Nutrient and plant dynamics in Lake Agmon Wetlands (Hula Valley, Israel):: a review with emphasis on Typha domingensis (1994-1999)

Shallow lake Agmon is a newly created subtropical wetland in north-eastern Israel. The lake is part of the Hula Project aimed at slowing down deterioration processes of the peat soils, to establish infrastructure for ecotourism as an income for the land owners, and nutrient removal from Lake Kinneret inputs. An onset of benthic filamentous macro-green algae during late winter-spring season, followed by submerged macrophytes vegetation during spring-summer was documented. The phosphorus summer loads are mostly plant-mediated internal fluxes and nitrogen intensively removed from lake waters by sedimentation and denitrification. The summer phytoplankton, mostly colonial cyanobacteria, are P limited. During 1995 and early 1996, dense Typha domingensis stands were developed in the southern half of the Lake (chalk-marl bottom sediments). The P-limited Typha vegetation collapsed within less than half a year and reappeared in the south-eastern part of the lake where sediments were exposed and oxidized. It is hypothesized that phosphorus cycle is a strong dependant of macrophyte mediation, and P deficiency in the sediments predominantly affected Typha decline and an increase of P availability later enabled the reappearance of the Typha stands.