)
  44. Microtopography of protected sandy beaches
    • Small -scale features of sediment
    • Burrows, ripple marks, crab tracks etc
    • Get many extremely tiny animals-Microfauna; 1mm or less
  45. Interstitial fauna
    • Microfauna that live between and on sand grains
    • Small enough to sit on individual sand grain
  46. Epibenthic animals
    • -live on top of surface
    • Juvenile blue crab, moon snail, lightning whelk, striped hermit crab
  47. Juvinile blue crab(allinectes sapidus)
    • Good nervous sytem and eye sight
    • HATE everyone
    • Can dig into sand so that only eyes, respiratory and anntenae
  48. Moon snail POLINICES
    • Eats clams-drills through shell with its mouth then eats it out
    • Drills through sand
  49. Lightning Whelk
    • 1 shell gastropod
    • Busycotypus
    • Scavenger and eats clams
  50. Striped hermit crab
    • As it gets bigger, moves from shell to shell
    • Can't live on land
    • Stores water in its shell so can survive at low tide for a couple hours
    • Not ones in pet store
  51. Fauna In water near sandy beaches
    • Shrimp farfantepenaeus
    • Commercial shrimp
    • Feed on organisms in sand=>
    • Fishes: red fish and croakers
    • Mouth on bottom
    • Come in at high tide and munch on all the smallers
    • Flat fish and stingray-do the shuffle
  52. Infauna:
    • lives buried in sand=> hard to see
    • hard clam, small clams, polychaets worms; lug worms
  53. Hard clam: Mercenaria
    • Early naturalists got the shells at the same time enligh were trading with native americans
    • Good to eat, but most we see will be from poluted areas=> bad to eat
  54. Lug worm-polychaete worm(segmented)
    • Feeds by swalloing sand/silt/mud
    • Digests whats edible(bacteria) then voids the rest
    • Direct deposit feeding
    • Leaves fecal castings
    • What comes out is primarily sand with little fecal mater
    • Valuable ecological service
    • Oxygenate sediment by moving it around
    • Have internal fertilization
    • Eggs are left in jelly coat before hatch out as larval stage
    • Egg sack Attached to mud by stalk "SNOT BALL"
  55. Sandy beach DEEP BURROWERS
    • Clams-Have neck to reach organism from surface
    • Record=5 ft
    • Dig in while juvenile, but if pulled back out, can't reburrow
    • Below redox level
    • GAPER clams: Tresus
    • Neck have fused in current and excurrent siphons
    • Burrow works as exoskelton
    • See whole or something