sandy beaches

Question 1

location

Answer 1

all over the earth

Question 2

tide

Answer 2

intertidal

Question 3

substrate

Answer 3

sand: Sediment particles have a diameter of 0.02 – 2 mm

Fine sand can retain water, but coarse sand allows water to
drain away

Not much detritus is retained in sand

Question 4

source of sand

Answer 4

depends on the location
rocks on land and/or
calcium carbonate (CaCO3) skeletons of animals and coralline algae, including parrotfish poop

Question 5

phys char: slope

Answer 5

variable over the seasons and varies with location

wave action

Question 6

phys char: energy

Answer 6

moderate to high

Higher energy beaches have a steeper slope and larger sediment particles

Question 7

DYNAMIC EQUILIBRIUM OF

SANDY SHORES

Answer 7

Beach shape & slope fluctuate about an equilibrium (which also
changes with time, but much more slowly)
Forces of erosion and deposition reach a dynamic equilibrium
Waves, tides, currents, and wind erode and transport sand

Question 8

beach equilibrium profile for storm beaches

Answer 8

• typical of winter and after storms
• erosional
• coarser erosion sediment
• steeper slopes
• large, high berms
• narrow back shores

Question 9

beach equilibrium profile for swell beaches

Answer 9

• typical of fair-weather conditions
• depositional
• finer-grained sediment
• gentler slopes
• small, lower berms
• broad back shores

Question 10

light

Answer 10

absorbed or reflected by the surface layer of sand, so no light in sediment below surface but with some transparent particles and spaces between particles light penetrates deeper than in mud

Question 11

temperature

Answer 11

within sand is quite stable
Just like mud, sand is a good buffer against temperature (and
salinity) changes
Below the first few centimeters, the temperature in the sand is the same as the surrounding seawater

Question 12

salinity

Answer 12

within sand is also quite stable

Below the first 10-15 centimeters, the salinity in
the sand is the same as the surrounding seawater

Even with precipitation & run-off, the more dense
saltwater will sink below freshwater

Question 13

nutrients

Answer 13

little to no nutrients in the sand as
nutrients move through with water and are used
quickly

BUT, waves do bring algae to beach

Question 14

oxygen

Answer 14

lots due to high wave action / energy especially at high tide May be reduced in interstitial water at low tide as oxygen is
consumed by organisms
Fine-grained beaches do not allow oxygen to enter as quickly and therefore may become hypoxic at low tide

Question 15

hydrogen sulphide

Answer 15

– little to none

Except at low tide in fine-grained beaches

Question 16

biodiversity

Answer 16

low (except meiofauna)

few organisms are adapted to high energy shifting of sand particles

Question 17

productivity

Answer 17

low (there are benthic diatoms in first few

millimeters of sand but producers get shifted around so much and nutrients are low)

Question 18

biomass

Answer 18

low to moderate

Question 19

meiofauna

Answer 19

Interstitial organisms (spaces between particles)

Size: 62 um to 0.5 mm

Benthic invertebrates (animals from many phyla)

Question 20

importance of meiofauna

Answer 20

decomposition

nutrient cycling

food for many consumers at higher trophic levels

very sensitive to anthropogenic pollution, making them excellent
indicators

Question 21

adaptations

Answer 21

Living among the shifting sands is the primary challenge here
– particles are always in motion

Burrowing is rapid & powerful (razor clam)

Question 22

bio adaptations

Answer 22

camouflage

• Most organisms depend on waves to bring food & nutrients
  e. g. mole crabs, sand dollars

Wrack line very rich in nutrients
Beach hoppers / amphipods

Question 23

zonation

Answer 23

Just like in the rocky intertidal, there is a pattern of zonation
due to tides at sandy beaches

Question 24

ECOSYSTEM SERVICES PROVIDED BY

SANDY BEACHES

Answer 24

sediment storage and transport;

wave dissipation and associated buffering against extreme weather events;

dynamic response to sea level rise;

breakdown of organic materials and pollutants;

water filtration;

nutrient mineralization and recycling;

storage of water in dune aquifers and groundwater discharge through
beaches;

maintenance of biodiversity and genetic resources;

providing a nursery area for juvenile fishes (e.g. sand lance, grunion);

nesting sites or rookeries for turtles, shorebirds, and pinnipeds;

prey for birds and other terrestrial wildlife;

scenic vistas and recreational opportunities;

functional links between terrestrial and marine environments

Question 25

human impacts

Answer 25

Disturbance of species & sand

Beach grooming

Pollution, especially plastic!

Resource exploitation

Clams, crabs for food

Shrimps, worms for bait

Seaweed as compost

Shells & other treasures

Coastal development

Invasive / alien / introduced species

European green crab, Carcinus maenus

Climate change / sea level rise (erosion)

Question 26

what’s the equilibrium beach profile?

Answer 26

Equilibrium beach profile (EBP) explains the balance between destructive and constructive forces acting on a beach.

Question 27

what’s equilibrium?

Answer 27

The slope of the floor of a sea, ocean, or lake, taken in a vertical plane, when deposition of sediment is balanced by erosion.