Transcript Ecological Zonation of the Marine Environment

MARINE ENVIRONMENTS
Marine Biologists categorize
communities according to WHERE
and HOW organisms live.

Benthic (or benthos) – organisms that
live on or buried in the bottom
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Sessile – attached organisms (do not swim)
Pelagic – organisms that live higher in the
water column (away from the bottom)
Pelagic organisms are further divided
according to how well they swim.
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Plankton – organisms that swim weakly
Drift in water
 Phytoplankton (example: algae) – most
important primary producers in marine
ecosystem
 Zooplankton – small heterotrophic organisms
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Nekton – animals that can swim well enough
to oppose currents
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Mostly vertebrates
Classification of the Benthic
Environment
Benthic environment on continental shelf is
divided into 2 regions:
 Intertidal (or littoral) zone – boundary
between land and sea;
shallowest part of the continental shelf
 At the mercy of the tides
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Subtidal (or sublittoral) zone – continental
shelf beyond the intertidal zone
The Benthic environment beyond the
continental shelf is called “the deep
sea floor”.

Abyssal Zone – deepest environment of
sea floor
< 4,000 meters deep
 Organisms in the abyssal zone are
adapted to extremely cold temperatures
and high pressures.
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Classification of the Pelagic
Environment – by depth
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Neritic Zone – pelagic environment that
lies over the continental shelf
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Less than 300 meters deep
Oceanic Zone – waters beyond the
shelf
Classification of the Pelagic
Environment – by amount of light

Photic zone - depths which receive
sufficient light to support
photosynthesis
100-200 meters deep
 Phytoplankton thrive in this area –
producing food for the rest of the
ecosystem
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Aphotic zone - depths that receive
insufficient light to support
photosynthesis
Zonation in a Marine Environment
Plankton
An Introduction to the Drifters
What are plankton?
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Planktos – Greek
meaning “to wander”
Weakly swimming or
drifting organisms
Microscopic or
macroscopic in size
Plant (phytoplankton)
or animal
(zooplankton)
Why are plankton important?
Food source (basis of the food web)
 Producer of oxygen (photosynthesis)
 Cause of toxic “blooms” (resulting in fish
kills and shellfish poisoning)
 Means for dispersal of organisms by
transport in currents
 Major players in the global carbon cycle
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How are plankton studied?
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Collected with
sampling bottles
Special nets
Microscopes
Cultured in labs
Photo by: Lisa Wu
Students aboard the R/V Slover in the
southern Chesapeake Bay
Collection Methods
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Fish and invertebrate
larvae (net plankton) are
collected during plankton
tows
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Depth, distance towed,
and the volume of water
sampled must be
calculated
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Mesh sizes of nets vary
depending upon what is
being researched
This plankton net is being deployed to collect nearsurface plankton in Maug caldera. The net is about
2 m (6.5 ft) long and has a mesh size of 236
microns (0.25 mm or 0.01 in).
The large aluminum frame of the neuston net is 1 meter high and
3 meters long. Here the net is being deployed off the starboard
side of the R/V Seward Johnson
Collecting Plankton
Bongo nets are towed
over the side of the
ship or carried by divers to
collect drifting organisms
Image ID: fish1014, NOAA's Fisheries Collection
Photo Date: 1987
Photographer: Captain Robert A. Pawlowski, NOAA Corps
Image ID: nur05536, Voyage To Inner Space - Exploring the Seas With NOAA
Collect
Photographer: J. Morin
Credit: OAR/National Undersea Research Program (NURP)
Deploying Bongo nets for
sampling plankton
Can plankton be studied from
space?
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Satellites equipped with
color scanners measure
the concentration of
chlorophyll in the ocean
Red = high concentration
of chlorophyll
Chlorophyll is the major
pigment for
photosynthesis in
phytoplankton
Data provides information
concerning biomass,
productivity, and changes
in plant populations
Satellite Image of the Gulf of Maine
Phytoplankton blooms observed in
the Atlantic Ocean off Africa
Image ID: spac0361, NOAA In Space Collection 2003 May 2
Do organisms spend their entire
lives as plankton?
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Holoplankton spend
their entire life cycle as
plankton. Examples
include: dinoflagellates,
diatoms and krill
Meroplankton spend
only a part of their life
cycle drifting. As they
mature they become
nekton (free swimmers)
or benthic (crawlers)
Examples include: fish
and crab larvae.
Charleston Bump Expedition. Zooplankton, crab larva.
Image ID: expl0172, Voyage To Inner Space - Exploring the Seas
With NOAA Collect
Location: Southeast of Charleston, South Carolina
Photo Date: 2003 August 7
Photographer: Jerry Mclelland
Credit: Charleston Bump Expedition 2003. NOAA Office of Ocean
Exploration; Dr. George Sedberry, South Carolina DNR, Principal
Investigator
Plankton Observation Worksheet
Specimen # ___________
Characteristics: Description
Body shape/Tail/flagella/appendages/eyes
Transparency/gills/other features
______________________
______________________
______________________
Circle one from each category:
Phytoplankton or Zooplankton
Holoplankton or Meroplankton
sketch
Examples of Plankton
Specimen #1
Specimen #2
Specimen #3
Specimen #4
Specimen #5
Specimen #6
Specimen # 7
Specimen #8
Specimen #9
Specimen #10
Intertidal Communities
Most studied and best understood marine
environment
 Intertidal – part of the sea floor that lies
between the highest and the lowest tides
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Unique due to
regular exposure
to air
 The size and
species
composition of
the intertidal will
vary with degree
of exposure
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Organisms must be adept at
surviving in these arid conditions
Problems to be dealt with because of
exposure to air:
 Desiccation (drying out)
Mobile organisms move in & out with tide
 Protective shells and/or mucus
 Store water efficiently
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Temperature (very warm temp)
Organisms have a wide temperature range
 Light color of shell reflects light
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Salinity (concentration of salt)
When it rains or snow melts, exposed plants
and animals have to endure fresh water
 Must have a wide range of salinity tolerance
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Wave Action (mechanical effects that smash
and tear away objects from substrates or to
alter seafloor)
 Adaptations to maintain position include:
becoming fixed to rocks (sessile), increasing
thickness of shell, enlarging muscular foot
Vertical Zonation of Intertidal
Zonation is a
vertical banding
of the organisms
living on the
rocky coastline
The Supralittoral Zone
“The Splash Zone”
Upper part of intertidal zone
 Size of this zone depends on slope,
splash, climate, and amount of shade
 Only covered briefly by water during
the highest tides
 Dissolved nutrients and oxygen are
limited
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Black Lichen
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Black, tar-like blotches on rocks
Symbiotic
relationship of fungi
and algae
 Fungi soaks up water
like a sponge, storing
it for long dry periods
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Cyanobacteria
Blue-green algae
 Protected from desiccation by a jelly-like
coating
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Periwinkles
Snail-like mollusks
 Abundant in intertidal
 Avoid desiccation by:
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clustering in moist, shady crevices.
 Sealing opening of shell
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Can breathe air
 Tolerate extreme temps.
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Limpet
Soft-bodied invertebrate protected by a
hard, cone-like shell
 Cling tightly to rocks using muscular
foot
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Intertidal communities are separated
by a process called Zoneation. Using
zoneation we can identify four
different zones; the upper, middle,
lower, and sub-tidal zones.
The upper inter tidal zone
contains creatures like
periwinkles, barnacles and
limpets.
Upper Tidal
Zone
The middle intertidal zone
supports more species of
barnacles including gooseneck
barnacles, as well as mussels and
other sea animals.
The lower intertidal zone
contains sea grasses, algae,
and many of the sea animals
that can be found in the
intertidal community.
Middle
Tidal Zone
Lower Tidal
Zone
The middle
intertidal zone
contains mussel
colonies like the
one seen here.
Mussels are
larger than
Gooseneck
barnacles, but
similar in
appearance.
Mussels are also
able to clamp
down during
periods of low
tide, but because
they are in a
lower tidal zone,
they are not
exposed to
desiccation as long as their counterparts in the upper intertidal zone. Mussels use strong hairs
called bysal threads to attach themselves to rocks. Once there, they feed on microscopic plants
filtered out of the sea water. They can grow anywhere from 3 inches up top 8 inches in length!
Mussels are very good to eat, and work as a good fish bait as well.
Vertical Zonation
of the Intertidal
Upper
Tidal
Zone
Middle
Tidal
Zone
Lower
Tidal
Zone
Upper Intertidal Zone
Harsh environment - exposed to rough
waves during high tide and the hot sun
during low tide
 Includes same species as supralittoral
(splash) zone
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Striped Shore Crab
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Square Body
Eyes at corners
movie
Eat algae growing on the rocks
by scraping with claws
• Also prey on dead animals and
live limpets & snails
Middle Intertidal
Most active intertidal zone because it is
fully covered and uncovered each day
 Upper boundary is always marked by a
band of acorn barnacles
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Acorn Barnacle
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Attach firmly to substrate
Valve-like "doors" in shell that
open when animal is submerged,
and close when it is exposed to
air
Feed on plankton by sucking in
the water around them, while
closing their teeth and opening
their mouth. Then they lick all
the plankton that are stuck in
their teeth.
Ochre Sea Star
Tiny suction cups called tube feet
cover the underside of their
five arms
 Vicious predator of mussels
 Extend stomach to
externally digest food.
 Regenerate body parts
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California Mussel
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Large colonies on exposed rocks
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Formation into dense clusters helps them
retain moisture and lessens wave shock.
Feed by filtering plankton
Provide shelter for smaller organisms
Often considered a delicacy, mussels
should not be eaten between the dates
of May 1 and October 31. During this
time mussels may filter and accumulate
an extremely toxic plankton. Consuming
mussels during this period can cause
paralysis and death in humans.
Lower Intertidal Zone
Dry only during lowest tides
 Contains greatest biodiversity of intertidal
zones
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Gooseneck Barnacles
Free-swimming larvae
 Develop and attach to rocks
 Long, neck-like stalk
 Produce very strong adhesives
 Use feathery feet to filter food from
passing water
 Live up to 20 years
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Limpet
Gooseneck
Barnacles
Sunflower Star
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Major predator
The older they
become, the more
rays they grow. (up to
24 rays)
When threatened,
these stars can drop
an arm in hopes of
appeasing the
predator. The arm will
later re-grow.