Nitrogen and Phosphorus Removal from Lake Kinneret Inputs

The Hula Valley was drained in 1957. The land use was modified from natural wetland and old shallow lake ecosystems to agricultural development. About half of the drained land area was utilized for aquaculture. Population size was enhanced and the diary was developed intensively resulting in the enhancement of domestic and husbandry sewage production that increased as well. The natural intact Hula Valley-Lake Kinneret ecosystem was heavily anthropogenically interrupted: The Hula was drained and Kinneret became a national source for domestic water supply. Some aspects of the environmental and water quality protection policy of the system are presented. The causation and operational management implications for the reduction of Nitrogen and Phosphorus migration from the Hula Valley are discussed. Drastic (81%) restriction of aquaculture accompanied by sewage totally removed achieved a reasonable improvement in pollution control which was also supported by the Hula Project. The implications of anthropogenic intervention in the process of environmental management design are presented.

Salinization-Desalinization (SDS) Processes—A Linkage between Hula Valley and Lake Kinneret Ecosystem Management

The salinization process resulted in agricultural damage in the Hula Valley and water quality deterioration in Lake Kinneret. Therefore, salinization-desalinization (SDS) processes have been emphasized in the last two decades. Global and regional extreme climatological events and water scarcity strengthen the link between Hula Valley and Lake Kinneret management design. A bond between optimizing Hula agricultural maintenance and Kinneret water quality protection is conclusively suggested. Saline contribution originated from the southern Hula Valley region to the underground and surface water is higher than from the northern organic soil. The impact of eastern water Intrusion from the Golan Heights as surface waters, river discharge and underground seepage into the Hula Valley represent north-south gradient enhancement. Salinized surface water contribution from the Hula Valley to Lake Kinneret is unwanted because presently Kinneret desalinization management policy is critically required. The present salinization of surface and underground water in the Hula Valley indicates the upper limit suitable for agricultural crop optimization and the decline of salinity is crucial. Enhancement of the portion of Jordan water within the total balance in the valley is beneficial for Hula agricultural crops but serves as a disadvantage to Kinneret desalinization implementation. Therefore, the enhancement of lake water exchange is recommended.

人为因素导致的盐度变化对Kinneret湖水细菌种群的影响

由于Ｋｉｎｎｅｒｅｔ湖周围的诸多盐泉被人为地导入其下游的约旦河，使得Ｋｉｎｎｅｒｅｔ湖水的盐度逐渐下降，这对作为主要工农业用水和饮用水资源的Ｋｉｎｎｅｒｅｔ湖来说是非常有价值的。然而，对湖水中的细菌来说则可能产生不同的影响。作者通过实验研究发现，湖水盐度的变化导致细菌种群的改变，从而使我们观察到盐度与细菌之间的关系。这些结果表明：盐度变化对湖水水质保护对策和将来一段时间内湖水管理政策的制定都具有重要的意义。

湖水含盐量和Cu^(2+)浓度变化对Kinneret湖浮游植物的影响

通过人为改变湖水中的Cu2 + 浓度和含盐量的方法 ,Cu2 + 浓度和含盐量变化对Kinneret湖水中浮游植物可能造成的影响进行了分析。结果表明 ,湖水Cu2 + 浓度增加会抑制Kinneret湖水中藻类等浮游植物的生长 ,这对改善湖水水质来说是非常有利的 ,但高的Cu2 + 浓度对农作物生长和人类健康是有害的。在另一方面 ,对含盐量较低的约旦河水来说 ,适当增加Cu2 + 浓度则有利于藻类的生长。Kinneret湖中浮游植物的年平均生物量随湖水含盐量的下降而有增加的趋势 ,特别是当含盐量低于 2 0 0 μg/L左右时 ,浮游植物中蓝藻占的比例会升高 ,这对作为饮用水资原的Kinneret湖水来说是不利的。由此可见 ,适当控制和维持Kinneret湖水Cu2 + 浓度和含盐量对湖水水质保护具有重要的意义。

The Impact of Available Nitrogen Deficiency on Long-Term Changes in the Lake Kinneret Ecosystem

Lake Kinneret Ecosystem structure has undergone significant modification since early 1990s. Scientists have indicated several causative factors for those long-term changes. The sharp decline of Peridinium and the upset of Cyanobacteria are the major changes. Several options were suggested as the reason for those changes. Among others are the followings: high amplitude of water level fluctuations, global warming, fisheries management, salts diversion, onset and offset of beach vegetation, anthropogenic operations in the drainage basin, allelopathic trait of algal competition, etc. It was suggested that the reduction of ammonia supply from the Hula Valley resulted in the conversion of the land from lake and swamps covered to agriculture followed by elimination of treated domestic sewage and fishponds effluents enhanced deficiency of available N in Lake Kinneret. This paper evaluates the impact of available Nitrogen decline which enhanced Kinneret ecosystem modifications.

Competitive Consumption of the Lake Kinneret (Israel) Plankton by <i>Hypophthalmichthys molitrix</i>and <i>Sarotherodon galilaeus</i>

An outdoor tank experiment was carried out for the assessing of the impacts of Sarotherodon galilaeus (Galilee Saint Peter’s Fish;Cichlidae) (SG) and Hypophthalmichthys molitriox (Silver Carp;Cyprinidae) (SC) on Lake Kinneret (Israel) plankton. In order to evaluate the interaction effect, the experiments were of replicated 2 × 2 factorial design: TG × SC. A lot of interaction effects were indicated showing that the effects of the two fishes were not independent and potentially competitors. SG suppressed most crustaceans and rotifers while increasing gross and net primary production and chlorophyll concentration. SC had less intense effects on zooplankton than SG. Although SC suppressed most crustaceans and rotifers, it had less interaction effects than SG. SC had no statistically significant effects on phytoplankton production or chlorophyll concentration. It is suggested that these experiments indicate that although the plankton community impacts of SG and SC do differ, both fishes utilize similar food resources in Lake Kinneret. Fingerlings of SG and SC are planted in Lake Kinneret annually aimed at the improvement of fishermen’s income and prevention of water quality deterioration. SC is known as efficient consumer of Microcystis. It is therefore recommended to limit SC introduction to periods when Microcystis is abundant.

The Impact of Water Level Decline on Water Quality in the Epilimnion of Lake Kinneret (Israel): Perennial Perspectives

Long term record (1933-2014) of Water Level (WL), nutrient concentrations, plankton densities, and temperatures in the epilimnion of Lake Kinneret was analyzed. The aim is to identify if water quality is deteriorated when the WL is low. It was found that water temperature increased and the composition and biomass of plankton communities were modified. Nitrogen and TDP decreased but TP slightly increased in the epilimnion during low WL conditions. The quality of epilimnetic water was not deteriorated and followed by a slight oligotrophism trend.

The Impact of Turbidity on Zooplankton Densities in Lake Kinneret (Israel)

Spatial survey of zooplankton community composition within the upper 10 m layer in Lake Kinneret was carried out. Samples were collected by plankton net (63 μ mesh size) and counted organisms were sorted by 2 groups: 1) Large-including Copepodite and adult Cyclopoid copepods and Cladocerans;2) Small nauplii and rotifers. It was found that in the northern part of the lake where turbidity is high, the density of small organisms is relatively lower, and in other parts of the lake where water is less turbid, large organisms are relatively less abundant. Speculative assumption about the impact of fish feeding behavior on that is presented.

Ecophysiology of Lake Kinneret (Israel) Zooplankton

A summary of a long-term research of Lake Kinneret zooplankton distribution is presented. During 1969-2002 several prominent changes have been recorded in the Kinneret ecosystem. This paper is an attempt aimed at analyzing the impact of these ecological changes on the zooplankton communities. The impacts of Phytoplankton, Bacteria, Protozoa, Temperature, Nutrient composition and fish predation on zooplankton dynamics are analyzed. It was found that periodical fluctuations of zooplankton density were mostly affected by fish predation as well as by temperature increase and food availability. Ecological conditions in Lake Kinneret have been modified since early 1990’s and the new conditions were consequently accompanied by zooplankton Homeostatic response. Moreover, as a result of the ecological changes fish intensified their pressure on zoo-plankton. The flexibility of food resource preference by zooplankton enabled its existence but fish predation predominantly controlled their density.

The Impact of Nitrogen and Phosphorus Dynamics on the Kinneret Phytoplankton: II: Chlorophyta, Cyanophyta, Diatoms and Peridinium

Lake Kinneret long-term data of the epilimnetic concentrations (ppm) and loads (tones) of the total Nitrogen (TN), total Phosphorus (TP), total inorganic Nitrogen (TIN), total Dissolved Phosphorus (TDP), Phytoplankton groups’ biomass, water level (WL) and Jordan River Discharge were analyzed. Previously collected data compiled aimed at an insight into the causative background for the modification of Phytoplankton community change. The study was carried out by searching for relations between algal groups’ densities and nutrient conditions in the Epilimnion by the use of statistical methods (Simple and Fractional Polynomial Regressions). The study is aimed at analyzing the relations between algal biomass and nutrient contents. It was found that Nitrogen decline and slight increase of phosphorus were followed by Peridinium (Photo 1)?decline and biomass increase of non-peridinium algae. It is suggested that nitrogen supply for algal growth is mostly from external sources, and the reduction of nitrogen in the epilimnion was caused by external removal. Contrary to nitrogen, phosphorus sourcing is only partly external (dust deposition, drainage basin) and mostly internal through double channels: Microbial mineralization of bottom sediments and Peridinium cysts mediation. The resulted complexity of the Kinneret ecosystem structure is nitrogen limitation, and enhancement of Non-peridinium algal growth, mostly Cyanobacteria.

The Impact of Nitrogen and Phosphorus Dynamics on the Kinneret Phytoplankton: I: Cyanophytes-Peridinium Alternate

During 1970-2001, several ecological changes were documented in the Lake Kinneret Ecosystem: Decline of total Nitrogen (TN) and increase of total Phosphorus (TP) loads with a corresponding decline of TN/TP ratio. The phytoplankton assemblages indicated consequence Increase of Cyanobacteria accompanied by elevation of the biomass of Chlorophyta and Diatoms. The Kinneret ecosystem functioning represented two superimposed events: the decline of TN enhanced Cyanobacteria and elevation of TP that was reflected by an increase of Chloropytes and Diatoms. Removal of Nitrogen was achieved but P load remained high enough to enhance Chlorophyta and Diatoms. Consequently, a top priority of future management perspective should be reduction of Phosphorus inputs.

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.

Fish-Zooplankton—A Predator-Prey Relations as a Key Factor for the Design of Zooplankton Distribution Sampling Program in Lake Kinneret, Israel

Long-term data record of Kinneret Epilimnetic Zooplankton biomass distribution and fish stock assessment was analyzed. The objective is aimed at defining the representativeness of the present sampling stations distribution for the measure of the entire Lake Kinneret zooplankton biomass. Previous studies documented the preeminence of temperature and fish predation impacts on zooplankton density: water temperature through growth rate trait and fish predation. Acoustic surveys indicated that fish shoals are mostly inhabiting the Peripheral region and much less the central part of the Kinneret pelagial. Due to fish zooplanktivory, densities of planktonic crustacean in the Pelagial periphery presented by 5 - 7 sampling stations are low. Nevertheless, large central lake area with higher densities of zooplankton biomass is presented by only one station. Therefore, stations average is incorrect as is total lake measure. The average result as indicated presently as total zooplankton biomass in lake Kinneret is, therefore, underestimated. Two optional corrective suggestions are concluded: 1) Additional sampling stations in the central part of the Pelagial region;2) Usage of station value of aerial coefficient (promoter).

On The Biology of Tilapia zillii (Gervais1848) in Lake Kinneret (Israel)

Fish (mostly Tilapia zillii), (TZ), mass mortality in Lake Kinneret initiated a study of the biology of TZ in Lake Kinneret. The study included several aspects: spawning and nesting behavior, feeding habits, the status of TZ in the Kinneret fishery and temperature tolerance. The merit of TZ to commercial landing fishery is negligible, but this specimen is one of the most common fishes in the lake. Several environmental factors are considered as promoters of the epilimnetic temperature decline: Jordan water inputs in winter season as a heat source parameter. ENSO (EL-NI&#209O/Southern Oscillation) acts as a cooling enhancement factor. Supportive data on the impact of ENSO were found in two terrestrial agricultural monitors in the northern and southern parts of the drainage basin. Gut content analysis of young fingerlings and an adult TZ specimen, indicated the significant contribution of benthic sources which are common in the shallows. The great adaptive capabilities of breeding TZ with various bottom habitats are demonstrated.

Population Dynamics of Cyclopoid Copepods in Lake Kinneret (Israel)

Reports on the Kinneret zooplankton in general and particularly on copepods are dealing recently with numerical densities of feeding habit classes. Nevertheless, for the evaluation of the integrated role of copepod assemblages in the entire lake ecosystem, their life cycle stages fluctuations are essential. It was not done in previous reports. Therefore, long term analysis of the cyclopoid copepods life stages dynamics in Lake Kinneret was carried out. Due to information availability, two complementary methods of density concentrations were evaluated for two consecutive data sets: 1) 1969-1985 numerical (No/L) documentation of life cycle stages of nauplii (I - III and III - V), copepodites (I, II, III, IV, V) and adults;2) 1969-2002 monthly averages of wet biomass density (g/m2) of zooplankton major groups combined with metabolic rates. nauplii densities represent June-August peaks and older stages spring decline and high levels during summer-early winter. Polynomial Regressions between Numerical annual averages of predator and Herbivore stages as well as young vs. older life stages indicate significant relations. During winter-spring season, temperatures are optimal for cyclopoid growth as a result of the high efficiency of metabolic activity and the low pressure of fish predation. The high rate of metabolism and intensive fish predation in summer enhance low densities of adult cyclopoids.

Limnological Changes in the Lake Kinneret (Israel) Ecosystem: The Beginning and Its Significance

The Lake Kinneret (Israel) ecosystem has undergone limnological changes. The trend of changes started in the mid 1990’s. The deviation from the previously known as stable long-term structure of the ecosystem included, among others, phytoplankton community structure, nutrient dynamics, zooplankton densities, water temperature increase, water level decline, and fishery management. This study is aimed at identifying ecosystem stability by focusing on three major compartments of the ecosystem: Total Dissolved Solids (TSS), Plankton (Phyto and Zoo), and Detritus (TSS minus plankton). It is suggested that although significant temporary changes of biotic and abiotic parameters were recorded and despite the existence of the normal seasonal fluctuations, the major compartments’ structural relations were not modified. The objective of the study is to analyze the process initiation of the modification trend. Previous studies and reports were focused on descriptive evaluation of the modified parameters. The expected outcome is a comprehensive evaluation of the modification process. Consequently, resulted prediction might be a tool for managers to improve management design.

The Impact of EL-NINO/Southern Oscillation (ENSO) on Fishery and Water Quality in Lake Kinneret (Israel)

A correlation between fishery and extreme winter conditions in Lake Kinneret was indicated: po pulations of Bleak fishes were enhanced and those of Sarotherodon galilaeus (SG) declined. The aim of the present study is to confirm the relation of those correlations to EL-NINO/Southern Oscillation and its impact on Kinneret fishery. The study is based on long-term data records of the Kinneret Epilimnetic temperatures, water level increase, precipitation and air temperatures in the drainage basin, together with a record of EL NINO/Southern Oscillation (ENSO) events. Results suggest a confirmation of the impact of ENSO events on lake population size of Bleaks and SG. It is likely that the influence of ENSO on the two key fish species in the Lake is contradictory: enhancement of reproduction of the winter spawner Bleaks and reduction of population recruitment of the early summer spawner, Sarotherodon galilaeus. It is likely that winter extreme in Kinneret region is a consequence of ENSO event and therefore negatively affecting Kinneret water quality.

A Review on Modeling of Kinneret Salinity with Practical Recommendations

Two models have been developed for the evaluation and prediction of salinity changes (chloride concentration;ppm;[Cl]) in Lake Kinneret. They are: 1) RM, which is based on the Salt balance and hydrological budget of the lake;2) GM which is based on the geo-hydrological regional properties of Kinneret’s geological structure. The concept of both is partly different: RM is correlating reduction of runoffs to salinity elevation and GM relates salt flux to the aquifer yield and the impact of lake water level is neglected. Long term statistical analyses justify support to GM, excluding conditions of heavy floods. This paper is a combination of a supplemental extended temporal study and a models review. Practical conclusions on Kinneret hydrological management within a frame of constrains aimed at prevention of salinity and eutrophication increase are presented.

Experimental Study in Out-Door Tanks of N and P Uptake by the Aquatic Communities of Lake Kinneret

Two trials (1st Trial-46 and 2nd Trial-64 hrs duration) experiment in 8 out-door tanks (5 m3) were carried out with similar design: 4 fish densities (0, 1, 5, and 10), 2 densities of zooplankton (high and low) and 4 increasing levels of P and N concentrations of nutrient enrichments. The consecutive changes of N and P concentrations were measured at 3 (Trial 1) and 4 (Trial 2) time intervals. It was found that nutrient uptake of the entire community, which is the differences between initial and final concentrations, was mostly affected by the initial enrichment. The ecological implications are discussed.