Lake ecology final

What acreage and depth legally defines a shallow lake?

50 acres or greater with 4.6 meters (15ft) or less

What organism helps promote a clearwater state?

Daphnia

What is a clearing event?

a clearing event refers to the natural, often seasonal, phenomenon where a lake's water becomes highly transparent, usually in spring, after algae blooms die off due to increased zooplankton grazing and nutrient shifts, revealing a blue or clear water state, but can also describe human-induced efforts (like aeration or bioaugmentation) to remove muck and clarify turbid water for ecological benefit. It signifies a healthy shift from a turbid, algae-dominated state to a clearer, nutrient-balanced state, often involving food web changes and stratification.

What invasive species is good at clearing water?

zebra mussel

What plant density do large mouth bass prefer?

moderate, medium

Interpret this figure

I think this figure shows that as percent plant cover increases, sunfish start to outcompete largemouth bass because greater plant cover is more ideal for sunfish than largemouth bass

What is aeration? (5)

Physical, chemical, or biological?

• Inject air or oxygen into anaerobic hypolimnion

• Increases oxygen, reduces taste/odor problems

• Appropriate for lakes with large anaerobic hypolimnion

• maintains lakes stratification

• Helps decrease phosphorus release from sediments and decrease cyanobacteria blooms

• physical

What are bubble curtains?

Physical, chemical, or biological?

Two aeration devices next to each other to create a somewhat controlled management

physical

Can be used to increase residence time of herbicides

What is Phosphorus Precipitation?

physical, chemical, or biological?

• Add a binding agent to precipitate and inactivate soluble P

• Usually uses alum which can be toxic to aquatic life

• Alum treatments may be wildly effective in situations with low external loading and high internal loading

  • chemical

when you introduce a living organism for management purposes?

Biological control

What is shading?

physical, chemical, biological?

• Add nontoxic dye to
water
• Reduces growth of
algae, macrophytes
• Reduces oxygen
consumption

• physical

What management is enforced when managing swimming zones?

Lake zoning

Creating/Limiting Public Access

How did hydrilla get into the US?

was used for aquariums because its a hardy, fast growing plant

what is hydrarch succession

the gradual change of a wet, aquatic environment (like a pond or lake) into a terrestrial (land) ecosystem

Modern view of lake ontogeny takes into account what?

disturbance

How did common carp get here?

intentionally introduced into Midwest waters as a game fish in the 1880s.

How did the sea lamp spread?

off of boats

How to manage cyanobacteria?

Adaptive Water management

Is water quantity a critical issue for the future

yes

Do different copper algaecides matter or are they all the same?

• Formulations have different chelators, pH, and chemical composition that effect their performance in varied water conditions
• Some copper formulations are only used for algae, some are almost exclusively used for vascular plants
• Not all copper algaecides are chelated equally

Which federal law affects point/nonpoint pollution?

Clean water act

What is the goal of aquatic plant management?

to achieve a balance in water bodies

Single best method for weed control

The easiest place to stop invasive species is at the border of

the host country

Treat before densities are absurd

Manage during lag phase

Characteristic of a shallow lake

• more sun + wind can reach bottom

• only littoral and photic zone

• more nutrient availability

• no stratification

Characteristic of a deep lake (4)

• sun and wind cannot reach bottom

• littoral, pelagic, photic, aphotic zone

• less concentrated

  • stratification occurs

4 main categories of in lake management techniques

• Physical
• Chemical
• Biological
• Institutional

Basic littoral food web

Basic pelagic food web

Clear water characteristics (6)

• more daphnia

• more vascular plants → more light attenuation

• less rough fish stirring bottom

• less cyanobacteria growth

• Minnows

• multiple positive feedback loops

turbid water characteristics (6)

• more sediment suspension

• more algae

• more secondary rough fish

• less apex predators

• bullheads

• multiple negative feedback loops

During a fish kill scenario would piscivores increase or decrease

decrease

During a fish kill scenario would planktivores increase or decrease

Benefits of dilution and flushing management (3)

physical, chemical, or biological

• decrease concentration of nutrients by adding water of lower nutrient concetrations

• flushing decreases retention time and increases turnover

• moves nutrients downstream

• physical

diver dredging

• divers use air lift system to remove plants from sediment

• expensive

• highly selective

hypolimnatic withdrawl

• remove nutrients from hypolimnion

• - requires lake with dam/water outlet at hypo

rotovating

eurasian watermilfoil

Institutional control

• docking regulations

• fishing regulation

• public access

classic biocontrol

Classical Biological Control introduces new, highly specific enemies

native biocontrol

uses or boosts existing local organisms