L4 Open Ocean And Vertical Zones

Question 1

Discuss productivity in the open ocean and the limiting factors

Answer 1

• open ocean has the highest net productivity of all major ecosystems
• uneven latitudinal distribution
  Limiting factors:
• photosynthetic light limitation
• photoinhibition
• nutrients - abundant: C,H,O limiting: N,P,Si
• zooplankton grazing

Question 2

What is a HNLC region and where do they occur ?

Answer 2

HNLC: high nutrient low chlorophyll area lacking key trace elements such as iron (Fe) vital to oxygen transport and silica (SiO2) from diatom shells
Santa Cruz,CA

Question 3

Classify zooplankton by their habitats with examples and adaptations
Classify zooplankton by life stage

Answer 3

-Euphotic zone: epiplanktonic species (pleustonic- vatella is a colonial cnidarian with air filled siphon) and (neustonic- glaucas)
> adaptations: air/ gas filled sacs to aid buoyancy
- disphotic zone: mesoplanktonic (shrimp and jellyfish)
> adaptations: bioluminescence to lure prey and for communication due to lack of light
- aphotic zone: bathyplanktonic
> adaptations: adapted to low food availability and lack of photosynthesis. Collect food from falling detritus and OM
- holoplanktonic: lifetime as plankton (jellyfish)
- meroplanktonic: larval stage as plankton (fish,molluscs)