Abstract
Current biodiversity is lost at a tremendous rate, and often the biggest losses are found in the highest trophic levels. The loss of top-predators can greatly affect the functioning of ecosystems, especially when this loss affects so-called ?ecosystem engineers? (i.e. organisms which alter their abiotic environment). Important ecosystem engineers in intertidal habitats are seagrasses. Their canopies attenuate currents and waves and thereby seagrasses not only improve the growing conditions for themselves but also for many other organisms. By contrast, crabs, through their bioturbating activities, often cause opposite erosion effects and thereby create sandy patches within seagrass beds. Predators that are able to control the activity and the number of crabs could potentially play a steering role in seagrass-based ecosystems. We want to study this idea in Barr al Hikman, an important intertidal ecosystem in the Middle East, where crab plovers feed on crabs on the edges of seagrass beds.
Netherlands