Limnology Key Concepts Flashcards

What are the 7 phytoplankton groups?

Cyanobacteria, Chlorophyta, Bacillariophyta (diatoms), Pyrophyta, Chrysophyta, Cryptophyta, Euglenophyta

What unique features do cyanobacteria have?

Gas vacuoles (buoyancy); heterocytes (N-fixation when N is low); produce toxins

What are diatoms made of and what problem does that cause?

Silica frustules → dense → sink fast (Stoke's Law)

Name the 3 phases of the P-I curve in order.

Light limited → Light saturated → Photoinhibition

Under what condition do cyanobacteria fix nitrogen?

When dissolved inorganic nitrogen is LOW

Are archaea closer to bacteria or eukaryotes?

Eukaryotes

What limits phytoplankton in the lacustrine zone of a reservoir?

Nutrients (not light; water is clear)

What is the main carbon/energy source for macroinvertebrates in high-order streams?

FPOM (fine particulate organic matter)

Name the 3 major crustacean zooplankton groups.

Cladocerans (Daphnia), Copepods (cycloid/calanoid), (rotifers also major)

What is parthenogenesis?

Asexual reproduction in rotifers and cladocerans

What is Diel Vertical Migration (DVM)?

Deeper by day, surface at night; caused by predation avoidance

What is cyclomorphosis?

Predator-induced seasonal shape changes (e.g., longer spines when fish present)

What did Brooks and Dodson demonstrate?

Zooplanktivores change zooplankton community composition and size

What do ciliates feed on?

Bacteria

Typical filtration rate of large Daphnia?

25 mL/individual/day

Lake with abundant algae → expect what about planktivorous fish?

Lots of planktivorous fish

Name the 3 attached macrophyte growth forms.

Emergent, submergent, floating-leaved

What is aerenchyma?

Gas-filled tissue in emergent plants for buoyancy

What is heterophylly?

Leaves change shape based on where they grow (water vs. air)

What are the 2 alternate states of shallow lakes?

Clear water + high macrophytes; OR Turbid water + low macrophytes

What triggers switch from macrophyte-dominated to algae-dominated?

Loss of fish that prey on zooplanktivorous fish

What type of plant is Eurasian watermilfoil?

Rooted submerged aquatic vegetation

What does a connectedness food web show?

Who eats whom (feeding links only)

What does an energy flow food web show?

Quantitative energy transfer between trophic levels

Distinguish trophic level vs. trophic position.

Level = integer (1,2,3); Position = continuous, accounts for omnivory (e.g., 2.4)

What is ecological efficiency?

Consumer production ÷ prey production (typical 10-25%)

State the Trophic Cascade Hypothesis.

Number of trophic levels determines biomass distribution; predators control prey when Cpred > Pprey

What 3 conditions favor a trophic cascade?

1) Cpred > Pprey; 2) Simple food web; 3) Size-selective predation

Predict: Add piscivores → effect on algae?

Decrease algae (piscivores ↓ zooplanktivores ↑ zooplankton ↓ algae)

What is biomanipulation?

Using fish management (trophic cascades) to improve water quality

Define riffle vs. pool.

Riffle = shallow, fast, turbulent; Pool = deep, slow, fine sediment

What does the y-axis of a hydrograph show?

Discharge

Name the 4 stream invertebrate feeding guilds.

Shredder, grazer, collector, predator

What do shredders eat? Where are they common?

CPOM (leaves, wood); low-order streams (allochthonous input)

What is the Nutrient Spiraling Concept?

Nutrients taken up, transported downstream, released, retaken; describes retention efficiency

What does the River Continuum predict for low-order streams?

Heterotrophic (P/R<1); shredder-dominated; allochthonous carbon

What does shorter spiraling length indicate?

More efficient nutrient retention

What is the riparian zone?

Land adjacent to stream; influences shade, nutrients, organic matter input

Name 5 fish feeding guilds.

Piscivore, zooplanktivore, herbivore/algavore, benthivore, omnivore

What is bioturbation?

Sediment mixing by benthic fish; releases nutrients

Name the 3 thermal guilds.

Cold (6-15°C), Cool (10-25°C), Warm (25-30°C)

Value of Lake Erie fishery?

~$1 billion

What happened to the blue pike?

Extinct subspecies from Lake Erie

Why do small fish hatch in spring?

To coincide with maximal zooplankton abundance

Name the 3 reservoir zones from inflow to dam.

Riverine → Transition → Lacustrine

Describe the lacustrine zone.

Broad, deep, lake-like; clear; nutrients limit PP; near dam

Describe the riverine zone.

Narrow, turbid, high flow; light limits PP; advective nutrients

Distinguish epilimnetic vs. hypolimnetic release.

Epilimnetic = warm, oxic; Hypolimnetic = cold, potentially anoxic

What device allows selective release depth?

Selective withdrawal tower

What limits PP in riverine vs. lacustrine zones?

Riverine = light; Lacustrine = nutrients

What are PCBs?

Polychlorinated biphenyls; 209 congeners; industrial chemicals

How does chlorine content affect PCB persistence?

More chlorine = more persistent

Why are PCBs found in fish fat?

Lipophilic (fat-soluble); bioaccumulate

Name the 3 forms of mercury.

Elemental Hg(0), salts Hg(II), methylmercury CH₃Hg

Which mercury form is most toxic?

Methylmercury

What was Minamata Bay Disaster?

Japan, 1950s; industrial mercury caused severe neurological damage

How are humans primarily exposed to mercury?

Eating top predator fish/seafood

What is DDT and why was it banned?

Insecticide; caused eggshell thinning in birds (ecological impact)

Who wrote Silent Spring and when?

Rachel Carson, 1962

What is the unrestricted PCB consumption threshold (ppm)?

What is a photolithoautotroph? Example?

Uses CO₂ + light + inorganic electrons; cyanobacteria

What is a chemolithoautotroph? Example?

Uses CO₂ + chemicals + inorganic electrons; nitrifying bacteria

Is 'all photosynthesis produces O₂' true or false?

False (anoxygenic photosynthesis produces sulfur)

Order the redox cascade from most to least energetic.

Aerobic → Denitrification → Iron reduction → Fermentation → Sulfate reduction → Methanogenesis

Which process is last from an energetics view?

Methanogenesis

To which kingdom do methanogens belong?

Archaea

What is fermentation?

Breaks down organics without oxygen

What is the microbial loop?

DOM → Bacteria → Protozoans → Zooplankton; makes DOM available to food web

What two factors cause bacterial loss?

Protozoan grazing; viral lysis (up to 50% mortality)

Can bacteria compete with algae?

Yes, for inorganic nutrients (N, P)

How did round goby invade the Great Lakes?

Ballast water from ships

How did sea lamprey bypass Niagara Falls?

Welland Canal

Why did sea lamprey invade so quickly?

Native fish had no defenses

Why do zebra mussels thrive in Lake Erie?

Calcium-rich bedrock (need Ca for shells)

Where did goldfish originate?

China; domesticated from carp over 1000 years ago

What limits goldfish growth in aquariums?

Build-up of growth-inhibiting hormones and ammonia

What type of plant is Eurasian watermilfoil?

Rooted submerged aquatic vegetation

Which lake is most likely to be invaded by watermilfoil?

Large, warm, deep lake near boat launch

What is NOT a way to reduce watermilfoil spread?

'Only plant watermilfoil on private property'

Name 3 economic impacts of invasive species.

Recreation loss, property value decline, water intake clogging

Daphnia filtration rate

25 mL/individual/day

Ecological efficiency

10-25%

PCB unrestricted threshold

Lake Erie fishery value

~$1 billion

Viral abundance in water

10-100 million/mL