Management Improvement of the Agmon Wetlands System (Hula Valley, Israel) Aimed at the Enhancement of Bird Populations and Kinneret Protection

An ecological project is proposed for the system of Lake Agmon (Hula Valley, Israel). The project indicates a change of the original concept of the Hula Project construction. Practically Lake Agmon system was found to remove negligible amounts of Nitrogen and Phosphorus from the Lake Kinneret budget. Moreover, Lake Kinneret ecosystem has undergone limnological changes. The P limited Kinneret system is currently N limited. Therefore reduction of P and enhancement of N from the Hula Valley outflow might be beneficial to the Kinneret ecosystem. Currently, the TN concentration in the Agmon outflow is lower than in its inflow and vice versa for P. Consequently, this paper recommends conveying peat soil drained waters, the Agmon inflow, directly to Lake Kinneret instead of letting the waters flow through Lake Agmon. Nitrogen reduction in Lake Agmon is due to de-nitrification and sedimentation and P increase is due to degradation of aquatic vegetation. Additional benefit of this change is the predicted improvement of the new infrastructure for the activity of aquatic birds aimed at eco-tourism improvement.

Chemical, Hydrological and Climatological Properties of Lake Agmon, Hula Valley (Israel), (1994-2006)

The first decade of monitoring program in Lake Agmon (Hula Valley, Northern Israel) is summarized. The presented part of the program include: water discharges, physico-chemical (pH, EC, Temperature) and chemical parameters (TP, TN, TDN, TDP, NO3, NH4, SO4, TDS, TSS,). It was found that Nitrogen concentrations decline from north to south and the opposite for Phosphorus. Resulting of re-suspension by wind direction of western-southern-eastern and averaged maximal velocities of 9 - 10 m/s is suggested. De-nitrification and particles sedimentation emphasize Lake Agmon as a sink for Nitrogen. Sulfate-Carbonates association and the production of precipitated Gypsum (CaSO4) highlight the sink property of Lake Agmon. Nevertheless Sulfate removal by the Lake Agmon hydrological system is significant.

Nitrogen and Phosphorus Dynamics in the Shallow Lake Agmon (Hula Valley, Israel)

Lake Agmon is a newly created shallow body of water which is a principle component of a reclamation project (Hula Project, HP) in the Hula Valley (Israel). The objectives of the HP are aimed at Lake Kinneret water quality protection, and improvements of the hydrological, and agricultural managements within the entire Hula Valley including the eco-touristic quality of the Agmon site. Thirteen years of research and monitoring, are summarized by focusing on nitrogen and phosphorus dynamics. It was found that the decay of submerged vegetation was the major P contribution to the Agmon effluents as dissolved (TDP) and plant debris particle forms. Peat soil gypsum dissolution contribute sulfate to drained waters and consequently to Agmon outflows. The Agmon system is operated as a nitrogen sink by de-nitrification and particulate sedimentation and contributor of plant mediated phosphorus. In the reconstructed Jordan flows into the Agmon, a stable composition of nutrients was indicated but those of the peat drainage and the lake effluents represented the higher level in winter and lower in summer. Anoxic conditions in the water column enhancing sulfate reduction are negligible and rarely observed. The Agmon merit to the reclamation process was achieved.

Seasonal Partitioning of Primary Production and Biomass between Phytoplankton and Metaphyton in a Shallow Lake Agmon, Hula Valley (Israel)

Agmon is a small, shallow man-made lake (area: 1.1 km2;mean depth 0.45 m), excavated in the peat soils of the Hula Valley in northern Israel, that was filled with water in August 1994. We followed the seasonal variations in phytoplankton and metaphyton biomass, primary production and related environmental conditions between December 1995 and July 1997. Water temperature ranged between 9.5°C - 30.8°C;pH ranged between 7.2 - 8.6. The algae in Lake Agmon were characterized by seasonal alterations between summer-fall phytoplankton blooms and spring proliferation of benthic algal mats, with a winter clear-water phase. Chlorophyll a content in the water, as a measure of planktonic algal biomass, was low in winter (1.75 - 5 μg·L-1) and high in summer (>100 μg·L-1), when planktonic cyanobacteria (Microcystis spp.) bloomed. Metaphyton biomass varied between 3.5 and 970 g·dry·wt·m-2, with chlorophyll a content ranging from 5 - 701 mg·m-2. The dominant benthic algal genera were Spirogyra and Oedogonium in 1996 and Cladophora in 1997. Phytoplankton primary production was high in summer-fall, with a maximum of 1200 mg·O2·m-2·h-1. Benthic primary production was high from March till May, with a peak of 2173 mg·O2·m-2·h-1 in April 1997. The rate of benthic algal primary production was positively correlated to benthic chlorophyll a (r2 = 0.90). Diel measurements of water column dissolved oxygen (DO) concentration, conducted monthly from January to May 1997, revealed that DO concentration ranged from a nighttime minimum of 5.3 to a noon peak of 15.3 mg·L-1. Only during January to February, no significant changes in DO with depth were found, suggesting that at that time the water column was well mixed. The most salient feature of primary production in the lake was the seasonal partitioning between its benthic and planktonic components. This was most evident in the significant inverse relationship between benthic and planktonic primary productivity rates (r2 = 0.78).