Temperate Rocky Reefs Flashcards
What is a phase shift?
a transition from one ecosystem type to another ecosystem type, prompted by a trophic cascade
What is the difference between a rocky reef and coral reef?
rocky reef is not biogenic (living)
Where are rocky reefs found?
up to 200m (photic zone) of (usually) temperate and subtropical areas/where coral cant grow
Define ‘kelp bed’
rocky reef with macroalgae - kelps not reaching the surface
Define ‘kelp forest’
a rocky reef with macroalgae/kelp canopies reaching sea surface
What benefits do kelp beds/forests bring to a rocky reef?
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.
What are the 3 layers of kelp forest?
Algal turf, understory, and canopy
How does kelp forest primary productivity compare to other marine and terrestrial environments?
Second to coral reefs, equal to tropical rainforests (640 - 1,800 g/m3/yr)
What is a foundation species?
A species which has a strong role in structuring the ecological community (i.e. keystone species)
Describe Laminariales / “true kelp”
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.
What are the 3 morphological forms of kelp?
canopy forming (reaches surface), stipitate (2m) and prostate (stays close to bottom)
What is the kelp thallus?
whole body
Which layer of a kelp forest has the greatest biodiversity?
the understory
What organisms are found in the understory?
tube-forming polychaetes, bryozoans etc on the kelp stipes, surf perches, topsmelt, blue rockfish (plankton feeders) and benthic larvae
Briefly describe the morphology of steller’s sea cows
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.
What was the geographical range of Steller’s sea cow?
north pacific ocean (Bering sea), ranging further south during pleistocene glacial period.
Describe the life history of the Steller’s sea cow
only produced a few offspring per year, long generation times and low population growth (= highly susceptible to extinction)
Describe the ecology of algal turf
small invertebrate (brittle stats, polychaetes, sea urchins etc) surround holdfasts, man species of adult rockfishes, sheephead and abalone
What controls the distribution of kelp beds?
substrate, light and nutrients (fewer nutrients in tropical zone)
What causes kelp deforestation?
physical anomalies (e.g. el nino, changes in temp and salinity), storms, sea urchin population increase
How does el nino effect kelp forests?
el nino’s intrustion of warm westerly waters causes a temperature increase, decrease in upwelling and resultant decrease in nutrient levels = fewer kelp forests
Define “phase shift”
when an ecosystem changes from one stable state to another due to perturbulations, e.g. from a kelp forest to an urchin barren.
