lec 20 Flashcards
Action we are performing that lead to habitat loss
- Habitat destruction
- Over exploitation
- Invasive species
- Pollution
- Climate change
Approximately _% of the worlds forests are _____
15
untouched by human hands
_% are impacted and most importantly _% of the land once containing forest __________
57
28
have lost so many trees that they cannot be called forests
Since the 1960s ___________ has expanded significantly in canada
the construction of dams
In many causes dams are considered _________ but this is
a renewable green source of power
not always the case
Many dams seriously __________
As well as _____
and _______
alter the flow regime of a river
water quality
aquatic/near shore habitat
____________ can be a major cause of extinction
introduced species
Species are introduced into new environments for many reasons such as
Intentionally for agricultural purposes (honey bees)
Intentially for sport (trout/pheasents)
Unintentionally transoported via human transport (zebra mussel/rusty crayfish)
Intentionally for the pet or gardent industries (dandelions)
Introduced species that survive and become invasive ___________
spread and outcompete native species for space and resources
Economic costs of invasive species in Canada have been estimated at
13 billion per year
Sea lampretys are a
primitive jawless fish native to the Atlantic Ocean
Lampreys entered the Great Lakes through the
ship canals and locks built to bypass obastcles in naigra falls
How lampreys kill kish
their mouth is an oral disc that is like a suction cup to attach to side of fish
- teeth on the tongue rasp through the skin
- an anticoagulant in saliva maintains blood flow in lampray feeds
Lake trout populations crashed as
lamprety population grew
Following the crash of the top predators
populations of invasive prey species like rainbow smelt and alewlife increased rapidly
these invasive species out competed native species
extinction so the deepwater sculpin and cisco
zebra mussels are native to _____
They were transported to the great lakes via ____
Sea water is pumped into and out of ______
An estimated ______
the Caspian sea region of Asia
ballast water from a transoceanic vessel
ballast tanks which serve to stabilize ships
zebra mussels first discoved in
Since then they have spread rapidly
The mussels attach onto any hard substrate
the great lakes in the mid 1980s
to all of the Great Lakes and connected waterways in many US staes, as well as Ontario, Quebec and Manitoba
including other organisms and are easily transported
A female zebra mussel can produce
whcich can establish dense population up to
May cover bottom waters or beaches with
Mussels reduces species of algae and microscopic aquatic animals
on million eggs per year
7000,000 per m^2
dead mussel shells up to 30 cm deep
that are imortant for the food web with their impressive filering capacity
Carp
Introduced _______
they escaped _____
They are voracious eaters ______
to the US from China in the 1970s to clean fish farm tanks and as a food source
and over the last 30 years have steadily moved north on the Mississippi River system
grow very large, have devastating effect on native fish populations
A less obvious cause of human damage
This is much more controversial and hard to quantify
Historically Co2 levels
is the alteration of biogeochemical cycles
compared with other human caused diversity losses
have been significantly higher than today, however it is not the level that matters per se, it is the rate of change and the fact that todays ecosystems have evolved to live within current CO2 levels
Temperature is similar in that recent trends
can not be conclusively linked to human activity but are undoubtedly rising
From a geoloical time point of view
it is uncommon to have glaciers that persist throughout the year; so perhaps it makes sense that the Earth is warming
It is not a matter of absolute temperature
but a matter of the rate of change
Ice caps have
been in retreat for 20,000 years
Is the current retreat part of an overall trend or due to climate change
Something that kills lamprey
lampricide
