The Sand prawn forms an important food source for long-billed waders, such as common terns, and many fish species, an example of one being white steenbras. They are therefore an important part of the food chain in estuarine ecosystems and any disturbance will have a ripple effect influencing many components of the ecosystem.
The prawn pump, which is used by anglers to collect prawns, disrupts the sediment structure which has serious detrimental impacts on organisms living below the surface. Organisms which have been physically damaged by the prawn pump or that have not managed to burrow back successfully are either left to die or eaten by opportunistic kelp gulls.Trampling also has a negative effect in that it causes the burrow to close up, trapping the organism and causing it to suffocate.
Research is being done on the sand prawns at the recreated mudflats near the Zandvlei estuary mouth.The research is to establish the rate at which they colonize this recreated habitat providing information which is helpful in managing this important resource and restoring other mudflat areas. Just 3 weeks after the mudflats were recreated, prawns were seen to start colonising them, with over 40 prawn holes now present 12 weeks later. This rate of prawn bed growth is a indication of the health of the Zandvlei estuary and the suitability of the habitat.
Elzette Krynauw – Student Zandvlei Nature Conservation Officer