Lecture 9- Ocean primary productivity Flashcards
What is the function of photosynthesis?
-light energy is captured by chlorophylls and stored in chemical bonds of carbohydrates (e.g glucose) -6CO2+6H2O= C6H12O6+ 6O2
How much of primary productivity occurs in the oceans?
-1/2
What is meant by primary productivity?
-taking inorganic material and changing them into organic (sunlight into energy)
What is respiration in relation to photosynthesis?
-the opposite reaction -C6H12O6+602=6CO2+6H2O -there must be more photosynthesis than respiration
What does chlorophyll in an environment indicate?
-photosynthesis -but not at night! they then respire
How does the distribution of chlorophyll change seasonally?
- it is more abundant in areas that are experiencing summer (mostly)
- dark blue= no chlorophyll
What organism contribute to marine primary productivity?
-algae (green, brown and red) -plants (seagrasses) -phytoplankton(bacterial and eukaryotic)
What is the algal contribution to marine primary productivity?
-they are limited in their growth by depth -only up to 50m as they have to be attached to the sea floor -only in coastal areas, not a major contributor to marine primary productivity, more habitats though!
What is the plants’ contribution to marine primary productivity?
-also only around coast -non-significant contributors
Who are the biggest contributors to primary marine productivity?
-phytoplankton as they are not limited by depth, can float
How large can phytoplankton blooms be?
-1000s of kilometers
What are the non-photosynthetic primary producers in the sea?
-chemoautotrophic bacteria by the volcano vents, not a major contributor to marine primary productivity
What are the characteristics of cyanobacteria? (type of cell, cell wall type and single celled?)
-part of phytoplankton -prokaryotes -gram negative cell walls -can be single celled, filamentous, or form thalli
In what ways can cyanobacteria be motile?
-can be motile (flagellar, gas vesicles=so they float, gliding) -gliding= freshwater
What colour are cyanobacteria and why?
-typically blue-green due to phycobiliproteins -aslo chlorophyll a
What element can cyanobacteria fix?
N2 -key nutrient for protein, these can take it out of the air and capture it so others can use it too
Is it true that cyanobacteria form toxins?
-some do -often freshwater that doesn’t move very much
Give an example of a cyanobacteria?
-Prochlorococcus -one of the most important organisms in the oceans
Can cyanobacteria form colonies?
- Trichodesmium
- common in tropical waters -colonies of aggregated filaments
- forms visible blooms
- in warmer waters
- can control their buoyancy and can float on the top
What is the colour and structure of diatoms?
-golden brown due to accessory pigments (chlorophyll c) -surrounded by intricate structures made out of glass= their cell wall -second most important primary producers after cyanobacteria -build a frostule= glass house, pure glass -little holes= for gas exchange, as glass nonpermeable
What is the structure of the glass house of diatoms?
- glass houses made up of two valves, (like a petri dish, one smaller and fits into the other one)
- then divides and form new 2 valves on the inside (so four cells now)
- but there is quite lot of variation, some insert girdle bands=make it possible to grow longer
What are the two major groups of diatoms?
1.Centric diatoms 2.Pennate diatoms
What are the characteristics of centric diatoms?
- radial symmetry -nonmotile= do not have flagellas
- planktonic(means they float around carried by the currents etc.)
What are the characteristics of pennate diatoms?
-bilateral symmetry -motile(gliding system) -sessile on rocks and ice -only sperm cells have flagellas -non-planktonic
What do centric diatoms have spines for?
-some centrics have long spines= helps them in the currents -the spines when divide hold cells together= colony
What is the structure and motility system of the pennate diatoms?
-pennates, have long slits that goes almost down to the middle -this slit secretes carbohydrate= this will help it stick to a surface, then motor molecules in the membrane and then pull the cell along -leave a little goo train, more an more on and then other organisms eat it biofoulling -they store some of the carbs they photosynthesise= lipids and chrysolaminarin sugar -important in arctic regions, not as important in coastal and warm oceans
Where do lot of pennate diatoms grow?
-grow beneath polar sea ice -estimated to contribute 20% of primary productivity of Southern Ocean
What is the lifecycle of diatoms?
- Form resting stages and spores to survive conditions unsuitable to growth
- cytoplasm is dense with lipid droplets and poly-phosphate granules
- can be dormant for decades
- when the ice melts= they float= form resting spores, withstand until ice forms again
What is the colour of haptophytes?
-golden brown due to accessory pigments (chlorophyll c)
What is the haptophytes’ cell wall made of?
-calcium carbonate scales (coccoliths)
What is the way of getting energy for haptophytes?
-they are both heterotrophic and autotrophic (some)
