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57 Cards in this Set

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  • Back
How does energy flow in an ecosystem?
solar energy --> autotrophs (primary producers/plants) --> heterotrophs (consumers/decomposers)
"self-feeders" obtain energy from sun and get materials from inorganic sources
organisms that obtain energy from organic material and convert to (chemical) energy
What is decomposition?
gradual breakdown of dead matter by physical and biological processes; releases inorganic nutrients back into the community making them available to the autotrophs
What major factors influence the rate of decomposition?
temperature (more=better)
precipitation/humidity (more=better)
oxygen (more=better)
presence of decomposers
pH (extremes=bad)
nutrient levels (more=better)
content/composition of dead (sugar<starch<proteins<cellulose< lignins<cutins)
What groups of organisms are involved in decomposition?
How do the decomposers work?
colonizers (bacteria, fungi): begin to break stuff down
scavengers (crayfish): rip off big pieces
shredders (freshwater shrimp,scuds): more fine scale ripping
collectors (caddersly larvae): collect fine particulate matter from shredders
scrappers: vacuum cleaners, get stuff that settles out
What variables do diversity indices typically include and why are these variables important?
- species richness: # of different species in a community
- species abundance: # of individuals of each species
- equitable distribution of individuals among the species
- important because fold into single index (Simpson's index), and a high index means increased functionality/stability of an ecosystem
How does temperature vary with depth by season?
uhhhhhhh yeah. bullshit.
What contributes to the dissolved oxygen of a water body?
photosynthesis, nutrients, air
Why is dissolved oxygen (DO) necessary?
for living things to live
What is Biochemical Oxygen Demand?
measure of the amount of oxygen consumed during decomposition of a certain type of organic material
What are potential sources of BOD?
raw sewage, runoff from feedlot, industrial sources (food cannery, pulp mill)
What are nutrients?
substances that promote the growth of aquatic plants and algae
What do plants require for growth?
- CO2/H20/sunlight (photosynthesis)
- essential minerals (iron, calcium, zinc)
- nitrogen and phosphorous
What is a limiting nutrient?
small amounts of the nutrient exist in an ecosystem, and certain amounts are required for plant growth and sustainability
What are sources of nitrogen?
-cycled through atmosphere
-animal waste
What are sources of phosphorous?
-not cycled through atmosphere
-erosion of phosphate rock
-animal waste
-industrial effluent
What are effects of added nutrients?
nutrient enrichment of an ecosystem leads to a stimulation of primary producers (plants) which leads to eutrophication
What is the natural sequence of eutrophication?
1) extensive growth of plants and algae
2) algae/plants die and become major sources of BOD
3) decomposition of BOD leads to decrease in DO
4) decomposers can't keep up with BOD
5) water becomes turbid
6) biomass begins to fill in lake
7) eventually not enough DO to support organisms
8) algae covers surface of water
9) anaerobic decomposers take over
10) cattails and lillie grow, lake becomes a swamp
What are the differences between an oligotrophic and a eutrophic lake?
oligotrophic = young, pristine
eutrophic = old, turbid
What is cultural eutrophication and what causes it?
eutrophication caused by humans (runoff from industries, agriculture, sewage) that speeds up process by 1000s of years
What is the impact of cultural eutrophication on a water supply?
eutrophic lakes don't make good drinking water
How do we assess the trophic state of a lake?
- concentration of algae
- what species are present (bioindicators)
- turbidity
- DO levels (bottom in summer)
- nitrogen and phosphorous levels
What factors influence the distribution of an organism?
- competitors
- food sources
- parasites/diseases
- human population
- pollinators
- predators
What are tolerance limits?
tolerance limits: minimum and maximum limit for an environmental variable beyond which a particular species cannot survive
What is a niche?
niche: includes the range of all physical, chemical, and biological conditions under which an organism can survive
What is a fundamental niche?
non-living components -- defines where a species can live
What is a realized niche?
living components -- defines the subset of the fundamental niche where you actually find the organism
How does a J (exponential) growth curve compare with an S (logistic) growth curve?
J curve: all populations start with exponential growth
S curve: populations then approach zero population growth
What is carrying capacity?
carrying capacity: maximum population of a particular species that a given habitat can support (puts a cap on population growth)
Is carrying capacity constant or dynamic for a given population?
carrying capacity is constant for a given population
What are acids?
- corrode metals
- sour taste
- cause carbonates to fizzle
- turn litmus red
What are bases?
- bitter tasting
- slippery feel in solution
- corrosive (etch glass)
- turns litmus blue
What is pH and how is it determined?
pH is the measure of the acidity or basicity of a solution; measured by -log(H+), logarithmic scale goes from 0-14, 7=neutral
What is the pH of unpolluted rain?
pH of unpolluted rain is about 5.2-5.3 (slightly acidic)
Acid deposition and the pH of rainfall across the US?
Rain is highly acidic in the eastern US because of large amount of industrial processes: production of steel and coal, cars, jet stream --> creates excess of sulfur dioxide and nitrogen dioxide
Sources of sulfur oxides?
mainly from coal combustion --> coal = complex mixture of solid hydrocarbons and minerals and sulfur
SOx levels are high in areas with:
coal fired power plants
steel plants
coal burning industries
Sources of nitrogen oxides?
come from any type of combustion
NOx levels are high in ares with:
industrial areas
urban areas with auto traffic
Primary vs. Secondary pollutants
Primary pollutants: pollute firsthand
Secondary pollutants: occur when primary pollutants undergo subsequent reactions
What are the effects of acid deposition on soil?
1) upper layer of soil = high biological activity --> lowers pH
2) presence of buffering minerals like carbonates neutralize and raise pH
3) cation exchange
4) when cation exchange capacity is exceeded, soil particles are weathered and produce aluminum, which is not very soluble, and TOXIC
What are the effects of acid deposition on lakes?
acid deposition disrupts the balance of minerals in the water body, and increases the solubility of toxic metals like aluminum
- lakes are dead below pH 5, most life disappears at 5, and life exists happily from pH 6-9
What is a buffer?
buffer: substance that resists a change in pH with added acid or base
what is acid neutralizing capacity (ANC)/alkalinity?
alkalinity = buffering capacity --> ability of a water body to resist change in pH
What types of minerals provide alkalinity?
"carbonate minerals" --> calcite-limestone, magnesite, dolomite, brucite
How is alkalinity measured and expressed?
Alkalinity is measured as the amount of mg CaCO3 in a liter of H20 --> ppm CaCO3 --> does not have to contain CaCO3, just buffer as if it contained that much CaCO3
What is hardness?
hardness is the presence of metal ions like Ca2+ and Mg2+
How is hardness expressed and how is it related to alkalinity?
Hardness is expressed as mg CaCO3/L H20 --> same as alkalinity expression, but hardness is ALWAYS greater than alkalinity because hardness = buffering minerals plus others
Why should we be concerned about hard water?
1) causes scale to form in pipes, heaters, etc
2) interferes with soap
How do organisms influence the pH of their surroundings?
1) photosynthesis and respiration --> photosynthesis increases pH and respiration decreases pH (because of CO2)
2) decomposition --> composition of leaf litter --> coniferous leaf litter leads to strongly acidic soil, decidious leaf litter leads to less acidic soils
3) active root exchange --> H+ goes out, Ca+ goes in (Ca+ is used by plants as an internal buffer against acidification)
How do we study the impact of acidification on organisms?
- observational studies compounded with some experimental studies
- people look at naturally acidic environments (acid peat bogs)
- sediment cores to look long-term at changes in community composition
What is the 6-pronged attack of acidification on terrestrial communities?
1) leaching of good nutrients/minerals
2) makes toxic alluminum available for plan uptake
3) slowed decomposition (cellulose and lichen) --> results in less nutrients available
4) mycorrhizal loss --> reduced nutrient uptake
above ground:
5) reduced photosynthesis and growth because of loss of nutrients and leaf damage (chlorophyll damage)
6) overall structural damage to leaves and bark
How does the leaching of calcium and the release of aluminum impact organisms?
Leaching of calcium means plants can't use it for buffering, and release of aluminum poisons organisms
Loss of calcium leads to deformities due to poor bone development, reduced ovulation, and poor or no shell (exoskeleton) development; aluminum release causes increased mucous production in fish, which suffocates them!
What are the various ways, in addition to directly causing death, that acidification compromises communities?
1) acidification changes pH, releases toxins, opens door for disease
2) organisms die off not because of change in pH but because of connections within a community
3) other potential toxins are released because of acidification (lead, cadmium, copper, zinc, etc)
4) extreme adaptations and rate
5) global scale and policy
We do have organisms that can survive at a pH of 0, so why are we concerned about the changes in pH we are seeing in historically non-acidic lakes and streams?
although some organisms can survive at a pH of 0, most thrive between pH 6-9, so we don't want places that weren't always acidic to suddenly become acidic
How have NOx and SOx emissions changed in the U.S. since 1970?
Good news: since 1970, there has been a 44% reduction in SOx from stationary sources
Bad news: there has been an 80% increase in NOx
Why is the development of developing countries relevant to acid deposition?
Development of countries means more industry and more automobiles --> more SOx and NOx!