New Worlds: Israeli scientists helping Egypt save Nile fish

Hungry Nile Perch threatens to deprive local fishermen of their main source of protein. Also: TAU group develops sensitive electro-mechanical sensors.

nile perch fish 311 (photo credit: Courtesy)
nile perch fish 311
(photo credit: Courtesy)
Nile Perch used to be so prolific in Africa’s Lake Victoria that it was called “Princess of the Nile” in Israel to encourage consumers to buy it. But the lake, discovered some 160 years ago, is currently in a poor state of health, and its fish population is depleted. The clear waters have turned murky and stinky, and it is full of algae. Some native fish species have even disappeared from the lake, which borders on Uganda, Tanzania and Kenya.
Now researchers at the Hebrew University in Jerusalem and Makerere University in Kampala have established unique “boutique” fish farms in small villages around the lake to help Uganda fight the declining fish population.
Locals used to catch carp and perciform fish near the shores of the lake, but half-a-century ago,  Nile Perch were introduced into Lake Victoria to increase local fishing. The authorities did not realize that the species is a predator that feeds on most of the other fish.
While the Nile Perch became the primary export of the countries around the lake, over the past decade it has devoured many smaller fish around the shores of the lake and deprived local fishermen of their main source of protein. Furthermore, fishing for the larger Nile Perch was unfeasible for local fishermen, as the fish reside in the middle of Lake Victoria, and larger fishing boats are required to catch them.
To combat this increasing problem, Prof. Berta Levavi-Sivan of HU’s Robert Smith Faculty of Agriculture, Food and Environment found a way to spawn several species of African carp and cultivate them in Ugandan fish farms. The project was initiated five years ago, and has been financed by the US Agency for International Development, in collaboration with Dr. Justus Rutaisire of Makerere University.
LAST YEAR, the developers began establishing ponds in small villages, stocking them with carp from the fish farms and enabling the local population to eat them. The project has since developed, and now four large fish farms whose owners were trained in Israel produce enough fingerlings to be raised in the ponds. Residents of each village – and especially their children – eat the carp as their main source of protein. Levavi-Sivan hopes that soon, every village around the shores of Lake Victoria will have its own “boutique” fish farm, and that the project will be expanded to include other countries in Africa. “We succeeded in inducing spawning in the carp – and these 14 villages are the success story.”
The effort is part of a program organized by Mashav (Foreign Ministry agency for international development cooperation) and the HU’s division of external studies to study inland water aquaculture and help develop the existing project in Uganda.
The scientists are now facing another challenge – with the depletion of the lake’s smaller fish, the Nile Perch have nothing to eat and are themselves dying off. So they are launching a new project, financed by the World Bank, to find ways of cultivating the Nile perch – thus helping boost Uganda’s fish exports, as well as the nutrition of the local population.
Electro-mechanical sensors tell the airbag in your car to inflate and rotate your iPhone screen to match your position on the couch. Now a research group of Tel Aviv University’s engineering faculty is making the technology even more useful. Prof. Yael Hanein, Dr. Slava Krylov and their doctoral student Assaf Ya’akobovitz have set out to make sensors for microelectromechanical systems (MEMS) much more sensitive and reliable than they are today. And they’re shrinking their work to nano-size to do it.
More sensitive sensors means more thrilling videogames, bette prosthetic limbs, cars that can detect collisions and dangerous turns before they occur, and – in the defense industry – missiles that can reach a target far more precisely.
Able to sense the movement of individual atoms, the researchers’ new MEMS sensing device uses carbon tubes about one-billionth of a meter long. Creating these tiny tubes using a process involving methane gas and a furnace, Hanein enables the atoms to “arrange themselves” on a silicon chip to accurately sense tiny movements and changes in gravity.
In the device the team developed, a nanometer-scale tube is added ontomuch larger micrometer-scale MEMS devices. Small deformities in thecrystal structure of the tubes register a change in the movement of thenano object, and deliver the amplitude of the movement through anelectrical impulse. “It’s such a tiny thing,” she says. “But at ourresolution, we are able to feel the motion of objects as small as a fewatoms. Originally developed for the car industry, miniature sensors areall around us,” she adds. “We’ve been able to fabricate a new devicewhere the nano structures are put onto a big surface – and they can bearranged in a process that doesn’t require human intervention. We candrive these nano-sensing tubes to wherever we need them to go, whichcould be very convenient and cost-effective across a broad spectrum ofindustries.”
Until now, the field of creating sensors for nanotechnology has beenbased mostly on time-consuming manual operation. but the team membershave developed a sensitive but abundant and cost-effective materialthat can be coated onto prosthetic limbs, inserted into new video gamesfor more exciting play and used by the auto industry to detect apotential collision.
The market for MEMS devices, which take mechanical signals and convertthem into electrical impulses, is estimated to be worth billions. “Themain challenge facing the industry today is to make these basic sensorsa lot more sensitive, to recognize minute changes in motion andposition. Obviously there is a huge interest from the military, whichrecognizes the navigation potential of such technologies, but there arealso humanitarian and recreational uses that can come out of suchdevelopments,” Hanein stresses. More sensitive MEMS could play a rolein guided surgery, for example.