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Chapter 10
Marine Ecology
Marine Ecology
• _____ is the interaction between organisms and their
environment.
• These interactions affect the survival and distribution of these
organisms.
• Organisms within a community interact with each other in
very complex ways.
_______
All populations of organisms living in a defined
area.
______
The physical place where an organism lives.
Niche
The resources (biotic & abiotic) an organism
uses for survival, growth and reproduction.
Needs of a Species
• Populations demand specific resources to
survive.
• These resources can affect population
growth if they are in short supply.
• These resources that have the ability to
affect the growth of a population are
called limiting resources.
Needs of a Species
• The limiting resources can include, but are
not limited to:
– Nutrients
– Light
– Space (habitat)
– Oxygen or carbon dioxide
– Inorganic compounds
Needs of a Species
• Even if an organism is able to acquire a
limiting resource, there is a maximum
number of organisms that any habitat can
support.
• This number is known as the carrying
capacity.
• As a population becomes more “crowded,”
the growth rate of that population will
decrease.
Marine Ecology
Ways that Species can Interact:
1. Competition
2. Predator-Prey Interactions
3. Symbiosis
Competition
• Competition occurs when organisms must
“fight” with one another over a limiting
resource they both require for survival.
• Organisms can compete with members of
their own species – intraspecific
competition – or members of other
species – interspecific competition.
Purple _____ exhibiting _____ competition and
Red (dark in photo)_____ exhibiting _____ with a ____
_____ competition between two hermit crabs
fighting over a mollusk shell
Competition
• An organism can use a resource at the
expense of another organism.
• This may result in reduced ability of that
individual to reproduce or even survive.
• Poorer competitors may die out due to this
competition.
• Interspecific Competition
Individuals of different species compete
for same resources (food, shelter,
space).
What are possible outcomes of interspecific
competition?
• one individual excludes the other
(principle of competitive exclusion) Ex.
Two fish species feed on seaweed and one
feeds faster and has more offspring until
the second species is gone
• they coexist (resource partitioning)
Resource partitioning Competing species can coexist if they use
the same resource in a slightly different
way or at a different time.
Ex. Two fish species that both eat
seaweeds. One might specialize on
brown algae while another might feed
on red algae
Symbiosis - one species living in or
on another.
Types of Symbiosis:
1. Mutualism - both species _____ (example: cleaning
associations).
2. Commensalism - one species benefits with no
apparent effect on the other (example: barnacles
living on whales; hermit crab).
3. Parasitism - one species benefits & the other is
harmed (examples: tapeworms in the guts of
whales).
More on Symbiosis
• If partners in a symbiotic relationship can
live without one another, this is known as
facultative symbiosis (cleaning symbiosis).
• If the partners cannot survive with the
other partner, this is known as obligate
symbiosis (marine lichens).
• The smaller partner is known as the
symbiont and the larger partner is called
the host. Name each in a marine lichen.
Predation
One species (predator) kills another (prey)
for food.
• Prey species often have adaptations that
help them avoid being eaten such as:
• Warning coloration (lionfish we discussed
in Fig. 8.10)
• Camouflage (stonefish and flounder)
• Physical adaptations (shells in mollusks)
• Behavior (schooling)
Ecosystem
All the _____ (living) and _____
(nonliving) components in a defined
area.
• Ecosystems interact.
• All ecosystems require a constant input
of energy.
• Chemicals and nutrients are cycled
within ecosystems.
Energy Flow
• Energy flows through an ecosystem
• Route of energy flow is determined by an
ecosystem’s trophic structure.
Where Does all the Energy Go?
Is all of the energy stored by individuals at
one trophic level available to the next?
No - energy needs of individual take up most of
the energy created or consumed.
On average, ~10% (5-20%) is transferred to
the next level of the food chain.
Food chains rarely extend beyond four trophic
levels except in the ocean community. Why??????
• There is more biomass created at the
bottom of the trophic level – at the
primary producer level. Think of all the
primary producers present in the marine
community and the VAST stretches of
ocean that support primary production.
• Therefore, the system can support
additional secondary consumers.
Major Marine Environments
• Benthic organisms – live in/near bottom
features
• This can be subdivided by the depth of the
benthic zone. Examples:
– Intertidal zone – benthic zone located
between high and low tide
– Subtidal zone – always submerged; below the
low tide level.
Major Marine Environments
• Pelagic organisms – live in the water column
• This zone, too, can be subdivided into different
areas:
– Epipelagic zone- extends from the water’s surface to
100-200 m; plenty of sunlight available to support
primary production
– Mesopelagic zone – extends from lower limit of
epipelagic to about 1000 m; although sunlight is not
plentiful, new research has shown that some
photosynthesis does occur in this zone, although it is
very reduced compared to the epipelagic zone.
– The Deep Sea zoned as bathypelagic (1000-4000m),
abyssopelagic (4000-6000m) and hadopelagic
(>6000m) where light does not penetrate. These will
be discussed in the chapter on deep sea organisms.
Measuring Primary Productivity
• The total amount of primary production is
•
•
known as the gross primary production.
The organic matter left over after the primary
producers meet their own needs is the net
primary production. Can be estimated using gas
detectors that measure carbon dioxide used or
oxygen produced.
The total amount of phytoplankton in the water
is called the standing stock. Can be measured
by instruments that quantify chlorophyll in
seawater. Also can be measured using satellite
photographs.
Standing Stock (the total amount of
phytoplankton) is estimated using
instruments that detect chlorophyll or satellite
photographs.
The Carbon Cycle
• Carbon is required for primary producers
to create organic molecules.
• This carbon is cycled through an
ecosystem. Carbon dioxide is released
during _____ and decomposition. It is
used by producers during ____.
Nitrogen and Phosphorus
Nitrogen and phosphorous are also
required for primary production
and must be cycled through an
ecosystem.
Figures 10.21 and 10.22 outline
this cycling.
Nitrogen is fixed by bacteria and
archaea.
Most nitrogen and phosphorous
compounds are produced during
decomposition and excretion.
Certain elements or compounds taken up by
organisms cannot be metabolized or excreted.
They accumulate in the organism
(bioaccumulation) and may reach toxic levels.
• heavy metals (lead, arsenic, mercury)
• nonbiodegradable pesticides (DDT)
• Even toxins produced by organisms can be biomagnified like
during red tides
The effects of bioaccumulated materials are
magnified through the food web
(biomagnification).