Scientists have discovered a new species of water flea that plays an essential role in maintaining ecological balance in the ponds and lakes of the UAE.
Given the name Daphnia arabica, the minuscule crustacean has led researchers to draw what might seem surprising parallels between the dispersion of water fleas and humans across the globe.
They have suggested that the Middle East provided a bridge for the spread across the globe of the group of water fleas to which D. arabica belongs, just as the region was a staging post for the migration of humans from Africa.
Details of the new species have been published in the journal Water and scientists are now carrying out detailed genetic analysis that could uncover which genes help the creature cope with the UAE’s high temperatures.
Tiny creatures play big role in marine sustainability
Although water fleas are not well known to the general public, the lead researcher in the UAE, Prof Waleed Hamza, of the College of Science at UAE University in Al Ain, said the animas — which reach up to 5 millimetres in length — are essential to the healthy functioning of water ecosystems.
As a form of animal plankton, they feed on plant plankton (phytoplankton), which they prevent from multiplying to levels that would cause harm to other organisms that live in the water.
Algal blooms can cause fish to suffocate because the decomposition of dead phytoplankton causes oxygen levels in water to fall.
"If there’s any imbalance in the ecosystem due to the lack of zooplankton or the consumption of zooplankton by fish intensively, the lakes become hypertrophic [with excessive nutrient levels] and becomes more green and this has consequences like fish suffocation. Zooplankton play a major role in keeping the trophic status of lakes stable," he said.
Using maps and satellite images, the researchers identified 114 locations in the UAE where freshwater was present, mostly human-made lakes in the north-east of the country.
They analysed water, sediment and mud samples from about 10 of these lakes, filtering thousands of litres to find the water fleas, which are crustaceans and unrelated to actual fleas, which are insects. Five species were identified – D. arabica and four others already known to science.
As well as looking at the species using microscopes, the researchers carried out genetic analysis, which showed the evolutionary relationships between the species.
Findings offer glimpse into the past
Based on genetic analysis, researchers think the presence of D. arabica in the UAE is the result of the Arabian peninsula having once been part of Gondwana, a supercontinent that existed between 180 million and 600 million years ago.
Today’s land masses that formed Gondwana, including Africa, South Africa, Australia and the Indian subcontinent, share many similarities in flora and fauna.
"Most probably this Daphnia arrived on some fragment of Gondwana, maybe Africa, maybe somewhere else, and then it was distributed through the Northern Hemisphere," said Dr Alexey Kotov, a researcher at the Severtsov Institute of Ecology and Evolution in Moscow, who led a team of Russian scientists involved in the project. "Now it’s mainly distributed in the northern portion."
The dispersion into Europe and Asia of the group to which Daphnia belongs is thought to have happened in the Miocene epoch, which ran from 23 million years ago to 5.3 million years ago.
"The most strange thing is this really is similar to the dispersion of humans, because humans originated in Africa and then were dispersed through the Arabian peninsula to Eurasia, like Daphnia," Dr Kotov added.
Globally, the distribution of some water flea species has changed in modern times but Dr Kotov said it was difficult to say whether this was due to climate change or because the creatures were being transported by human activity.
In some areas, the movement of water fleas has caused ecological harm. Spiny water fleas from Europe and Asia are now found in the Great Lakes of North America and are an invasive species causing significant ecological harm, including damage to fish populations. According to the department of environmental conservation of New York State, "there is no successful method of control".
Dr Hamza said it was likely that there were other undiscovered species of Daphnia present in the UAE and would like to continue the research to find some of them.
"We have 114 places. We only visited 10 of them. I think we need to have a big project to cover the whole territory of the UAE," he said.
The scientists also hope to publish full details of the genetic make up of D. arabica, which could help to pinpoint the genes that help the creatures to cope with the UAE’s high temperatures.
So, there remains much left to learn about this modestly sized creature recently discovered in the Emirates.