Temperate Rocky Reefs

Question 1

What is a phase shift?

Answer 1

a transition from one ecosystem type to another ecosystem type, prompted by a trophic cascade

Question 2

What is the difference between a rocky reef and coral reef?

Answer 2

rocky reef is not biogenic (living)

Question 3

Where are rocky reefs found?

Answer 3

up to 200m (photic zone) of (usually) temperate and subtropical areas/where coral cant grow

Question 4

Define ‘kelp bed’

Answer 4

rocky reef with macroalgae - kelps not reaching the surface

Question 5

Define ‘kelp forest’

Answer 5

a rocky reef with macroalgae/kelp canopies reaching sea surface

Question 6

What benefits do kelp beds/forests bring to a rocky reef?

Answer 6

high productivity/carbon sequestration, regulation of the recruitment of coastal species by providing food and shelter, important habitat for juvenile fish, buffer and protection against the effects of waves and storms.

Question 7

What are the 3 layers of kelp forest?

Answer 7

Algal turf, understory, and canopy

Question 8

How does kelp forest primary productivity compare to other marine and terrestrial environments?

Answer 8

Second to coral reefs, equal to tropical rainforests (640 - 1,800 g/m3/yr)

Question 9

What is a foundation species?

Answer 9

A species which has a strong role in structuring the ecological community (i.e. keystone species)

Question 10

Describe Laminariales / “true kelp”

Answer 10

large, brown subtidal seaweed which form dense forests. Flat blades containing chlorophyll, with high SA:V ratio, air-filled pneumatocytes allowing blades to float close to surface, long photosynthetic stipe, strong holdfast.

Question 11

What are the 3 morphological forms of kelp?

Answer 11

canopy forming (reaches surface), stipitate (2m) and prostate (stays close to bottom)

Question 12

What is the kelp thallus?

Answer 12

whole body

Question 13

Which layer of a kelp forest has the greatest biodiversity?

Answer 13

the understory

Question 14

What organisms are found in the understory?

Answer 14

tube-forming polychaetes, bryozoans etc on the kelp stipes, surf perches, topsmelt, blue rockfish (plankton feeders) and benthic larvae

Question 15

Briefly describe the morphology of steller’s sea cows

Answer 15

same order as manatees and dugongs (Sirenia). Up to 10m long and weighing 5-10 tonnes. Believed to have been to blubberly/buoyant to dive down, so fed exclusively on kelp in the canopy. Had broad bony pads instead of teeth. Hunted to extinction 27yrs after they were discovered 250 years ago.

Question 16

What was the geographical range of Steller’s sea cow?

Answer 16

north pacific ocean (Bering sea), ranging further south during pleistocene glacial period.

Question 17

Describe the life history of the Steller’s sea cow

Answer 17

only produced a few offspring per year, long generation times and low population growth (= highly susceptible to extinction)

Question 18

Describe the ecology of algal turf

Answer 18

small invertebrate (brittle stats, polychaetes, sea urchins etc) surround holdfasts, man species of adult rockfishes, sheephead and abalone

Question 19

What controls the distribution of kelp beds?

Answer 19

substrate, light and nutrients (fewer nutrients in tropical zone)

Question 20

What causes kelp deforestation?

Answer 20

physical anomalies (e.g. el nino, changes in temp and salinity), storms, sea urchin population increase

Question 21

How does el nino effect kelp forests?

Answer 21

el nino’s intrustion of warm westerly waters causes a temperature increase, decrease in upwelling and resultant decrease in nutrient levels = fewer kelp forests

Question 22

Define “phase shift”

Answer 22

when an ecosystem changes from one stable state to another due to perturbulations, e.g. from a kelp forest to an urchin barren.