Freshwater Ecology Exam 1

limnology

study of lakes

oceanography

study of water

lentic

standing water, lake

lotic

running/moving water. streams, rivers, spring

E.A birge and C. Judy did what

influential work on plankton at the university of Wisconsin

the river continuum concept (RCC)

attempt to describe structure and function of lotic systems from source-to-mouth using an analogous approach to hydro-geomorphical approaches

water is only one of __ inorganic substances that can exist as a liquid on the surface of the earth at an ambient temp and position , the second substance is mercury

two

total global water

97.5% salt water

2.5% freshwater

unique properties of water that make life possible include

surface tension

soluble

has high specific heat

weak hydrogen bonding between water molecules permits association of water molecules as a liquid

dynamic structure

as h2o freezes what happens

molecules stop and expand, forming a lattice like structure. this makes ice LESS dense than liquid water

with increased temp, h20 molecules:

tighter packing of molecules, leading to increased density and flowing water molecules

the hydrologic cycle

continuous cycling of water from atmosphere to earth

name the components of the hydrologic cycle

evaporation

precipitation

surface runoff

groundwater runoff

the watershed

drainage basin/containment. all water drains to the same place

determination of direction of why water flows based on ridges of the land, anything that happens in a watershed could have effects downstream

do lakes have watersheds

yes

loss of water from lakes

evaporation

evapotranspiration

direct outlet

groundwater seeping out

origins of lakes

typical product of natural disasters

not meant to be there forever

in a geologic sense; wont be able to support changing environment , will fill up with sediment through time.

shifts in tectonic activity, glaciers, etc

inland water makes up _ of earths surfacr

2%

caspian sea

largest inland body of water

lake superior is the largest lake in terms of __

area

lake baikal is the largest lake in terms of __

volume

why is light important in aquatic ecosystems?

heating

photosynthesis

vision

ultimately drives water movement

what is light?

part of the electromagnetic spectrum , photons/quanta

plants operate in the same range of __

light

when energy is it behaves as a __

propagated, wave

long wavelength + low frequency =

low energy

short wavelength + short frequency =

high energy

infrared energy is essentially heat

photosynthetically active radiation is __

400-700 nm

maxes out at violet/blue and red

plants reflect and dont absorb __ light, making it useless to photosynthesis

green

plants use diff __ to increase spectrum of light they can absorb

pigments, in this case chlorophyll

quantity and quality of light striking the surface of a lake depends on factors such as

latitude, season, time of day, elevation, meteorological conditions

reflections of light on the water surface depends on

angle of the sun

waves

average reflection is 6.5%

as light enters water, what 3 things occur

transmission: transit between anything in the water

absorption as heat

scattering by h2o solutes of suspended particles

__ penetrates the furthest down in water

UV light

humic substances(tannins) important in lake water are

decomposing plants , they reduce the potential for photosynthesis, creating a brownish lake color due to aromatic compounds

__ __ absorbs and scatters light

particulate matter

turbidity

ability to scatter light , plankton cause turbidity in water

two zones of lakes

photic zone: photosynthesis occurs here

aphotic zone: no light

heat in aquatic ecosystems

regulate chemical reactions and metabolic rate

__ __ is the greatest source of heat

light absorption

geothermal

earth itself is warmer than the surrounding air

losses of heat

thermal radiation

evaporative cooling

convection (At night)

thermocline

plane of fastest temperature change within metalimnion

What is the epilimnion

Warmest water

What is metalimnion

Transition zone

Thermocline ?

Plane of fastest temperature change within a metalimnion

Hypolimnion

Coldest water temperature

Resistance to mixing is proportional to __ differences between two water layers

Density

Wind mixes ___ waters

Shallow

As temp begins to cool, the gap in the thermocline gets smaller, eventually temp at the top is the same as the bottom and water density (is the same) mixes, what is this called?

Turnover

During fall turnover what happens

Lake mixes from top to bottom, nutrients get mixed

During winter the temp at the top of a lake is different, colder, then the temp at the bottom, this is called

Inverse stratification

During spring turnover

Lake mixes from top to bottom , same as fall

amictic stratification

Ice covered year round, mostly in Antarctica

Cold Monomictic stratification

Water temp never exceed 4* C

Only 1 period of mixing (summer) a year

Deep lakes

Arctic / mountain lakes

Warm Monomictic stratification

Circulate freely in winter

Do not freeze typically

Great Lakes

Dimictic Stratification

Circulate freely twice a year

Stratified in summer

Inversely stratified in winter

Oligomictic

Stratified year round

Only rarely cools sufficiently to circulate

Never ice covered

Polymictic Stratification

Frequent, continuous periods of mixing

Shallow lakes in temperature regions

Cold Polymictic

Circulate at night

Warm polymictic

Circulate often , tropical lakes

Holomictic lakes

Lakes discussed so far

Circulate top to bottom

Meromictic

Only partially circulate

Chemcially stratified

Divided into monimolimnion: deep isolated stratum, does not mix

Mixolimnion: stratum that periodically mixes

What effects heat in lotic systems

Ground water, run off

What is diel temperature change

Temp change over 24 h

Streams that are ground water fed tend to be ___ in the winter, making them less likely to freeze over

Warmer

If stream is too small/big the temp won’t change much, __\ change more

Average

Oligotrophic lakes often have ___ productivity

Low

Clinograde oxygen profiles are found at ___ lakes

Eutrophic (photosynthesis occurs here)

What causes the curve to the right in positive heterograde curve

Lots of plants / algae at this level, there could be phytoplankton here

Phytoplankton drop with temp to a place where they can remain bouyant

What causes the graph in negative heterograde curve?

Respiration of organic matter that is sinking into the metalimnion and stopping when it hits more dense water

Due to large numbers of zooplankton

RARE

What kind of D.O curve is this?

Clinograde

What kind of D.O curve is this?

Positive heterograde

What kind of D.O curve is this?

Negative heterograde