Saltwater - open seas, estuaries and saltwater
Approximately 65% of the Earth's surface is
covered by oceans. Tides, currents, waves and
wind continuously move the water in the surface
Freshwater - include still water such as lakes and
ponds, swamps, and moving water such as springs
creeks and rivers.
Terrestrial environments vary as a result of
topography, climate, availability of water, and human
Examples: rainforest, open forests, mountain tops,
deserts, grasslands, farms and cities.
A group of living organisms of the same kind
living in the same place at the same time.
Organisms living together in a particular place.
The habitat of an organism is the place where it lives.
These can vary in size e.g. desert, under tree bark,
within the digestive system of another organism.
Ecosystems will fail if they do not remain in
No community can carry more organisms than
its food, water and shelter can accommodate.
Food and territory are often balanced by natural
phenomena such as fire, disease, and the
number of predators.
Temperature (daily and seasonal)
Topography (altitude and depth)
Tides, currents and waves
Water (salinity, pH and availability)
Substrate (surface on which an organism grows
or is attached)
Space and shelter
Availability of food
Number of competitors
Availability of mates
Number of predators
Disease causing organisms
Limiting factors - anything that makes it difficult
for a species to live and grow, or reproduce in its