Expedition to Oman

21-11-2011   From mid November to mid December, Roeland Bom and Jan van Gils will carry out research in the Barr al Hikman wetlands in Oman. This research expedition is part of Roeland Bom’s PhD research project.

Biodiversity is currently rapidly declining, and it is generally the higher trophic levels that suffer most losses. The disappearance of top predators may have significant effects on the functioning of ecosystems, especially if the losses affect the so-called biobuilders (organisms that influence the abiotic components in their environment). Important biobuilders in tidal areas are seagrasses whose leaves slow down the rate of flow and thus improve the living conditions for the seagrasses themselves and for other organisms.

Crabs have the opposite effect as their digging creates open sandy patches in beds of seagrass. Predators that control the number of crabs and thus limit the digging could well play an influential role in seagrass ecosystems. Roeland Bom and Jan van Gils will explore this hypothesis in Barr al Hikman, an important wetland area in the Middle East where Crab Plovers feed on crabs on the edges of the seagrass fields.

They will make use of the latest high-tech developments in the field of GPS technology by fitting birds with tiny GPS transmitters, developed by the University of Amsterdam. The transmitters provide location data at four-second intervals, and they include an accelerometer, which measures the rapidity of an object in relation to gravity and can be used to predict bird behaviour. In March 2011 during a pilot expedition, the scientists fitted three Crab Plovers with these transmitters and the initial data they received seem promising. They also found out that the response of the crabs to the Crab Plovers, as well as the impact the crabs have on the seagrass can be studied in an experimental setting.