Cyanobacteria III/IV Flashcards
What temperature water do cyanobacteria dominate in
In warmer temperatures - Higher temperatures promote increased recycling of nutrients, this causes a shift towards small fish species which eat the zooplankton that would otherwise be eating the algae (so you get a lot of algal biomass then), all the algae then has to go to the top of the water body to get more sunlight leading to shade (here cyanobacteria have a competitive advantage over the others as they can control their buoyancy and rise to the top)
The synergistic effect between what two factors can shoot up cyanobacterial blooms
- warm temperatures and nitrogen
Phosphorous stimulates cyanobacterial blooms more so in what types of lakes
- In thermally stratified deep lakes rather than in wind mixed shallow lakes
- the thermally stratified deep lakes don’t mix readily and so phosphorous gets stuck at the bottom and highly available to the cyanobacteria
What type of metabolites do cyanobacteria produce that function as toxins
They produce secondary metabolites that function as toxins
Describe anatoxins
- these are simple alkaloids that function as neurotoxins
- they mimic the neurotransmitter acetylcholine
- they can also block the enzymatic activity of acetylcholinesterase
Describe hepatotoxins like microcystin
- these are more molecularly complex proteins that function as toxins that target the liver
- these affect the liver tissues by degrading capillary membranes, resulting in the cell lysis and the accumulation of blood
Describe cyanotoxins as an anti predator strategy
- toxic Microcystis can suppress grazing of the zooplankton Daphnia, but Daphnia can acquire tolerance following chronic exposure to cyanotoxins –> so tolerant populations evolve and therefore adaptation suggests that this isn’t a long term strategy then (cyanobacterial toxins are not strong anti predator strategies)
How effective is bio remediation
- This is where you biologically alter a lake to suppress how well the cyanobacterial bloom can take place (so like doing manipulation of the trophic cascade)
- Successful bioremediation of cyanobacterial blooms in lakes is often short lived - thereby requiring additional management strategies (e.g. chemical remediation)
What is a quick fix for cyanobacteria
going the chemical route and spraying a chemical
What is a top down control via the trophic cascade
this is where you control how many predators etc. there are (bioremediation)
What is a bottom up control of cyanobacterial blooms
using chemical additives
Describe Phoslock
- this is a chemical that locks up the phosphorous so the cyanobacteria don’t have access to nutrients then
- it is a clay based product that is added to the bottom of the water body
- can only add it to artificial water bodies
What is less expensive to use than phoslock
using aluminum sulfate or alum to bind phosphorous and reduce the cyanobacterial blooms
Describe aeration remediation
- aeration pumps take water from the bottom, pump it out and aerate it
- circulation of water maintains well mixed water column in which oxygen levels remain near saturation
- oxic conditions then enable oxidized iron to bind and precipitate with phosphorous
- anoxia is prevented which otherwise reduces iron and releases bound phosphorous