While some people are still debating whether there is really
such a thing as 'global warming', the effects of climate change can
already be seen in southern Africa. Natal is the province most
affected in South Africa, and the area between the Drakensberg and
the coast, i.e. the Midlands, have seen the most dramatic changes
in recent years. In the Tugela area, the average mean temperature
has risen by 4.5 degrees centigrade, and annual rainfall has
increased by 13% over the past decade! Furthermore there has been a
shift in weatherpatterns, so that rainfall is spread more evenly
throughout the year, and thus the average humidity has risen by
8%.
These effects amplify themselves in secluded ravines, that are
narrow and protected from wind, but benefit from water drainage
from surrounding hillsides. The micro climate here has shifted to
sub-tropical for most of the year, which now creates a habitat for
fauna and flora previously unknown to this area.
One prominent example is an invader from Brazil, that is to be
found on the fringes of subtropical forests in South America.
This large snail, a relative of the apple snail, is known as the
'Giant Amazon' or by its Latin name Pomacea Luksogai. It thrives on
dense vegetation and is usually found near water. An interesting
thing about Giant Amazons is that they are amphibious (they live
and move about in and out of the water - fresh water only - never
salt water). They usually sleep under their watery home during the
day, hidden in vegetation near the waters surface, then at night
they get more active and they actually leave the water in search of
their favorite foods - fresh tender plants.
It can produce up to 250 offspring per year but the young are
heavily predated on by the local snake and bird population.
It is belived that the snails got to South Africa on a cargo ship
from South America and they have since moved along the Tugela
Valley, up to an elevation of 1000m.
The Intsongela Valley evidently provides a perfect habitat for
these new invaders!