Posted by: Bystander PJ19 SEP 2012
Carnivorous?animals can be harmed by a build-up of toxic substances acquired from prey that has fed on contaminated plants. In the mid-20th century, the widespread use of DDT as a farm pesticide almost wiped out several raptor species in Britain.
More recently, three formerly widespread species of Asian Gyps vulture have become critically endangered because they eat the carcasses of animals treated with diclofenac, which is highly toxic to them (Didapper, PJ 2011;287:515).
But it is not just meat-eating animals that may be endangered by a tainted diet. The problem also affects carnivorous plants. Although we may think of carnivores as the tough guys at top of the food chain, plant carnivores are actually sensitive creatures that have developed the habit of eating insects as a way of surviving in soils that lack essential nutrients.
A rapid global decline in the numbers of carnivorous plants has recently been attributed to their consumption of insects contaminated with toxic metals, which can harm the plant by interfering with the uptake of water and nutrients.
One metal of particular concern is cadmium. Found in products such as fertilisers and metal coatings, it can accumulate in the environment through inappropriate waste disposal.
Researchers studying the endangered white-topped pitcher plant (Sarracenia leucophyla) fed a group of plants with housefly maggots contaminated with cadmium and copper. They found that the plants could easily process their copper intake without any toxic effects but the cadmium accumulated in their stems and disrupted growth.
It seems that urgent action is needed to limit the environmental effect of dumping toxic metals.