Lecture 10- Ocean primary productivity II Flashcards
How are haptophytes important for the carbon cycle?
-they continually shed the calcium carbonate scales they grow (only some of them have those)
How are the calcium carbonate scales of haptophytes made?
-made inside, in he golgi apparatus, first organic material template and then put calcium (inorganic)on it and then secrete it out, pop it out,-continuous process, shed them and make them
What are the types of appendages haptophytes have?
-usually 3 appendages -2 are flegellas used for locomotion -1 is called haptonema and is used for prey capture as some haptophytes are heterotrpohic, haptonema is a linear row of microtubules
How does the outer calcium covering of the haptophytes affect their ability to access light?
-less light gets through but enough to photosynthesise -it scatters light so we can see the haptophytes when in large numbers
What is the role of haptophytes in the creation of chalk cliffs in Dover?
-almost entirely made of haptophyte scales -still can see the scale shapes under the microscope
What do haptophytes secrete for buoyancy and other reasons?
-secrete mucilage for buoyancy, protection from micro preditors, used also as energy store and trace mineral store
What is the feeding process of dinoflagellates?
-50% photosynthetic and 50% heterotrophic -most of them are heterotrophic to some extent
What are the flagellas of dinoflagellates like?
- have 2 flagellas
- one is transverse, coiled up around the cell and this one accounts for most of the movement forwards of the cell as it has lot of little hairs on it
- second flagella is an extended long one
What is the cell structure of dinoflagellates?
-the structure is not a cell wall as it is not external of the plasma membrane -in the plasma membrane there is an alveolar membrane and inside that are cellulose plates called THECAL PLATES
What was the experiment with prey hunting in dinoflagellates?
-K. veneficum with prey=slows down and swims in tighter,left or right-handed spirals • P.piscicida with prey speeds up with large right-handed spirals •Both organisms clearly sense the presence of prey and adopt a“hunting”behaviour
What colour are the dinoflagellates?
-golden brown due to chlorophyll c and peridinin pigments
In what for do haptophytes store energy as?
-lipid droplets and chrysolaminarin
In what for do dinoflagellates store energy as?
-starch grains
How can dinoflagellates be dangerous to bigger organisms?
-cause harmful algal blooms, when in high densities then they deplete oxygen levels and cause hypoxia= kills other aquatic life -this is due to a high number of them and they respire and deplete O2 -or some also release toxins that are on their own dangerous to animals even as large as doplphins
What is the lifecycle of dinoflagellates?
can form resistant cysts that persist in sediments for decades
How are dinoflagellates important for corals?
-they make the coral reefs possible -dinoflagellates are providing sugar and the animal provides protection - Corals, anemones, jellyfish, clams, nudibranchs are all animals (cniderians or molluscs).They are not photosynthetic. BUT… • They can obtain energy from photosynthesis via symbionts called zooanthellae. • Almost all zooanthellae are dinoflagellates from the genus Symbiodinium
What is the relationship between dinoflagellates and corals?
-Symbiodinium dinoflagellates provide energy and nutrients for the host by translocating up to 95% of their photosynthetic production • In return they receive crucial nutrients (ammonia and phosphate) from the host. • The exact metabolites that are exchanged and the mechanism by which this occurs are not yet known
What is coral bleaching?
-coral bleaching= diying of the dinoflagellates, most pigmnet in those -when die, the animal doesn’t get enough carbohydrates
How are the dinoflagellates in corals transferred?
-Symbionts are either inherited (vertically) within the cell • Or acquired from the ocean (horizontal) • One animal may contain many different strains or species of Symbiodinium
What are the factors involved in phytoplankton patchiness?
-lot of patchiness in where phytoplankton is, over area and time - light availability - nutrient availability - organism availability - temperature - salinity - water movement= i) ocean currents ii) mixing between depths -All can vary on a seasonal basis throughout the year
What does this graph show?
idealised yearly cycle in the temperate zone (so like port philip bay) winter= relatively dark, cold, less light, not much algae, more nutrients (as nothig is growing) spring= more algal growth = more phytoplankton with more light -as they grow= less nutrients as they all eat and that is why they die zooplankton= things that eat the algae, delayed -then the breakdown of the dead ones etc, brings an autum bloom
How does the irradiance of light decrease with depth?
exponentially
- if water is clearer= the light gets deeper (at about 1000 m not anymore)
- coastal are usually less clear
What is the photic zone?
- (or euphotic) zone to depth where light is 1% of surface sunlight (0-200 m)
How is light attenuated in the water?
i) scattering (angle of incidence, dissolved and particulate matter) ii) absorption
What wavelengths of light are absorbed by chlorophylls and which by accessory pigments?
-ight greater than 600 nm mainly absorbed by chlorophylls, light smaller than 600 nm absorbed by accessory pigments -Therefore different algae have preferred depths
How does the wavelength of light change with depth?
different wavelengths get absorbed differently
- red absorbed really quickly
- depends where an organism lives= if close to surface you can still do red if deeper than not
What is the compensation point?
-depth where rate of photosynthesis = rate of respiration (no net oxygen production) (-organisms close to surface= more photosynthesis than respiration -deeper living ones= due to lack of light= more respiration)
What is the effect of compensation point on phytoplankton?
Compensation depth effects if phytoplankton are net producers or net consumers
How does the compensation point vary?
- varies according to: - latitude - season - water transparency
What does this graph show?
amount of respiration doesn’t change with depth
- photosynthesis does due to lack of light
- net consumer of O2 below the compensation depth
What is critical depth?
- Critical depth above which total photosynthesis = total respiration
- area where there is no net production of O2 above that point
What does this graph show?
- the floating warm water in summer= casues stability, less mixing
- in winter less temp difference in water, =less photosynthesis, so the compensation point will be closer to the surface= also more cells below the critical depth= less likely to divide and grow, not enough food,
- Spring: compensation point deepens, water column stablizes (thermocline), mixing is lessened
- summer= compensation point goes deeper, less mixing
