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
What is the relationship between snow geese and saltmarshes?
pre-population boom: snow geese brought nutrients in to saltmarshes through defecation, vegetation benefitted from the nutrients and grew
post-population boom: more snow geese grazing on saltmarshes destroyed vegetation
What ecosystem services do saltmarshes supply and how are they threatened?
- coastal protection
- nursery habitats
- water filtration
- filling/draining
- development
- invasive species
What are key environmental features of mudflats?
- flat and broad
- fine sediment
- anaerobic/anoxic
Define the redox potential discontinuity (RPD) layer
- rapid change from aerobic and anaerobic conditions
- high productivity from chemoautotrophs
- has some O2 but very low H2S
- represented by a shift from brown to gray to black sediment
How have organisms adapted to anaerobic conditions in mudflats?
- burrows connect to surface air
- hemoglobin more sensitive to O2
- glycogen stores
What are the main characteristics of a mudflat food web?
- high primary productivity by diatoms and chemoautotrophic bacteria
- detritus and biofilm based
- diatoms make up biofilm
What is the relationship between sandpipers and diatoms?
sandpipers use their barbed tongues to scoop up biofilm and consume diatoms directly
What ecosystem services do mudflats supply and how are they threatened?
- coastal protection
- migratory bird habitat
- fisheries (mussels/clams)
- urbanization
- land drainage/filling
- pollution
What important roles do oysters play in oyster reefs?
- filters nitrogen and deposits it into sediment for aerobic + anaerobic bacteria to convert (nitrogen cycle)
- retains sediment to form substrates
What are the main characteristics of a oyster reef food web?
- primary productivity from phytoplankton as the base layer
- small contribution of detritus
What ecosystem services do oyster reefs supply and how are they threatened?
- water filtration
- habitat provision
- coastal protection
- food
- fishing
- pollution
- aquaculture
- invasive oysters
Define ecological connectivity
the ability for a landscape to allow species (i.e larvae) to move between ecosystems freely and for processes to flow between
What are some examples of ecological connectivity of species in estuarine ecosystems?
- striped bass: breed in estuaries, larvae travel downstream towards sea as they grow
- croaker: breed in high salinity waters and travel towards freshwater in estuaries
- flounder: feeds in saltmarshes/mudflats in high tide and estuaries in low tide
Where would you expect N-15, C-13 and S-34 to be higher?
more N-15 in higher trophic levels
more C-13 in inshore organisms, in saltwater settings
more S-34 in aquatic settings
Define autochthonous and allochthonous detritus sources
autochtonous = from within the estuary (i.e microalgae, phytoplankton)
allochtonous = brought into estuary from other sources (i.e from land, adjacent systems)
What were the main findings from the paper by Wood?
- western sandpipers’ tongues are finely forked and are used to mop up biofilm
- diatoms in biofilm provide rich carbohydrates that sandpipers stock up on for migration
What were the main findings from the paper by McAfee and Connell?
- native oyster reefs have been threatened by oyster fishing and invasion of Pacific oysters
- Pacific oyster reefs can provide ecosystem services like structures for other species to colonize, and economic benefits like fishing but will still outcompete native species
What is the difference between a kelp bed and kelp forest?
kelp forest = kelp stretch across water column and canopies float on the surface
kelp bed = kelp never reach the surface
What are the four kelp genera?
- macrocytis (giant kelp)
- nereocytis (bulb kelp)
- laminaria
- ecklonia
Where are different types of kelp found?
- macrocytis = west coast of NA/SA, eastern tip of SA, southern Africa, western coast of Australia
- ecklonia = southern Africa, western coast of Australia
- laminaria = Atlantic Canada/NE USA, Europe, eastern Asia, southern Africa
- nereocytis = west coast of NA
What are key environmental features of kelp forests?
- shallow (due to light requirements, ~15-20 m up to 60 m deep)
- low temperatures
- high in nutrients (especially nitrates which are present near upwellings)
- low water movement (avoid being ripped up, kelp can also buffer waves)
- hard substrate
Where are NO3 and NH4 sourced from and which do plants prefer?
NO3 is from upwellings, nitrification, NH4 is from animal waste
NH4 is prefered as it can be consumed without extra processing steps
What did Em Lim find during her kelp research?
kelp grew at faster rates in sites with high ammonium (NH4) vs without ammonium
What ecosystem services do kelp forests supply and how are they threatened?
- nursery habitats
- supports diversity
- stores carbon
- harvesting
- loss of predators
- climate change
What are the main characteristics of a kelp forest food web?
- high primary productivity of kelp relative to biomass
- top down control by predators like otters/sea stars
