Download Chapter 9 Marine Ecology - Lamont–Doherty Earth

Chapter 9
Marine
Ecology
©2003 Jones and Bartlett Publishers
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9
Marine Ecology
 Ecology
-From greek ‘oikos’ meaning ‘house’.
-The study of organisms ‘at home’.
-More formal definition: The science of the
interrelationships between living
organisms and their environment (Odum).
Marine Provinces
There are two major marine provinces:
the benthic (bottom) and the pelagic
(water column).
• The benthic environment is divided by
depth into the following zones:
–
–
–
–
–
Littoral
Sublittoral
Bathyal
Abyssal
Hadal
(<1%)
(8%)
(16%)
(75%)
(1%)
intertidal- between the tides
low tide to edge of cont. shelf, 0-200m
200 – 2000 m
2000 – 6000 m
> 6000 m
Marine Provinces
There are two major marine provinces:
the benthic (bottom) and the pelagic
(water column).
• The pelagic environment is divided by depth into
the following zones:
– Neritic
– Oceanic
•
•
•
•
•
Shallow water overlying cont. shelves.
Deep water beyond shelf edge.
Epipelagic
Mesopelagic
Bathypelagic
Abyssalpelagic
Hadalpelagic
(3%)
(28%)
(15%)
(54%)
(<1%)
0 – 200 m
surface, illuminated
200 – 1000m
1000 - 2000 m
2000 – 6000 m
>6000 m
In trenches.
Marine Provinces
Light Zones
• Yet another way to
classify the ocean
• Photic zone
– light is sufficient for
photosynthesis
– to 100 (or 200 m)
• Dysphotic zone
– light is too weak for
photosynthesis
– twilight zone
– < 5% sunlight
– 100 to 200 m
• Aphotic zone
– no light
Classification of Organisms
In 1735 Linnaeus developed the
taxonomic classification used in zoology.
Kingdom (Metazoa)
-Phylum (Chordata)
-Class (Mammalia)
-Order (Primate)
-Family (Hominidae)
-Genus (Homo)
-species (sapiens)
• The scientific name of an organism consists of its
genus name (capitalized) combined with a species
name (lower case), both italicized or underlined.
• Ex. Homo sapiens
Classification of Organisms
The five major kingdoms in the ocean
are:
• Monera:
single-celled organisms without nucleus (Prokaryotes)
• Protista:
single-celled organisms with nucleus (Eukaryotes).
• Fungi :
important in decomposition and recycling.
• Metaphyta: plants that grow attached to the sea floor.
• Metazoa:
all multicellular animals in the ocean.
Classification of Organisms
Marine organisms can also be classified
by lifestyle.
• Plankton –float passively, can swim vertically, but not
against currents.
• They can be divided into phytoplankton (plants) and
zooplankton (animals).
• Nekton
– active swimmers (marine fish, reptiles, mammals, birds and
others)
• Benthos
– live on the bottom (epifauna)
– within the bottom sediments (infauna)
• Some organisms cross from one lifestyle to another
during their life, for example being planktonic early in
life and benthic later (seaweeds, clams, etc).
Classification of Organisms
Epiflora
Epifauna
Infauna
Classification of Organisms
Flounder: Benthos or nekton???
Classification of Organisms
Clam:
Benthos or
plankton???
Classification of Organisms
Classification of Organisms:
The 5 Kingdoms
Monera: bacteria
-no internal cell membranes
-planktonic or benthic
-recycle organic material
-some photosynthetic
heterotrophic
Blue-green algae
(photosynthetic)
Classification of Organisms
Protista: foraminifera, diatom, seaweed
-planktonic or benthic
-internal membranes
-planktonic, benthic, eat or photosynthesize
Foram.
Diatom
Seaweed
Classification of Organisms
Fungi: single and multi-cellular
-decomposers
-planktonic or benthic
Classification of Organisms
Metaphyta: multi-cell plants
-primary producers in intertidal
-benthic
Salt marsh
eelgrass
Mangroves
Not seaweeds!
Classification of Organisms
Metazoa: multicellular animals
-planktonic (jellyfish, shrimp), nektonic
(fish,whales), and benthic (crabs, worms).
jellyfish
Fish
whales
Basic Ecology
• Ecosystem is the total environment
including the biotic (living) and abiotic
(non-living) physical and chemical
aspects.
– Examples of marine ecosystems:
•
•
•
•
•
•
Salt marshes
Mangrove
Intertidal
neritic
Benthic
Or, global ecosystem.
Basic Ecology
•Environmental factors in the marine environment
include:
-temperature
-salinity
-pressure
-nutrients
-dissolved gases
-currents
-light
-suspended sediments
-substrate (bottom material)
-river inflow
-tides and waves.
Basic Ecology
Temperature:
•
Temp ranges in ocean between -2 to ca. 40 C.
•
More than 90% of ocean is <5 C.
•
Can control distribution, degree of activity, and reproduction
of an organism
•
Temperature controls the rate of chemical reactions within
organisms, thus their rate of growth and activity
– Most organism’s are ‘cold-blooded’ or ectothermic.
– 10oC rise in temperature, doubles the activity
Temperature Effects: barnacles
• more activity
with higher
temperature
Temperature Effects: clam harvest
Salinity Effects
• Can control the distribution or behavior of organisms.
– Epipelagic more S-tolerant than mesopelagic organisms.
• Nearshore organisms more tolerant to salinity changes.
– Large S-variations results in tolerant organisms.
– Sessile benthic can close shells.
• Availability of dissolved elements (calcium and silicon)
can limit an organism’s ability to construct shells.
– Silica depletion results in reduction in diatom production.
• Marine organisms’ body fluids have the same
proportion of salts than sea water.
– Sometimes more salt, sometimes less, than surrrounding
sea.
– Diffusion, osmosis and osmoregulation.
Salinity Effects: Diffusion
Definition: physical process whereby molecules move
from areas of higher concentration to areas of lower
concentration.
Salinity Effect: Osmosis
Definition – Diffusion of water molecules
through a semi-permeable membrane.
Remember: “salt sucks”
Osmoregulation by Marine and
Freshwater Fish
Marine fish must
control osmotic
water-loss or fish
will dehydrate.
Freshwater fish
must control
osmotic
water-gain or fish
will swell &
explode.
Hydrostatic Pressure
• The pressures exerted by a
column of water
surrounding an organism.
– 10 m column of water = 1
atm.
Hydrostatic Pressure
3 Styrofoam cups sent to 5000 meters depth.
Hydrostatic Pressure
•How do deep-dwelling animals survive high
pressures?
•Answer: many have no body cavities containing
gasses.(Gasses are more compressible than
liquids).
•Fish use gas-filled swim bladders to regulate
depth.
Selective Adaptive Strategies: Plankton
Plankton include plants (phytoplankton)
and animals (zooplankton).
More than 90% of marine plants are
algae and most are unicellular and
microscopic.
Phytoplankton photosynthesis
Selective Adaptive Strategies: Plankton size- one way
plankton defy gravity to stay suspended in photic
zone
Some Characteristics of Phytoplankton
•Size: 0.5 micron to 1 mm
•Eukaryotes and prokaryotes (bacteria)
•Some motile with flagella (dinoflagellates) some not (diatoms)
•Contain chlorophylls and other pigments for photosynthesis.
•Silica, Calcium carbonate, or no shell.
•Responsible for ½ oxygen production on Earth.
•Major sink for atmospheric CO2.
•Major types:
•Diatoms (require silica for growth)
•Dinoflagellates (some toxic; symbiotic with corals)
•Synechococcus and Prochlorococcus (tropical)
Some Diatoms
General Diatom Structure
Chloroplast
Diatom Cell Division
Phytoplankton “blooms”
Diatoms and other
phytoplankton can
divide many time
per day producing
large blooms that
are sometimes
visible from space.
Zooplankton
Zooplankton include the copepods and
foraminifera.
• Copepods are small herbivores (planteating organisms) that filter diatoms from
the water.
• Foraminifera are single-celled animals
which build shells of calcium carbonate.
Zooplankton
Zooplankton include the copepods and
foraminifera.
Live foraminifera
(size ca. 0.5 mm)
Copepod
(size ca. 1-5 mm)
Selective Adaptive Strategies: Copepod feeding
Selective Adaptive Strategies: Fish
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
– turbulent drag.
Selective Adaptive Strategies: Fish
• Surface Drag: Friction between the moving
body and surrounding fluid.
– Decrease surface area, decrease surface drag.
– Sphere has least surface area for given volume,
so sphere is best shape for reducing surface drag.
– But fish aren’t shaped like an orange, so what
else is important?
Selective Adaptive Strategies: Fish
• Form Drag: Proportional to cross-sectional
area of fish’s body.
– larger x-sectional area, more water needs to be
‘pushed aside’.
– Narrow pencil-shaped body best for moving
through fluid.
– But not all fish are shaped like pencils either, so
what else is important?
Selective Adaptive Strategies: Fish
• Turbulent drag: friction arising from
turbulent eddies of water that form behind
an object moving through a fluid.
– Reduced by having classic ‘torpedo shape’.
– Torpedo shape displaced water with minimal
disturbance.
– What fish is most superbly adapted for swimming
at high speeds for extended periods of time??
Selective Adaptive Strategies: Fish
The Tuna!!
Selective Adaptive Strategies: Aspect ratio
The speed of a fish is related to the shape of its caudal fin:
Aspect ratio, AR = (Caudal Fin Height)2/Caudal Fin Area
Quick, darting
movement
High-speed
cruisers
Selective Adaptive Strategies: Fish
classification scheme based on locomotion
9-5
Selective Adaptive Strategies
Intertidal benthic communities generally
are arranged in distinctive bands,
termed vertical zonation.
• Zonation reflects the amount of time the
area is submerged and the ability of the
organism to survive the stress of
exposure.
• Benthonic communities also vary in
response to substrate (bottom material).
Some organisms are adapted to rocky,
sandy, or muddy sea bottoms.
Banded Benthic Communities
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.
2-5 Geophysical Surveying
THE END
Selective Adaptive Strategies: Fish
• Surface Drag: Friction between the moving
body and surrounding fluid.
– Decrease surface area, decrease surface drag.
– Sphere has least surface area for given volume,
so sphere is best shape for reducing surface drag.
– But fish aren’t shaped like an orange, so what
else is important?
Selective Adaptive Strategies: Fish
• Form Drag: Proportional to cross-sectional
area of fish’s body.
– larger x-sectional area, more water needs to be
‘pushed aside’.
– Narrow pencil-shaped body best for moving
through fluid.
– But not all fish are shaped like pencils either, so
what else is important?
Selective Adaptive Strategies: Fish
• Turbulent drag: friction arising from
turbulent eddies of water that form behind
an object moving through a fluid.
– Reduced by having classic ‘torpedo shape’.
– Torpedo shape displaced water with minimal
disturbance.
– What fish is most superbly adapted for swimming
at high speeds??