A Related "Aquatic" Plant Story

Well that holiday didn't seem long.

I went to the Kruger National Park and discovered a very interesting fact about a "marginal aquatic" plant that is creating a potentially devastating impact upon crocodile populations.

I don't think many of you have crocodiles in your pond but this is a fascinating story for anyone interested in ecology as all pond keepers are I am sure. The story concerns an invasive riverside plant called the Triffid Weed (Chromolaena odorata) which originates in South America.

The sex of unborn crocodiles is apparently determined by the egg temperature during the incubation period. The cooler the temperature then the greater the ratio of females to males and vice versa. It is possible therefore to get a complete clutch of either female or male crocodiles. A significant impact on this ratio can be made by as little as a change of between 1 and 2 degrees Fahrenheit (0.5 to 1 degrees C). The incubation temperature for almost all crocodiles wherever they live is close to 30 degrees Centigrade (86 F).

In the Lake St Lucia region of Eastern South Africa the accidental introduction of Triffid Weed is creating a situation where traditional crocodile nesting sites are now experiencing more shade and therefore lower incubation temperatures. The result is high ratios of female to male hatchlings which is threatening to wipe out crocodiles in that region. No it is not April 1st and the threat is being taken very seriously. Read more about this at

http://www.issg.org/features/chromolaena.html

On our trip it was fascinating to observe larger fish catching smaller fish in the shallows of rivers at night ... what a life these fish must lead. Of course the crocodiles fed on the larger fish as we also witnessed.

Back to pond keeping now.