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Abstract

Exploitation of land and water resources has increased rapidly in North Africa during the 20 th century, paralleling regional population growth. As part of the CASSARINA Project (see , the environmental status of nine wetland lakes in Morocco, Tunisia, and Egypt was evaluated. All are conservationally important habitats and several are Ramsar Sites (internationally recognized bird reserves) and several support significant fisheries. All are shallow (<2 m in depth) but vary greatly in area.Where available, documentary information on relevant 20 th century changes is given. Survey transects for aquatic vegetation were established and used to provide baseline ecological information on the aquatic plant communities during 1997-1999. Unusually, one site (Tunisian Megene Chitane) supported acidophilous vegetation (some taxa being nationally rare). Aquatic macrophytes declined catastrophically at two sites during the 1990s. Merja Bokka was drained in 1998 and, at Garaet El Ichkeul, fringing Phragmites and Scirpus spp. were lost, mainly as a result of salinity changes. Elsewhere, fringing macrophytes remain (extensively so in the Nile Delta lakes) common, despite major land reclamation and water quality problems, or are degraded by grazing (Merja Zerga). Marginal vegetation during 1997/98 changed markedly at Megene Chitane due to water level lowering.Documentary records indicated that throughout the 20 th century, reclamation and hydrologic modifications, mainly for agricultural purposes, affected all nine sites. The loss of lake area by reclamation is substantial for the Nile Delta lakes (Edku, Burullus and Manzala). For the western sites, 2 some data indicate increasing salinity in the most recent decade but the Delta lakes have become generally fresher during the 20th century, as supply of Nile water for irrigation increased.Despite intense human disturbance, many of the remaining CASSARINA sites still support regions of high aquatic diversity. Spatial scale monitoring of the larger sites for seasonal and inter-annual changes in open water area and in aquatic plant abundances is a key requirement for integrated environmental change assessment in the 21 st century.

Microbial diversity alteration reveals biomarkers of contamination in soil-river-lake continuum

“…Its hydrological flow, due to its connection with the Bizerte Lagoon, results in salinity variations according to seasons (Ben Salem et al, 2017). The salinity fluctuation contributes to maintain an important level of biodiversity from microorganisms (Ben Salem et al, 2019) to higher macroorganisms such as birds (Ramdani et al, 2001) and fishes (Gharbi-Bouraoui et al, 2008). Because it is an area concentrating diverse human activities (e.g.…”

Mapping and Quantification of the Dwarf Eelgrass Zostera noltei Using a Random Forest Algorithm on a SPOT 7 Satellite Image

“…Furthermore, it represents a significant ecological resource that has attracted the interest of many scientific researchers. This lagoon has been part of the CASSARINA and MELMARINA projects during the last two decades [37]; thus, several studies have been based on observations and fieldwork in the Merja Zerga, mainly treating hydrological characteristics, environmental changes, contaminants in sediments, plankton, and fish fauna [34,35,[38][39][40][41][42].…”

Hydrology, biogeochemistry and metabolism in a semi-arid mediterranean coastal wetland ecosystem

“…The latter, considered unique ecosystems at the land-sea continuum, are characterized by high spatial and temporal variability and provide the highest ecosystem services along with coral reefs, seagrass meadows, and algae beds 5 , 16 , 17 . In particular, coastal wetlands in arid and semi-arid regions, conspicuously in North Africa, are foci of human settlements and activities making them particularly vulnerable since their spatial range has been contracting and their ecological condition deteriorating 18 , 19 . Among these wetland ecosystems, the Ichkeul Lake is jeopardized by climatic and human pressures.…”