Tuesday, June 10, 2008

See posted comments (0) Post a Comment

Lake Ichkeul

Image does not exist Image does not exist
Ichkeul National Park includes Lake Ichkeul and surrounding wetlands that form an important wintering and breeding area for migratory birds. It has been designated as a UNESCO Biosphere Reserve and a Ramsar Wetland of International Importance. Lake Ichkeul is fed by seven small rivers but is considered a lagoon because of its connection with the sea via Lake Bizerte (1987 image top left). During the wet season, Ichkeul fills with fresh water from these rivers. During the dry season, the lake's water level falls, allowing an influx of saltwater from Lake Bizerte. These alternating conditions create an ideal environment for Potamogeton pectinatus (yellow arrows)—a pondweed and principal food source of migratory birds and waterfowl.

Construction of three dams along rivers that feed Lake Ichkeul modified this fragile ecosystem by decreasing freshwater inflow and increasing salinity during the dry seasons of 1977, 2001, and 2002. Two periods of drought (1993-1995 and 2001-2002) aggravated this trend, leading to a total disappearance of Potamogeton pectinatus from 1994 to 2002. In 2002, a mere 10 000 migratory birds came to Lake Ichkeul, the lowest numbers ever recorded.

The Tunisian government responded by increasing water releases from the dams. Helped by favorable rainfall conditions, the Potamogeton pectinatus started to recover in 2003, reaching 70 km2 in 2006 (2005 and 2007 images above right). Concurrently, migratory birds began returning. In 2004/2005 their numbers had climbed to 30 000. View detailed information

No comments: