Louisiana red swamp crayfish and common carp are two of the most invasive species on the planet yet how they interact has only recently been revealed by scientists at Queen Mary, University of London.
The study, published in the online journal PLoS ONE, investigated the interaction between the crayfish and carp in Kenya's Lake Naivasha between 2001 and 2008.
The crayfish were introduced to the Lake in the 1970s and have adopted a central role in the food web for more than 30 years, yet the carp, introduced a little more than a decade ago, appear to have driven the crayfish away.
Lead author Dr Jonathan Grey from Queen Mary's School of Biological and Chemical Sciences said: "We first noticed the carp in our nets in 2003; by 2006 it was the dominant fish species in the Lake and at the end of our research in 2008, carp completely dominated the system.
"Although the carp have been fantastic for the local community's commercial fishing industry, it's been to the detriment of the crayfish."
The aim of the study was to see how the carp and Louisiana red swamp crayfish interacted between one another in Lake Naivasha, a large scale natural experiment which would help ecologists understand and predict changes in ecosystems with successive invaders.
Dr Grey said: "The movement of organisms around the globe is an important aspect of human-mediated environmental change.
"Classical studies have tended to focus on the effects of an invasive species on a native species; of course the reality is that many ecosystems will receive multiple invaders which will interact not only with the recipient community but also with each other."
Many interactions between existing and introduced species are realised through diet so the research team used a natural chemical signal of diet in the species' tissues to determine how they react to each other, a technique called stable isotope analysis.
|Contact: Bridget Dempsey|
Queen Mary, University of London