Freshwater Ecology - Exam 3 Comprehensive

anadromous

fish spend lives in saltwater, lay eggs in freshwater

catadromous

fish spend lives in freshwater, lay eggs in saltwater

list features about salmonidae?

includes salmon and trout. predators important in structuring stream ecosystems, fond of cold water. salmon in particular are anadromous.

list features about percidae?

includes perch and darters. largest fish family in NA. they rest on the bottom sediment using their pelvic fins and are major sport fish.

name 2 fish families

salmonidae, percidae

dissolved

smaller ions in the water

colloidal

particles that won’t settle with gravity

particulate

larger, will settle with gravity

total dissolved solids (TDS)

total mass of materials dissolved in the water

salinity

mass of dissolved salts per unit volume

conductivity

proportional to amount of electricity that can be conducted by water

how does an increase in ions affect conductivity of water?

more ions = more conductivity

where does freshwater pH usually range?

6-8

what is pH the measure of?

the concentration of Hydrogen cations in a solution

what is the equation for pH?

-log10[H+]

increase in CO2 increases or decreases pH? why?

decreases the pH, making the water more acidic since CO2 creates carbonic acid when dissolved in the water

alkalinity

the ability of water to buffer changes in pH

karst areas have higher or lower alkalinity?

higher due to limestone content in these areas

hardness

a measure of the amount of dissolved calcium and magnesium ions in the water

what is colorimetric analysis?

a way to measure ion density within water.

reagents are added that bind to the ion of interest to create a color. this water is then put into a spectrophotometer so that the absorbance can be measured because the relationship between absorbance and concentration is linear.

reduction

gain of an electron

oxidation

loss of an electron

% saturation

percent of oxygen that could be dissolved given the saturation concentration

saturation concentration

the maximum amount of substance (solute) that can dissolve in a solvent (water) when water is in the contact with the atmosphere for extended periods of time

what is Gross Primary Production (GPP)?

the total photosynthesis an organism does

what is Net Primary Production (NPP)?

excess energy, GEP - R

EXPERIMENT: 3 clear bottles and 3 dark bottles are suspended in the lake for 1 hour. how do you estimate GPP, NPP, and R?

NPP is the average of the values from the clear bottles. R is the average of the values from the dark bottles. GPP is obtained by adding NPP + R.

Net Ecosystem Production (NEP)

the excess energy of an entire ecosystem

Gross Ecosystem Production (GEP)

all energy made from photosynthesis in an ecosystem

how is total ion mass estimated as? (3 ways)

total dissolved solids (TDS), salinity, conductivity

how do chemicals get in water?

dissolved from land, weathering from land (chemical or mechanical (freeze,thaw,erosion))

ppm

parts per million

ppt

parts per thousand

mg/L

weight of ion per volume of water

activation energy

how much energy a reaction needs to take place

explain how iron works regarding O2 and redox potential.

when reduced, iron exists as Fe2+, ferrous iron. this iron is soluble in water. however, when oxidized (as it occurs with O2), iron exists as Fe3+, precipitating out and settling to the sediment. as oxygen is depleted in the hypolimnion, iron reduces again and dissolves back into the water. thus, the cycle continues if exposed to oxygen again.

what affects saturation concentration?

goes up with lower temperature, higher atmospheric pressure (lower elevation), lower salinity, higher water pressure (depth)

oxic

has some oxygen (aerobic)

anoxic

has no oxygen (anaerobic)

what is the chemical formula for photosynthesis?

CO2 + H2O + light → CH2O + O2

what is the chemical formula for respiration?

CH2O + O2 → CO2 + H2O + energy

what does the DO of an oligotrophic lake look like in the summer?

what type of lake and in what season is this graph representing?

oligotrophic summer lake

what type of lake and in what season is this graph representing?

oligotrophic summer lake

what does the DO graph for an eutrophic summer lake look like?

what does the DO graph for an oligotrophic winter lake look like?

what season and type of lake does this DO graph represent?

winter oligotrophic lake

what season and type of lake does this DO graph represent?

winter eutrophic lake

what does the DO graph for a winter eutrophic lake look like?

at what time during a 24h period is the Oxygen highest for a lake or stream?

about 6pm / late afternoon

nutrient

any element required by organisms for growth

uptake

taken into cells

assimilation

incorporated into organic molecules for growth

nutrient limitation

the control of growth or production by a nutrient or nutrients

what controls nutrient limitation?

nutrient availability, nutrient requirements, stoichiometry

nutrient availability

the general availability of a nutrient; is its source common?

what is generally the source of limiting nutrients?

geologic weathering

stoichiometry

relative ratio of nutrients in an organism

what is redfield’s ratio?

a molar ratio of C:N:P required by phytoplankton. the ratio is 106:16:1.

colimitation

more than one nutrient is limiting

nutrient remineralization

release of inorganic nutrients by organisms

ecological subsidies

movement of resources from one ecosystem to another

trophic state

level of ecosystem productivity

heterotrophic state

more heterotrophy than autotrophy

autotrophic state

more autotrophy than heterotrophy

external loading

supply of nutrients from outside the system

point source

a specific location where pollutants enter the water

nonpoint source

a pollutant source that doesn’t come from a single, identifiable location. instead comes from many diffuse sources over a large area

TRUE OR FALSE: it takes more energy to use NO4+ than NO3-

false

how do you test which nutrient is limiting?

use containers floating to the lake and add different nutrients to each. examine the response of algal biomass in each after ~1 week.

TRUE OR FALSE: in highly eutrophic lakes, the nutrient concentrations will be low for dissolved nutrients and high for total nutrients.

true

TRUE OR FALSE: in highly oligotrophic lakes, the nutrient concentrations will be low for dissolved nutrients and high for total nutrients.

false

remineralization is dominated by large or small organisms?

small

what are some examples in which large animals dominate remineralization?

salmon dying after spawning, duck and geese excreting in wetlands, amphibians depositing eggs

how is trophic state characterized?

water clarity, phytoplankton biomass, nutrient concentrations

what are 3 reasons algal blooms matter?

bad for drinking water, kill fish, decrease biodiversity

how do algal blooms kill fish?

hypolimnion anoxia leaves no refuge for cold water fish, anoxic conditions. however, cyanobacterial toxins float at the top.

how does natural eutrophication (ontogeny) occur?

a deep, oligotrophic lake fills with sediment over time and becomes a shallow, eutrophic lake

which occurs faster: cultural or natural eutrophication?

cultural (except volcanoes)

what was one of the first steps to lowering Phosphorus in lakes and streams?

banning phosphates in detergents

TRUE OR FALSE: lake water treatment is more difficult when the hypolimnion is anoxic. explain.

true; when anoxic, phosphorus is locked in sediment. however, when aerated, the phosphorus is released from the sediment into the water.

what are 2 lake treatment methods to lower cyanobacterial algal blooms?

1) adding copper to the water

• can contaminate sediments

• toxic to crustaceans

• should be used as a short term treatment

2) adding barley straw to water

• effective at lowering algal biomass, DP, lowering cyanobacteria, decreasing water taste and odor problems

• seems to allow substrate to microbes that uptake nutrients

• mechanism not well understood

biomass

amount of living tissue

production

the flux of carbon or energy through an ecosystem compartment

autochthonous carbon

carbon obtained from primary production within the system

allochthonous carbon

carbon obtained from external carbon imports

a negative NEP indicates what type of carbon imports?

allochthonous

a positive NEP indicates what type of carbon imports?

autochthonous

secondary production

tissue elaboration by heterotrophs regardless of fate

assimilation efficiency

how good an organism is at extracting nutrients from its food

TRUE OR FALSE: high biomass = high production. explain.

false; an example is that decomposer biomass is often low, but their production is often very high.

assimilation = ? - ?

ingestion - egestion

what causes variation in assimilation efficiency?

food quality, digestive system morphology and physiology, temperature

TRUE OR FALSE: endotherms have a higher assimilation efficiency than ectotherms

true