Transcript SCIENCE 1.12

SCIENCE 1.12
Investigate the biological impact of an event on a New
Zealand ecosystem.
Internal – 4 credits
What are we thinking about?
• There are numerous events which affect New Zealand’s ecosystem,
from short storms to long-term climate fluctuations, from slow
erosion to sudden landslides, from creeping evolution to the sudden
introduction of foreign species.
• You will study one event and the biological impact that event has
had on an ecosystem.
• Our ecosystem is the Kaimanawa ranges ecosystem
• Our event is the a human action – the introduction of the
Kaimanawa wild horses
• You will look at the changes in environmental factors due to the
introduction of the horses.
• And how these environmental changes effect organisms within the
ecosystem and the ecosystem as a whole.
But before we start…..
• We need to talk about some of the terminology that we will
be using and that you need to think about when you write up
your report.
• Some of the terms:
1. Ecosystem
2. Habitat
3. Environmental factors, abiotic and biotic
4. Ecological nice
5. Organism
6. Population
7. Biological community
Ecosystem
• Definition: All the organisms living in an area and all the
environmental factors that affect them.
• This means that an ecosystem can be a tiny piece of decaying
fruit or as large as the Southern Ocean.
• What are some examples of Ecosystems that you can think of?
Some examples of ecosystems
• A mountain
Alpine tussock grassland
• Lammermoor
range, Otago
Alpine tussock grassland ecosystem
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Alpine rock and snow
Large rivers
Tussock grasslands
Rock outcrops
Kaimanawa ranges sub-alpine
ecosystem
Ocean ecosystem
Pasture ecosystem
Mangrove ecosystem
• The removal of mangroves growing on a tidal mudflat may
increase the effect of waves, leading to greater erosion of the
coastline, which may lead to the death of more mangroves.
Some others
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Sand dunes
Native forest
grasslands
Tidal areas such as mangroves, mud flats, rocky shores
Communities in ecosystems
Mountain ecosystem
• Alpine rock and snow
• Alpine tussock
• Steep mountain streams
• Isolated forests
• Native and introduced grasses
• What sort of communities do you think you could find in the
Kaimanawa Ecosystem?
Communities
• Ecosystems are made of the habitat (non-living) and
communities within it (living organisms).
• Defined as all the organisms living in an area and the
relationship between them.
• All the plants and animals living in an area, being part of a
complex food web are all heavily reliant on each other.
• Relationships can be so strong that the presence or absence of
one key species can change a whole community.
• Think of the Kaimanawa Ecosystem, how has the addition of
the horses into the community impacted other organisms in
the community? Has it become part of the food web? What
could result from it’s integration?
Population
• Group of individuals of the same species living together in the
same area at the same time. They can be large or small.
• Eg, takahe in the Murchison Mountains
• Rainbow trout in Lake Taupo
• Kiwi in Rotoiti National Park
• Kaimanawa horses in Kaimanawa ranges
Species
• A group of organisms that can interbreed to produce fertile
offspring.
• Members of the same species belong to the same gene pool
and are reproductively isolated from other species. This
means that they can’t breed successfully with other species.
Habitat
• The habitat is the place where an organism lives.
• Usually includes all the physical features of the environment,
eg, the habitat of the black mussel is the mid-tidal zone of the
rocky shore
• What is the habitat of the kaimanawa horses?
Adaptations
• Inherited characteristics that enable organisms to survive or to
reproduce effectively. Every adaptation has a purpose.
• Structural – eg wings on a tui are for flight
• Physiological – digestive enzymes enable food to be broken
down quickly
• Behavioural – migration of oyster catches between the North
and South Islands allows food stocks to regenerate in both
places
Ecological Niche
• The role or way of life of an organism in its biological
community. The niche is a combination of where the
organism lives, its habitat, and how it lives there, its
adaptations.
• Name the organism
• Describe its way of life – feeding habits and patterns of activity
(nocturnal? Diurnal? Migratory?)
• Describe its adaptations to its feeding habitat and activity
patterns
• Describe other adaptations to its particular habitat and way of
life.
Each species has a unique niche and two species can not
occupy the same niche - competition
Environment
• Surroundings of an organism and includes all the factors that
act on an organism. They can be living or non living.
Environmental factors
• The event (introduction of horses) will have caused a change
in environmental factors.
• You will need to identify what environmental factors have
changed and are causing the change in organisms.
• Ecosystems are often controlled by one factor in particular,
such as the length of time spent in sea water on a rocky shore.
• But there are also many other interactions happening in an
ecosystem.
• What do you think could be some of the environmental
changes that may have occurred as a result of introduced
horses?
Abiotic and biotic
• Biotic factors – living factors, including interactions
between organisms, such as supply of food,
competitions, predation, parasitism and disease.
• Abiotic factors – non-living, physical factors such as
moisture levels, wind speed, wave action, temperature,
oxygen levels and light intensity.
• After watching the videos, make a list of some of the
biotic factors you can think of that could be part of the
environmental factors in the Kaimanawa area
• Make a list of the abiotic factors that could be associated.
Interrelationships
• The interrelationships between species and between
individuals are a key aspect of biological communities.
• The relationships may be important biotic factors in the
environment.
• The availability of food and the actions of herbivores and
predators are important in determining the presence and
abundance of organisms in the community.
• Predation is an important factor in controlling the size and
density of populations of prey species, typically herbivores.
Feeding relationships
• Where an organisms fits in the food web of the community is
important.
• Any change to the density or distribution of one organism in
the food web can impact other organisms that rely on it for
food.
• Competition for food can lead to a reduction in survival rate of
an organism or cause the organism to move elsewhere for
food.
• Horses are herbivores. There are no carnivores in New
Zealand that naturally predate on them to control their
numbers.
Competition
• Competition occurs when resources are in short supply.
Competition is important in determining the presence, size,
and density of population in a community.
• Intraspecific – between members of the same species
• Interspecific – between members of different species. This is
harmful to both species involved.
• Plants compete for light, space, water, nutrients. Weeds can
be a problem competing with native plants.
• Animals mostly compete for space, food, water, shelter,
nesting sites.
A biological impact
• A biological impact could be a change in the number (density)
or range (diversity) of organisms. This change could have an
impact on the ecosystem as a whole, effecting food chains and
food webs, etc.
• When you consider a impact, you don’t make a judgement
whether it is good or bad, you just consider data, evidence
and known facts.
• What are some biological impacts that could be occurring as a
result of the introduction of the horses?
Combined effects
• Within an ecosystem if one factor is changed, it can have an effect
on other factors.
• Can you think of any examples?
Human effects on ecosystems
• Humans can have a direct or indirect effect on an ecosystem.
• For example, humans can spill oil which may cover a shoreline
with thick, black crude oil. The fact that humans did it, makes
it a biotic effect, but the effect on the shore will be due to
abiotic factors such as reduced oxygen levels, lower light levels
or an increase in the levels of toxic chemicals.
Indicator species
• Organisms have preferences and limits for environmental factors
and where they want to live.
• An indicator species is one whose numbers are sensitive to
environmental threat, and which can be used to indicate the state
of health of that environment.
• When we know what effects a species, we can use their number,
health and distribution to identify issues in an ecosystem.
• Do you know any of these?
Plant indicators
• Because plants can’t move, they are good indicators. They are
affected by the nutrients and water that their roots can
obtain.
• Plants will then show the effects of ground disturbance, like
that caused by being trod on all the time. (especially from
above)
• Trampling by horses? Could this be an issue and how? See if
you can find some plant species that are being trampled by
the horses which could have an impact on the ecosystem as a
whole (impact on the food web)
Insect indicators
• Insects are widespread and involved in nearly every
community relationship including decomposition of forest
litter, pollination, parasitism and predation.
• Also important food sources for birds, lizards, tuatara and
freshwater fish.
• Insect larvae are often found in streams, their abundance
indicates a lack of pollutants and good oxygen levels.
• How might this relate to the Kaimanawa Ecosystem?
Some examples of indicator species
Woodrose – a parasitic flowering plant
• Forest health in parts of the North Island
• If there is lack of woodrose, it indicates presence of browsers,
native pollinators, seed dispersers and host trees.
Kiwi
• lack of kiwi indicates an abundance of mammalian predators
Most destructive species in NZ
What do you think is the most destructive species in NZ?
Probably humans!
• Why? We have altered nearly every Ecosystem in New
Zealand.
• We have introduced over 32 mammals, 33 birds, 3
amphibians, 18 fish, 33 reptiles, thousands of species of
invertebrates, plants and micro-organisms into New Zealand
who have all had an affect on Ecosystems, eg, rat, possum,
goat and wild horses.
Introduced species
• Of all of the species introduced, many didn’t survive,
thankfully! Eg, Zebra, camel, squirrels.
• Of those that survived, many became major pests within a few
years.
• To exterminate little ones such as rabbits and hares their
natural predators were introduced – weasels, ferrets and
stoats.
• Larger pests such as deer and pigs were shot as their natural
predators (wolves, tigers, lions) were too dangerous! Really?
• Didn’t work well – what do you think was the consequence?
• One of the worst is the possum along with many plants
1. Environmental Factors
• Describe how the event changed environmental factors in the
ecosystem you are investigating.
• You need to find information on at least two factors.
• Eg, In the stream that ran through native bush, average water
temp was 15C during the sampling period. In the stream in
the industrial area, average water temp was 17C
• Organisms need to be adapted to environmental factors to
survive, so if they change, an organism may be affected.
• see hand out.
• What sort of environmental factors do you think the horse
could impact?
2. Changes to environment
• Explain how the introduced horses changed the
environment:
• Eg, the suspended particles in the water in the stream in
the industrialised area contributed to heating the water
as the particles warmed up. There is less dissolved
oxygen in warm water than in cold. The warmth of the
water in the stream in the industrialised area meant
there could be little dissolved oxygen in that part of the
stream.
• You can consider changes to light intensity, pH, amount
of moisture, stream clarity, temperature, oxygen levels,
shelter, food availability, competition, composition of
substrate (soil) etc.
3. Impact – effect on
population of organisms.
• Explain how these changes have had an impact on the
organisms in the ecosystem (2)
• You can discuss diversity and density of species (plants or
animals) that have been effected here. – eg, changes in
population numbers, distribution of organisms, density
of populations, size of organisms in a population, age
structure of population, key species, feeding
relationships, interrelationships (eg, mutualism,
parasitism)
4. Implications for ecosystem
• The implications that the changes have for the ecosystem as
a whole can be discussed here.
• Consider changes in biodiversity, food chains/webs, energy
flow, nutrient cycles, density and distribution patterns,
presence or absence of key species, substrate.
• You need to link your findings and biological ideas into a
comprehensive discussion of the biological impact of the
event on the ecosystem.
• Make causal links – constantly explaining how or why one
change caused another change.
• Also discuss the implications of these changes for the
organisms and the ecosystem.
Ecosystem – impact of removal
of some species
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Habitat destruction
Few organisms in food web
Links may be removed
Decreased stability of web
Likely loss of biodiversity as plants die out and animals die or
migrate
• Remember to compare the ecosystem with and without the
horses and use data, photos – evidence to support it.