Sandy Intertidal Ecology Flashcards
what three factors are sandy beaches defined by?
wave action, particle size, slope
how do the amount of organisms and particle size correlate?
coarse beach = few organisms.
fine beach = many organism
why is particle size important to sandy shores?
- vary among the beaches, seasonally
- water retention
- desiccation
- suitability for burrowing
how is the slope of a beach defined? what factors?
formed from the interaction of wave action and particle size, swash and backwash
define swash and backwash
swash: water running up a beach after a wave breaks. carries particles, may accrete.
backwash: water flowing down the beach. removes particles from the beach, rate size dependent
what are the physical factors in the sandy beach and tidal flats?
- wave action
- substrate movement
- heavy wave action
- light wave action
why is substrate movement an important physical factor of the sandy shore?
- product of wave action
- not stable
- unlike rocky shores
- particles are (picked up, churned, re-deposited, continually moved and sorted)
what is they physical difference between heavy wave action and light wave action
HWA: fine grain remains in suspension, is carried. heavy grains settle immediately, substrate of deeper depth affected.
LWA: only particles close to surface are affected, substrate stabelizers.
what is the affect of substrate movement, and how is it a habitat changer?
affects limitation of biotic diversity.
changes habitat through stabelization, submerges aquatic vegetation and benthic animals.
describe a dissipative beach
wave action is strong, wave energy is dissipated over a broad flat surf zone, located away from the beach face. Results in gentle swash and fin sediments.
Describe a reflective beach
FRANCE
wave action impinges directly on beach face, sediment is coarse, no offshore surf zone, waves produce large swashes, beach slope is steep, backwash and swash collide to deposit sediment, wave energy is directed against the face of the shore.
what conditions are the best to support more abundant fauna? (regarding type of beach)
highly exposed beach better than less exposed, dissipative, not reflective.
what type of fauna is associated with dissipative beaches?
high biomass of filter feeders
what is the difference between winter and summer profiles?
-wave action changes:
gentle wave action replaced by heavier ( grain size, profile, uniformity, physical factors, sand depth).
what are the differences between sandy shores profile and rocky shores?
-smooth, uniform profile, lack topographical diversity, no crevices, overhangs, permanent tide pools, slopes facing different directions.
how does the uniform profile of sandy beaches reflect in environmental factors?
Environmental factors are uniform:
- temp, desiccation, wave action and salinity
- insulating properties in sand
- interstitial water
- density of salt water
- buffers
why is the O2 content never limited in beach water?
- turbulence of wave action
- ensures saturation
- limit in temperature change
- needs replenishement
what is the organismal diversity is sandy shores, and what is it lacking?
Has: seagrasses, ephemeral algae, polychaetes, bivalve molluscs, crustaceans
-lacks: large plants, sessile organisms
what are the main organisms you would find at the sandy shore?
- annelids (polychaetes)
- Molusca (razor clams)
- arthropods
ALSO: a diatom layer on the surface of the sand.
what is the feeding biology of the inhabitants of the sandy intertidal?
-phytoplankton carried in
-organic debris
-other beach animals
THEREFORE:
-filter feeders, detritus feeders, scavengers. A few resident carnivores and opportunists.
Who are the main suspension feeders? what do they feed on?
bivalve molluscs, razor clams, surf clams, coquiinas. they feed on plankton, resuspended organisms.
who are the filter feeders, how do they feed, what do they feed on
- sand crabs trap debris in wash
- Olivella create a mucus net
- sand dollars
- bivalves and polychaetes
deposit feeders: what do they feed on, who are they in the PNW.
- detritus feeders
- convert detrital organic material into macrofaunal biomass
- significant bioturbators
- Maldanid polychaete
what are the sandy shores zones? who occupies these zones?
- Supralittoral fringe: fast movers, excavate burrows, scavengers (sand fleas)
- midlittoral zone: barnacles, isopods, sand crabs
- infralittoral zone: surf zone, greatest number of species, large surf clams, sand dollars, polychaetes, crustaceans.
