AICE Exam Review: Unit 3

Unit 3: Interactions in
Marine Ecosystems

3.1 Interactions

3.1.1 Describe the meaning of parasitism, commensalism, and mutualism, and
understand that they are all examples of symbiotic relationships

3.1.2 Describe the parasitic relationship between copepods and marine fish

3.1.3 Describe the commensal relationship between manta rays and remora fish

3.1.4 Describe the mutualistic relationship between boxer crabs and anemones

3.1.1 Describe the meaning of parasitism, commensalism, and mutualism, and understand that
they are all examples of symbiotic relationships

Symbiosis: Relationship between 2 different species that live closely
together

1.

Parasitism: 1 species benefits (parasite) & other is harmed (host)

2.

Commensalism: 1 species benefits & other is unaffected

3.

Mutualism: both species benefit from the relationship

3.1.2 Describe the parasitic relationship between copepods and marine fish

Fish infested with external parasitic copepods are often lethargic and may rub against
substrate

The host may end up with frayed fins, gill hyperplasia, or patchy epidermal damage
and necrosis. Infections with secondary pathogens often occur. Damage to eye(s)
/blindness.

3.1.3 Describe the commensal relationship
between manta rays and remora fish

Remora benefits from transportation,
protection, & scraps of food

Manta ray is unaffected

3.1.4 Describe the mutualistic relationship between boxer crabs (AKA Pom Pom Crabs) and
anemones

Anemone receives food

Boxer crab uses the
anemones as protection
from predators

Coral and zooxanthellae

Multiple Choice

A commensalism relationship is when

• one organism benefits and the other is harmed.

• one organism benefits and the other provides nutrition.

• one organism benefits and the other is unharmed.

• both organisms benefit.

Open Ended

Describe the relationship between copepods and marine fish. [3 points]

3.2 Feeding Relationships

3.2.1 Explain the following terms in relation to feeding relationships: consumer (primary, secondary, tertiary, & quaternary),
producer, herbivore, carnivore, omnivore, decomposer, predator, prey, food chain, food web, trophic level

3.2.2 Represent & interpret feeding relationships in an ecosystem as food chains & food webs

3.2.3 Understand that producers can be photosynthetic or chemosynthetic

3.2.4 Explain that photosynthesis captures the energy of sunlight and make some of the energy available to the food chain,
and, it can be summarized by the word equation

3.2.5 Investigate the effect of light intensity on the rate of photosynthesis

3.2.6 Understand that some of the glucose produced by photosynthesis is used to produce biomass

3.2.7 Understand that some of the glucose produced by photosynthesis is used in respiration to provide usable energy and can
be summarised by the word equation

3.2.8 Define productivity as the rate of production of biomass per unit area or volume, and explain how high primary
productivity may influence food chains

3.2.9 Calculate and explain the energy losses along food chains

3.2.10 Draw, describe, & interpret pyramids of energy, #s and biomass, including those that incorporate parasites & periods of
plankton bloom

3.2.1 Explain the following terms in relation to feeding relationships: consumer (primary, secondary, tertiary, &
quaternary), producer, herbivore, carnivore, omnivore, decomposer, predator, prey, food chain, food web, trophic level

Consumer: one that eats/consumes another organism

Producer: uses non-living environment to produce glucose/sugar/food for rest of the food chain/web OR makes energy
available for the rest of the food chain/web

Herbivore: consumes producers

Carnivore: consumes animals

Omnivore: consumes both producers & animals

Decomposer: breaks down dead, decaying organic matter (bacteria, some worms, etc) so it can return to the food chain/web
(for producers)

Predator: animal that hunts & consumes another animal

Prey: animal that is hunted & consumed by another

Food chain: singular feeding relationships

Food web: multiple food chains

Trophic level: feeding/nourishment level in a food chain/web

Multiple Choice

An example of a first level organism would be a(n)

• phytoplankton

• zooplankton

• omnivore

• herbivore

More ecological vocabulary

Ecosystem: system of organisms and their nonliving environment

Habitat: place where an organism/species lives

Species: similar organisms that can interbreed and produce fertile offspring

Niche: the role of an organism in its environment/ecosystem

Biodiversity: # of species that live in an ecosystem/habitat

Population: group of the same species that live together in the same habitat

Community: group of different species/populations that live together in the same habitat

Feeding Relationships- Producers

Producers provide food for
virtually all other organisms
in food chains and food
webs. As autotrophs, they are
‘self-feeders’ and synthesise
organic ‘food’ from simple
inorganic compounds and an
energy source. There are two
types of producers.

I.Photoautotrophs

Use pigments including
chlorophyll to trap light energy
from the sun. Marine
photoautotrophs include: kelp,
sea moss, cyanobacteria, algae,
& phytoplankton.Photosynthesis.

II. Chemoautotrophs

Use energy from the oxidation
of sulfur in hydrogen sulfide to
make their own food energy in
the form of glucose. Aerobic
chemoautotrophs need oxygen,
whereas anaerobic
chemotrophs do not need
oxygen. Chemosynthesis.

Multiple Select

This synthesizes organic compounds from inorganic compounds with the use of chlorophyll. (select all that apply)

• Photoautotrophs

• Chemoautotrophs

• Producers

• Consumers

Consumers

Consumers are organisms that obtain their
energy by eating other organisms. The rate at
which consumers convert the chemical energy
of their food into their own biomass is called
secondary productivity.

Consumers include:

●Predators that kill and eat animals (tuna,
shark, jellyfish)

●Herbivores that eat plants (manatees)

●Suspension feeders that filter water for
food (mussels, clams)

●Grazers that scrape algae (limpets, sea
urchins, parrot fish)

Zooplankton: Are important consumers and
include copepods, foraminifera and krill. Copepods
are small herbivores that feed on diatoms.
Foraminifera are single-celled animals with
calcium carbonate shells. Krill are shrimp like
carnivores that feed on other zooplankton species
and phytoplankton. Krill are important food
sources for birds, fish, seals, and Baleen whales.

PLANKTON= POOR SWIMMER, creatures that are
carried by the currents.

Multiple Choice

Which is NOT considered plankton?

• krill

• phytoplankton

• parrotfish

• copepods

3.2.2 Represent & interpret feeding
relationships in an ecosystem as food
chains & food webs

The arrows
represent the
transfer of
energy AND
biomass

Trophic Levels

The term refers to the ‘feeding level’ in a
food chain or web. Producers occupy the
first trophic level, primary consumers
(herbivores) occupy the second,
secondary consumers (carnivore or
omnivore) occupy the third level, and so
on. If carnivores are at the end of the food
chain, they are called top predators.

In a food web, you may also find detritivores (worms, certain fish, crabs, starfish, urchins) that eat
detritus (dead and decaying material). This makes it easier for decomposers (bacteria and fungi) to
convert the organic molecules back to inorganic nutrients. Detritivores and decomposers both gain
energy from recycling nutrients and energy found in detritus.

Multiple Select

Which are the primary consumers according to this food web?

• limpets

• algae

• zooplankton

• octopus

3.2.3 Understand that producers can be photosynthetic or chemosynthetic

3.2.4 Explain that photosynthesis captures the energy of sunlight and make some of the energy available to the
food chain, and, it can be summarized by the word equation

Photosynthesis: plants, phytoplankton, kelp, seagrass, mangroves, cyanobacteria

Photosynthesis: Water + Carbon Dioxide → Glucose + Oxygen

Chemosynthesis: chemosynthetic bacteria at hydrothermal vents

Chemosynthesis: Water + Carbon Dioxide + Hydrogen Sulfide → Glucose + Sulfur

Same: Both use carbon dioxide & both produce glucose

Differences: P uses light energy / C uses chemical energy (hydrogen sulfide); P
produces oxygen / C produces S; P in shallow water / C in deep water in the absence of
light at HTV (by bacteria)

sunlight

chlorophyll

Photosynthesis

●The process in which the
inorganic compounds carbon
dioxide and water are combined
to produce glucose and oxygen.

●Process requires sunlight and
must be absorbed by pigments
in the plants or algae.

●Most common pigment is
chlorophyll, found in
organelles called chloroplasts.

Chemosynthesis

●Happens where light is not available for photosynthesis.

●Deep ocean hydrothermal vents.

●Defined as a process where carbon dioxide is turned into useable organic
molecules using the energy stored in dissolved chemicals.

●Chemoautotrophs- species of bacteria able to make their own food using
chemical energy. First discovered in hydrothermal vents- 1977.

Watch this video on chemosynthesis: https://www.youtube.com/watch?v=BLOUFrncG7E

Comparison

Photosynthesis

●Byproduct =
Oxygen & Sugar

●Equation= Only 1

●Requires sunlight.

Chemosynthesis

●Byproduct= Depends on
the chemicals being
used. Sugar and
Sulphur are the most
common products.

●Equation= Can be
several

●Requires chemicals.

Both
●Use carbon dioxide

●Require an energy
source to produce sugars

●Sugars are used to
provide metabolic
energy through
respiration, or built up
into other chemicals
needed by the organism.

Open Ended

What is the word equation for photosynthesis?

3.2.5 Investigate the effect of light intensity on the rate of photosynthesis

Factors Affecting Photosynthesis

The rate of photosynthesis can be affected by several factors:

-temperature

-concentration of carbon dioxide

-nutrients

-amount of light

In a marine environment, the most important factors are the availability of
nutrients and light.

https://youtu.be/J0KxRX3fyoI

Temperature and Carbon Dioxide

In marine environments, there is always an abundance of water and the water
contains dissolved carbon dioxide.

Rates of photosynthesis are also affected by temperature, but temperature of each
area in the ocean is very stable, so has little effect on the rate.

Nutrients and Light

Algae and plants both need nutrients in the form of mineral ions in order to grow.

A lack of a particular nutrient would affect the rate of productivity of new biomass
because it affects the rate of growth.

Photosynthesis can only occur in a thin layer of ocean that has enough light.

This is the photic zone, the only layer where enough light is available for photosynthesis.
This zone is where the majority of biomass is contained.

Upper 200m of water.

Light Variations

●Sunlight is scattered and absorbed by water and the amount of scattered light
depends on the state of water: more waves = more reflected light.

●Light is refracted inside of water because water moves slower in water than
air and more solid particles in water continues to scatter and absorb light.

●Sunlight absorbed by water increases the temperature= molecules have more
kinetic energy and move quickly. Warmer water= less dense and more
buoyant than cold water.

●This is important to phytoplankton as it keeps them floating near the surface
near the light (photosynthesis).

Fill in the Blank

As light intensity increases, the rate of photosynthesis _______.

3.2.6 Understand that some of the glucose produced by photosynthesis is used to produce biomass

●Primary productivity is the amount of new biomass made by producers.

●Biomass is plants/animals consumed for energy (fuel).

●Not all biomass is available for consumers to eat.

●Some glucose is used to produce biomass like cell walls & other cell components.

3.2.6 Understand that some of the glucose produced by photosynthesis is used to produce biomass

Glucose is used
to produce
biomass like cell
walls & other cell
components

3.2.7 Understand that some of the glucose produced by photosynthesis is used in respiration to
provide usable energy and can be summarised by the word equation

Respiration:

Glucose + Oxygen → Carbon dioxide + Water

The 1st stages occur in the cytoplasm of plant &
animal cells

Most of the stages that release energy happen in
the mitochondria (bacteria lack membrane-bound
organelles, so it happens only in the cytoplasm)

Open Ended

What is the word equation for cellular respiration?

3.2.8 Define productivity as the rate of production of biomass per unit area or volume, and
explain how high primary productivity may influence food chains

3.2.8 Define productivity as the rate of production of biomass per unit area or volume, and
explain how high primary productivity may influence food chains

More biomass created = more producers = more food for herbivores = more
herbivores = more food for rest of food chain

More organisms / More trophic levels = longer food chains

Methods of Measuring Productivity

1)

Rate of photosynthesis- change in oxygen or carbon dioxide concentrations.

Methods of Measuring Productivity

2) Changes in biomass

Measure biomass by
harvesting producers,
dry them to remove
water, and find the
mass.

Methods of Measuring Productivity

3) Satellite Imagery

Productive areas are
found in the tropics and
higher latitudes (green
and orange).

Least productive areas
have small amount of
nutrients and deep
waters (blue and purple).

Eutrophication

There does come a point where productivity can be too high.

This leads to eutrophication- the process by which a body of water becomes
enriched in dissolved nutrients (such as nitrates and phosphates) that stimulate
the growth of producers, resulting in depletion of dissolved oxygen.

This causes dense algae and clogs the gills of fish so that they are unable to
obtain enough oxygen.

When algae dies, they are broken down by decomposers (bacteria)= increased
bacterial populations.

Bacteria respire and grow= use up oxygen in water=
hypoxic conditions (lacking oxygen)

Multiple Select

How can productivity be measured? (select all that apply)

• changes in oxygen and carbon dioxide levels

• changes in biomass

• rate of photosynthesis

• satellite imagery

3.2.9 Calculate and explain the energy losses along food chains

How much energy passes between
trophic levels? Why? https://youtu.be/0glkXIj1DgE

Energy is LOST due to:

Heat / respiration

Not all parts are consumed

Death

Feces

Urine

Marine
snow

Marine snow
& vampire
squid

Trophic Level Transfer Energy

What is the energy transfer between producers and
herbivores?

TLTE= 9,000 kcal x 100 =

90,000 kcal

TLTE= 0.1 x 100 =
(multiply by 100 to get a percentage)

TLTE = 10 %

3.2.9 Calculate and explain the energy losses along food chains

Calculate the efficiency of energy transfer between the sun and the 1st trophic level:

(5300 / 500000) X 100% = 1.1%

Why isn’t all of the sun’s energy used by the producers?

Some energy is reflected by the surface of the ocean

Some energy is absorbed by the surface of the ocean

Producers don’t have all of the pigments & therefore can’t absorb all of the wavelengths

Light doesn’t hit the chloroplasts

Calculate the efficiency of energy transfer between the kelp and sea urchins: (412 / 5300 ) X 100% = 7.8%

Calculate the efficiency of energy transfer between the sea urchins and sunflower sea star: (15 / 412) X 100 % = 3.6%

Sun 500,000 au

Kelp 5,300 au
Sea urchins 412 au

Sunflower sea star 15 au

Open Ended

Calculate the efficiency of energy transfer between the sea bream and the consumer as a percentage. Show your work. [3 points]

3.2.10 Draw, describe, & interpret pyramids of energy, #s and biomass, including those that
incorporate parasites & periods of plankton bloom

Producer

Primary consumer

Tertiary consumer

Secondary consumer

Pyramid of energy, biomass, or #s

Pyramid of biomass

Pyramid of numbers with parasite

algae

small crustacea

sea
bream

nematodes

tuna

phytoplankton

zooplankton

Pyramid of plankton bloom (in English Channel)

Because the phytoplankton have a short turnover time;
they reproduce rapidly & are consumed quickly

Do NOT draw a
pyramid with
this triangular
shape!!

DRAW all of
these
“block”-shaped
pyramids!

https://youtu.be/ug8f3YPoE2s

In rare situations, for some ecosystems, you will see an inverted/upside-down pyramid of numbers (only). The reason is, if
the numbers present in an ecosystem are counted after most have been eaten, then the pyramid will be inverted and look
as though there are fewer plankton than consumers.