Temperate Ecosystems Flashcards
What are the 5 zones of a temperate ecosystem?
- estuary
- mudflat
- oyster reef
- eelgrass
- saltmarsh
What is an estuary?
the zone where saltwater and freshwater mix
What are the four types of estuaries?
- coastal plain/drowned river valley
- tectonic
- fjord
- lagoon
What are coastal plains/drowned river valleys?
estuaries that are formed by glaciers melting and causing seawater to flood plains and neighbouring rivers
ex. Saint Lawrence river, Chesapeake bay
What are tectonic estuaries?
estuaries formed during earthquakes causing land to sink which allows seawater to connect with wetlands
ex. San Francisco bay
What are fjord/fjard estuaries?
estuaries formed by glacial movement cutting into terrain towards the coast and any remaining glaciers melting, filling up the new valley
What are the differences between fjords and fjards?
fjords = straightforward path, shallow sill (raised sediment underwater) and deep basin, little mixing of fjord water and seawater
fjard = winding path, can have islands, irregular shape, less defined sills
ex. Burrard inlet, Indian arm, NFL, Norway
What are lagoon estuaries?
estuaries formed from sand building up into barrier islands that partially block ocean water from mixing with the river mouth
What is the difference between positive and negative estuaries?
in positive = flow of freshwater causes mixing of freshwater and saltwater, salinity is highest closer to ocean, evaporation is low towards river head
in negative = low river flow, evaporation is high all across estuary, hypersaline water sinks and returns to ocean
What are the four patterns of estuary mixing?
- salt wedge: surface river flow and bottom sea flow creates an angled current of mixing, salinity is clearly divided –> influenced by river flow
- partially mixed: strong river flow and sea flow creates a gradient of mixing, salinity differs by depth –> influenced by river flow and tides
- well mixed: low river flow causes salinity gradient that does not change with depth –> influenced by tides
- fjord: freshwater remains at surface while saltwater sinks between sill and fjord, salinity is horizontally stratified, little mixing
What do euryhaline and stenohaline mean?
euryhaline = species that can tolerate fluctuations in salinity
stenohaline = species that cannot tolerate changes in salinity (restricted to either freshwater or saltwater)
What are the differences between osmoconformers and osmoregulators?
osmoconformers match their environment (are isotonic), osmoregulators undergo processes to maintain a concentration internally
How do osmoregulators maintain a salt concentration?
- absorb ions
- concentrate ions when salinity is low
- excete ions when salinity is too high
How do freshwater and saltwater fish osmoregulate?
freshwater = does not drink, water enters skin and ions through gills, is internally saltier than environment, urine is diluted
saltwater = drinks water, loses water out of skin and excretes ions through gills, has less solutes internally than environmetnt, has a concentrted urine
What do epifauna and infauna mean?
epifauna = species that attach to substrate or other animals
infauna = species that live within the sediment
Why do some species inhabit the sediment?
- less variation in salinity/temperature
- protection
What are some characteristics of estuarine food webs?
- detritus based (vs. primary productivity)
- detritus is broken down by bacteria and consumed by detritivores (suspension/deposit feeders etc.)
- prominant role of shore birds/waterfowl as predators
What are key environmental features of estuaries?
- salinity (varied)
- temperature
- mixing/water movement
- DOM
- sediment
What ecosystem services do estuaries supply and how are they threatened?
provides protection and nursery habitats
threatened by conversion and pollution
Briefly describe a saltmarsh
- sediment dominant
- transition point for aquatic and terrestrial ecosystems
- lots of vegetation emerging from water (seagrasses/shrubs)
- tide cycles multiple times a day
What are some characteristics of Spartina (smooth cordgrass)?
- ecosystem engineer (traps sediment + creates new land for other species)
- rhizome network
- has aerenchymal tissue in leaves (oxygen transport)
- is mostly indigestable (cellulose/silica in leaves)
- can tolerate a range of salinities
What type of vegetation is found in the different zones of a saltmarsh?
in low marsh (high salinity) = only Spartina
in high marsh = mix of grasses
in upland border = reeds and larger plants
What are key environmental features of saltmarshes?
- salinity (fluctuates from tidal movements + evaporation)
- oxygen availability in soil (anoxic)
What are the main characteristics of a saltmarsh foodweb?
- primary productivity by saltmarsh plants but little herbivory experienced
- detritus + phytoplankton based
- saltmarsh creeks rely on plankton as base level
- marshes rely on detritus as base level