1. Evaluate
the causes of the global amphibian decline. The following references
will help you:
(a)
Carey, C. and Alexander, M. A. (2003) Climate
change and amphibian declines: is there
a link? Diversity and Distributions 9,
111–21.
(b) Carrier,
J.-A. and Beebee, T. J. C. (2003) Recent,
substantial, and unexplained
declines of the common toad Bufo bufo in lowland England. Biological
Conservation 111, 395–9.
(c) Green,
D. M. (2003) The ecology of extinction:
population fluctuation and decline
in amphibians. Biological Conservation 11,
331–43.
(d) Kats,
L. B. and Ferrer, R. P. (2003) Alien
predators and amphibian decline: review
of two decades of science and the transition to conservation.
Diversity and Distributions
9, 99–110.
(e) Storfer,
A. (2003) Amphibian declines: future
directions. Diversity and Distributions
9, 151–63.
(f) Collins,
J. P. and Storfer, A. (2003) Global
amphibian declines: sorting the hypotheses.
Diversity and Distributions 9, 89–98.
2. Pick
a biome and find out the likely changes in it global warming will
cause.
3. The following
data are concentrations of DDT (ppm) in various trophic levels of
the Long
Island estuary, New York, USA, recorded in the mid 1960s:
(a)
Top carnivore: Merganser 22.8; Cormorant 26.4
(b)
Carnivore: Billfish 2.07; Blowfish 1.17 Herbivore: Mud snail 0.26;
Clam 0.42
(c)
Plant: Water plants 0.08; Plankton 0.04
Calculate:
(a)
the maximum and
(b)
the minimum degrees of biomagnification from one feeding level
to the next. For example, plankton to mud snail is a magnification
of 0.42/0.04 = 1050 per cent.
4. Draw
box-and-arrow diagram showing some of the interactions between the
chief drivers
of global change:
land-cover change, changes in atmospheric
carbon dioxide concentrations, nitrogen deposition and acid rain,
climatic change, species exploitation and species exchange (the
accidental or deliberate introduction of plants an animals to
ecosystems outside those in which they live).
5. Find
two land-cover maps of different dates for an area of your choice.
See if you can see any
changes in land cover. Suggest what might have caused
the changes.
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