The oil spill in the Evrona Nature Reserve, in December 2014, was estimated by the Ministry for Environmental Protection as one of the most severe environmental disasters that has taken place in Israel and sparked broad media interest. About 100 hectares were damaged, and since the leak occurred in the extremely arid desert region (less than 50 mm annual rain) with high ecological sensitivity, serious concerns were raised about long-term damage to the region’s unique flora and fauna.
The Nature and Parks Authority appointed HaMaarag to develop a monitoring plan for evaluating the ecological consequences of the oil leak and the naturally-occurring rehabilitation process within the ecosystem. ‘Time zero’ monitoring – initial monitoring for a period of six months (April to October) has already begun, and a five-year monitoring plan is currently being developed, which is expected to begin in late 2015 – early 2016.
The large organisms with the greatest influence are the Acacia trees. In this region there are two species of Acacia – Umbrella Thorn Acacia (A. tortilis) and Twisted Acacia (A. raddiana) – of which 84 trees came in direct contact with the oil. The effects of direct contact between Acacias and crude oil are not clear; in the worst-case scenario, this contact will lead to tree death. As mentioned above, the Acacia trees are the main organisms in this ecosystem and are considered ‘umbrella species’, species with which many other organisms interact and on whose functioning they rely.
Which species of Acacia is more sensitive? Will younger trees be damaged more than mature ones? What will be the consequences of the oil spill on these trees’ functioning and their health? And how will their state of health affect other species in the ecosystem? The monitoring program should provide answers to these and other questions.
Monitoring of the Acacias is conducted using the following indices: stem circumference, photosynthetic efficiency, vitality, percentage leaf cover and more. In addition to the Acacias, soil properties such as moisture, carbon and nitrogen content and the presence of soil-dwelling macrofauna such as isopods and mites, will also be monitored.
The long-term monitoring will also evaluate additional components of the ecosystem, both biotic and abiotic, and will compare between damaged areas and clean areas. All of the organizations involved in the monitoring program hope that it will provide an account of the effects of the oil spill on the ecosystem and will contribute knowledge and tools for dealing with future spills.