Transcript 3.3 How Introduced Species Affect Ecosystems

3.2 Summary: How Human
influence Ecosystems
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Sustainability: is the ability of an ecosystem to sustain itself or
the ability of an ecosystem to continue its existence over
time.
Q. How do human effect the sustainability of the ecosystem
we live in?
 1. Resource use/Land use:
All of the land around us, even in cities, was once a
part of an ecosystem (Urbanization)  no longer
the original species live there
 2. Habitat loss: because of human expansion,
habitats have been lost or fragmented.
“Habitat fragmentation” :
the splitting of large habitats into many smaller
ones, resulting in disrupted natural activities for
plants and animals.
 3. Deforestation: the more forest we cut down
to build industry , the more CO2 we are leaving
in the atmosphere because the tress take it out
through photosynthesis. Also cause soil
degradation
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4. The effects of agriculture: soil compaction
occurs when soil particles are squeezed together
and the air spaces between them particles are
reduced Because of soil compaction water runs
off the soil instead of soaking in.
 5. Resource Exploitation:
Includes fishing, hunting , mining minerals or
growing food. Contamination can occur when
harmful chemicals are released into ecosystems
as a result of our resources exploitation
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6. Over exploitation: when we use a resource all
the way up , it can said to become extinct. Over
fishing of cod has reduced its number to less than
90 percent of its original number
7. Traditional ecological knowledge
3.3 How Introduced Species Affect Ecosystems
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Native species naturally live in an area.
Introduced species (aka foreign species, non-native species, exotic species or
alien species).
– they have been introduced accidentally (& on purpose) here over the past
400 years due to immigration.
– Many of these species are harmless, even beneficial.
The sea lamprey arrived in the
Great Lakes via the canal built
between the Great Lakes in
estern Canada. The sucker-like
“mouth” of the sea lamprey
allows the lamprey to attach to
this fish. Lampreys suck the
body fluid out of fish. .
Invasive Species
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Invasive : are introduced species that often take advantage of their new habitat.
– They may have no predators, are aggressive competitors, & reproduce fast.
 Eg. Purple Loosestrife, negatively impacts native species, and often
reduces biodiversity as a result.
Biodiversity: varieties of all living species of plants, animals, and microorganisms
on Earth.
In Europe, the
population of purple
Loosestrife is
controlled by leaffeeding Beetles. But,
here, Native wildlife
avoids it.
The impact of Introduced Species:
Introduced species can affect native species through competition, predation, disease, parasitism and habitat alteration
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Competition: one species takes away resources from another.
50 breeding pairs of the European
Starling were brought to BC in the
late 1800’s. It now out-competes
western bluebirds for nesting habitat.
The American Bullfrog was brought
to BC in the 1930’s by restaurants
for their legs. It has since taken
over the habitats of native frogs.
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Predation: if the invasive species is a predator, it may
have a huge advantage, as the native species may have no
methods to survive.
The Norway rat escaped from early
European explorer and fur-trading ships.
On Queen Charlotte Islands, they have
caused a decline in ground-nesting sea
birds by eating their eggs and young.
West Nile virus was recently introduced to the United States
in 1999, when it started causing deaths in birds and illness
in humans in New York City. It is a vector borne disease,
carried by the mosquito.
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Disease & Parasitism: by weakening certain species, a microorganism invading an ecosystem can drastically alter the entire
ecosystem and the niches within it.
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Habitat Alteration: some invasive species can change the
physical structure of the ecosystem by digging, burrowing,
blocking sunlight or changing the chemistry of the
ecosystem.
Eurasian Milfoil was first identified in
Okanagan Lake in 1970. It forms wide,
dense mats at lake surfaces, cutting off
sunlight to organisms below and
interfering with recreational activities. It
can grow from plant fragments, which
are often spread by boats.