Rocky Shore Ecology

Question 1

Describe the ROCKY SHORE.

Answer 1

It’s the benthic environment exposed by tidal action with a large particle size (rocks instead of sand)
The littoral zone, the area between high and low water

Question 2

Why is the ROCKY SHORE important?

Answer 2

Wide species diversity (they have to be adapted to survive for long times out of the water and live as a high no. of species in close proximity)
We can use it to test/study ecological models (interspecies competition ect…)

Question 3

Describe the WET/DRYNESS GRADIENT on the rocky shore.

Answer 3

Its defined by low tide position because no rocky shore species can survive indefinitely out of water
Tolerance to desiccation/drying out influences upper limits (movement, shell morphology, metabolic pressures)
Biological pressures influence lower limits (predation, competition)

Question 4

Describe the WAVE ACTION GRADIENT.

Answer 4

Determined by fetch and wind which drive period, height and swell
Steep cliffs with deep water= max impact
Shallow coasts and kelp beds=min impact
Species prevent displacement by timing, positioning, burrowing, attachment (byssal threads, cementing)

Question 5

Describe the PARTICLE SIZE AND SALINITY GRADIENT.

Answer 5

Size varies greatly due to wave action and substrate deposition or erosion
Salinity: rockpools are hypersaline because of evaporation mostly but others have low levels because of rainfall and runoff

Question 6

Explain ZONATION.

Answer 6

Organisms are grouped by shared conditions e.g.
Niche partitioning
Physical and biological forces
Upper limit desiccation tolerance
Lower limit competition

Question 7

What are the PRIMARY PRODUCERS on the rocky shore?

Answer 7

Algae, lichens, cyanobacteria (microalgae)
Simple algae (short-lived with few defences from grazers)
Complex algae (canopy forming)
Encrusting algae (calcifying CaCO3)

Question 8

What are the GRAZERS on the rocky shore?

Answer 8

Sweepers (topshells and nerites which have rows of many small blunt teeth to sweep up dislodged detritus)
Rakers (winkles, isopods, amphipods and grapsid crabs with sharp teeth to bite off macroalgae)
Diggers and abraders (limpits, chitons and urchins with hardened teeth to dig into rock surface)
Biters and cutters (herbivorous fish scrape algae from rocks and majid crabs and nudibranchs)

Question 9

What are the SUSPENSION FEEDERS on the rocky shore?

Answer 9

Individuals (barnacles, mussels and solitary ascidians)
Colonial (polychaetes, byozoans, sponges and ascidians)

Question 10

What are the PREDATORS on the rocky shore?

Answer 10

Borers and drillers (whelks)
Crushers and crackers (non-grapsid crabs)
External digesters (starfish)
Browsers and partial predators (nudibranch, molluscs)
Mobile vertebrates (fish and birds)
Sit and wait (anemones, hydroids)

Question 11

Which organisms could you find in the SPLASH ZONE?

Answer 11

Lichens (orange or grey)
Cyanobacteria
Periwinkles
Limpets
Isopods

Question 12

Which organisms could you find in the HIGH INTERTIDAL ZONE?

Answer 12

Barnacles
Limpets

Question 13

Which organisms could you find in the MID INTERTIDAL ZONE?

Answer 13

Mussels
Oysters
Limpets
Periwinkles
Sea stars
Urchins
Hermit Crabs
Anemones

Question 14

Which organisms could you find in the LOW INTERTIDAL ZONE?

Answer 14

Seaweeds
Sea anemones
Sea stars
Sea urchins
Brittle stars
Sea cucumbers
Sea slugs
Crabs

Question 15

Define the SPLASH ZONE.

Answer 15

Above the line of the highest spring tides so it only receives spray from the waves
Very sparsely populated because few organisms can withstand the harsh conditions

Question 16

Define the HIGH INTERTIDAL ZONE.

Answer 16

Only completely submerged during spring tides so some parts are exposed to air for days to weeks
Harsh environment

Question 17

Define the MID-INTERTIDAL ZONE.

Answer 17

The area between average high tide and average low tide so most of it is submerged for prolonged periods
Densely covered by a variety of marine plants and animals

Question 18

Define the LOW INTERTIDAL ZONE.

Answer 18

The area between low tide level and lowest spring tides which is completely submerged during most tide cycles
Least physically stressed