aquatic sldieshow 12, limnetics 2

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