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Who, What, When, Where, Why, and How
of Marine Ecology
• Who studies marine-life habitat, populations, and
interactions among organisms and the surrounding
environment including their abiotic and biotic
factors?
• What factors contribute to the distribution of
marine organisms in their environment?
• When do temperature changes affect communities?
• Where is the benthic zone?
• Why are trophic pyramids important to Marine
Ecologists?
• How are heterotrophs related to autotrophs?
Chapter 2
Fundamentals of Ecology
Karleskint
Turner
Small
Marine Ecology
• Marine Ecology is the scientific study of
marine-life habitat, populations, and
interactions among organisms and the
surrounding environment including their
• abiotic factors - non-living physical and chemical factors
that affect the ability of organisms to survive and
reproduce and
• biotic factors - living things or the materials that directly
or indirectly affect an organism in its environment
Study of Ecology
• Ecology
– from the Greek word oikos meaning “home”
• Environment
– biotic factors (living)
– abiotic factors (non-living)
• Habitat: where an organisms lives
• Ecosystems
– composed of living organisms and their nonliving environment
Study of Ecology
• The study of organisms interacting with
one another and their environment.
This entails:
– biological (biotic) factors
– environmental (abiotic) factors
– the organism’s behavior
• Niche: an organism’s environmental role
• Its “job” in the environment
Homeostasis and Distribution
of Marine Organisms
• Maintaining homeostasis
– changes in external environment
– internal adjustments to maintain a stable
internal environment
• optimal range
» For example, we have optimum temperature
(98.6), pH, etc.
• zones of intolerance
Characteristics of the Physical Environment
that Affect Organism Distribution
• Organisms might be limited as to where
there is sunlight:
– For photosynthesis
– For vision
• Organisms might be limited to location by
temperature
– ectotherms
– endotherms
Characteristics of the Physical Environment
that Affect Organism Distribution
• Organisms might be limited to where
they can live by salinity
–Some can withstand higher salinity than
others
Characteristics of the Physical
Environment that Affect Organism
Distribution
• Some organisms are limited to location
by pressure
–760 mm Hg or 1 atmosphere at sea level
–increases 1 atmosphere for every 10
meters below sea level
–Deep sea animals are adapted to living at
high pressure
Characteristics of the Physical
Environment that Affect Organism
Distribution
• Metabolic requirements
–nutrients and limiting nutrients
–oxygen as a requirement for cell respiration
– Anaerobic organisms – don’t need oxygen
– aerobic organisms – do need oxygen
–Excess nutrients can result in eutrophication
and algal bloom
• Metabolic wastes
–carbon dioxide is a common byproduct of
metabolism
• As a review:
– Physical characteristics of the environment
will effect organism distribution
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–
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Temperature
pH
Salinity
Sunlight
Pressure
Nutrient availability (oxygen, nitrates, phosphates,
etc)
• Individuals
• Population – group of individuals of same
species
• Community – different species living
together
• Ecosystem – community plus abiotic
factors
Populations
• A group of the same species that
occupies a specified area
– Geographic range
» For example, the lagoon, open ocean, deep sea, etc.
– Population size
Distribution of Organisms in a Population
• Population density (abundance)
• Dispersion
– clumped
– uniform
– random
Changes in Population Size
• Can occur through:
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reproduction
immigration
death
emigration
• Can be affected by:
– survivorship
– life history
– opportunistic and equilibrium species
Population Growth
• Many ways a population can increase in
size, depending on the carrying capacity
of the environment
– exponential/logarithmic growth
– logistic growth
Exponential growth
Logistic growth
Communities
• Composed of populations of different
species that occupy one habitat at the
same time
• Niche: what an organism does in its
environment
– fundamental niche
– What all that species could do in the environment
– realized niche
– Species are going to be limited by other species in the
area that might have similar niches
Communities
• Biological environment
– competition
• may be interspecific or intraspecific
• may result in competitive exclusion
• resource partitioning allows organisms to share a
resource
– predator-prey relationships
• balance of abundance of prey vs. predators
• keystone predators
Communities
• Symbiosis: living together
– mutualism – both organisms benefit
– commensalism – one organism benefits, the
other is nether harmed nor benefited
– parasitism – one organism benefits, the
other is harmed
Ecosystems: Basic Units of the Biosphere
• Energy flow through ecosystems
• Producers = Autotrophs
– auto = self, troph = feed
– Convert energy from the sun and harness it into organic
molecules that will make their way up the food chain
• Photosynthetic producers – some bacteria, algae, plants
» Majority of primary producers on the planet
• Chemosynthetic producers – some bacteria that live in
hydrothermal vents
» Do not use energy from sun, instead use energy from inorganic
molecules being released from hydrothermal vents at bottom
of the ocean
Ecosystems: Basic Units of the Biosphere
• Consumers = Heterotrophs
– hetero = other, troph = feed
– Different levels of consumers:
• first-order consumers (herbivores)
• second- and third-order consumers (omnivores and
carnivores)
• detrivores
• decomposers
• Food chains and food webs
Ecosystems: Basic Units of the Biosphere
• Trophic levels
– number of levels is limited because only a
fraction of the energy at one level passes
to the next level
– ecological efficiency
• ten percent rule
– trophic pyramids
• as energy passed on decreases, so does the
number of organisms that can be supported
Biogeochemical Cycles
• Hydrologic cycle
– water is lost through evaporation
– carried north and south from equator
– carried west to east within each
hemisphere
– returned through precipitation and runoff
Biogeochemical Cycles
• Carbon cycle
– Cellular respiration
– carbon released from organisms through respiration
and decomposition
– That’s why we breathe out CO2
– Photosynthesis
– The carbon in CO2 isrecycled by photosynthetic
producers
– carbon is used in shells, corals and skeletons
as part of calcium carbonate
– fossil fuels, when burned, release CO2 back
into atmosphere
Biogeochemical Cycles
• Nitrogen cycle
– fixation of atmospheric nitrogen by microorganisms
that have symbiotic relationship with plants
– Producers (plants) use nitrogen to synthesize amino
acids to form proteins
– Other organisms eat those producers, to form their
own proteins, nitrogen makes it’s way up the food
chain
– bacteria recycle nitrogen from wastes and
decomposing, dead organisms
Biosphere
• Includes all of earth’s communities and
ecosystems
• Examples of ecosystems:
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–
–
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estuaries
salt marshes
mangrove swamps
rocky and sandy shores
kelp forests
coral reefs
open ocean
Distribution of Marine Communities
• Pelagic division
– Zones according to location to land:
• neritic zone (nearshore) and pelagic zone (open ocean)
– Zones according to light penetration:
• photic zone (light), disphotic zone (little light), and aphotic zone (no light,
majority of the ocean)
– Majority of the biomass of ocean is in photic zone
– Organisms that live in the pelagic:
• Plankton (organisms that float) and nekton (organisms that swim)
• Benthic division
– Bottom sediment area:
• shelf zone, bathyal zone, abyssal zone, and hadal zone
– Organisms that live in the benthic zone are divided into:
• Epifauna (organisms that live on top of sediment) and infauna (organisms
that live in the sediment)