One of the most invasive species on the planet is able to source food from the land as well as its usual food sources in the water, research from Queen Mary, University of London has found. Scientists analyzed1 the of red swamp（沼泽，湿地） crayfish（小龙虾） in Kenya's Lake Naivasha and found that when the water level of the lake was low, the crayfish found additional food sources on land. The study was published in the journal PLoS ONE August 3, 2012.
Lead author Dr Jonathan Grey from Queen Mary, University of London explained: "These crayfish are incredible
survivors2; our research shows they are able to feed off terrestrial plants directly, as well as
aquatic3（水生的） plants -- the first study to demonstrate this.
"It has significant implications for anyone looking to introduce these species in other areas."
The research team looked at the diet of the crayfish through a technique called stable
isotope4 analysis, where they used a natural chemical signal of diet in the species' tissues to determine what they were eating.
They found a proportion of the crayfish population had left the main lake and were surviving by
burrowing5 in
hippopotamus6 footprints which left small pools of water. After dark the crayfish clambered out from the footprints and grazed on the surrounding terrestrial plants.
"This study demonstrates how the red swamp crayfish is such an
extraordinarily7 successful invader," Dr Grey said.
The red swamp crayfish has been introduced to multiple locations throughout East Africa from the 1960s to enhance fisheries and to attempt to control populations of
snails8 which carry a
parasite9 causing river blindness in humans.
"While they are useful to
counteract10 other harmful species in
ecosystems11, they are also extremely damaging to fish populations and the balance of the food web. They eat plants, fish eggs, fly
larvae12, snails and
leeches13 and since we have now shown that they are able to tap into extra resources from the land, they can sustain higher populations under
adverse14 conditions such as low water and could cause more of a problem in a variety of environments than we
initially15 thought."
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