quiz 4- abiotic factors + plankton

Question 1

Describe the major drivers of patchiness in plankton distribution

Answer 1

• horiz. changes in physical/chem conditions
• depth gradients
• grazing - zooplankton feeding or phytoplankton, for ex.
• reproductive behaviors
• feeding behaviors
• swimming capabilities (eg. flagella in dinoflagellates, jellyfish, pteropods)

Question 2

Diel Vertical Migration: what is it, why does it happen, how are plankton adapted to moving vertically in the water column?

Answer 2

zooplankton move toward surface at night + descend during the day
(cntrlled by a bio clock that is helped by envi light)

Question 3

Compare and contrast typical Diel Vertical Migration with what happens in the Arctic

Answer 3

migration based on lunar schedule

Question 4

Connect vertical migration of zooplankton with the food web in the deep sea.

Answer 4

dying phytoplankton, small zooplankton, embedded microbes, zooplankton fecal pellets all sink–> “marine snow”- important carbon transport to the deep sea

Question 5

Explain how and why seasonality drives phytoplankton abundance, and how this differs in shallow water vs deeper water environments.

Answer 5

Seasons change as a result of changes in sun angle + exposure- photosynthesizing plankton likely increase metabolism + reproduction in areas of high sun exposure + vice versa

Question 6

Analyze the connections between abiotic factors, phytoplankton blooms and zooplankton dynamics, and explain their role in carbon sequestration in the world’s oceans.

Answer 6

water motion + mixing depth- mixing depth lower in winter bc density gradient is less extreme- summer surface water is MUCH hotter than deep water

Question 7

List the major forms of nitrogen and phosphorus in the oceans.

Answer 7

N2 gas from the atmosphere- made into bio usable forms thru fixation (like bc of cyanobacteria?)
P- weathering of minerals, runoff from human activity

Question 8

Describe the various microbial transformations involved in the nitrogen cycle.

Answer 8

n2–> ammonium, nitrite, nitrate

Question 9

Explain how nutrients like Nitrogen and Phosphorus influence phytoplankton dynamics.

Answer 9

P is a limiting factor for phytoplankton photosynthesis

Question 10

Use your understanding of phytoplankton biology, and the factors that influence phytoplankton distribution and abundance, to describe how and why Harmful Algal Blooms (HABs) form

Answer 10

stable water column, input of nutrients, + input of resting stages (grow in good conditions)