Lecture 2 Flashcards
What is the range where photosynthetic organisms access visible light?
400-700 nm
What is the name for the range of light that photo synthetic organisms access?
Photosyntheitcally active radiation
Whatis photosynthetically active radiation?
400-700 nm/the range of light that photosynthetic organism access
What is the limit for incidence radiation?
1%
Define euphotic zone
The zone where-photosynthesis occurs ( the surface to one percent)
What’s the secchi depth?
-Depth of 10% irradiance in the waterbody
What type of visible light is
Most absorbed by algae? Why?
Blue because it penetrates greater depths within the waterbody
What is the type of chlorophyll in algae that allows them to absorb light?
Chlorophyll a
Where does the euphotic zone sit in nutrient poor water?
Deep
Where is the euphotic zone in nutrient rich water?
Shallow
Why is the euphotic zone shallow in nutrient rich water?
Because the water is unclear so the range of visibility is smaller
What is humid material?
The organic compounds that make up hummus(a major soil component)
Which types of waters are influenced by their catchment, and which aren’t?
Fresh water-influenced by their catchment
Open ocean-no catchment
What factors (four) influence catchment and subsequent clarity of water?
- Altitude
- Size
- Catchment utilisation (eg farming)
- Geology
In what temperature water is oxygen most soluble?
Cold
When is water at sterilisation?
100% oxygen saturation, no organism are present
What determines tropic status?
Nutrient availability
How busy is the food web when there’s one of oxygen at the BOTTOM of the water body?
The food web is not busy, and the lower the nutrient content
In which two tropic status leaves can oxygen use get to high it leads to anoxic conditions at the bottom of the water bed?
Eutrophic and hyper eutrophic
Define functional guild
Organism that exploit the same class of environmental resources in a similar way, regardless of their taxonomical position
What is algae a generic term for? What are the two types?
Anything that photosynthesises in an aquatic system
Macroscopic and microscopic algae
What are the three main limiting factors for algae in aquatic systems? Say whether they are limiting or not
- Inorganic carbon-never limiting
Inorganic nitrogen-can be limiting
Inorganic phosphorous- can be limiting
Sunlight- can be limiting dependant on the euphotic zone position
What is the red field ratio?
The ideal ratio of carbon:nitrogen:phosphorous
106:16:1
What are oceans and freshwater limiting in?
Oceans are NITROGEN LIMITING
Freshwater is PHOSPHOROUS LIMITING (with some exception)
When is a water body nitrogen or phosphorous limiting?
Ratio <16 is nitrogen limited
Ratio >16 is phosphorus limiting
What are the key types of algae?state of prokaryote or eukaryote
Eukaryotes: Diatoms Green algae Chlorophytes Autotrophic flagellates Dinoflagellates Prokaryotes: Cyanobacteria
Why are Cyanobacteria so efficient at photosynthesis?
They have two additional light pigments: phycoerythrin and phycocyanin
