1/24/2017
I. Pelagic zone
Bio 125 lecture #2:
A. Environment
B. Vertical zones (by light)
C. Challenges for living in the ocean
1. Light
2. Water movement
3. Dissolved gases
4. Nutrient availability
D. Plankton (con’t)
1. Phytoplankton
a.Cyanobacteria
b. Silicoflagellates
c. Diatoms
d. Dinoflagellates
2. Zooplankton
a.Holoplankton vs. meroplankton
b. Larval stage & bipartite life cycle
c. Unicellular zooplankton: Protozoans
i. Ciliates: Tintinids
ii. Amoebas: Foraminiferans & Radiolarians
II. Adaptations for Epipelagic Life:
A. Staying afloat
1. Sinking resistance
a. Size
b. Surface:Volume ratio
c. Shape
2. Buoyancy
a.Gas pockets
b. Lipids
3. Lighten body (exchange chemicals)
1/19/17
Reminders:
• 1st lecture quiz on lectures
1 & 2 on Tuesday 1/24!
Challenges for life in the ocean
Fig. 3.11
Light
Challenges for life in the ocean
Dissolved Gases:
CO2 O2 N2
Ocean &
atmosphere gas
concentrations
are affected by
each other
The Pelagic Zone (Open Ocean)
https://www.youtube.com/watch?v=hV438IrJg2w
Challenges for life in the ocean
Staying where you want to be
Dissolved Gases
• Dissolved gases are required for
life in the ocean
• Water temperature affects gas
solubility
• Gases dissolve
more readily in
cold than warm
water
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Oxygen
Atmosphere:210 ml/L O2 (21%)
Ocean: 0-8 ml/L O2 (<1%)
Cyanobacteria
Prochlorococcus- most abundant phytoplankton
Challenges for life in the ocean
Nutrient
availability
Photosynthetic nanoplankton
Silicoflagellates
Synechococcus
Phytoplankton: Diatoms
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Harmful Algal Blooms (HABs)
Pseudo-nitzschia australis
Domoic acid poisoning
Harmful algal blooms of dinoflagellates:
Red Tides
Zooplankton
Calif. Spiny Lobster phyllosoma larva
(Late June and July Only)
Meroplankton –
live only part of
life as plankton
(larval stage)
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Marine Reproduction
Larval Dispersal
Unicellular Zooplankton:
Kingdom Protista, Phylum Protozoa
1. Ciliates:
2. Ameobas:
a) Foraminiferans
Tintinnids
(Discorbis sp.)
b) Radiolarians
Zooplankton: Phylum Arthropoda
Copepods (holoplankton)
Adaptations for life in the Pelagic Zone
http://www.nick.com/videos/clip/100great-plankton-clip.html
Size Matters
Shape influences sinking rate
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Buoyancy Adaptations:
Air pockets
Buoyancy Adaptations:
Fish air bladders
Portuguese man-o-war
Cyanobacteria - dark spots are
air vacuoles
Adaptations for Epipelagic Life
Buoyancy: lipids
Adaptations for Epipelagic Life
Buoyancy: lipids (shark livers)
Diatoms – oil vacuoles
Adaptations for Epipelagic Life
Buoyancy:
‘lighten’ body fluids
Lecture 2 (1/19/17): Study Questions
1. List the 3 main vertical zones of the ocean & the
average depth ranges of each (in meters).
2. How does water affect sunlight? Which color gets
absorbed 1st? Which penetrates the deepest?
3. Which gas is more soluble in water and thus more
abundant in the ocean– CO2 (carbon dioxide) or O2
(oxygen)?
4. How does temperature change the solubility of
gases in water?
5. Are nutrients more or less abundant in the ocean
vs. on land?
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1/24/2017
Lecture 2 (1/19/17): Study Questions
6. Compare diatoms & dinoflagellates in terms of their
physical structure (what their shells are made of).
7. What types of plankton can cause HABs (Harmful
Algal Blooms)? Briefly describe 2 different ways they
can be harmful for marine & coastal organisms.
8. Define larvae & describe what a bipartite life cycle is.
9. What is a benefit of having a planktonic larval stage?
10. List 3 types of Protozoan (single-celled)
zooplankton. Note what each of their shells are made
of.
11. Define surface to volume ratio and explain why it is
important for planktonic organisms.
Lecture 2 (1/19/17): Study Questions
12. What 2 benefits does being very small provide
to plankton?
13. List 3 different shapes help plankton to resist
sinking.
14. List 3 different ways that epipelagic organisms
can increase their buoyancy & provide an example of
an organism that does each one.
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