Ocean Ecosystem
Goal:
To understand the factors (both biotic and abiotic) that control
the distribution and abundance of life in the oceans
Ecosystem Review
Ecosystem:
“Any area of nature that includes living
organisms and non-living substances that
interact to produce and exchange of materials
between living and non-living parts is an
ecological system or ecosystem.” (E.P.Odum)
Ecosystems consist of 4 components: abiotic,
producers, consumers, and decomposers;
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Ecology is the study of the interrelationships between the
physical and biological aspects of
the environment. It is the study of
how organisms adapt to their
environment and in turn alter it.
Ecosystem Review
Biotic Components of the Ecosystem
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•
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plants
animals
bacteria
Abiotic Components of the Ecosystem
•
•
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geological

basin shape, size, & topography
physical

temperature, currents, pressure, light)
chemical

carbon, nitrogen, phosphorus, oxygen, salinity, trace
metals, vitamins
The Environment
•
The ocean water column can be separated into 2 distinct
zones: the surface zone and the deep zone
1.
Surface zone
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extends down to about 100- 300 meters
•
well mixed
•
known as the “mixed layer”
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includes the photic zone
2.
Deep zone
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the rest of the water column
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dark and cold with much less productivity
•
includes the aphotic zone

the pycnocline forms a physical barrier between the surface and deep
zones
Biozones
Shelf Versus Basin
Production
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There are two types of organisms in any given ecosystem:
autotrophs and heterotrophs

autotrophs make their own food (organic matter) from inorganic
nutrients (C, N, P, S, trace metals and vitamins) and either light
or chemical energy, they ‘fix’ CO2
–
they ‘fix’ CO2 via photosynthesis (light E) or chemosynthesis (chemical E,
i.e. H2S)
6 CO2 + 12 H20
C6H12O6 + 6 H2O + 6 O2
light OR
chemical E
–
–
–
autotrophs form the base of the food web (i.e. primary producers) and are
ultimately responsible for all life in the world’s oceans
marine examples include phytoplankton, cyanobacteria, and sulfide
oxidizing bacteria (i.e. at hydrothermal vents)
phytoplankton are the most abundant primary producers in the oceans
Hydrothermal vents –
‘primary production’ is
done by a type of
extremophile, that is, a type
of microorganism that can
thrive under extreme env.
conditions (temp > 80° C
or below 90° C); these
extremophiles are also
chemoautotrophs – they
use hydrogen and sulfur
compounds as sources of
energy (with or without
oxygen) (chemosynthesis);
Hydrothermal vents and Chemosynthetic
bacteria
Production (cont’d)
•
autotrophs vs heterotrophs (cont’d)
–
heterotrophs consume food (organic matter) that has
already been produced

they derive energy (ATP) from the breakdown of organic
compounds via respiration
C6H12O6 + 6 O2


6 CO2 + 6 H2O + ATP
when there is no light (i.e. at night or in deeper waters)
phytoplankton and cyanobacteria respire the organic
compounds that they produced during photosynthesis
examples of marine heterotrophs include all marine animals
and most marine bacteria
Photo from: Science.nasa.gov
Production (cont’d)
•
Productivity is high in the surface waters (i.e. photic zone), due
to ample sunlight for photosynthesis, and then decreases with
depth (i.e. aphotic zone)
Production (cont’d)
•
The critical depth is where total production (PT) equals
total respiration (RT): PT = RT
–
occurs at the 1% light level
Production (cont’d)
•
Productivity is highest in coastal waters and upwelling zones
due to higher nutrient concentrations
Average Global Primary Production (Chl a) March 6-13 2001
Terra MODIS NASA/GES/DISC/DAAC
Biological Productivity in the Ocean
Phytoplankton Blooms
Bands of the dionflagellate
Lingulodinium polyedrum
moving onshore over the
troughs of a series of internal
waves
Lingulodinium polyedrum: ~50 μm.
Neritic; warm temperate to tropical waters; forms large blooms
off of California; can be toxic.
Mixed Marine Plankton
Plants animals larvae adults
vertebrates invertebrates
carnivores and herbivores are all
represented in the plankton
community.
NASA SeaWiFS satellite image of
the large phytoplankton bloom in
the Bering Sea in 1998
Dinoflagellate Gonyaulax sp.
A sudden growth or bloom of th
dinoflagellate, Gonyaulax, caus
"red tide" .
Humans have died from eating
infected clams and mussels.
Researchers with bongo plankton net
Antarctic krill, 3.8 cm long
Northern krill
Trophic Interactions
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To understand ocean ecology we need to know how the
autotrophic and heterotropic components are related
to each other (i.e. energy transfer and exchange)

we examine trophic level dynamics
–
trophic levels describe who eats whom
Trophic Interactions cont’d
•
The traditional view in ecology viewed these interactions linearly
as a FOOD CHAIN: phytoplankton
zooplankton
fish
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This food chain view is really too simplistic, it’s really more like
a FOOD WEB with many links and complex branching between
and among the various trophic levels
One Ocean Drop:
1000s of planktons…
Radiolaria
Foraminifera
Diatoms
• http://en.wikipedia.org/wiki/File:Cc3s.gif
• http://www.youtube.com/watch?v=kjp_jumlO3A
• www.youtube.com/watch?v=eyCigZ_bsTM
Jellyfish invasion
Trophic Interactions cont’d
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The abundance of biomass in each link is dependent on the food
supply to that link
Trophic Interactions cont’d
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At each step in the food web, some energy is transferred to
the next level and some energy is lost
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This relationship can be depicted as a trophic pyramid
•

the shape shows the loss of energy as you move upward
On average, only about 10% of the energy from one trophic
level is transferred to the next trophic level
Trophic Interactions cont’d
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Areas of high productivity (high nutrients and ample sunlight)
have less trophic levels, therefore less energy is lost and more
energy is available to the next trophic level (greater fish catch!)
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–
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upwelling areas have 20% energy transfer efficiencies
coastal areas have 15% energy transfer efficiencies
open oceans globally averaged have only a 10% energy transfer efficiency
UPWELLING
COASTAL
OPEN OCEAN
Normal conditions
El Nino conditions
http://www.forces.si.edu/
Classification of Organisms
In 1735 Linnaeus developed the
taxonomic classification used in
zoology.
• The categories are from largest to smallest:
kingdom, phylum, class, order, family, genus
and species.
Marine organisms can be classified by
lifestyle:
• Plankton are the organisms which float in the water and have no ability
to propel themselves against a current.
• They can be divided into phytoplankton (plants) and
zooplankton (animals).
• Nekton are active swimmers and include marine fish, reptiles,
mammals, birds and others.
• Benthos are the organisms which live on the bottom (epifauna) or
within the bottom sediments (infauna).
• Some organisms cross from one lifestyle to another during their life, for
example being planktonic early in life and benthonic later.
Crab larva – in plankton
Plankton include plants (phytoplankton) and animals
(zooplankton). More than 90% of marine plants are
algae and most are unicellular and microscopic.
• To photosynthesize (produce organic material from
inorganic matter and sunlight) plants must remain
within the photic zone.
• Diatoms are single-celled plants enclosed in a
siliceous frustrule (shell) that is shaped like a
pillbox.
• Dinoflagellates are single-celled plants with two
whip-like tails (flagella).
Zooplankton include the
foraminifera & copepods
Foraminifera are
single-celled animals
which build shells of
calcium carbonate.
1 mm
• Copepods are
small
herbivores (planteating organisms)
that filter diatoms
from the water.
Seamount sessile fauna is dominated by suspension feeders
Suspension feeding invertebrates – sponges, bryozoans, corals
add structural complexity and offer a great variety of
microhabitat for a diversity of species
www.mcbi.org
Before trawling
www.mcbi.org
After trawling
www.mcbi.org
Deep sea bottom trawling
poses the greatest threat to
the coral habitats
It does not just take away
targeted fish species
There is a considerable amount
of bycatch and corals are a
major part of it
Seamounts – underwater mountains rising >1000m from
the seabed without breaking the oceans’ surface
- generally of volcanic origin
- often occur in chains or cluster resulting from a
seafloor hot spot
- 30 000-100 000 seamounts worldwide
Global seamount distribution map
DSCC Policy Paper : Seamounts and cold-water corals
RV Atlantis
DSV Alvin
Classification of Organisms
In 1735 Linnaeus developed the
taxonomic classification used in
zoology.
• The categories are from largest to smallest:
kingdom, phylum, class, order, family, genus
and species.
Three domains:
http://darwin.nmsu.edu/~molb470/fall2005/projects/pan/images/PhylogeneticTreeOfLife.jpg
http://ccnmtl.columbia.edu/projects/biology/lecture1/sixkingdoms.htm
Classification of Organisms
• Eubacteria- There are typically 40 million bacterial cells in
a gram of soil and a million bacterial cells in a milliliter of
fresh water;
• Archaebacteria – single celled microorganisms, most are
extremophiles
• Protista are single-celled organisms with a nucleus (e.g.
amoeba, paramecium; algae – green, red, brown)
• Fungi, only few found in oceans, abundant in the intertidal
zone and important in decomposition.
• Metaphyta are the plants (multicellular) that grow
attached to the sea floor (seaweeds).
• Metazoa include all multicellular animals in the ocean.
Kingdom: Protista
(e.g. algae, plankton)
1 mm
100 micro-mm
100 micro-mm
Kingdom Fungi
• Some members of the Kingdom Fungi (in the
fungal classes Ascomycetes and Basidiomycetes)
are associated with algal cells of the Kingdom
Protista (in the algal division Chlorophtya) and/or
prokaryotic cyanobacteria of the Kingdom
Monera. This complex symbiotic, mutualistic
relationship is called lichen – ‘nature’s perfect
marriage’; (Beatrix Potter, 1896)
Yaquina Head on the
Oregon coast - with darkgreenish marine lichen
Verrucaria sp.
Coccotrema maritimumwhite marine lichen; and
Kingdom: Metaphytae
Caloplaca coralloides (Monterey shores)
Kingdom: Metazoa
(animals)
NEKTON
Selective Adaptive Strategies
• Speed of a fish is dependent upon body
length, beat frequency, and the aspect ratio
of the caudal fin.
• There is a strong correlation between
predation success and mode of locomotion.
Atlantic menhaden
Fastest fish: sailfish, marlin, bluefin tuna
Selective Adaptive Strategies
The morphology of fish has evolved to
allow them to move through the water
easily.
• The fish’s body must overcome three types
of drag (resistance): surface drag, form drag,
and turbulent drag.
• Aspect ratio is the ratio of the square of the
caudal fin height to caudal fin area:
AR = (Caudal Fin Height)2/Caudal Fin Area
Osmoregulation by Marine and
Freshwater Fish
The Ocean Sciences: Ecology of
the Giant Kelp Community
A complex interaction among
kelp, sea urchins, and sea otters
controls the kelp community.
• Macrocytis is a brown algae that grows up
to 40m long in extensive beds on North
America’s Pacific continental shelf.
• Sea urchins feeding on kelp detach them
from this holdfast and devastate the kelp
beds.
Kelp Forest Ecology
The Ocean Sciences: Ecology of
the Giant Kelp Community
• Sea otters feed on sea urchins and control
the size of their population.
– Where sea otters abound, sea urchins are few,
kelp beds thrive and sea otters feed mainly on
fish.
– Where sea otters are few, sea urchins abound
and kelp bed are thin. Sea otters then mainly eat
sea urchins.
Blue mussels, Mytilus edulis
(or M. galloprovincialis)
Green mussel,
Perna viridis
Zebra mussels, Dreissena
polymorpha
http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/HTML/oceanography_how_deep.html
Links to Oceans:
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http://www.oceansatlas.org/
http://reefgis.reefbase.org/default.aspx
http://www.gosic.org/ios/G3OS-maps.htm
http://www.theoceanproject.org/resources/c
onservation.php?category=Maps
• http://earth.google.com/ocean/
Quantum Secrets Of Photosynthesis Revealed
http://www.sciencedaily.com/releases/2007/04/070412131257.htm
Sunlight absorbed by bacteriochlorophyll (green) within the FMO protein
(gray) generates a wavelike motion of excitation energy whose quantum
mechanical properties can be mapped through the use of two-dimensional
electronic spectroscopy (using femtosecond temporal resolution)
(Credit: Greg Engel, Lawrence Berkeley National Laboratory, Physical
Biociences Division)