Marine Biology
• Study of living organisms in the ocean
• LIFE = ?
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Ability to capture, store, and transmit energy
Ability to reproduce
Ability to adapt to their environment
NASA: A self-sustained chemical system
capable of Darwinian evolution
Evolution
• Explains the unity and diversity of life
• Charles Darwin and Alfred Wallace
• Definition?
– Change
• Mechanism = natural selection
– reproduction, mutation/variation, selection
Diversity of Life
•Land is more
variable- leads to
more species
•Likely between 612 million species
total
•Likely about 1
million marine
species
•2000 new marine
species discovered
each year
Classifying marine organisms
• Pelagic
– Plankton
– Nekton
• Benthic
Living in the Ocean:
Advantage= Water everywhere
Living in the Ocean:
Disadvantage= Hard to move
Living in the Ocean:
Disadvantage= Hard to move
Common
Problem:
Surface
Area to
Volume
Ratios
Primary Producers
• aka autotrophs
• Organisms that can capture solar energy and
convert it to chemical energy by building
organic compounds
• Photosynthesis
Fig. 12-2, p. 238
Primary Producers
• Others use chemosynthesis
– Much less common
– Use the oxidation of inorganic compounds as
energy source,
– ex: bacteria use hydrogen sulfide at
hydrothermal vents
Cellular Respiration
• Opposite of photosynthesis
• Breakdown of food
• All organisms
Figure 13.1
Consumers
• aka heterotrophs
• Must consume (eat) other organisms
Consumers
• Primary consumers
– Eat producers
• Secondary Consumers
– Eat primary consumers
• These all are Trophic Levels
Food webs
• Complex representation of who eats who
Primary Productivity
• Refers to how active the producers are
• grams of Carbon bound into organic
material per square meter per year
(gC/m2/y)
Figure 13.18
Only 10% of “food” gets transferred to the next trophic level
Figure 13.19
Ocean’s Primary Producers
• Algae – in Kingdom Protista
– Have chlorophyll but no vessels to conduct
fluids
– Unicellular = phytoplankton – pelagic
– Multicellular = seaweed – benthic
• Plants
– Angiosperms = flowering plants
The Pelagic Zone
• Pelagic organisms are suspended in the
water
– Plankton = drifters
• Phytoplankton= unicellular photosynthetic algae
• Zooplankton = “animal” plankton
– Nekton = swimmers
Phytoplankton
• 95% of ocean’s primary productivity
• Mostly Single-celled organisms
• Diatoms & Dinoflagellates
Diatoms
• Dominant (>5600 species)
• Silica shell – two valves
• Produce large portion of O2 in ocean and
atmosphere
Dinoflagellates
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•
•
•
Mostly autotrophs
Most are free living (except zooxanthellae)
Two whip-like flagella
“Red tides” or HABs (Harmful Algal
Blooms)
Phytoplankton Distribution
• Depends on:
– light availability
– nutrient concentration
• Varies with:
– Depth, Proximity to land, Location on the earth
Phytoplankton Distribution
• Compensation Depth
– Where rate of photosynthesis = rate of
respiration
– Below this phytoplankton will die
Phytoplankton Distribution
• Higher near coast
– Runoff
– upwelling
Figure 13.6
Phytoplankton Distribution
Varies across the globe – How?
Phytoplankton Distribution
• Tropics
– Low
– Nutrients trapped below thermocline
Phytoplankton Distribution
• Poles
– Mostly Low (except for summer peak)
– Insufficient light
Phytoplankton Distribution
• Temperate Regions
– Highest overall
– sufficient light & nutrients
– Spring Peak
• Increasing sunlight
– Fall Peak
• Increasing mixing of nutrients
Zooplankton
• Animal plankton – many different types
• Heterotrophic – primary consumers
• Based on the phytoplankon abundance
graph…how would you expect zooplankton
abundance to vary?
Figure 13.11a: Arctic Ecosystem
Figure 13.13a: Temperate Ecosystem
Zooplankton
• Major types –
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Radiolarians
Foraminifers
Copepods
Krill
Zooplankton
• Holoplankton
– Spend their entire life in plankton
• Major types –
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–
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Radiolarians
Foraminifers
Copepods
Krill
Jellyfish (cnidarians) and comb jellies
(ctenophores)
Figure 14.3: Radiolarians
Singlecelled;
Hard shell
made of
silica
Figure 14.4: Foraminifers
Single-celled;
shell made
from calcium
carbonate
Copepods
Small crustaceans
(<1 mm)
Very abundant
Figure 14.5: Copepod diversity
Krill – Important in Antarctic Ecosystem
Fig. 13-9, p. 265
Fig. 13-10c, p. 266
Zooplankton
• Meroplankton
– Only found in plankton for part of their life
cycle
– Larvae of benthic adults & fish
Meroplankton