Chapter 8: Continental Shelf Seabeds Flashcards
(36 cards)
what percentage of the global sea habitats are the continental shelf seabeds?
8%
What are some defining characteristics of the continental shelf seabeds?
- mostly euphotic
- mineral and organic inputs from rivers
- strong mixing
- upwelling
- most productive marine biome
- fuels strong secondary production
what percentage of the word’s fisheries are taken from the continental seabed?
90%
what changes are being caused to the continental shelf seabed from overusage?
- overfishing
- eutrophication
- mineral extraction
- waste dumping
- oil spills
what are some physical forcing processes in which the CSS are influenced?
- glaciation events
- currents
- waves
- the formations of fronts
- water turbidity
how has wave action influenced secondary production?
by limiting the body size of organisms that can survive in a highly energetic environment
what influence does current flow have on organisms?
- the active/passive transport of organisms, gametes, and food supply rate
- causes physical limitations on organism types that can survive
when are currents increased?
when water moves through, or around, land-bounded restrictions or across irregularities in the seabed topography
describe the differences btwn east and west coast shelves
West: narrow shelf steep slope inward prevailing winds East: broader shelf gradual slope outward prevailing winds
what areas are algae restricted to?
narrow zones of near-shore shallow waters in regions where major riverine discharge and near-bed tidal resuspension of sediments increase the turbidity of the water column.
what are some constraints attached to a biota’s body size in regard to habitat?
- burrowing restricted by respiration and burrowing ability
- attached biota restricted by physical processes, like current velocity
what are some typical characteristics of biota that live in high levels of shear stress?
- highly flexible or encrusting
- shelter seeking
explain frontal systems
- full salinity water approaches the coastline
- interacts with lower salinity water discharged as an estuarine plume
- difference in density btwn the 2 bodies of water sets up a frontal system
depth and turbidity: why does it matter?
- important determinants of the distribution of benthic algae in the shallow waters
- estuarine plumes usually severely light-limited
- turbid areas may be dominated by animals, and algae restricted to shallowest waters.
the seven continental shelf ecosystems are categorized according to what?
physical processes and biology
what are the 7 continental shelf ecosystems?
1-polar: perm ice cover
2-polar: partial/complete ice disp
3-mid-latitude: spring/autumn blooms
4-topo forced Summer production
5-inermittent production at coastal divergence
6- small response to Trade Wind seasonality; coastal river discharges
7-small response to trade wind seasonality; insignificant river discharge
Region 1
Polar; permanent ice cover
- light limited
- low phyto- and zooplankton product.
- many benthic invertebrates, low fish and squid pop diversity
Region 2
Polar; partial or complete ice dispersion
- shallow halocline
- light limited
- productivity increase with ice-melt, then declines
- productivity>consumption, supporting rich and diverse macrobenthos
- low fish diversity
Region 3
Mid-Latitude; spring/autumn blooms.
- winter and autumn mixing
- spring water column stability, productivity pulse
- summer stratification, low productivity
- wind induced coastal convergence and divergence
- abundant, diverse autotrophic production passing through macrobenthos
Region 4
Topography-forced summer production
-similar to region 3, but phytoplankton peak mid-summer, not spring.
Region 5
Intermittent Production at coastal divergence
- trade winds (strong Ekman drift, causing upwelling. Lot of 1* produc)
- high biomass, little diversity
- abundant benthic consumers
Region 6
Small response to Trade wind seasonality, coastal river discharges
- weak seasonality in depth of mixed layer
- strong seasonality of riverine discharges into low salinity surface layer (rainy/dry seasons)
- resuspension of inshore organic rich sediment by monsoon waves
- small sized autotrophs and consumers
- diverse fish fauna
Region 7
Small response to Trade wind seasonality, insignificant river discharge
- dry coast
- weak seasonality in depth of mixed layer
- photic depth is deeper than nutrient cline
- benthic primary production
- high water clarity
- diverse coral reef formation and fish fauna
- high density of filter-feeding crabs
- complex trophic link between fish and benthic invertebrates
what are the sea bed position of biota?
- epibiota
- epibenthic
- infaunal
- microbial communities
