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Unformatted text preview: Life on the Ocean
Life on the Ocean
Chapter 13 s 1.
3. The marine environment is a hard
ecosystem to study for several
iit's hard to get to;
cruise down in a deep-sea
Are expensive to build, and to operate. s
s iit's hard to get your samples back to the lab in
Animals are built to withstand the huge
pressures of great water depths,
When they are brought to the surface they
blow up. blow
The whole system is permeated with
hydrogen sulfide, which is the smell of rotten
eggs s We can define each part of the ocean on the
basis of the following characteristics:
7. temperature amount of light currents salinity nutrient supply water depth nature of the sediment on the bottom TEMPERATURE
s The most important, for all organisms, not
just the coral.
Most oceanic organisms are cold-blooded
they cannot regulate their internal temp.
Their body temperature is near the
temperature of the water they live in.
Animals that can maintain a warmer-thansurroundings internal temperature are
homeothermic s s
s Only organisms that
left the sea for land
or freshwater and
returned to the sea
Big fish like marlin,
tuna, and tarpon are
s s s The process by which all organisms extract
energy from food, is a chemical reaction that
is strongly influenced by temperature.
The warmer the temperature, the faster
metabolism will be.
Organisms that normally live in cooler waters
may burn themselves up if taken to warmer
water. s s And organisms that normally live in warm
waters won't have enough energy to power
their vital organs, like the brain and heart, if
they move to cooler waters.
Organisms living in warmer waters tend to
grow faster, have a faster heartbeat,
reproduce more rapidly, swim more swiftly,
and live shorter lives than those living in
cooler Remember, AMOUNT OF DISSOLVED
GAS in the ocean is also determined by
s Fast swimmers such as salmon, trout,
and pike need to live in cold waters
because their oxygen demand is high.
s AMOUNT OF LIGHT
s s s
s Determines how productive plants can be.
determined by water depth and water
turbidity (how much sediment is suspended
in the water).
Light is composed of different colors and
most light penetrates only about 100 m into
less if there is much suspended sediment in
Blue light can penetrate deepest, to about
450 m. s s Green light can
penetrate to about
300 m water depth,
but plants do not
use green light-they
reflect green light.
This is why plants
look green to us. The depth to which light can penetrate
defines an important area to plants: the
s Plants have enough light to
photosynthesize in the photic zone.
s They can't photosynthesize in deeper
determines how successful filterfeeders can be.
s They need some current to bring food
particles their way, but not so much
current that it just blows the food past.
s Currents can drag plankton along to
colder or warmer waters than the
s s s We are all composed of cells that are
surrounded by a membrane.
That membrane can allow water to pass
through it readily, but not salt.
An organism's body fluids must be the same
salinity as seawater, or the organism needs
to exert energy to either keep water in its
body, or keep water out.
body, s The process
moves across the
membrane but salt
doesn't is called
13.15-16) If an organism is less salty than
seawater, water from the organism's
body moves out (to increase its
s The organism will dehydrate if it doesn't
actively drink water and get rid of
excess salt that comes from drinking
s If an organism is more salty than
seawater, water from the ocean moves
into the organism's body and it blows
s For higher marine organisms, such as
the arthropods and chordates, the
problem is the former: we are slightly
less salty than seawater.
s A marine fish
Its salinity is only 18
parts per thousand.
s It loses water by
osmosis to increase
its salinity, but gains
it by drinking.
s However, seawater
is too salty for it, so it
secretes salt via the
gills, and produces
hardly any urine.
s A fresh water fish
Its salinity is higher
than the environment.
s It gains water by
its salinity, avoids
s However, fresh water
moves in, so it
s NUTRIENT SUPPLY
s s s Determines how abundant life can be.
iinclude organic compounds such as
proteins, vitamins, and inorganic
compounds, called 'minerals', such as
calcium, magnesium, selenium, etc.
Nutrients for plants are all inorganic and
include nitrogen, phosphorus, potassium, and
a host of others.
The nutrient supply to plants is the more
important. Without plants, there can be no
nutrients for the animals. s 1.
2. Nutrients for plants come from one of
runoff from continents products of
upwelling from the sea floor. s 1.
2. Where upwelling
currents currents WATER DEPTH
s determines the amount of pressure an
organism experiences and the amount of
light it has.
Water depth defines ocean provinces.
A province is an area where we expect to find
similar plants and animals, depending on
other environmental factors (temperature,
current, salinity, nutrient supply)(f.13.19)
current, s Provinces have different names
depending on whether we are
considering benthonic organisms or
nektonic and planktonic organisms. s Pelagic Provinces
– (nekton, plankton) s Benthic Provinces
– epipelagic 0-200 m
– littoral intertidal (foreshore)
– mesopelagic 200-1000 m – sublittoral 0-200 m (continental shelf)
– bathypelagic 1000-4000 m
– bathyal 200-4000 m (continental slope and
rise; mid-ocean ridges)
rise; – abyssopelagic 4000-6000 m
– abyssal 4000-6000 m (abyssal plains)
– hadalpelagic >6,000 m
– hadal >6,000 m (trenches) s
s s Most plankton live in the epipelagic, photic
Most light penetrates into the epipelagic and
littoral to sublittoral zones.
Some whales and giant squid live in the
mesopelagic and even into the top of the
We still have so much to learn about life in
the meso-, bathy- and abyssopelagic realms!
the Nature of the bottom
sediment (sandy, muddy, carbonate), or
rocky. Particularly important to the
s All of the physical factors interplay.
s If the sun warms up water at the
equator, water may evaporate from the
ocean and raise the salinity.
s s Dissolved oxygen levels will go down,
but plant growth will speed up which
can raise oxygen levels back up during
the day, but drive them down again at
s All the physical factors together make up a
Each province of the ocean then has a
unique set of plants and animals that are
adapted to that province.
The set of plants and animals is a
A community is all of the organisms living in
the same environment (province) and
interacting with one another.
interacting s In the ocean, we see that animals and
plants fit into one of four basic
4. planktonic nektonic nekto-benthonic benthonic Each community has its share of
plankton, nekton, and benthos.
s The really defining members of most
communities would be the BENTHOS
because some nektonic organisms can
swim into an area and swim out of it
s s So a particular community exists because it
shares the following characteristics:
• physical characteristics of the water water
s temperature amount of light vigor of the currents salinity nutrient supply water depth • characteristics of the sea floor the benthos live on
or in (sandy, muddy, rocky, carbonate) and
• the types of animals and plants within each.
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This note was uploaded on 09/24/2011 for the course OCE 1001 taught by Professor Staff during the Spring '11 term at Broward College.
- Spring '11