3. Energy flow and nutrient cycling Flashcards
A habitat is
a place where organisms live –
for example, a coral reef crest
One species of organism you will probably find in the coral reef crest habitat in the Caribbean is
the elkhorn coral, Acropora palmata
how to actually describe the habitat for elkhorn coral a little more precisely
It lives in and around exposed reef crests and in the forereef, in depths of generally less than 6m
Figure 3.2 Fringing reef
chegg
Figure 3.2 Barrier reef
chegg
Figure 3.2 Atoll
chegg
Ecology is
the study of the interactions of organisms with each other and with their physical environment
An ecosystem is
all the organisms that occur together in a particular place and the environment with which they interact
The Earth is divided into large regions known as
biomes that have similar climatic features
Each ecosystem has a border with
adjacent ecosystems with which it exchanges resources
Communities are
larger groupings that include all the populations of plants, animals, microorganisms that live together in a particular place
Population is
groups of individuals of one species that occur together in a particular place.
The interactions of an organism with members of its
own species, unrelated species and the environment all contribute to
its ability to survive, grow and reproduce
The major kinds of interaction between species or organisms include (6)
mutualism, competition, commensalism, plant–herbivore, predator–prey parasitism
Mutualism is a
biological interaction in which the growth, survival and reproduction of both interacting species are enhanced and neither species can survive without the other
example of mutualism with fungi and plants
Fungi may be associated with plant roots and have an important role in the absorption of phosphates and
other essential minerals required for plant growth.
Fungi enhance plant growth, while receiving shelter and food molecules
Competition is
the interaction between members of the same population in order to obtain a limited resource such as food and fertile mates
Competition also occurs between members of different populations.
In competition, one species may interfere with another species to prevent or restrict access to a resource.
eg of completion in plants
plants may produce toxic chemicals in response to grazing by herbivores.
The toxic chemicals make the plants distasteful to herbivores, thereby giving them a competitive advantage over plants that do not produce toxins
Commensalism is a
type of symbiotic relationship in which one organism benefits from the other, but the other is neither helped nor harmed.
example of commensalism with egrets
cattle egrets ride on the backs of cattle.
As the cows walk in fields, they disturb grass and shrubbery, and insects like grasshoppers and crickets fly up.
The cattle egrets spot them easily and eat them.
So, the cattle egrets benefit from riding on the cows, whereas the cows neither benefit nor suffer from the presence of the cattle egrets.
Biotic refers to the
living components of a habitat or ecosystem
Abiotic refers to the
non-living components of an ecosystem
The ecological niche of a species is
the functional position it occupies in its environment
The ecological niche encompasses what?
an organisms’ habitat
the periods of time that it is active (e.g. foraging and mating)
the food, shelter and other resources that it obtains
Examples of ecosystems
rainforest, coral reef, savannah, desert, ocean
Examples of habitats
under a rock, tide pool, cave, tree-tops
examples of niche
temperature range an organism tolerates
time of day an organism is active
sizes and types of prey an organism eats
the niche of the queen parrotfish, which includes grazing on seaweeds, is important in what?
the recovery of reefs following damage.
why do coral reefs only occur to maximum depths up to about 70m and most are in tropical areas
because reef-building corals cannot live at depths where the light is weak
location of most coral reefs are
The coral reef ecosystem is quite uncommon globally and the Caribbean contains a significant proportion of the world’s coral reefs
The large numbers of different species found in coral reefs make them
one of the most diverse ecosystems there are
Reefs are generally under threat around the world, which makes their study
a matter of international importance
succession is
the process where one ecosystem replaces another ecosystem
The ecosystems that exist today did not always exist. They have developed from
other previous systems by succession
Why can 2 different species not occupy the same ecological niche?
interspecific competition will take place for the limiting factors/resources (abiotic & biotic factors) – better adapted species will out compete the other = competitive exclusion principle
How to sample plant species over a large area?
- obtain a map of the area
- divide the map into grids
- select a large number of coordinates using a running mean
- select a random set of coordinates using a random number chart
- in each coordinate place a quadrat
- measure abundance of the plant species in each quadrat = frequency or percentage cover
- calculate average for the whole area
How to sample plants species along a path?
- use a transect
- place a tape along the path, count number of plants touching tape (Line Transect)
or
-place a tape along the path, at regular intervals along the tape place a quadrat, measure abundance within the quadrat (Belt Transect)
How to sample animal species in an area?
- mark-release-recapture technique
- set a trap
- capture the animal species [Sample 1]
- mark them (tag or fluorescent marker – ensure its non-toxic and not harmful)
- release them
- after some time (sufficient time for them to mix with the whole population), replace the trap
- count number in 2nd set [Sample 2] and count the number marked
- estimate population size by: number in sample 1 x number in sample 2 marked in sample 2
What are the 3 stages of population growth?
1) slow/lag phase: species becomes adapted to new environment
2) rapid/log phase: species adapted, abundant resources, doubling with reproduction, birth rate>death rate
3) stationary phase: resources become limited, intraspecific competition occurs, birth rate = death rate
What are the 2 types of competition?
intraspecific and interspecific
What are the 2 types of succession?
primary (occurs on new land) and
secondary (occurs on previously colonised land that has become bare e.g. after a forest fire)
biosphere is
the surface of the earth where life exists. it is irregular in thickness and in density
An ecosystem supports a certain size of population of any one species. This population size may vary as a result of
the effect of abiotic factors
interactions between organisms
inter-and intra-specific competition
predation
Pioneer species are
the first species to occupy a new habitat, starting new communities.
They have rapid reproductive strategies, enabling them to quickly occupy an uninhabited area.
Many have an asexual stage to their reproduction
Seres are
the various stages that follow on from the pioneer species
Climax community is
the stable community that is reached, beyond which, no further succession occurs
