Marine Ecology
Section 1: Energy Flow in the Ocean
1) Energy Flow in Ecosystems
a) Energy flows through an ecosystem in one direction.
i) This means energy enters an ecosystem in one form and never is converted back to that form again
(1) I.E- Energy enters as light, that light energy is converted into chemical energy (sugar) through
photosynthesis and it is never converted back to light again
ii) Food chains and food web show the flow of energy
(1) Trophic Levels – each step in a food chain/web
(2) Ecological Pyramids – shows relative amount of energy at each level
(a) Because some energy is lost or used up every time it moves up a trophic level, the higher an
organism eats on the food chain/web the more that organism needs to eat in order to get a
sufficient amount of energy
1) Interpretation of a food web
a) Arrows point from prey to predator
b) Apex predator – the organism(s) that are not consumed by any other organism
c) Primary producer – the organism(s) that do not consume any organism (photo or chemo synthesizers)
Divide this Food web into all its trophic levels and label them
1) What is the primary Producer?
5) What would happen to the Krill population if the adult herring
population increased?
2) What is the apex predator?
3) Name some Primary consumers?
6) What would happen to the comb jelly population if the Barnacle larvae
population increased?
4) Name some secondary consumers?
7) What would happen to the water flea population if the adult herring
population decreased?
2) How energy enters the marine ecosystem
a) Autotrophs /Primary Producers– Organisms
that convert energy from the sun or chemicals
into food
i) In the marine ecosystem the most
productive autotrophs are algae like
phytoplankton and seaweed (on land its
plants)
ii) certain bacteria and plants play a smaller
role in production in the ocean
3) What is chemosynthesis?
a) Chemosynthesis – the use of inorganic chemicals to make energy (not light)
4) What are inorganic chemicals?
a) Chemicals that do not contain carbon, (H2S, NH4+, NO2, Fe)
5) How does chemosynthesis relate to photosynthesis?
a) Photosynthesis: CO2 + H2O  C6H12O6+ O2
b) Chemosynthesis: Inorganic chemicals + O2  C6H12O6 + Oxidized chemicals
i) O2 + H2S  C6H12O6 + SO2
ii) O2 + NH4 C6H12O6 + NO2
iii) O2 + NO2 C6H12O6 + NO3
iv) O2 + Fe  C6H12O6 + FeO
6) What types of organisms perform
chemosynthesis?
a) Prokaryotic organisms (Bacteria and
Achaea (bacteria like)
7) Where does chemosynthesis happen?
a) Mud
b) Hydrothermal vents – deep sea hot springs
that dissolve large amounts of chemicals in
the superheated water
8) What is plankton?
a) Plankton- organisms that drift or float
because they cannot fight against the
prevailing water currents.
i) Plankton may be microscopic or not
ii) NOT ALL PLANKTON IS
PHOTOSYNTHETIC
iii) Plankton are classified in numerous
ways:
(1) Size
(a) Whether the plankton could be caught in a fine net was the first way plankton was classified
(b) Net plankton – any organism large enough to be caught in a fine plankton net (Micro, meso, macro
and megaplankton)
(c) The problem was that many types of plankton were so small that they passed through the net and
thus went unstudied for decades
(i) femtoplankton otherwise known as marine viruses,
(ii) picoplankton otherwise known as marine bacteria
(2) Trophic level
(a) When you classify plankton by trophic level you divide all plankton into 2 groups
(i) Phytoplankton – organisms that drift or float and photosynthesize
1. Diatoms, Dinoflagellates, Cyanobacteria, Coccolithophorids, Silicoflagellates
(ii) Zooplankton – organisms that drift or float but don’t photosynthesize
1. Copepods are Small crustaceans that make up to 70% of all oceanic zooplankton
2. Because copepods are zooplankton they feed on phytoplankton as well as other
zooplankton instead of photosynthesize
3. Protistan, foraminiferans, radiolarians, tunicates, andarrow worms
4. Jellyfish and comb jellies are not small organisms however, they are considered by some
biologists to be plankton because they cannot fight the prevailing water currents in most
cases
a.
5. The length of time an organisms spends as plankton
a. Holoplankton are organisms that spend their entire life as plankton (bacteria)
b. Meroplankton are organisms that only spend a portion of the life as planklton(larval
forms of fish)
9) Plankton populations in the ocean
a) Plankton populations increase and decrease
depending on the availability of sunlight and
nutrients
b) Limiting Resource- a resource in short supply and
restricts population growth
i) Light and nutrients act as the limiting
resources for primary production in different
parts of the ocean
(1) Polar waters – the regions of the ocean
farthest away from the equator that
experience a single bloom of
phytoplankton during the summer due to
the limitation of light
(a) Although the water in polar regions is
packed with nutrients, the availability
of light is limited to half the year
(2) Tropical waters – the regions of the
ocean closest to the equator experience a
consistent level of population of
phytoplankton due to the limitation of
nutrients
(a) Although the water in tropical regions
stays lit for long periods of the day,
the availability of nutrients is limited due to the large population of organisms
(3) Temperate waters – the regions of the ocean between polar and tropical waters experience two pulses
of phytoplankton in the spring and fall due to the limitation of both light and nutrients
(a) During the winter in temperate waters, there is not enough light to support photosynthesis.
(b) Once light becomes available populations of plankton start to grow exponentially and so nutrients
quickly become limited
c) Seaweeds - multicellular photosynthetic algae
i) Seaweed is usually classified by color
ii) Look similar to plants but do not have true roots, stems and leaves and so they are not plants
(1) Blade = leaf
(2) Stipe = stem
(3) Hold fast = roots
iii) Pneumatocysts- air-filled sacs in the seaweed that helps the blades float
(1) This helps seaweed photosynthesize by causing the blades to float higher in the water
d) Marine Plants – plants that are adapted to be partially or completely submerged in sea water
i) Sea Grass -the only true marine plant that can survive fully submerged in salt water for its entire life cycle.
ii) All other plants spend most of their live above water, only having their roots submerged in salt water.
(1) Cord Grass – a type of grass that grows along the coast in temperate areas.
(a) Cord grass can only have its roots submerged for part of the day
(2) Mangrove forests – large trees and other plants
that grow along the coast in tropical areas.
(a) Mangroves are easily identified by their roots
witch stick up in the air and water to those
parts of the plant get enough oxygen
10) Organism Interactions
a) Symbiosis- any relationship where two species live closely
together.
i) Mutualism- Both benefit
(1) How do the clownfish and anemone benefit each other.
ii) Commensalism – one benefits, the other is not helped nor harmed
(1) Ex: Remoras and Sharks: remora follows the sharks to eat the left over scraps.
iii) Parasitism – one benefits, other is harmed
(1) Ex: An isopod sucking blood from a fish.
iv) Predation - One organism consumes another organism.
(1) Why predation is not considered a symbiotic relationship?
(2) What is the difference between predation and parasitism?
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Section 4: Nutrient Cycles
11) Nutrients are constantly cycling in the environment.
a) Nutrients come from the atmosphere or from weathering rock.
b) Nutrients are used by organisms to build
molecules (proteins, carbohydrates, DNA and
fat) that are essential to life.
c) When organism eventually die, some parts of
the organism dissolve in water while other
parts do not.
i) Detrius - particles of nonliving organic
material (bodies of dead fish, animal
poop)
12) Phosphorous Cycle
a) There is no phosphorous gas.
i) Phosphate is add to through weathering
rock and fertilizer runoff.
ii) Phosphate is taken up by autotrophs
which are eaten by animals.
iii) Once any organism dies phosphorous is re dissolved in the ocean through decomposing bacteria or becomes
fossilized in sedimen
13) Carbon Cycle
a) Carbon moves back and forth
between the ocean and the
atmosphere as CO2.
i) Dissolved carbon is absorbed
by autotrophs and used in
photosynthesis
ii) After being converted to
sugar through
photosynthesis, it is
converted back to CO2
through respiration
iii) CO2 can also be absorbed by a
number of organisms that can
convert CO2 to CaCO3
(limestone) which they use to
make shells or exoskeletons
14) Nitrogen Cycle
a) Most nitrogen exist as nitrogen gas (N2) which most living things cannot use.
i)
Nitrogen gas is converted to
useable forms of nitrogen
through Nitrogen fixing
bacteria
(1) Nitrogen fixing bacteria the only organism that
can take nitrogen gas (N2)
and convert it into
ammonia (NH3), nitrite
(NO2) and eventually
nitrate (NO3).
(2) Nitrate is the only
compound that is not
toxic and can be used by
plants and animals.
(3) Denitrifying Bacteria Converts nitrates (NO3),
nitrite (NO2) and
ammonia (NH3) back into
nitrogen gas