Lecture 10- Ocean primary productivity II

Question 1

How are haptophytes important for the carbon cycle?

Answer 1

-they continually shed the calcium carbonate scales they grow (only some of them have those)

Question 2

How are the calcium carbonate scales of haptophytes made?

Answer 2

-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

Question 3

What are the types of appendages haptophytes have?

Answer 3

-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

Question 4

How does the outer calcium covering of the haptophytes affect their ability to access light?

Answer 4

-less light gets through but enough to photosynthesise -it scatters light so we can see the haptophytes when in large numbers

Question 5

What is the role of haptophytes in the creation of chalk cliffs in Dover?

Answer 5

-almost entirely made of haptophyte scales -still can see the scale shapes under the microscope

Question 6

What do haptophytes secrete for buoyancy and other reasons?

Answer 6

-secrete mucilage for buoyancy, protection from micro preditors, used also as energy store and trace mineral store

Question 7

What is the feeding process of dinoflagellates?

Answer 7

-50% photosynthetic and 50% heterotrophic -most of them are heterotrophic to some extent

Question 8

What are the flagellas of dinoflagellates like?

Answer 8

• 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

Question 9

What is the cell structure of dinoflagellates?

Answer 9

-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

Question 10

What was the experiment with prey hunting in dinoflagellates?

Answer 10

-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

Question 11

What colour are the dinoflagellates?

Answer 11

-golden brown due to chlorophyll c and peridinin pigments

Question 12

In what for do haptophytes store energy as?

Answer 12

-lipid droplets and chrysolaminarin

Question 13

In what for do dinoflagellates store energy as?

Answer 13

-starch grains

Question 14

How can dinoflagellates be dangerous to bigger organisms?

Answer 14

-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

Question 15

What is the lifecycle of dinoflagellates?

Answer 15

can form resistant cysts that persist in sediments for decades

Question 16

How are dinoflagellates important for corals?

Answer 16

-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

Question 17

What is the relationship between dinoflagellates and corals?

Answer 17

-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

Question 18

What is coral bleaching?

Answer 18

-coral bleaching= diying of the dinoflagellates, most pigmnet in those -when die, the animal doesn’t get enough carbohydrates

Question 19

How are the dinoflagellates in corals transferred?

Answer 19

-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

Question 20

What are the factors involved in phytoplankton patchiness?

Answer 20

-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

Question 21

What does this graph show?

Answer 21

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

Question 22

How does the irradiance of light decrease with depth?

Answer 22

exponentially

• if water is clearer= the light gets deeper (at about 1000 m not anymore)
• coastal are usually less clear

Question 23

What is the photic zone?

Answer 23

• (or euphotic) zone to depth where light is 1% of surface sunlight (0-200 m)

Question 24

How is light attenuated in the water?

Answer 24

i) scattering (angle of incidence, dissolved and particulate matter) ii) absorption

Question 25

What wavelengths of light are absorbed by chlorophylls and which by accessory pigments?

Answer 25

-ight greater than 600 nm mainly absorbed by chlorophylls, light smaller than 600 nm absorbed by accessory pigments -Therefore different algae have preferred depths

Question 26

How does the wavelength of light change with depth?

Answer 26

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

Question 27

What is the compensation point?

Answer 27

-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)

Question 28

What is the effect of compensation point on phytoplankton?

Answer 28

Compensation depth effects if phytoplankton are net producers or net consumers

Question 29

How does the compensation point vary?

Answer 29

• varies according to: - latitude - season - water transparency

Question 30

What does this graph show?

Answer 30

amount of respiration doesn’t change with depth

• photosynthesis does due to lack of light
• net consumer of O2 below the compensation depth

Question 31

What is critical depth?

Answer 31

• Critical depth above which total photosynthesis = total respiration
• area where there is no net production of O2 above that point

Question 32

What does this graph show?

Answer 32

• 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