Terrestrial & Aquatic Ecology
UNIT 1
GRADE 12 ENVIRONMENTAL SCIENCE
How do Organisms get Energy?
 Photosynthesis: Converting light energy (from
the sun) into usable chemical energy
How do Organisms get Energy?
 Cellular Respiration: The process of breaking
down simple sugars to release energy.
How do Organisms get Energy?
How do Organisms get Energy?
 Chemosynthesis: process in which organisms
convert inorganic chemicals (H2S or H2) into usable
energy.
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Deep-sea hydrothermal vents
Hot springs
Intensely salty lakes
Deep in rock formations
Deep-sea (w/o thermal vents)
Levels of Organization in an Ecosystem
 Species: all organisms of the same kind that are
genetically similar to breed in nature and produce
fertile, live offspring.
 Population: all members of the same species living
in a given area at the same time.
 Community: all populations interacting together
in a given area at the same time.
 Ecosystem: a community and its environment
(abiotic – nonliving factors) (biotic – living factors)
Transferring Energy in an Ecosystem
 Producers: organisms the photosynthesize
 Productivity: amount of biomass produced in a
given period of time.

Biomass: biological material
 Food Chain: a linked feeding series
 Food Web: a diagram of interconnected
food chains
Transferring Energy in an Ecosystem
 Trophic Level: an organism’s feeding status in an
ecosystem
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Producer
Primary Consumer (Herbivore)
Secondary Consumer (Carnivore, Omnivore)
Tertiary Consumer (Carnivore, Omnivore)
Quaternary Consumer (Carnivore, Omnivore)
 Consumer: eat producers for energy
 Herbivore: eats only plants
 Carnivores: eat flesh (meat) only
 Omnivore: eats both plants and animals
Transferring Energy in an Ecosystem
 Other Consumers:
 Scavengers: eat and clean up dead carcasses of larger
animals.
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Detritivores: eat litter, debris, dung

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Crows, jackals, vultures
Ants, beetles
Decomposers: complete final breakdown and recycling of
organic materials.

Fungi, bacteria
Transferring Energy in an Ecosystem
Consumers that feed at
all levels:
Scavengers &
Decomposers
Transferring Energy in an Ecosystem
Biogeochemical Cycles
 Hydrologic Cycle (aka water cycle):
Biogeochemical Cycles
 Carbon Cycle:
 Needed to make
organic molecules
 Bonds with carbon
contained “stored”
energy
Biogeochemical Cycles
 Nitrogen Cycle:
 An element needed in making
organic molecules
 Assimilation: the taking in of
nitrogen by plants
 Nitrogen fixation: bacteria
combine N with H to form
NH3 (ammonia)
 Nitrification: bacteria turn
ammonia into nitrates (NO3)
 Denitrification: bacteria
convert NO3 into N2
Biogeochemical Cycles
 Phosphorous Cycle:
 More phosphorous =
more lush plant growth
but also more water
pollution
 Phosphorous has
NO atmospheric
form
Biogeochemical Cycles
 Sulfur Cycle:
 Important
for making
proteins
Speciation & Evolution
 Adaptation: acquisition of traits that allow a
species to survive in its environment.
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Acclimation – immediate response to a changing environment,
but not past on genetically
Natural Selection –
organisms better suited to the environment survive 
 offspring inherit the beneficial traits 
 over generations, these become the traits of a population
 Evolution brought on by an accumulation of mutations over time.

Speciation & Limitations
 Limitations to where a species can live
 Physiological factors
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Moisture, temperature, light, pH, or a specific nutrient
Competition with other species
Predation, parasitism, disease
Luck
 An organisms design may allow it to only live within
certain conditions

Critical Factor: the single factor in shortest supply relative to
demand.

Saguaro Cactus – so sensitive to freezing temperatures that one
freezing night below O for 12 hours or more stunts its growth, and
it can no longer develop.
Speciation & Limitations
 Tolerance Limits: each factor has a minimum and
maximum level in beyond which a species would not
be able to survive or reproduce.
Speciation & Ecological Niches
 Habitat: place or environmental conditions in which a
species lives.
 Ecological Niche: role played by the species in their
community or a total set of environmental factors that
determine the distribution of a species.
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Generalist: has a wide range of tolerances for many factors
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Specialist: have exacting habitat requirements, lower reproductive
rates, and care for their young.

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Brown rat
Giant Panda
Endemic: highly specialized to their habitat and do not exist
anywhere else

Flora & Fauna on the Galapagos Islands
Speciation & Ecological Niches
 Competition: fighting for
the same resources

Competitive Exclusion
Principle: no two species
can occupy the same
ecological niche for a long
period of time.
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The more efficient will
survive, while the less will
either find another habitat,
die out, or experience a
change in its behavior or
physiology.
Resource Partitioning:
several species can use
different parts of the same
resource and coexist.
Speciation & Diversity
 Speciation: the development of a new species
 Gradualism
 Punctuated Equilibrium
Speciation & Diversity
 How speciation occurs:
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Geographic Isolation
(Allopatric Speciation):
species arise in separate
geographic regions due to
physical barriers causing
reproductive isolation.
Behavioral Isolation
(Sympatric Speciation):
behaviors that cause
reproductive isolation even
though the organisms live in
the same place.
Species Interactions
 Competition:
 Intraspecific Competition: competition within a species

Reducing competition:
 Dispersal of young
 Strong territoriality
 Resource partitioning between generations
• Young/adults feed differently
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Interspecific Competition: competition among different
species
The species living in the optimal range of their tolerance limits
will have an advantage over a species living outside of their
optimal range.
Species Interactions
 Predator: any organism that feeds directly on any
other living organism.
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Predators: herbivores, carnivores, omnivores
NOT Predators: scavengers, detritivores, decomposers
 Predator-mediated Competition: a superior
competitor in a habitat will build up a larger
population than its competing species; predators
notice and increase hunting pressure of the superior
species, reducing the superiors abundance, allowing
the weaker species to increase its numbers.
Species Interactions
 Predator-Prey Relationships can lead to co-
evolution.
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Co-evolution: when two interacting species evolve with each
other because of their interactions.

Cheetah & Gazelle
Species Interactions
 Mimicry
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Batesian mimicry:
harmless species look like
poisonous or distasteful
ones to scare of predators.
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Mullerian mimicry:
two harmful species look
alike and predators learn
to avoid both.
Species Interactions
 Camouflage: Use of
color, patterns, and form
to blend in to the
environment.
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Helps prey hide from
predators BUT
Also helps predators hide
while lying in wait for
their prey
Species Interactions
 Mutualism: relationship
between two organisms
benefit each other.
 Commensalism: one
organism benefits, but the
other organism in not
affected.
 Parasitism: one organism
benefits and the other
organism is harmed.
Keystone Species
 A species who has a large influential impact on its
community or ecosystem than its abundance would
suggest.
Properties of Ecosystems
 Primary Productivity: Rate of biomass
production (conversion of solar energy to chemical
energy)

Energy left after respiration = net primary production
Properties of Ecosystems
 Abundance: total number of organisms in a
biological community.
 Diversity: measure of the number of different
species, ecological niches, or genetic variation
present.
 Abundance is usually inversely related to diversity
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Diversity up, Abundance down
Diversity down, Abundance up
 Generally diversity decreases but abundance within a
species increases from the equator toward the poles.
Properties of Ecosystems
 Ecological structure: patters of spatial distribution
of individuals and populations within a community
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Random
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Live where resources are available
Uniform
Physical environment
 Biological competition
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Clustered
Protection
 Mutual assistance
 Reproduction
 Access to resources
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Properties of Ecosystems
 Complexity: number of species at each trophic level
and the number of tropic levels in a community.
 Stability or Resiliency:
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Constancy: lack of fluctuations in composition or function
Inertia: resistance to disturbances
Renewal: ability to repair damage after a disturbance
 The more complex and interconnected an ecosystem, the
more stable and resilient it is.
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Many species in one trophic level, one can replace another
However, removal of a keystone species can greatly affect any system
Properties of Ecosystems
 Edge Effects: change is species composition,
physical environment or other ecologic properties
between ecosystems
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Sometimes sharp and distinct
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Woodlands  grasslands
Gradual integration to from one to another
 Ecotones: boundaries between adjacent
communities
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Sharply divided: closed community
Indistinctly divided: open communities
Changing Communities
 Ecological succession: changes in an community as
organisms occupy a site and the change the
environmental conditions.
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Primary Succession: land that is bare of soil and colonized by
organisms where none lived before
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Secondary Succession: existing community is disturbed and a
new one develops from the disturbance
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Sandbar, mudslide, rockface, volcanic flow
Wild fire, clear cut forests, urbanization
Successions occur by:
Modifying soil
 Light levels
 Food supplies
 microclimate
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Changing Communities
 Terrestrial Primary Succession
 Primary species: first colonists
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Microbes, mosses, lichens (live off few resources)
When primary species die = organic matter = soil production
Seeds lodge in soil and grow
Succession progresses  more diversity
Changing Communities
 Disturbances: anything that disrupts established
patterns of species diversity and abundance,
community structure, or community properties
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Landslides, mudslides, hailstorms, tidal waves, tornadoes,
volcanoes (natural)
Animal disturbances
elephants ripping down small trees
 Agriculture, forestry, urbanization, dams, pipelines
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 Disturbance-adapted species: species that
recover quickly from a disturbance
Biomes
 Biomes: ecosystems with similar climate, growth patterns, and
vegetation.
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Temperature & Precipitation – important characteristics for terrestrial (land)
biomes
Tropical Rainforest
Tropical dry forest
Tropical Savanna
Desert
Temperate grasslands
Temperate woodlands and shrublands
Temperate forests
Northwestern coniferous forest
Boreal forest (Taiga)
Tundra
Marine Ecosystems
 Mostly dependent on photosynthetic organisms to
support the food web
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Algae
Phytoplankton (tiny free-floating plants)
In oceans, most photosynthetic activity is near coastlines
Nitrogen, phosphorous, other nutrients runoff into the ocean
 Ocean currents distribute nutrients and phytoplankton by carrying
them away from shore

 Dying organisms sink to bottom, feeds bottom feeders
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Craps, filter-feeders, etc
Upwelling brings this “marine snow” back up to the surface for other
fish as well
Marine Ecosystems
 Vertical Stratification
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Light/temperature decrease
with depth
Colder H20, more O2
Photic zone – light reaches
(about 20m)
 Pelagic – near the top
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Epipelagic: photosynthetic
organisms
Mesopelagic
Bathypelagic
 Benthic – live near bottom
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Abyssal
Hadal
 Littoral – shoreline
 Intertidal – are exposed by
low tide
Continental Shelf
Marine Ecosystems
 Deep Ocean
 Relatively low productivity
 Around equator, many
fish and phytoplankton
 Sargasso Sea – blankets of
brown algae support many
diverse animals
 Deep-sea thermal ventschemosynthetic
Tubeworms, mussels,
microbes
 Thousands of microscopic
organisms

Marine Ecosystems
 Coral Reefs:
 High productivity/diversity
 Protect shorelines
 Shelter fish, worms, crustaceans, etc.
 Shallow warm waters, sunlight
 Dependent on photosynthetic algae
 Coral Bleaching: warms waters are killing coral.

1/3 destroyed by 2006, by 2030 60% expected to be gone
Marine Ecosystems
 Mangroves
 Trees that grow in salt water
 Calm, shallows, tropical coastlines
 Stabilize shorelines
 Nurseries for fish, shrimp, other commercial species
 Clear-cut for timber, make room for fisheries

Mangroves provide protection for these fish the are being removed
for.
 Reduced catches, falling income
Marine Ecosystems
 Estuaries:
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Bays where rivers empty
into the sea
High
productivity/diversity
“dead zones” : excess
nutrients stimulate
bacteria that uses O2
needed for other life
 Tide-pools:
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Depressions in rocky
shoreline that flood at
high tide, retain water at
low tide
Specialized species

Starfish, sea anemone, ect.
Marine Ecosystems
 Barrier Islands
 Low, narrow, sandy island
parallel to the coastline
 Protect inshore lagoons
and salt marshes from
storms, waves, tides
 Critical in preserving
coastlines, estuaries, and
wetlands
 Human occupation speed
up erosion of barrier
islands, vulnerable to
storms
Freshwater Ecosystems
 Lakes

Vertical zones
Open water: plankton,
microscopic plants,
animals, & protists, water
striders, mosquitoes
 Water column – variety of
fish
 Benthos: bottom, snails,
worms, fish, other
organisms
 Littoral: plants
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Conditions that affect lake
productivity
Nutrient availability,
nitrates, phosphates
 Suspended matter, silt,
affects depth of light
 Depth
 Temperature
 Currents
 Bottom: muddy, sandy,
rocky floor
 Connections to other
ecosystems

Freshwater Ecosystems
 Lakes
Freshwater Ecosystems
 Wetlands
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Shallows, land surface that is
submerged part of the year
Rich biodiversity
Essential for breeding and
migrating birds
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5% of US is wetlands, but
1/3 of endangered species
call the wetlands home
Retain storm water, control
flooding, filter/purify urban
and farm runoff
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Swamps- wetlands w/ trees
Marshes- wetlands w/o trees
Bogs – areas of saturated
ground (usually composed of
peat)
Fens – bogs fed by
groundwater, mineral rich,
specially adapted plant
species
Swamps & Marshes- high
productivity
Bogs & Fens – low
productivity
Freshwater Ecosystems
Human Disturbance
 Conversion of natural habitat to human use = largest
single cause of biodiversity loss
 Human dominated biome: temperate broad leaf
forests
 Others highly disturbed: temperate grassland,
rainforests, tropical dry forests, and many islands
 Least disturbed: tundra, arctic deserts, temperate
conifer forests