midterm 2 aquatics total

How does energy flow through lake food web

Producer(phytoplankton/plant) to primary consumer (zooplankton/grazer) to secondary consumer (small fish) to tertiary consumer (large fish/birds) then decompose recycled

What’s the PEG Model of seasonal lake succession

Describes how plankton communities change throughout yr

Winter: nutri present after fall mix but ice means low light for phytoplankton

Spring : mixing , nutrients and light raised , diatom blooms. Little grazing

Late spring : zoo plank raise n graze algae (clear water)

Summer zooplank lower ( cus less food) and more fish pred, graze resistant algae n macrophyte increase

Late summer warm water n low nitrogen favor Cyanobacteria

Fall mixing supply nutrients again for second phytoplankton bloom n larger zooplankton

What’s the microbial loop n why important

A pathway that recycles doc back into food web

Plankton release organic compound n organisms produce waste, then bacteria consume dom, flag n dilates eat bacteria, then zooplankton eat these organisms, then fish eat zoo plank

Compare the 4 groups heterotrophic plankton

Viriplankton : mostly viruses infecting bacteria ( bacteriophage) contribute to microbe recycle

Bacterioplankton: free living bacteria use om n recycle nutrients

Fungi : decompose detritus, recycle nutri, can be parasite

Protozoa: hetertrophic/mixotrophoc protists consume microbes, some r parasites

Compare rotifer, cladocerans, and copepods

rotifer: eat 1-20 micrometer clearing 1-5ml a day, parthenogenesis, distinguishing feature is small so rapid generations

cladocerans eat 1-50micrometer clearing 5-30ml a day, parthenogenesis or sex, efficient filter feeder

copepods eat 5-100 clear around 35 ml a day sex repro

12 life stages

What is zooplank grazing n what determine grazing rates

Zooplank eat phytoplankton n other suspended particles. Grazing depends on particle size,food selectivity, completion n grazer size

What are the main groups zooplank predators

Cladoceran, copepods,flatworm,hydrozoan, malacostracans, aquatic insect larvae, water mites

What are the 6 fish trophic guilds

Planktivore- eats plankton

Piscivore-eats fish can be cannibalism

detrivore- eats om including dead/decay

Herbivore- eats plant/algae

Omnivore- eats plant an animal

Benthivore- feed in bottom dweller

What determines fish distribute in limnetic zone

Food avalibity, do, water temp

How does fish predation effect zooplankton

Fish are visual pred and prefer to eat big/slow zooplankton reducing their abundance so envior favors small species

what does the size effiecency hypothesis explain

larger zooplankton are normally more efficent grazers but fish prefer to eat them. fish predation allows smaller zooplankton species to coexist by reducing their competition

what are karimones and induced defences

kairomones are chemical cues released by predators they prey can detect to know nearby

they trigger induced defenses in zooplankton such as change in body size, shape(caps and spikes) or transparency

how do zooplankton defense differ between fishes and invert predator

fish defenses: favor smaller, thinner, transparent

invert defense: larger or defensive structure to be to big to eat

what dvm and why occurs, trade off?

diel vertical migration, daily movement of zooplankton between water depths to avoid predators

with predator cues, daphnia may move deep in day (avoid visual pred) and return to surface at night to feed

trade off deep is cold and can reduce food

what caused 2011 algae bloom n where

lake Erie, increased phosphorus from agricultural land use, increased rainfall so lots runoff, and weak circulation lead to massive cyanobacteria bloom

how does eutrophication change lake communities

initially, high nutri increases plants/algae, lead to less macrophytes and less o2 and therefore fish n birds associated with them decline and so sediment destabilize allowing turbidity and erosion

some fish do good at first and some straight dive

what are the ecological and industrial cost of eutrophication

ecological:

lower: deep water o2 ,whitefish and salmonids, and habitat/diversity

raised: p,s and cyprids

industrial:

tastes bad, up disinfect costs, toxic compounds

compare bottom up and top down causes of eutrophication

Bottom-up causes include nutrient excess(especially p) from runoff causes lots phytoplankton

top-down causes involve the removal piscivores fish, means more zooplanktivore fish, means less zooplank means more algae

what are alternative stable states in shallow lakes

a shallow lake can remain stables in 2 ways b

clear water state: macrophytes dominate stabilizing sediment and clarifying water

turbid water state: phytoplankton dominate reducing light and suppressing macrophyte

tipping point can cause rapid shift between states

why can lake restroration require greater nutrient reduction than expected

hysteresis: the nutri level needed to clear turbid lake can be much lower then the level that originally caused it to become turbid cus sedimets n such store nutri to keep algae alive

how can biomanipulation restore lake water clarity

change fish communities to increase zooplank grazing

stock piscivores, lessen zoo plank eating fish, raises zooplank, lowers phytoplank

what other lake restortaion methods exist aside from putting in piscivores

overfishing: stocking and fishing regualtion

drinking water: filter chem treat and source water protection

resivoirs: manage fluctuation water levels to maintain good eco flow patterns

what characterizes profundal zone

deep water, below o2 comp depth, with not enough light for food photosynthesis,

calmer, colder, & more stable temperatures; typically inhabited by benthic organisms.

what organims live in profundal reigon and what do they eat

copepods, ampipods, ostracods,insect larvae

eat bacteria coated detritus and settling phytoplankton (often omnivores)

why does the profundal region species diversity decline with depth

deep water can limit what lives cus low o2

adaptions include: hemoglobin ( to store o2), lower resp rates and anaerobic capabilities

how does light affect how far in the littoral zone extends depth wise

littoral depth into the lake depends on light penetration (k)

turbid lakes( shallow littoral zone under 1m)

clear lakes( the litoral zone can be over 10m)

how do wave actions and light penetrations influence littoral communities

high wave action: exposed, rocky sediments, fewer rooted plants

low wave action: find sediments accumulate, more macrophytes

less light with depth limits plant growth

compare the 3 main types of macrophytes

emergent: rooted in sediment grow above water

floating: no roots and float above water

submerged: grow underwater entirely

how do macrophyte communities indicate ecological status

healthy lakes: diverse submerge macrophytes

degraded lakes: have more algae and less submerged macrophytes

what are the ecological effects of macrophyte beds

lower water movement( allow sediment)

raise organic matter(lowers o2 and allows nutri cycle)

provide refuge, habitat n feed areas

can release chemicals that inhibit other organism growth(allelopathy)

what are the 4 resources macrophytes provide for food webs

resources, refuge,detrius, n surface area for organisms

how are stable isotopes used to study food webs

scientists measure isotope ratios in organisms to determine who is eating who and trace energy through food web

important isotopes for trophic levels in lakes

delta carbon 13 identify the original carbon source (terrestrial vs aquatic) cus dif producers have dif carbon isotope signatures

delta nitrogen 15 identifies organism positions in food chain cus it increase 2-4 % per trophic level

why do producers discrimiate between carbon isotopes

producers normally like lighter ones 12c over 13c leaving dif isotpe signatures

how does macrophytes complexity affect food chain length

intermediate complexity/diversity= longest food chains ( too little veg gives no habitats ) ( too much restricts predator vison n feed)

what is periphyton

a community of algae, cyanobac ,fungi, bacteria, and protozoa attached to submerged surface make own little ecosystem and does not penetrate surface

what organisms inhabit littoral zones

benthic(bottom sediments/plants) - insect larvae, snails,worms,mussles, fish

pelagic(open water):zooplankton, copepods, cladocerans,rotifers,fish

how do heterotrophic realtionships differ across littoral habitats

in sediment: anerobic microbes/redox

on sediment surface: grazer n pred

among plants/epiphyton: grazer n pred

neuston: organisms at water surface like water strider

what characterizes limnetic zone

open water, dynamic habitat with no physical barriers, dom by phytoplank and zoo plankton

compare phytoplankton, zooplankton and nektons

phytoplankton: photosynth, primary producer

zooplankton: consumers eat phytoplank

nektons: active swimmers(mainly fish) that can move against current

why can spring/fall overturn cause phtoplankton blooms?

mixing brings nutrients from deep water to surface

what are the phytoplankton size categories

algae/protozoa (all under 60 micrometers, microplank20-60)

small protist/bac(nanoplankton 5-20, ultraplankton 2-5, picoplankton 0.2-2)

virus (femoplankton 0.02-0.2)

what are the main phytoplankton groups

cyanobacteria, chrysophyta, chlorphyta, diatom, euglenophyta

what controls phytoplankton sinking

cell size, shape, density difference with surrounding water, water viscosity and boancy adaptions. sinking affects access to light n Nutri

how do phytoplankton size n cell shape affect survival

small cells useful when resources limited

large useful for protection

and they impact buoyancy and sinking

how do phytoplankton respond to nutri deficencies

n deficient : uptake more nh4 and raise carotenoid to chlorophyl ratio

p deficient: raise acid phosphate activity when free phosphate scarce

how do phytoplankton groups differ per environmental preferences

cyanobacteria: prefer warmth

diatoms: prefer turbulent well mixed water

other groups differ: per light, temp and, stratification

what are the seasonal patterns of phytoplankton

spring/fall lots diatoms ( like turbulent mixing)

stable summer has lots of green algae, Flagulates and dinoflagellates and cyanobacteria

late summer has lost of n2 fixing cyanobacteria cus now nutri are scarce and they can work with n2

what is the dcm

DCM= deep chlorophyll maximum + depth where chlorophyll conc peaks often near metalimnion reflecting peak place for phytoplankton growth

lake zones based on light

euphotic ( phtotsynth level light)

dysphotic( low light)

aphotci(no light)

what determines the chemical composition of lakes

atmosphere( gases n2,o2,co2), nutrients (n,p) and percip/evap

watershed( dissolved minerals depending on geology)

groundwater(contributes dissolved substances)

how does lake chemistry change with age

Lowers: ca2=, alkalinity, ph

raises: doc,total nitrogen(TN)

stable: Total phosphorus (TP)

compare TDS, connectivity, and hardness

TDS: total dissolved solids(slats, and other substances)

Conductivity: ability to conduct electricity, related to ion conc

hardness: concentration of calcium and magnesium ions in water.

what is an endoheric basin and what happens to its salts upon evap

a basin with no outlet, evap removes water and salt precipitates, making salt pans

whats DIN and DIC

DIN: dissloved inorganic nitrogen ( no2,no3 and nh4 produced from microbes and n2 fix)

DIC: dissolved inorganic carbon ( c02, hco3, co32-, porportion depends on ph)

how does ph affect DIC forms

low ph= co2 and hco3

intermediate ph= hco3

high ph=co32-

what causes lake whitening

intense photosyth removing co2, ph increases, caco3 precipitates making the white color

what determines dissolved oxygen(do) saturation

high temp lowers do

high salinity lowers do

high pressure raises do

compare sub saturation, supersaturation, hypoxia and and anoxia

sub saturation: do below atmospheric equalib sat

supersaturation: do above equalib sat

hypox:do bellow 2mg/L

annox:below 1mg/L

what are the main sources n sinks of DO

sources : atmosphere, Photosynth

sinks: respiration, decomp and redox

how does stratification effect do distribution

epilimnion: atmospheric exchange and photosynth replenish o2

metalimnion: thermocline restricts vertical exchange

hypolimnion: isolated from atmosphere, has low oxygen levels cus organism n sediment demand

how does seasonal stratification affect lake oxygen

summer Strat isolate deep water, so do declines

fall overturn: mixing redistribute o2

winter: ice restrict atmospheric o2 exchange so oxygen can lower

compare HOD and SOD

HOD (hypolimnetic oxygen demand): oxygen consumed in dep water affected by organic matter input ,time stratified,hypolim volume n temp

SOD(sediment oxygen demand):o2 consumed at sediment affected by temp,nutrient overlying do n water velocity

when does hypolimnetic hypox/annox develop

when hod+sod approaches or exceeds avalible deep water DO

compare olgiotrophic, mesotrophic and eutrophic lakes

oligotrophic: low nutri,low algae, clear water and high DO

mesotrophic: moderate nutri, algae, clarity and DO

eutrophic:High nutri, alage, turbid and low DO

compare hypereutrophic an dystrophic lakes

hypereutrophic: excessive nutri, excessive production leads to hypoxia and degradation

dystrophic: excessive DOM leads to high organic accumulate and to anoxia

how do Secchi depth, chlorphyll a and total phosphorus indicate trophic status

secchi: water clarity, decreases as trophic increases

chlorphyll a: shows algae abundance, increases with trophic

tp: total phosphorus increases with trophic

compare the 4 vertical DO profiles

orthograde: high do throughout deep water (olgiotroph)

clinograde:( do decreases with depth)

positive heterograde: do peaks in metealim( deep chlorophyll or trapped o2)

negative heterograde: do minimum in metalim( zooplank resp/ microbial decomp)

what nutrient commonly limits freshwater primary production

phosphorus ( experimental lakes showed increased algae growth wiht increased p additon)

how does hypox/annox regen phosphorus

low o2 in deep water promotes p release into the water increasing avlalible phosphorus

how does hypox vs annox effect nitrogen

microbes use nox under low oxygen making n2

/nh4 also increases in hypox/annox

why is silicate important to lake chem and when does it become limiting

diatoms use silicate to build silica cell walls

5mg/L diatoms tressed, 0.1-0.5 growth stops

after death silicate may decompse to recycle

what causes lake acidification AND WHAT is the affects

nox and so2 produce acidic compounds that lower lake ph

watershed anc can buffer acidity

toxic metal mobilize

mortality increases

compare DOM DOC and CDOM

DOM: dissolved organic matter

DOC: dissolved organic carbon

CDOM: colored dom

how does brownification affect lakes

dark water absorbs more heat

raises strat strentgh, lowers mixing depth, lower light penetration, raises energy for microbes

what is lake snow (TEP) varves and paleolimnology

lake snow: aggregated particles that sink n settle

varves: paired/coarse fine sediment layers

paleolimnology: reconstructing past lake conditions from sediment record

what controls lake sedimentation rates

watershed/lake productivity, lake age, lake size, latitude/climate/ bedrock erodibility

how can climate change effect lake chem and processes

warming ( lower dissolved gasses, raises evap, metabolism and toxin soluble)

more rainfall(raises nutrient and sediment runoff)'

drought( more evap)

more wind(more mixing and shoreline interact)

compare lakes, shallow lakes, and ponds

lake; large body or standing/slow moving water

shallow lake: easily mixed to the bottom by wind

pond: small, shallow, light reaches bottom

how are different types of wetlands distinguished

swamp: trees, nutrient rich

marsh: nutrient rich, grasses/emergent plants, no trees

peatland: accumulated undecomposed om

• 1. bog: acidic, nutrient poor, rain fed

• 2. fen is neutral/alkaline, mineral rich, groundwater/surface water fed

how are lakes distributed globally

cover 3-3.7 of land, small lakes are numerous while large are more rare

what are the 11 categories of lake origins

tectonic, volcanic, landslide, glacial, karstic, fluvial, costal, deflation, plant/animal, artificial, meteor impact

how do tectonic(2 types) n volcanic lakes form

tectonic: crustal movements, graben(sink), rift(split)

volcanic; water fills volcanic craters

how do landslide and karstic lakes( name of type) form

landslide: debris blocks drainage, trapping water

Karstic: specifically (sinkhole) dissolution of rock creates sinkholes

what are the 8 types glacial lakes and how formed

alpine glacier scour lake( erodes rock basin by glacier)

moraine dammed (glacial derbis make dam)

proglacial(water collects in front glacier)

fluvioglacial plain(depressions from in glacial deposits)

plunge pool ( meltwater eroded basin)

alpine lake basin( glacier carves cirque and fills)

patterned ground( permafrost thaws n forms depression)

continental glacial scour(ice sheets erode basin)

how do fluvial, costal and deflation lakes form

fluvial: river in floodplain creates a natural lake during flooding

coastal: coastal barriers isolate water from sea

deflation: wind erodes n creates depression

how do plant/animal, artificial and meteor lakes form

plant/animal: organic accumulate or beaver dams

artificial: human made basins/reservoirs

meteor: impact craters fill

what 5 factors describe lake structure

morphometry (basin shape), hydrology (retention time), light, temp, turbulence

what are the three major lake zones

littoral: shallow, nearshore

limnetic; open water, well lit, above compensation depth

profundal: deeper low light , past o2 compensation depth

what is compensation depth

depth where photosynth=respiration

bellow this respiration exceeds photosynthesis

what are the three main energy inputs affecting lake mixing

1. thermal: heating, cooling, convection, percip and evap

2. wind: waves, seiches, horizontal mixing

3. density interactions: stratification, instabilities and water movement

what causes thermal stratification

heating and limited mixing create layers of dif densities, less dense water/warmer floats

compare the three thermal layers of a lake

epilimnion: upper, warm, mixed

metalimnion: middle, rapid temp changes, thermocline
hypolimnion: lower, cold, stable

what is the seasonal cycle of dimictic lake

winter: inverse stratification ( coldest h20 near surface ), spring: mixing occurs as ice melts, summer: thermal stratification forms, fall: mixing begins as surface cools and sinks.

why does winter have inverse stratification

freshwater most dense at 4 degree Celsius, so it sinks as colder water is above

what is the densimetric froude number (frd)

ratio comparing inertial forces to buoyant forces

frd bigger then 1 its mixing

frd smaller then 1 stratification

what is the gradient Richardson number (Ri)

compares density gradient effects to velocity shearing

ri bigger then 0.25 = stable (strat)

ri smaller then 0.25 =unstable(mixing)

compare lake mixing patterns ( when they mix/amount per yr)

diel( daily)

dimictic( twice per yr0

monomictic(once per yr)

amictic(no mix)

polymictic(more then twice per yr)

holomictic(entire water mixes)

meromictic(water column doesn’t mix completely)

what is a surface seiche

standing oscillation of water, strong wind or pressure changes push water to one ends then rebound occurs

what are internal waves

waves traveling along inner boundary between layers of different densities such as metalimnion